Maersk Training Centre A/S
Anchor Handling Simulator Course
“Best Practise in Anchor Handling”
Maersk Training Centre A/S
1.
Program. Abbreviations Introduction to Anchor Handling Course
2.
“MAERSK TRAINER” Technical Specifications
3.
Company Policy. Procedures
4.
Risk Assessment. Planning
5.
Anchor Handling Winches. Chain Wheels
6.
Shark Jaws, Triplex
7.
Shark Jaws, Karm Fork
8.
Wire Rope, Guidelines, Maintenance
9.
Anchor Handling Equipment Swivel – Pin Extractor – Socket Bench
10.
Chains and Fittings Chasers and Grapnels
11.
Anchor Handling Breaking the anchor…..
12.
Anchor Deployment – PCP
13.
Vryhof Anchor Manual 2000
14.
Ship Handling. Manoeuvring
15.
Drilling Units / - Operations
MTC
COURSE NAME
Manual standard clause This manual is the property of Maersk Training Centre A/S (hereinafter “MTC A/S) and is only for the use of Course participants conducting courses at MTC A/S. This manual shall not affect the legal relationship or liability of MTC A/S with or to any third party and neither shall such third party be entitled to reply upon it. MTC A/S shall have no liability for technical or editorial errors or omissions in this manual; nor any damage, including but not limited to direct, punitive, incidental, or consequential damages resulting from or arising out of its use. No part of this manual may be reproduced in any shape or form or by any means electronically, mechanically, by photocopying, recording or otherwise, without the prior permission of MTC A/S. Copyright MTC 2002-09-10 Prepared by: PFR Modified & printed: 2003-01-07 Modified by: Internal reference: M:\ANCHOR HANDLING\Course Material\Training Manual New\Chapter 00\2.0 Index.doc
Contact MTC Maersk Training Centre A/S Dyrekredsen 4 Rantzausminde 5700 Svendborg Denmark Phone: Telefax: Telex: E-mail: Homepage:
+45 63 21 99 99 +45 63 21 99 49 SVBMTC
[email protected] WWW.MAERSKTRAININGCENTRE.COM
Managing Director: Claus Bihl
2.0 Index.doc
Chapter 00
Page 2
MTC
Anchor Handling Course
Introduction to the Anchor Handling Course Background A.P.Møller owns and operates a modern fleet of anchor handling vessels. The vessels are chartered to oil companies, and rig operators; the jobs are anchor handling, tow and construction jobs. The technical development of these ships has been fast to meet the increased demands. The demands to the performance of the ships have been increased too. A few hours off service can mean large economic losses for the different parties involved. In the last years an increased focus have been on avoiding accidents, and the frequency of these accidents are low. To get the frequency even lower, actions to avoid accidents are needed. “Learning by doing”, on board an anchor handling vessels as the only mean of education, will not be accepted in the future. Part of this training process needs to be moved ashore, where crew, ship and equipment can be tested without risk in all situations. Here we will use the anchor-handling simulator. A study of accidents and incidents occurred on anchor handling vessels (AHV) during anchor handling operations reveals that some of the most common causes leading to incidents and/or accidents are lack of or inadequate: • Experience • Knowledge • Planning • Risk assessment • Communication • Teamwork • Awareness The keywords for addressing these causes are: “training, training and more training” The value of on-board, hands-on training is well known and beyond any doubt but the knowledge and experience gained is sometimes paid with loss of human life or limbs, environmental pollution and/or costly damage to property. This simulator course was developed in order to give new officers on AHV’s the possibility of acquiring the basic knowledge and skills in a “as close to the real thing as possible” environment, the only thing, however, that might get damaged is “ones own pride”. The aims of the anchor handling course are: • To promote safe and efficient anchor handling operations by enhancing the bridge teams knowledge of, and skills in anchor handling operations.
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Chapter 01
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Anchor Handling Course
The objectives of the anchor handling course are: By planning of and, in the simulator, carrying out anchor handling operations under normal conditions, the participant shall demonstrate a thorough knowledge of and basic skills in: • Planning and risk assessment of anchor handling operations adhering to procedures and safety rules • As conning officer carry out exercises in anchor handling operations • As winch operator carry out exercises in anchor handling operations • On user level, the design, general maintenance and correct safe use of anchor handling equipment • The use of correct phraseology The simulator course The course consists of theoretical lessons alternating with simulator exercises. The theoretical lessons The theoretical lessons addresses: • AHV deck lay-out and equipment • AH winch (electrical and hydraulic) lay-out and function • Anchor types, chain, wires, grapnels, etc. maintenance and use • Planning of AH operations • Risk assessment • Procedures • Safety aspects and rules The simulator exercises The simulator exercises consist of one familiarisation exercise and 3 to 4 AH operations. The weather condition during the exercises will be favourable and other conditions normal. The tasks in the AH exercises are: • Preparing the AHV for anchor handling • Running out an anchor on a water depth of 100 to 700 meters • Retrieving an anchor from a water depth of 100 to 700 meters • Operating an anchor system with insert wire During the simulator exercises the participants will man the bridge. They will be forming a bridge team, one acting as the conning officer the other as the winch operator. A captain/chief engineer will act as a consultant. Before commencing the exercise, the participants are expected to make a thorough planning of the AH operation. They will present the plan to the instructor in the pre-operation briefing for verification.
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Chapter 01
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Anchor Handling Course
During the exercises, the simulator operator will act and communicate as all relevant personnel e.g.: • Deckhands – engine room • Rig crew – crane driver – tow master • Etc. The instructor will monitor the progress of the exercises and evaluate the performance of the team and each individual. Debriefing Each exercise will be followed by a debriefing session during which the instructor and the team will discuss the progress and the outcome of the exercise.
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Chapter 01
Page 3
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Anchor Handling Course
Commonly used abbreviations: AHTS: PSV: DVS: SV: MODU: FPU: FPDSO: FPSO: FPS: TLP: SBM: SPM: CALM: SALM: SSCV: HLV: RTV: PLV: SSAV: ROV: ROT: AUV: DP: DPO: HPR:
Anchor Handling tug supply Platform supply vessel Diving support vessel Survey vessel Mobil offshore drilling unit Floating production unit Floating production, drilling, storage and offloading Floating production, storage and offloading Floating production system Tension leg platform Single buoy mooring Single point mooring Catenary anchored leg mooring Single anchor leg mooring Semi submersible crane vessel Heavy lift vessel Rock dumping/trenching vessel Pipe laying vessel Semi submersible accommodation vessel Remotely operated vehicle Remotely operated tool Autonomous underwater vehicle Dynamic positioning Dynamic positioning officer Hydroaccoustic positioning reference
TW: AHW: DMW: PCP: HHP: VLA: SCA: DEA: Sepla: QMS: HSE: ISM: WW: VSP:
Towing winch Anchor Handling winch Dead Man Wire Permanent chaser pennant High holding power anchors Vertical load anchors Suction caisson anchor Drag embedded anchor Suction embedded plate anchor. Quality management system Health, safety and environment International ships management Work Wire Vertical seismic survey
Weight in water: Weight x 0,85
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Chapter 01
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Anchor Handling Course
“MAERSK TRAINER” Technical Specifications: LOA: Breadth:
73,60 m. 16,40 m.
Propulsion:
15600 BHP. 2 Propellers. 2 Spade rudders (Not independent).
Thrusters:
Forward: Aft:
Deck Layout:
1 x 1088 BHP, Azimuth. 1 x 1000 BHP, Tunnel. 1 x 1000 BHP, Tunnel.
2 Tuggers, 15 T pull. 2 Capstans, 15 T pull.
A/H Equipment: 2 sets of Triplex Shark Jaws. SWL: NA 2 sets of Guide Pins. 2 wire lifters. 2 stop pins, 1 each side. Distance:
From centre AHW to Stern Roller: 50 m. From centre AHW to “visibel” from bridge: App. 20 m.
Breaking load: DMW, WW & Insert Wire: Chain:
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77 mm and BL= 300 T. 77 mm and BL= 600 T.
Chapter 02
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Anchor Handling Course
”MAERSK TRAINER” Winch Layout: AHV01: AHV02: A/H Drum (1):
Max pull, bare drum: Static brake: Kernal diam.: Width of drum: Flange diam.:
500 T. 650 T. 1,50 m. 3,55 m. 6,50 m.
250 T. 400 T. 0,90 m. 1,225 m. 2,50 m.
Tow Drums (2): (TW2: Starboard) (TW3: Port)
Max pull, bare drum: Static brake: Kernal diam.: Width of drum: Flange diam.:
250 T. 650 T. 1,50 m. 2,05 m. 3,60 m.
125 T. 400 T. 0,90 m. 1,225 m. 2,50 m.
Wildcats fitted on Tow Drums. Rig Chain Lockers:
1 each side. Capacity: No limits!! Bitter end: Between 0 m. and 75 m. each side.
All winches are electrically driven. Winch computter: SCADA • No pennant reels fitted. • Wires and / or chain can`t be stowed on the aftdeck either “in the water” – the equipment has to be connected up, in the system. • The winch used for decking the anchor will be “locked” as long as the anchor is on deck. • The anchor can not be disconnected from the PCP.
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Chapter 02
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Anchor Handling Course
“MAERSK TRAINER” Vessel and Deck Layout:
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Chapter 02
Page 3
“MAERSK TRAINER”
Maersk E-procurement Training Centre work group A/S
Winch Layout:
Technical Specifications. Ch. 2 Page 4/05
Power Settings / Bollard Pull Handle 100 90 80 70 60 50 40 30 20 10 00 - 10 - 20 - 30 - 40 - 50 - 60 - 70 - 80 - 90 -100
Bollard Pull (T) 144 143 142 125 98 69 43 23 9 3 0 3 7 15 25 45 54 65 77 105 105
Bollard Pull 200 150 100 50
Tons
Maersk E-procurement Training Centre work group A/S
“MAERSK TRAINER”
0 -1,5
-1
-0,5
0
0,5
1
1,5
-50 -100 -150 Handle
Anchor Handling. Chapter 2 Page 5/05
MTC
Anchor Handling Course
3. Company Procedures All operations on board must be performed in accordance with Company Procedures. The updated procedures can be found on CD-ROM (Q E S System) issued by Technical Organisation in Copenhagen. Please make sure that the latest version is in use. Any copies of the procedures used on the Anchor Handling Course are all:
UNCONTROLLED COPIES.
Following procedures can be useful: •
1, Quality 7.: Plans for Shipboard Operations (Risk Assessment)
•
2, 0357: Prevention of Fatigue – Watch Schedules – Records of Hours of Work or Rest
• •
7, 0014: Communication with Maersk Supply Service (Supply Vessels) 7, 0176: General Order Letter (Supply Vessels)
•
8, 0020: Salvage (Supply Vessels)
• • • •
11, 0015: Bridge discipline (Supply) 11, 0234: Safe Mooring Peterhead Harbour (Supply) 11, 0596: DGPS Installations (Supply, Brazil waters) 11, 0792: DP Operating Procedure (Relevant Supply Vessels)
• • • • • • • • •
13, 0042: Transport of Methanol (Supply Vessels) 13, 0065: Cargo (“Fetcher”) 13, 0207: Tank Cleaning. Water/Oil Based MUD, H2S (Supply Vessels) 13, 0249: Transportation of Tanks Containing Liquid Gases (Supply Vessels) 13, 0251: Hose Handling Alongside Installations (Supply Vessels) 13, 0498: Cargo Handling (Supply Vessels) 13, 0681: Cargo Pipe Systems – Segregation of Products (Supply Vessels) 13, 0766: Deck Cargo Stowage Procedure for Stand-by Mode (“NORSEMAN”/”NASCOPIE”) 13, 0812: Cleaning of Hoses after Transfer of Oil, Brine and MUD to or from Rig (Supply Vessels)
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Chapter 03
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Anchor Handling Course
• • • • • • • • • • • • • • • • • • • • • • • • •
15, 0007: Brattvaag Anchorhandling Winch 250 T (Supply Vessels) 15, 0009: Aquamaster TAW 2500/2500E (Supply Vessels) 15, 0010: Aquamaster TAW 3000/3000E (Supply Vessels) 15, 0016: AH & Towing Wire Maintenance (Supply Vessels) 15, 0019: Towing (Supply Vessels) 15, 0024: Ulstein Brattvaag AH Winch 450-IT (“Provider”) 15, 0066: Stern Roller Bearing lubrication (Supply Vessels) 15, 0082: Deck Lifting Tool (Supply Vessels) 15, 0142: Wildcat Maintenance (Supply Vessels) 15, 0252: Wire Spooling (Supply Vessels) 15, 0256: Diving Support Vessels Assistance (Supply Vessels) 15, 0258: Working alongside Installations (Supply Vessels) 15, 0259: Wire Rope Sockets (Supply Vessels) 15, 0266: Anchor Handling – Deep Water (Supply Vessels) 15, 0273: Triplex Shark Jaw (Supply Vessels) 15, 0538: Safety during Anchor Handling and Towing Operation (All AHTS) 15, 0542: VSP Surveys (Supply Vessels) 15, 0649: Whaleback Re-enforcement (Supply Vessels) 15, 0680: AH & Towing Winch gearwheel (open) greasing (Supply Vessels) 15, 0741: AH & Tow Wires lubrication (Supply Vessels) 15, 0786: Mono Buoys – Recovery of Hawsers (Supply Vessels) 15, 0788: Repair of Stern Roller (“Pacer”, “Puncher”, “Promoter”) 15, 0932: Towing Pin Roller (Supply Vessels) 15, 0950: AH & Towing Equipment (Supply Vessels) 15, 1345: Triplex Shark Jaw – Control Measurements (Supply Vessels)
• •
19, 0500: Transfer of Personnel and Cargo by MOB Boat (Supply Vessels) 19, 0764: Transfer of Personnel between Ship and Offshore Installation by Basket. (Supply Vessels)
•
23, 1092: Welding Equipment
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Chapter 03
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Anchor
Planning and Risk Assessment Risk Assessment Some people have a hard time believing that risk assessment has been in the Maritime industry since “Day One” – since plans for the “ARK” were drawn up. Hazards were appreciated and control measures added mentally before activities were completed safely. The difference to day is that they have to be documented like so many other items under the banner of the ISM code and national / international legislation. It is not a blame culture as seen by a hard core of seafarers. Obviously it is easy to stand back and comment with hindsight: "If this had been done, then this would not have occurred". The company is required to comply with customers' requirements, and to ensure protection of the environment, property, the health and safety of the employees and other persons, as far as reasonably practicable, by the application of certain principles. These principles include the avoidance of risks, the evaluation of unavoidable risks and the action required to reduce such risks. A "Risk Assessment" is a careful examination of the process and its elements to ensure that the right decisions are made and the adequate precautions are in place thereby preventing risks. Risk is formed from two elements: • The likelihood (probability) that a hazard may occur; • The consequences (potential) of the hazardous event. To avoid or reduce damage to: • Human life • Environment, internal and/or external • Property Minimise risks by listing the possible effects of any action, and assessing the likelihood of each negative event, as well as how much damage it could inflict. Look for external factors, which could affect your decision. Try to quantify the likelihood of - and reasons for - your plan failing. Itemising such factors is a step towards the making of contingency plans dealing with any problem. Use judgement and experience to minimise doubt as much as possible. Think through the consequences of activities, be prepared to compromise, and consider timing carefully. Be aware of that people are not always aware of the risks, as they can’t see them. An example: “A man standing close to the stern roller”: One of the risks is, that he can fall in the water. As a matter of fact he is not falling in the water – he is able to see the hazard – so he is aware.
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MTC
Anchor
On the other hand: “During an anchor handling operation an AB is hit in his forehead by a crowbar while he is punching a shackle pin out using a crowbar. The wire rotates caused by torsion in the wire – he can’t see the hazard – so he is not aware of the risk when using a crowbar. An initial risk assessment shall be made to identify and list all the processes and their associated hazards. Those processes having an inconsequential or trivial risk should be recorded, and will not require further assessment. Those activities having a significant risk must be subject to a detailed risk assessment. A risk assessment is required to be "suitable and sufficient" with emphasis placed on practicality. The level of detail in a risk assessment should be broadly proportionate to the tasks. The essential requirements for risk assessment are: • A careful examination of what, in the nature of activities, could cause risks. Decisions can then be made as to whether enough precautions have been taken or whether more should be done to prevent the risks. • After identifying the risks and establishing if they are significant, you should consider if they are already covered by other precautions. These precautions can for example be Work Place Instructions, Work Environment Manual, Code of Safe Working Practices for Merchant Seaman, Procedures, checklists etc. and also the likelihood of failure of the precautions already in place. Where significant risks have been identified a detailed risk assessment in writing must be carried out and recorded appropriately. The assessment should consider all potential risks, such as who might be harmed and how, fire and explosion, toxic contamination, oil and chemical pollution, property damage and nonconformances. What may happen? Get a general view of: • The process, i.e., materials to be used, activities to be carried out, procedures and equipment to be used, stages of human involvement, and the unexpected operational failure which may result in further risks. Determine the probability: • Quantification: Low - Medium - High Focus on the potential hazardous situations and assess consequences if it happens: • Quantification: Low - Medium - High. How will it be possible to intervene, and / or to reduce the risk? • What can be done to reduce the probability? • What can be done to reduce the consequences? • Decide whether existing precautions are adequate or more should be done. • Record it. Review the risk assessments from time to time and revise, if necessary.
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MTC
Anchor
Planning Why? So everybody knows what is going to happen. Take care of inexperience personnel, so they know what to do and when. They do not have the same life experience as the well experience personnel– they can’t just look out though the windows and say: “Now we do this and this”. Quotation from new 3. Engineer: • “Planning is the only thing we as inexperienced can hold on to”.
- Company’s Core Valure • • • • • • •
Constant care No loss should hit us which can be avoided. Planning is important. Be prepared at all time. Developments may be difference from what you expected. Make sure to have an overview of the situation at all times. Follow the established procedure and make your own procedure to awoid any unnecessarily riscs. Use your commen sence. Training of the crew/staff.
Planning and risk assessment can effective be done in one and same working procedure. On the page 6/06, you will find an example of a form which can be used for this purpose.
Have a visual plan
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MTC
Anchor
Planning: Goal
Descibe the goal. When do we have to be ready. Collect data – check systems
What
What to do to reach the goal
Who
Delegate tasks – make sure everybody knows who are responsible for each task
How
Make job descriptions, descripe standard procedures, make risk assessment
When
When do the tasks need to be finished? Prioristising of tasks Be ready to correct the plan as necessary
Have status meetings Work as a team Keep the leader informed Goal, example:
Be ready for anchor handling at POLARIS Water depth 500 meter Retrieve anchors No 1, 4, 5 and 6 Move rig to position: Run anchors No 4, 6 and 3
Collecting data:
Rig move report Anchor type PCP, length, chaser type Chain / Wire combination Chain, length and size Wire, length and size Winch drum capacity Load calculations, maximum weight of system, how much force can I use on engines Power consumption Communications: Contact persons VHF channels Charts and drawings
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MTC What to do:
Anchor Prepare deck:
Which drums Check correct spooling of wires Chain wheel size – correct size Shark Jaws size – correct size Chain lockers
Prepare engine room: Defects, out of order, limitations Power consumption Ships stability Ballast, bunkers, trim Make risk assessment on each job Voyage planning:
Precautions when: Approaching, Working alongside Moving off / on location Contingencies
Prepare checklists Brief crew of coming job – ToolBox Meeting Who:
Make sure all know their job Make sure all know the difficult / risky part of the operation
How:
Prepare job descriptions and safe job analysis Use standard procedures as far as possible Apoint responsible person for each job
When:
Time consumption for each job Time schedule Alternative plans Do status, can we reach the goal on time The leader to stay on top of the sistuation
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MTC
Anchor Handling Course
Planning and Risk Assessment Job:________________________________________________________ Working process / Plan
Hazard
Consequence
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Probability Action to eliminate / avoid risk
What to do, if risk cannot be avoided
Chapter 04
Page 6
ANCHOR HANDLING CALCULATIONS
The 5 steps to success in Anchor Handling
ANCHOR HANDLING CALCULATIONS
The TASK : 600 Meters water depth 10 T Anchor 3” Wire / Chain 3000’ = 914 Meter Dead Man Wire
Can we run and retrieve the anchor ? Can we deck the Anchor ?
ANCHOR HANDLING CALCULATIONS
Planning APM-Procedure: Deep-water A/H. 15, 266
ANCHOR HANDLING CALCULATIONS
STEP 1 : Wirelength Wirelenght 1.5 in shallow water, but less in deep water (>300 Meter)
600 x 1.1 = 660 Meters 600 x 1.2 = 720 Meters 600 x 1.3 = 780 Meters
ANCHOR HANDLING CALCULATIONS STEP 2 : Winch Capacity Connection on drum you maybe loose 30-50 meters
A B
D C
Winch Capacity = AxCx¶x(A +B) dxd B = 1020 mm, C = 1300 mm, D = 2650 mm, d = 76 mm A = (D-B) / 2 = (2650-1020) / 2 = 815 mm 815 × 1300 × π × (815 + 1020 ) CAPACITY = = 1030M 2 77
ANCHOR HANDLING CALCULATIONS STEP 3 : Winch Max. Pull
(Max pull 1.) * B = K * (Actual diam.) Max pull 1. = 260 T K = (260*1020)/2560 = 100 T (Dynamic) The static holding force (Bandbreak) is bigger. Probably 30-50 %
ANCHOR HANDLING CALCULATIONS STEP 3 : Winch Max. Pull Quadratic equation. Ax2 + Bx + C = 0 _______ X = -B ±√ B2-4AC 2A
____________________________________________________________________________
Capacity on drum = A * C * 3.14*(A+B) d d 914000 = A * C * 3.14*(A+1020) 77 77 914000*77*77 =A2 + 1020A 3.14*1300
(-C = Ax2 + Bx)
ANCHOR HANDLING CALCULATIONS STEP 3 : Winch Max. Pull (Ax2 + Bx + C = 0) A=1 B=1020 C=-1327561,5 A2+1020A-1327561,5 = 0 ___________________ A = -1020 ±√ 10202-4*1*(-1327561,5) 2*1 __________ A= -1020±√ 6350645,9 2 A= -1020 ± 2520,0 2 A = 750 MM
ANCHOR HANDLING CALCULATIONS STEP 3 : Winch Max. Pull
(Max pull 1.) * B = K * (Actual diam.) Max pull 1. = 260 T K = (260*1020)/1020+(2x750) = 105 T (Dynamic)
ANCHOR HANDLING CALCULATIONS STEP 4 : SYSTEM WEIGHT Chain : 126 kg/m 3” Wire : 25 kg/m 3” Weight 600 * 0,126 Anchor + ?? (10 + 5) Totalt: Incl. Bouyancy 90,6 * 0,85
= = = =
Bouyancy = 15 %
Must only be used as safetyfactor According to proc. 15,266,
600 M 75,6 T 15,0 T 90,6 T 77,0 T
Density iron = 7,86 1000kg Iron = 1 / 7,86 = 0,127 M3 1000kg-(127Lx1,025kg/L)= 872,7 kg
ANCHOR HANDLING CALCULATIONS STEP 4 : SYSTEM WEIGHT Decking the anchor Weight without bouyancy 600 * 0,126 Anchor + ?? (10 + 5) Totalt:
= = =
75,6 T 15,0 T 90,6 T
To deck the anchor you maybe need another 30-50 T It can be necessary to make a crossover to a drum with less wire on and therefore closer to the center
ANCHOR HANDLING CALCULATIONS STEP 5 : Bollard Pull
200 M
ANCHOR HANDLING CALCULATIONS STEP 5 : Bollard Pull 43 T
43 T
43 T 77 T
88 T 90 T
99 T
? ? 600 m
Probably using 40% pitch on Maersk Trainer = 43 T Bollard Pull
MTC
Anchor Handling Course
Electrical winches The winches mentioned are based on A-type winches. The winches are of waterfall type. Electrical winches are driven via shaft generator or harbour generators through main switchboard to electronic panel to DC motors. The winch lay out is with anchor handling drum on top and 2 towing winches underneath and forward of the A/H winch. The towing winches each has a chain wheel interchangeable according to required size. The winch has 4 electrical motors. The motors can be utilised with either 2 motors or all 4 motors for the AH drum depending on required tension or with one or two motors for the towing drums. The coupling of motors is via clutches and pinion drive. The clutching and de-clutching of drums is done with hydraulic clutches driven by a power pack. This power pack is also used for the brake system on the drums, as the band brake is always “on” when the handle is not activated. Apart from the band brake there is also a water brake for each electric motor as well as a disc brake. The disc brake is positioned between the electric motor and the gearbox. The water brake is connected to the gearbox and within normal working range, 50% of the brake force is from the water brake and 50% from the electric motor brake. The drums are driven via pinion shafts clutch able to pinion drives on the drums. Pinion drives are lubricated continuously by a central lubricating system to ensure a good lubrication throughout the service. The control handle for the winch activates the lubrication system, and only the active pinions are lubricated. Each winch also has a “spooling device” to ensure a proper and equal spooling of wire on the drum. The spooling device is operated by means of a hydraulic system supplied from the same power pack as mentioned above. Finally, separating the winch area and the main deck is the “crucifix” which divides the work wires in compartments for each winch. It is also part of the winch garage construction.
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Chapter 05
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Anchor Handling Course
Winch operation The winches are operated from the aft desks in port side, but can also be operated at the winch. When operated locally from the winch only ½ speed can be obtained. There are different bridge lay outs but they are all to some degree based on previous design and partly identical. To ensure a good overview for the operator a SCADA system has been installed showing the winch status. Further there is a clutch panel allowing the operator to clutch drums in and out according to requirement. On the panel lub oil pumps for gearboxes, pumps for hydraulic system and grease pump for gearwheels are started. Winch configuration and adjustment is done on the panel, which here at Maersk Training Centre is illustrated by a “touch screen” monitor. The different settings can be done on the “touch screen”. Normally the winch drums are not visible from the bridge. Instead the drums are monitored via different selectable cameras installed in the winch garage. These are connected to monitors on the aft bridge allowing the operator and the navigator to monitor the drums.
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Chapter 05
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Anchor Handling Course
General Arrangement
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Chapter 05
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Anchor Handling Course
A/H-Drum at full Capacity
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Chapter 05
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Anchor Handling Course
SCADA: Supervisory Control and Data Acquisition This system gives the operator an overview of the winch status as well as a warning/alarm if anything is about to go wrong or already has gone wrong. The system is PLC governed – “Watchdog”. 3 types of alarms are shown: Alarm:
A functional error in the system leads to stop of winch.
Pre alarm:
The winch is still operational but an error has occurred, which can lead to a winch stop/failure if the operation continues in same mode.
Warning:
Operator fault/wrong or illegal operation
The clutch panel On the clutch panel the different modes of operation can be chosen. In order to clutch all functions must be “off”. It is not possible to clutch if the drum is rotating or a motor is running. Change of “operation mode” can not be done during operation. Speed control mode Motors can be operated with the handle in: Manual clutch control. If no drum is clutched in. When drums have been chosen. Tension Static wire tension:
The pull in wire/chain is measured from the braking load. The drum is not rotating and the band brake is “ON”. The pull is calculated from “strain gauges”.
Dynamic wire tension: The pull in the wire/chain is measured from the actual torque in the motor. The drum is rotating or almost stopped but not braked. Max wire tension:
Highest possible pull in the wire/chain that can be handled by the motor converted from static pull to dynamic pull.
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Over speed Over speed of the motor has been the most frequent cause for winch breakdowns. Therefore it is of utmost importance to protect the motor against overspending. Over speed occurs when the load on the wire/chain surpasses what the motor can pull/hold and the drum starts uncontrolled to pay out. The winch is protected against over speed in the following way: 1.
When pay out speed exceeds 100 %. Full water-brake in stead of 50% electrical brake. Automatic return to 50% electrical brake and 50 % water brake when speed less than 100 %.
2.
When pay out speed exceeds 105 %. Band brake is applied with 50 % Opens automatically when pay out speed less than 100 %.
3.
When pay out speed exceeds 110 %. Band brake is applied 100 %.
4.
When pay out speed exceeds 120 %. Shut down. The disc brake is applied and the motor remains electrical braked until balance or break down of the winch.
Water brake The water brake is installed as a supplement to the motor brake in order to prevent “over speed” of the motors. Due to the characteristics of the water brake it will work as a brake amplifier when the braking power of the electrical motor starts to give in. The winch motor has great braking effect at low rpm whereas the water brake has very little effect. With higher rpm the braking effect of the water brake increases and the total outcome of the characteristics is very great. Electrical brake (Resistor banks) Resistor banks have been installed to absorb the current generated during pay out. Part of the current will be supplied to the circuit-reducing load on shaft generators but in situations with too small consumption to absorb the generated current it has to be “burnt off” in the resistor banks. The shaft generators are protected from return current and can not receive current from the main switchboard. The resistor banks are clutches in steps according to requirement.
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Band brake The winch is equipped with a band brake that works directly at the drum. This band brake ensures that the drum is unable to rotate when the handle is in zero as well as when changing modes. If a drum is able to rotate while changing mode it can lead to a break down. 50% of the brake force comes from springs built in to the brake cylinder and the last 50% from hydraulic pressure. The band brake is activated via a hydraulic power pack supplying power to the hydraulic cylinder of the brake. “Band brake mode” is used if you want to control a payout without damaging the motor with over speed. In this mode the drum is de-clutched only being braked by the band brake. The band brake is set to maximum holding power (less 2 %) which closes the brake almost 100 %. Then the band brake can be adjusted to tension wanted. The tension controller can be set from 0 % to 100 % where 0 % means brake fully closed and 100 % means brake fully open in which case the drum is free to rotate. Spooling of wire When spooling of wire it is of utmost importance that the wire is spooled correct. There is no automatic spooling device as the wires are of different types and dimensions. Furthermore care has to be exercised when spooling connections such as shackles on the drum as these can damage the wires. Care must also be exercised specially when spooling long wires as it is very important these are spooled on very tight to prevent the wire to cut into lower layers when tension increases. The length of the wire is measured with raps on the drum and if the wire is not spooled correct the figure showing wire length on the SCADA monitor will be wrong. “The spooling device” can be damaged if the guide rollers are not opened sufficiently when a connection is passing through. It is very important always to keep an eye on the wire and the drum. It may be difficulty to get used to operate the winch using cameras but usually it quickly becomes natural. Cameras are located in different places in the winch garage giving opportunity to watch the desired winch drum from different angles. Adjustment of motor torque The torque of the motors can be adjusted (HT control). This can be utilised when working with wires of smaller dimensions which can easily be broken by the power of the motors. The torque can be adjusted to correspond with the breaking load of the wire. It is done with a pot-meter on the winch control panel. The torque can be adjusted between 0 % and 100 %. Normally the HT controller is set at 100 %. Care must be exercised when adjusting below 100 % as the holding power is reduced and case the wire is strong enough there is a risk of over speed or other malfunction – shut down of the system.
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Tension control: To be used during chasing out of anchors. By pressing “CT ON” once the winch is in chasing mode, and the required tension are to be set on CT-Potentiometer. During chasing out to anchor the winch will start paying out when the actual tension is more then the adjusted tension. QUICK & Full Release At quick release the following actions will be executed automatically. Preparation: Quick releases (quick release push button pressed). a) Hydraulic accumulator 1 and 2 (solenoid KY1 andKY2) on. b) Band brake closed to 100 % and de-energise the active motor(s) in order to get the active clutch out while the belonging disk brake(s) are lifted. The quick release procedure will be continued if the winch is clutched out. Execution quick release when clutch is out (quick release push button remains pressed): a) Disc brake closed b) Band brake closed to 7% when pressing the quick release button only. c) Band brake 100%open when pressing the quick release and the full release button both. Stop quick release (quick release push button released): a) Band brake closed to 100% when the hydraulic pump is running or to 50% when the hydraulic pump is not running. (Spring operation only).
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Hydraulic winches General remarks There is little difference in running a hydraulic winch and an electrical winch. The winch is operated with handles for heave in and pay out and for controlling the speed. The lay out of the winch configuration can vary according to ship’s type. Some ships are equipped with 2 towing winches and 2 anchor handling winches. (P type) Latest deliveries (B-type) with hydraulic winches have 1 anchor handling winch and 2 towing winches. Both types have chain wheels installed on the towing winches.
Lay out (B-type) The winch is “waterfall type” and consists of 1 anchor handling winch and 2 towing winches. For running the winches 4 big hydraulic pumps are installed in a pump room. They supply hydraulic oil to 8 hydraulic motors. The motors transfer power to close clutches which again transfer the power to a drive shaft. The drive shaft is common for the towing winches. The anchor-handling winch is not clutch able but is clutched in permanently. It is possible to route the hydraulic oil round the anchor-handling winch by remote controlled switches on the control panel. The winch has 4 gearboxes. 2 gearboxes for the anchor handling winch and 1 for each of the towing winches. Clutch arrangement In order to clutch and de-clutch winch-drums a power pack is installed to supply all clutches. The following options exist for clutching. Either the anchor-handling drum or a towing drum. 2 winches can be clutched at the same time. “High speed” or “low speed” clutching is not an option as one some ships. Clutching is done at the panel on the bridge. From there clutching and de-clutching is done as well as choosing routing of the hydraulic oil for either anchor handling winch or towing winches. Before clutching the brake must be “ON”. A passive surveillance will warn if trying to perform an illegal act.
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Brake arrangement The hydraulic winch has 2 braking arrangements. The hydraulic brake acts via the motors and the mechanical band brake, which is manually operated. The hydraulic brake is activated when the oil is passing discs in the motors. A certain slippage will. Always exist in the hydraulic motors giving a slight rotation with tension on the wire. It is therefore quite normal to observe the winch paying out slightly even though the handle is not activated. If the operation demands the wire to be 100 % secured it is necessary to put the band brake “ON”. Tension control The maximum tension, which can be applied to the wire/chain, depends on the pressure in the main hydraulic system. This can be adjusted by a potentiometer installed in the control panel for each winch. If the tension raises to a higher value than the adjusted, the winch will pay out. This is very useful when chasing for an anchor, as it can avoid breakage of chaser collar and PCP. Emergency release and ultimate release When the emergency release button is pushed, the band brake is lifted and the pressure in the hydraulic system is reduced to a minimum, causing the winch to pay out. The normal over speed protection is active. If a winch drum which is not connected to a motor is emergency released, a small brake force will be applied by the band brake, just enough to prevent the wire from jamming on the drum. The ultimate release button has the same function, the only difference is that the over speed protection system is not active. This might lead to serious damage of the winch motors.
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Hydraulic winch, “B-type”
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TOWCON TOWCON 2000 is a control system for controlling and monitoring all towing functions, shooting the tow wire, towing the towed object and hauling the tow wire. The system handles both dynamic towing, hydraulic braking and static towing with brakes. All data as wire lengths, adjusted max tension, actual wire tension, wire speed, motor pressure, motor temperatures and motor R.P.M. is presented on a high resolution LCD graphical monitor. The system alarms the user in case of unexpected occurrence, or to warn about special conditions. Alarm limits; wire data and control parameters can easily be programmed. Several functions can be simulated, and there is a system for error detection. Statistical data can also be read. The system has small mechanical dimensions, and is easy to mount.
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Instruction for use of Wire Drums Following text and sketches are from the instruction books for the hydraulic winches delivered to the “B – type”. Sales & Service, I.P.Huse, Ulstein Brattvaag, Norway issues the instructions. Please note the last four lines in section 4.2
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Changing of Chain Wheels (Wildcats / Chain Lifter) It will occasionally be necessary to change out the chain wheels depending on the size of chain to be used. As the size of chain wheels has to fit to the size of chain. Chain wheels are manufactured for chain of a certain size and using it for other sizes can cause damage to both the chain and the wheels. It is important that the chain fits exactly in the pockets to prevent the chain from slipping. A chain, which is not fitting in size, can wear the chain wheel down in a short time and is timeconsuming to weld and repair. It can be a troublesome task to change out a chain wheel if it is stuck on the shaft. Which is often the case when working for a long time with tension of 150 tons or more. Also if some of the links in the chain did not fit exactly in the pockets and have been slipping which gives large loads on the chain wheel. Large hydraulic jacks and heating is not always sufficient to dismantle a chain wheel. In most cases time can be saved by fitting an "I" or "H" girder to support in one of the kelps of the chain wheels and welded to a Doppler plate on deck to distribute the weight. The winch is then rotated in “local control” counter wise to create a load on the chain wheel. This should cause the chain wheel to come loose allowing the wheel to be dismantled. Changing of chain wheel can take anything from 8 hours to 24 hours depending on where and who changes the chain wheel and is often subject to discussion between charter and company as time used is often for charters account. It is still the responsibility of the ship to ensure that safety rules and procedures are adhered to even when shore labour is assisting. Emphasising the need to observe that pulling devices are used in a correct manner to avoid damage to threads. Likewise it is important to supervise the use of hydraulic tools to prevent damage to winch motors and anything else which might be used as a “foundation” for the hydraulic tool. When the chain wheel has been changed often the changed out wheel is stored at shore. Before sending ashore it is imperative to preserve it in a satisfactorily way. Lots of chain wheels have been stored out doors without proper protection and supervision. These chain wheels have to be scrapped. It is the responsibility of the ship to ensure the proper preservation and storing. NOTE. A return advice must always be filled out for chain wheels being landed.
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TRIPLEX - SHARK JAW SYSTEM. This equipment has been installed with the objective of safe and secure handling of wire and chain and to make it possible to connect/disconnect an anchor system in a safe way. Most vessels are provided with a double plant, - one at the starboard side and one at the port side of the aft deck. The largest plants installed in the vessels today have an SWL of 700 tonnes and they are able to handle chains of the size of 7” or wires with diameter up to 175 mm. Two control panels are installed in the aft part of the bridge console close to the winch operating panels. The panels are located in port side and in starboard side referring to the respective plant. The port side panel serves the port side TRIPLEX shark jaws and pins and the starboard side serves the starboard side TRIPLEX. Before any operation of these panels it is most important that the operator has studied the manuals and made himself familiar with the functioning of the plant and that any operation complies with the navigator’s instruction. If an order has been indistinct or ambiguous the operator MUST ask for correct info to avoid any doubt or misunderstanding of the operation to take place. This instruction of the TRIPLEX plant has been adjusted to comply with the latest layout and to describe exactly the plants as they appear in the latest and future new buildings and where the company has decided to modify the existing plants in order to comply with safety. The layout is mainly TRIPLEX but APM has added quite some changes to the plant in order to improve and optimise the safety and reliability. The manufacturer, TRIPLEX, has not implemented this modification as a standard version in their basic plants. The development of this modification was prepared and completed by APM based on experience. The Danish Maritime Authorities have approved this improvement.
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Operation To oblige accidents most possible an operating procedure has been prepared. The operator must carefully study this procedure in order to obtain and ensure full understanding of the function of the plant. The marks welded on the links indicate whether the jaws are locked or not. The links MUST pass 180 degrees to achieve “Locked position”. If any irregularity in this respect should occur due to e.g. wear down it will be indicated clearly, as the marks are no longer aligned. It is as a fact ALWAYS the deck crew who make the final decision if the jaws are locked or not. As they have to convince themselves by visual check of marks and upon this turn a lever outside the crash barrier as a confirmation to the operator on the bridge. When this has been performed the jaws are to be considered “Locked”. After the acceptance from the deck the bridge operator can not operate any part of the shark jaws. The only option for overruling this condition is the “Emergency release”- buttons!
Emergency operation In cases of power failure (Black Out) it is still possible to operate the shark jaws as the plant is supplied from the vessel’s emergency generator. Should even the emergency power supply fail it is possible to release the jaws by the “Emergency Release” system. In this case the system is powered by nitrogen loaded accumulators located in the steering gear room and from the vessel’s 24 volt battery supply. The accumulators are reloaded at each operation of the hydraulic power pack for the TRIPLEXsystem.
Maintenance and inspections The maintenance and frequent inspection of the shark jaws system is very important and should be complied by the vessel’s programmed maintenance system, please see procedure 15, 1345: Triplex Shark Jaw – Control Measurements (Supply Vessels). Defects or damages are often revealed during inspections or lubrication. Special attention should be shown to the lower part of the shark jaws – trunk. In spite of drainage from this compartment the environment is rather harsh and tough to the components located at the bottom of this area. Hydraulic hoses and fitting are constantly exposed to salt water as well as the suspension of the shark jaws components. A procedure concerning the treatment of the hydraulic hoses and fittings has been issued, Densyl tape. The shark jaws trunk is often used as “garbage bin” for various items such as mud from anchors, used rags, mussels from chains, chopped off split pins, remains of lead and much more. Due to that fact it is very important to clean this compartment frequently.
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Check of “Lock”- position It is very important to make sure that the shark jaws links are able to reach the correct position when in “Lock”- position. The links have been provided with indication marks that have to be aligned when locked and a special ruler is included in the spare parts delivered along with the equipment. This ruler is used to check that the links are well above 180o. Ref. Chapter 1, Section 7.2.4, - drawing B-2209 section C. Please see procedure 15, 1345: Triplex Shark Jaw – Control Measurements. Also refer to wooden model for demonstration. This check has to be performed frequently and should be comprised by the Programmed Maintenance System on board the vessel. If the equipment has been exposed to excessive load or at suspicion of damage check must always take place and the result entered in the maintenance log. The shark jaws may often be exposed to strokes and blows from anchors tilting or other objects handled.
Safety It is most important to oblige safety regulations and guide lines connected to the operation of the plant. Ensure that all warning signs are located as per instructions - ref. Chapter 1, section 1. If maintenance or repair work has to be performed inside the shark jaws compartment the plant MUST be secured in order not to operate the unit unintended or by accident. This includes the emergency operation as well. To eliminate the risk of emergency release of the system the accumulators have to be discharged by opening the return flow valve to the power pack. This will ensure safe access to the shark jaws compartment. In case repair or check is performed inside the trunk and the jaws are in upper position it must not be possible to lower the jaws as the compartment leaves no room for both the jaws and a person. This may require mechanical fastening of the jaws. (No former accidents reported).
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Guide Pins / A-pins Together with the shark jaws plant two guide pins are provided. These pins are to ensure guidance of wires and chains. The guide pins are hydraulic operated from the power pack common with the shark jaws. The rollers on the guide pins may be manufactured as single roller or divided into two rolls. To ensure proper operation of the guide pins it is very important that they are well greased at all time. In case the rollers are not able to rotate they will be damaged very fast and they will damage e.g. wires as well. Good maintenance and greasing is essential to ensure good and safe performance. A central lubricating plant has been installed in the steering gear room for the greasing of both the shark jaws, guide pins and the stern roller. Daily check of this greasing unit is important to ensure sufficient lubricant in the reservoir. Rather too much lubrication than too little.
Wire Lifter The wire lift is located just in front of the shark jaws and is a part of the same unit. This item is used to lift a wire or chain if required in order to connect or disconnect.
Stop Pins / Quarter Pins The stop pins are located on the “whale back” in order to prevent a wire or chain to slide over the side of the cargo rail. They function exactly as hydraulic jacks controlled from the shark jaws panel on the bridge. The stop pins are often exposed to wear and strokes from the wires and the wear may sometimes cause need for repair. Especially the collar and bushing may require repair as a wire could have ground the bushing and created burrs which prevents the hydraulic piston from proper operation. Due to that fact it is important to frequently check the functioning of the stop pins and to ensure proper greasing. If these pins are not used for a period they easily get stuck.
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2. OPERATION: 2.1
OPERATION OF THE SHARK JAW CONTROL PANEL BUTTON AND SWITCHES.
PUMP START:
Starts hydraulic pump. The pump works at constant high pressure. It is equipped with a time relay which will let the PUMP START LAMP start flashing if it has been switched on but not used for a set period of time.
NOTE!
Ensure that valves on suction line are opened before starting up.
PUMP STOP:
Stops hydraulic pump.
WIRE LIFT UP:
Raises the wire lift pin.
WIRE LIFT DOWN:
Lowers the wire lift pin.
The following controls of the panel are arranged so that those on the right side of the panel are connected to port and those on the left side to starboard.
LOCK-O-OPEN:
Each of these two switches raises locks and opens one Jaw of the Shark Jaw respectively. These switches can be operated simultaneously or individually. When in the central "0" position each switch stops its respective Jaw of the Shark Jaw in whatever position it has reached. This is the normal off position for the switches when the Shark Jaw is not in use. When turned to the LOCK position each switch raises and locks its respective Jaw of the Shark Jaw. When turned to the OPEN position each switch lowers its respective Jaw of the Shark Jaw.
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LOCK-O-OPEN:
When full lock pressure is obtained the LOCK PRESSURE lamps comes on, and when the locking cylinders are in the extended position, the JAW IN POS. lamps comes on. The work deck-operator inspects the marks on the link joints, and if the marks indicate that the jaws are locked, he turns the lever located in the JAW POS. ACCEPT box to JAW LOCK POSITION ACCEPTED. On the control panel the ALARM light goes out and the JAWS LOCKED light comes on. The jaws are completely locked when the link joints passes 180 degrees, and marks on link joints are on line. When the Shark Jaw is locked, both switches remain at the LOCK position. If the lock pressure falls on either one or both jaws or the locking cylinders are not in the extended position the respective LED goes out. Then the JAWS LOCKED -right goes out and the ALARM LIGHT comes on. Under JAWS LOCKED conditions the PUMP STOP cannot be operated.
QUICK RELEASE:
Before operating the QUICK RELEASE, Guide Pins and Wire Lift Pin must be in level with the deck. Two push buttons. To operate the QUICK RELEASE with only the jaws in raised position both OPEN-O-LOCK switches must first be moved to the central "0" position and the JAW LOCK POSITION ACCEPT lever turned to JAW READY FOR OPERATION. The alarm light goes out and the buzzer and alarm on deck comes on when the QUICK RELEASE button cover is opened. Then both QUICK RELEASE buttons must be pressed at the same time.
The system is reset by pressing and reset the E-STOP button.
EMERGENCY RELEASE: Two push buttons on the emergency release panel. For retracting of Guide Pins, wire lift pin first and then the jaws. To operate the EMERGENCY RELEASE the both buttons must be pressed at the same time. The buzzer comes on when the EMERGENCY RELEASE button cover is opened. When the buttons are pressed the lights above them will come on. The system is reset by pressing the E-STOP button.
GUIDE PIN UP:
Two buttons, which when pressed raise the respective guide pins.
GUIDE PIN DOWN: Two buttons, which when pressed lower the respective guide pins. EMERGENCY STOP:
E-STOP button. When pressed the current to all functions of the control panel is cut.
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OIL LEVEL LOW -TEMP HIGH:
If the oil level in the hydraulic oil tank becomes too low or the oil temperature gets too high, the OIL LEVEL LOW / TEMP HIGH lamp comes on.
LAMP TEST:
When the lamp test button is activated, all lamps on the panel will light up.
CONTROL PANEL
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Marks for Locked on Hinge Link The marks welded on the links indicate whether the Jaws are locked or not. The links MUST pass 180 degrees to achieve “Locked Position”.
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2.2- OPERATION OF THE "JAW IN POSITION ACCEPT" LEVER: "Jaw in Position Accept Box" placed on the work deck with lever inside for operation to JAW READY FOR OPERATION or JAW LOCK POSITION ACCEPTED.
JAWS LOCK POSITION ACCEPTED:
When the OPEN-O-LOCK switches on the main control panel are in LOCK position and all lamps for JAW IN POSITION and LOCK PRESSURE light, the work deck operator inspects the marks on the link joints. When the marks indicate that the jaws are locked he turns the lever to position: "JAW LOCK POSITION ACCEPTED". On the control panel the JAWS LOCKED lamp then comes on. The Shark Jaw is now ready to hold the load. When the lever is in the JAW LOCK POSITION ACCEPTED the LOCK-O-OPEN and QUICK RELEASE buttons cannot be operated without first turning the JAW POSITION ACCEPT lever to the JAW READY FOR OPERATION position. The EMERGENCY RELEASE operates even with the lever in position: "JAW LOCK POSITION ACCEPTED". Before operating the Shark Jaw the JAW POSITION ACCEPT lever has to be turned to JAW READY FOR OPERATION. If the pump stops when the jaws are in locked position and JAW LOCK POSITION ACCEPTED the JAWS LOCKED lamp goes out and alarm lamp comes on. Procedure for control of the jaws in locked position then have to be repeated, marks on the link joints inspected and confirmed with operating JAW LOCK POSITION ACCEPTED.
2.3
OPERATION OF THE CONTROL PANEL AT EMERGENCY POWER.
2.3.1 Emergency power to the bridge Control Panel. Functions to be operated at emergency power. • Only the buttons for moving jaws and pins down. • Pump start. • Emergency release.
2.3.2 Emergency Power to the Main Junction Box. All functions to be operated as on normal power.
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3.
ELECTRIC AND HYDRAULIC POWER SYSTEM.
3. 1.
ARRANGEMENT OF SYSTEM. Refer to enclosed hydraulic diagram (section D). A variable displacement hydraulic pump supplies the system. The oil is distributed to the various electrically operated solenoid valves. When activated these valves supply the oil to the hydraulic cylinders, which power the Jaws, Wire Lift Pin, Guide Pins and Stop Pins. The pump is connected to accumulators, which are charged as soon as the system reaches maximum working pressure. As shown in the hydraulic diagram, all the necessary relief valves over centre valves and check valves are fitted to enable the system to function efficiently. The electric system is powered from 220 or 110 Volt AC and is transformed / rectified to 24 Volt DC. The system must have a 24 Volt Direct Current emergency power supply.
3.2.
FUNCTIONING OF QUICK RELEASE - JAWS ONLY. Wire or chain held by the Shark Jaw can be released by turning the OPEN-OLOCK switches to the OPEN position, or by operating the QUICK RELEASE. When required the QUICK RELEASE system can be used to open the jaws. QUICK RELEASE is operated by turning both OPEN-O-LOCK switches to the central "0" position and the JAW POSITION ACCEPT lever turned to READY FOR OPERATION. The alarm light goes out and the buzzer comes on when the QUICK RELEASE button cover is opened. Then both QUICK RELEASE buttons must be pressed at the same time. The need to operate two sets of controls to activate the QUICK RELEASE system is a safety device to prevent the QUICK RELEASE from being operated by accident.
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FUNCTIONING OF EMERGENCY RELEASE A separate control panel on the bridge operates the EMERGENCY RELEASE. When the EMERGENCY RELEASE is operated, solenoids nos. 42 and 35 are activated (refer to hydraulic diagram) The solenoid valve pos. 11 then releases pilot pressure from the accumulators, supplying high pressure oil to the Wire Lift Pin and Guide Pins hydraulic cylinders, to retract WIRE LIFT PIN and GUIDE PINS to deck level before the Jaws open. Following this, even if the WIRE LIFT PIN or GUIDE PINS do not fully retract for any reason, the Jaws will automatically open and reach deck level in 10 - 20 seconds. - Pressing the E-STOP button can stop the whole procedure -
3.4.
EMERGENCY RELEASE UNDER "DEAD SHIP" CONDITIONS. The EMERGENCY RELEASE system can also operate under "dead ship" conditions and under load. This is possible because the accumulators are charged at the same time as the jaws are locked and the system reaches maximum working pressure. Should "dead ship" condition occur and the pump stop the emergency current from the battery makes it possible to release with. power from the accumulators in the same way as described above. Even under "dead ship" condition, with no power from the pump, a load can safely be held in the Jaws, as the link joints are "locked" past 180 degrees.
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Testing program for the Triplex Shark Jaw H-700. Recommended and approved by the Norwegian Maritime Directorate.
4.1. Triplex Shark Jaw. The Triplex Shark Jaw and central manoeuvring components have been tested by manufacturer with 240 bar oil pressure.
4.2
Test without Load. To be carried out on board after installation and start up. a) The jaws to be closed and opened separately and simultaneously. b) The wire lift to be moved to up and down positions. c) QUICK RELEASE for jaws to be tested with the wire lift down. d) EMERGENCY RELEASE to be tested when jaws have been locked and the pump is disconnected. e) Check marks on link joints when Jaws are locked. If marks are not in line the Shark Jaw must be repaired before use.
4.3 Test with Load. Wire of necessary strength to be locked in the Shark Jaw and a static load test to be carried out by pulling with a load corresponding to the ships bollard pull.
5.
General Maintenance For Triplex Shark Jaw Type H-700 Triplex Guide Pins Type S-300
5.1
Accumulators Depressurising Important! Before maintenance work on Shark Jaw it is important to empty the accumulators for oil by opening of the ball valve on the power unit.
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Shark Jaw Unit Check regularly before use, that link joints and jaws have no wear and tear or damages that can cause any danger. All bearings and bolts in all joints should be tight. Check tightness of all bolts and nuts regularly or minimum two times per year. The inside of the Shark Jaw housing and the moveable parts must be cleaned regularly. Lubricate according to the lubricating chart.
Shark Jaw Unit Service / Inspection Safety Device:
Before service or inspection of parts inside the Shark Jaw with the jaws in locked position the jaws must be secured by welding a clamp on top of the Jaws. Remember to remove the clamp before starting pump.
5.3
Guide Pins Units Check torque on bolts for the top hats and guide plates on the lower end of the guide pins, regularly minimum two times per year. Recommended torque for M24 bolts 10.9 qualities black and oiled is 108 kpm. Recommended torque for M30 bolts 10.9 qualities black and oiled is 175 kpm. Check and clean regularly the inside of the guide pin housing. Lubricate according to lubrication chart.
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Anchor Handling Course
Guide Pins Service / Inspection Safety Device:
Before service or inspection of parts on Guide Pins with the pins in upper position the pins must be secured with a support inside. Remember to remove the clamp before starting pump.
5.4
Hydraulic System The filter element for the H.P. – and return line filter on power pack have to be changed when indicators show blocked filter or minimum one time per year. Check regularly all high pressure hoses inside the Shark Jaw and Guide Pins. Ensure that spare high pressure hydraulic hoses are always carried on board. Hydraulic oil according to lubrication chart.
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Chapter 06
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MTC 5.5
Anchor Handling Course
Electric System
5.5.1 With Power Switched off. Tighten every screw connection for electrical termination. Check all cables for damage.
5.5.2 With Power Switched on. Check that all operations from the control panel are functioning. The same procedure shall be followed, also for the emergency release box.
5.6
Control of Operation with Current from the Emergency Power Supply. Switch off the automatic fuse inside the junction box and check the operation of the Shark Jaw from the control panel. Check also the alarm functions.
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Anchor Handling Course
6.
Control Measurements / Adjustments.
6.1
Control Measure in Lock Position:
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MTC
6.2
Anchor Handling Course
Adjustment of inductive proximity switches on lock cylinders. 1. 2. 3. 4. 5. 6.
Change inductive proximity switch if defect. Dismantle cover on link joint. Move jaws to LOCK position. Adjust proximate switch until light on sensor comes on. Tighten contra nut on proximate switch. Open and lock jaws to check that light on sensor comes on. Check that adjustment of proximate switch lamp goes out before link joints reach minimum over centre measurement.
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MTC 6.3
Adjustment of Pressure Switches for Lock Pressure. 1. 2.
7.
Anchor Handling Course
Adjust pressure to 115 bar. Use horizontal adjusting screw on pump pressure compensatory valve. Adjust pressure switch until green lamp on control panel comes on. Use alternative voltmeter and measure on cables for pressure switches.
Test Program – Periodical Control Triplex Shark Jaw Type H-700 Triplex Guide Pins Type S-300
7.1
The Triplex system is installed and used under rough conditions. Due to mechanical stress, vibrations and aggressive atmosphere and the equipment needs to be maintained carefully for safe operation.
A functional dry run test is recommended before every anchor handling operation. The owner is responsible for all maintenance on the Triplex equipment. He must perform his own routines and schedules after the following guidelines.
7.2
Checking List – Periodic Control Mechanical / Hydraulic. Procedure for Personal Safety See Section 1; Have to be Followed! Recommended Regularity: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
MONTHLY
Dismantle manhole cowers on Shark Jaw and Guide Pins. Check H.P. hoses, pipes and fittings. Poor H.P. hoses to be changed. Check that all bolts are properly tightened. Check that link joints are over centre when jaws are in locked position. See drawing B-2209. Check wears on jaws, rollers and bearings. Repair and change where necessary. Movement of bolts and link joints to be controlled under the function test. Look carefully for cracks and deformations. Check sea water drain pipes from Shark Jaw and Guide Pins. Check oil lever in hydraulic oil tank. Starts pump and check that hydraulic pressure raise to max. working pressure (175 bar). Check accumulator nitrogen pressure: 35 Bar. It’s important first to empty the accumulators for oil by opening the ball valve on the power unit. Then connect gas-filling equipment according to accumulator precharging procedure.
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MTC 11. 12. 13.
7.3
Anchor Handling Course
Auxiliary equipment as lubrication system to be checked according to the grease system manual. (LINCOLN) Check that gaskets for manhole covers are in good condition. Fit all manhole covers.
Checking List – Periodic Control Electrical Procedures for Personal Safety see Section 1. Have to be followed! Recommended Regularity: 1. 2.
3. 4. 5. 6. 7.
8. 9.
MONTHLY
Switch power off. Perform Visual inspection for mechanical damage on: - Junction boxes, control panels and cabinets. - Cables. - Indicators and switches. - Electrical components mounted on the entire Triplex equipment / delivery. Open every electrical cabinet, panel and boxes one by one, inspect for damage and heat exposure. Control that all components are firm fastened, and relays are firm in their sockets. Screw connections for every electrical termination to be carefully tightened. Damages and other un-regularities must corrected immediately. Power on, and perform complete functional test programs: - Normal operation of all functions. - Quick release. - Emergency release. Check emergency power (24 V) to junction box. Remount all panels and doors / covers.
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7.4 Testing without Load – Yearly Testing. Checklist (Accept with OK) 1 Remote pump start 2 Remote pump stop 3 Local pump start 4 Local pump stop 5 Pump lamp auto flicker 6 Emergency stop 7 Wire lift pin up 8 Wire lift pin down 9 Starboard jaw close 10 Starboard jaw open 11 Port jaw close 12 Port jaw open 13 Jaws close simultaneously 14 Jaws open simultaneously 15 Alarm light jaws open 16 Lock pressure lights 17 Jaw in position lights 18 Jaw in position accepted 19 Jaws locked light 20 Guide pins up 21 Guide pins down 22 Towing pins up 23 Towing pins down 24 Emergency release 25 Quick release (Jaws only) 26 Reset Quick release buttons 27 Oil temperature high alarm light 28 Oil level alarm light 29 Emergency power supply junction box connection (193-194) 30 Emergency power supply control panel bridge connection (77-78) 31 Jaw in lock position marks in line check, starboard 32 Jaw in lock position marks in line check, port
Control Motor/pump Panel Bridge starter -
JAW POSITION ACCEPTED -
7.5 Load Test – Emergency Release – 5 Year Control. Wire with required strength to be locked in the Shark Jaw. Make emergency release with a load of 90 tons on the wire (Jaws). First test: With the pump running. Second test: With the pump stopped and accumulators fully loaded.
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Maersk Training Centre A/S E-procurement work group
“In closed / locked position” View from astern of Jaws.
Triplex Shark Jaw System Anchor Handling Course, chapter 6
Maersk Training Centre A/S
“Mark on line !”
Triplex Shark Jaw System Anchor Handling Course, chapter 6
Maersk Training Centre A/S
“In closed / locked position” Looking aft. Wire lifter 1/3 up, Guide Pins in closed position.
Triplex Shark Jaw System Anchor Handling Course, chapter 6
Maersk Training Centre A/S
“Double set of Jaws, Pins and Wire lifter” Looking aft. A- type vessel.
Triplex Shark Jaw System Anchor Handling Course, chapter 6
View from the bridge.
Maersk Training Centre A/S
A-type vessel.
Triplex Shark Jaw System Anchor Handling Course, chapter 6
Maersk Training Centre A/S
“Chain stopped off by the Shark Jaw” Looking aft.
Triplex Shark Jaw System Anchor Handling Course, chapter 6
Maersk Training Centre A/S E-procurement work group
“JAW READY FOR OPERATION”
Triplex Shark Jaw System Anchor Handling Course, chapter 6
Maersk Training Centre A/S E-procurement work group
“JAW LOCK POSITION ACCEPTED”
Triplex Shark Jaw System Anchor Handling Course, chapter 6
MTC
Anchor Handling Course
KARM FORK – SHARK JAW SYSTEM. This equipment has been installed with the objective of safe and secure handling of wire and chain and to make it possible to connect / disconnect an anchor system in a safe way. Most vessels are provided with a double plant, - one at the starboard side and one at the port side of the aft deck. The Karm Fork system is a patented design for anchor handling and towing operations. The unit consists of a wide, strong foundation that is inserted into the deck structure. The Fork runs vertically up and down in the foundation. High-pressure hydraulic cylinders power the Karm Fork unit. The Karm Fork can easily be adapted to different wire / chain dimension by changing the insert. The Karm Towing Pins system is a patented design for anchor handling and towing operations. The unit consists of a wide, strong foundation that is inserted into the deck structure. The Towing Pins run vertically up and down in the foundation. The Karm Towing Pins have flaps for horizontal locking. As the pins move upward they turn the flaps towards one another. This system traps the wire / chain inside a “square” avoiding it to jump of the towing pins. High-pressure hydraulic cylinders power the Karm Fork unit. The Karm Fork & Towing Pins are all placed in the same foundation. The largest plants installed on board the APM vessels today have a SWL of 750 tonnes and they are able to handle chains of the size of 6”. Before any operation of these panels it is most important that the operator has studied the manuals and made himself familiar with the functioning of the plant and that any operation complies with the navigator’s instruction. If an order has been indistinct or ambiguous the operator MUST ask for correct info to avoid any doubt or misunderstanding of the operation to take place.
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Anchor Handling Course
KARM FORK Shark Jaw Wire and chain Stopper
Fig 1
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Chapter 07
MTC
Anchor Handling Course
Inserts for KARM FORK
Fig 2
Inserts and Carpenter Stoppers for KARM FORK
Fig 3
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Chapter 07
Maersk E-procurement Training Centre work group A/S
Karm Fork in top position with top cover on. Towing Pins in parked position. Looking aft. MAERSK DISPATCHER
Karm Fork Shark Jaw System Anchor Handling Course, chapter 7
Maersk Training Centre A/S
Karm Fork and Towing Pin in top position. Looking aft. MAERSK DISPATCHER
Karm Fork Shark Jaw System Anchor Handling Course, chapter 7
Maersk Training Centre A/S
Karm Forks and Towing Pins in top position with Safety Pins in. Looking towards port. MAERSK DISPATCHER
Karm Fork Shark Jaw System Anchor Handling Course, chapter 7
Maersk Training Centre A/S
Karm Forks and Towing Pins in top position with Safety Pins in. Chain stopped off in both sides. Looking aft. MÆRSK DISPATCHER
Karm Fork Shark Jaw System Anchor Handling Course, chapter 7
Maersk Training Centre A/S
Both sets of Towing Pins in up / locked position. Both sets of Karm Forks in parked position, ready for use. Looking aft. MÆRSK CHIEFTAIN
Karm Fork Shark Jaw System Anchor Handling Course, chapter 7
MTC
Anchor Handling Course
“Good Advises and Guidelines” in use of NON rotation-resistant steel wires. First of all it is recommended to read the Technical Information regarding steel wires by Fyns Kran Udstyr / Randers Reb. These information make the foundation for the following “Good Advises and Guidelines”. The wire-thread, which is used in the production of a steel wire, has a very high tensile strength compared by ordinary steel. Trade steel (“Steel 37”) has a tensile strength at app. 37 kp/mm2 (362 N/mm2) Wire steel has a tensile strength from app. 140 to 220 kp/mm2 (1370 – 2160 N/mm2) The fact that the wire-thread is so strong has the disadvantage that the bending strength will be reduced. The wire-thread breaks easily, if it is bent – especially under the circumstances as a “Work wire” is working under. Below different subjects concerning or are used in connection with steel wire will be covered. Especially the negative influence on the steel wire will be covered. Swivel:
The breaking load will locally be reduced by app. 30% When a steel wire is under load it opens and at the same time it will be extended. The swivel “makes” it easier for the wire to open, stress failure will occur and the life expectancy will be reduced.
Working Load:
A steel wire must maximum be loaded with 50% of the breaking load. The material reaches the yield point at 50% of the breaking load. The wirethreads get stiff and will break when they are bent. The life expectancy will be reduced. If the load constantly is about the 50%, the steel wire will break.
Loops / kinks:
Gives a reduction in the breaking load at app. 50% The steel wire will be heavily deformed, when e.g. a kink is straightened out by applying of a load. A kink is formed due to extraction of a loop.
Fleet angle:
Does not matter on ships with spooling devices. But the steel wire has to run straight into a block.
Running in Steel Wire Rope: Is recommended, if time. In this way the steel wire will gradually become accustomed to the new conditions.
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Fitting to Drum:
Fundamentally you ought to follow the recommendations made by the manufacturer. But this does only matter with the first layer of steel wire. It doesn’t matter on drums with several layers of steel wire. If it isn’t possible to fit the steel wire at the right side due to the construction of the drum, you must subsequent keep away from the first layer on the drum.
Spooling:
Care must be taken to ensure that the reel and the drum are running in the same direction. That means from under-turn to under-turn and from overturn to over-turn. If this isn’t done correctly, the steel wire is subjected to torsion. In order to achieve problem-free spooling on multi-layer drums it is extremely important that the steel wire is spooled on with tension. If the layers are too loose; the upper layers can damage or cut into the layers below when tension is applied, resulting in damage to the steel wire. Spooling from drum to reel: All tension / torsion must first be released by deploying the wire into the water – at sufficient water depth – before the steel wire is spooled on to the reel. The best-recommended way of doing this transferring; is first to deploy the steel wire into the water, secure it in the Shark Jaws and afterwards spool the steel wire directly from the water onto the reel. It is of course a demand, that the reel is able to lift the weight of the deployed steel wire.
Bending around a mandrel: (Can be compared with a U-lift.) When the steel wire “works” on the stern roller or is spooled on the drum this is “Bending around a mandrel”. How big / small this proportion is, depends on the diameter of the “drum” (Winch drum, stern roller, guide pins) and the diameter of the wire which is supposed to “work” on the drum. Depending on the proportion between mandrel diameter and steel wire diameter, reduction in the breaking load will be: (d = diameter of the steel wire) Mandrel, diam.: 40 d 15 d 5d 4d 3d 2d 1d
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Breaking load, reduced: 5% 10% 20% 25% 30% 40% 50%
Chapter 8 / 1
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MTC
Anchor Handling Course A few examples:
3000 mm drum / 76 mm wire = app. 40 d 3000 mm drum / 86 mm wire = app. 35 d 1500 mm drum / 86 mm wire = app. 17 d 900 mm drum / 76 mm wire = app. 12 d
The same is also valid, when the steel wire makes a big change in the rundirection. E.g. when the steel wire is forced round a guide pin, the proportion will only be app 4 d (300 mm guide pin / 76 mm wire = 4 d). For steel wires 6x36 and 6x41 a minimum of 20 d is recommended. The bigger – that better. Some suppliers of steel wires recommend a minimum of 40 d. E.g. a 44-mm steel wire “demands” a sheave with a minimum diameter at 880 mm A more essential fact is the stress, which will occur when a steel wire runs round a drum, roller and sheaves or change run of direction due to a guide pin or a spooling device. This stress will give a shorter life of the steel wire and the steel wire will be worn down before time as well. When a steel wire is fed over e.g. a winch drum, stern roller, guide pin or a sheaf, certain complex tensions (a combination of bending, tensile and compression stress) are generated in the steel wire. The greatest tension occurs in the wire threads furthest away from the steel wire’s bending centre. After repeated bends, stress failure will occur in these wire threads. These stress failures occur due to many factors. E.g. the steel wire rope construction, tension applied, the ratio (d), use of a swivel, wear and tear of guide pins, spooling devices and stern roller together with martensite formation. Martensite:
Martensite formation. Martensite is a structural change in the wire material causes by a very sudden cooling of the steel wire after a strong local heating generated by friction. E.g. bad spooling of the steel wire on the winch drum may cause the friction. This structure change gives a hard and brittle surface and may cause fractures during normal operation or when spliced, even though the steel wire doesn’t show any visible signs of external wear If a steel wire carries a current or the steel wire is wound on a drum in several layers, there will often be sparks. The surface temperature where the sparks appear will be over 800° C, making it quite probable that martensite will be formed. If there are many sparks, fracture on wire threads will happen and the wire may break.
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Anchor Handling Course Precautions against martensite: •
• • • •
The blocks, guide pins, stern roller and spooling devices must not be worn down and should turn easily. Must be kept in good condition. If equipment is repaired by welding, care should be taken to ensure that hardness of the welding material is maximum 300 Brinel. When a steel wire is wound on a drum, it should be in tight wraps without the layers crossing each other in order to prevent the top layer from cutting into the underlying layers. The steel wire should be lubricated at regular intervals in order to minimise the friction between wires and strands. The best would be to make a sort of continuously lubricating. The steel wire should be checked at regular intervals for crushing, minor cracks and mechanical damages, all of which might indicate martensite spots. Use of wires with less contents of carbon in the wire. (Are used in the fishing industry for trawl wires).
Re-socketing of steel wire: • •
The old steel wire is cut of at the socket base. The steel wire piece is pressed out by use of a mandrel / jack.
When heated: • Only slowly and equably. • Only up to maximum degrees – depending on the product. Do “bend / break – test” on the wire from the piece of steel wire, which is leading into the socket. If the wire threads break, they have been exposed to martensite. The steel wire will break in the area around the socket base because the steel wire works heavily in this area.
After Re-socketing remember to: • •
The socket base to be filled with grease or oil. To be re-filled, when the steel wire isn’t in use over a long period, as the steel wire will dry out. The re-greasing is very important, when the socket in hanging down.
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Recommendations: •
You must aim at a working load of maximum 1/3 of the Breaking load. In this way the steel wire can be loaded with peaks up to 50% of the original breaking load. You will also have room for using the swivel without complications.
•
Guide pins, blocks, spooling devices and stern roller must be kept in a good condition. If equipment is repaired by welding, care should be taken to ensure that hardness of the welding material is maximum 300 Brinel.
•
Avoid that the steel wire is slipping across the connections between the two stern rollers.
•
The ratio of “d” to “D” must be as big as possible – and always at least 20, when we are dealing with a steel wire under load.
•
The steel wire must be lubricated in order to minimise the martensite formations.
•
Martensite formations must generally be avoided – if possible.
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Side 1
TEKNISK INFORMATION 1. STÅLTOVETS GRUNDELEMENTER
1. THE BASIC ELEMENTS OF STEEL WIRE ROPE
Et ståltov består normalt af tre komponenter (fig. 1):
A steel wire rope normally consists of three components (fig. 1):
· Ståltråde der danner en dugt. · Dugter der slås omkring et hjerte. · Hjerte.
- Steel wires that form a strand. · Strands that are wrapped around a core. · The core.
Disse elementer udføres i forskellig udformning/design afhængig af, hvilke fysiske krav der stilles til ståltovet samt hvad det skal anvendes til. Én dugt kan i visse tilfælde med fordel anvendes som et ståltov.
These elements are available in various models/designs, depending on the physical requirements of the steel wire rope and its intended application. A single strand can in certain cases be used quite properly as a steel wire rope.
En fjerde komponent, der er lige så vigtig som udformningen og kvaliteten af de tre basiskomponenter, er indfedtningen af hjerte og dugter (se afsnittet "Vedligeholdelse af ståltovet").
Fig. 1.
Ståltråd Der findes mange forskellige materialetyper og kvaliteter af tråde. Randers Reb kan levere de fleste af disse kvaliteter. De stålkvaliteter, som Randers Reb anvender til fremstilling af standard ståltove, leveres fra få af Europas førende trådproducenter og opfylder som minimum internationale standarder (EN 10264). Herved opnår Randers Rebs ståltove en høj grad af ensartethed. Minimum brudstyrken på tråden angiver klassifikationen af ståltovet. Randers Reb anvender bl.a. følgende trådtyper: · Ugalvaniserede tråde (primært elevatortove) N/mm2 (140 kp/mm2). · Zink-galvaniserede tråde (primært fiskeri) N/mm2 (160 kp/mm2). · Zink/aluminium-galvaniserede tråde (primært fiskeri) N/mm2 (160 kp/mm2). · Rustfrie tråde (brudstyrken er dimensionsafhængig) N/mm2 (170 kp/mm2). · Zink-galvaniserede tråde (primært industri) N/mm2 (180 kp/mm2). · Zink-galvaniserede tråde (primært industri) N/mm2 (200 kp/mm2).
1.370 1.570
1.670 1.770 1.970
Dugter En dugt er fremstillet (slået) af minimum 3 tråde, der er lagt i én af mange forskellige designs (geometrisk opbygning). Dugten er næsten altid opbygget omkring en centertråd. Som regel er trådene af stål, men de kan også være af fiber (natur- eller kunstfiber) eller af en kombination af stål og fiber. Antallet, størrelsen og materialet af de enkelte tråde kendetegner tovet og dets egenskaber. Få og tykke tråde giver stor slidstyrke,
Jan 2002
A fourth component, that is equally as important for the steel wire rope's performance as the design and quality of the three basic components, is the lubrication of the core and the strands (see "Maintenance of Steel Wire Rope").
Steel Wire There are many different types of material and qualities of wire. Randers Reb can supply most of these qualities - contact us to find out how Randers Reb can meet your own particular needs. The qualities of steel that Randers Reb uses in the production of standard steel wire rope are supplied by a select few of Europe's leading wire manufacturers and as a minimum requirement meet international standards (ISO 2232). In this way Randers Reb's steel wire ropes achieve a high degree of uniformity. The minimum tensile strength of the wire defines the classification of the steel wire rope. The tensile strength of wires in Randers Reb's standard product range is as follows:
1.570
Randers Reb kræver, at alle trådleverancer ledsages af et trådcertifikat.
FKU LIFTING A/S
10-1
Randers 89 11 12 89
· Ungalvanised wires (mainly elevator cables) N/mm² (140 kp/mm²). · Zinc galvanised wires (mainly fishing) N/mm² (160 kp/mm²). · Zinc/alum. galvanised wires (mainly fishing) N/mm² (160 kp/mm²). · Rustproof wires, tensile strength dependent on size N/mm² (170 kp/mm²). · Zinc galvanised wires (mainly industry) 1,770 N/mm² (180 kp/mm²). · Zinc galvanised wires (mainly industry) 1,970 N/mm² (200 kp/mm²).
1,370 1,570 1,570 1,670
Randers Reb always demands that all wire consignments are accompanied by a wire certificate. Strands A strand is laid by a minimum of three wires that are arranged in many different designs (geometric patterns). The strand is almost always arranged around a centre wire. The wires are made from
Odense 63 96 53 00
København 43 73 35 66
10
10
Afsnit 10 - 2001 m ny standard 2.qxd
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10:19
Side 2
TEKNISK INFORMATION hvorimod mange og tynde tråde giver stor fleksibilitet (se også afsnittet "Dugttype/dugtdesign"). Hjerte Næsten alle ståltove har et hjerte. Hjertets funktion er at understøtte og fastholde dugterne i deres relative stilling under brugen. Hjertematerialet kan enten være stål eller fiber eller en kombination af disse (se fig. 2). Hjertet er normalt af typen: Fig. 2 · FC (natur- eller kunst fiber, Fibre Core). · WSC (stålhjerte, Wire Strand Core). WSC'et er en dugt og af samme konstruktion som ståltovets dugter. · IWRC (stålhjerte, Independent Wire Rope Core). IWRC'et er et selvstændigt ståltov med et fiberhjerte eller WSC. 2. STÅLTOVSKONSTRUKTIONER Et ståltov bestemmes ikke kun ud fra dets grundelementer (tråde, dugter og hjerte), men også ud fra hvordan de enkelte tråde er slået sammen for at danne en dugt samt hvordan dugterne er slået omkring hjertet m.m. Ståltovets konstruktion er fastlagt, når følgende er defineret: · Antal tråde i dugt. · Dugttype (dugtdesign). · Antal dugter. · Hjertetype. · Slåningsretning (ståltov og dugt). · Formlægning. Ståltove er benævnt efter antallet af dugter, antallet af tråde i hver dugt, designet (typen) af dugten og hjertetypen. F.eks.: · 6x7 Standard med FC (fiberhjerte). · 8x19 Standard med WSC (stålhjerte). · 8x19 Seale med IWRC (stålhjerte). · 6x36 Warrington Seale med FC (fiberhjerte). Antal tråde i dugt Antallet af tråde i en dugt varierer fra 3 til ca. 139, mest almindeligt er 7, 19, 24 eller 36 tråde. Trådenes antal og tykkelse afhænger af dugtdesignet og har indflydelse på ståltovets egenskaber.
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either steel or fibre (natural or man-made), or a combination of these.The quantity, size and material from which the individual wires are made characterise the rope and its qualities. Fewer, thicker wires create greater abrasion resistance, whereas a greater number of thinner wires creates greater flexibility (see also section 2: "Types of Strand"). Core Almost all steel wire ropes have a core. The core's function is to support and retain the strands in their respective positions while the steel wire rope is being used. The core may be made of either steel, fibre, or a combination of the two. The core is usually one of the following types: - FC (natural or man-made fibre, Fibre Core). · WSC (steel core, Wire Strand Core). The WSC is a strand and is of exactly the same construction as the strands in the steel wire rope. · IWRC (steel core, Independent Wire Rope Core). The IWRC is an independent steel wire rope with a fibre core or a WSC (see also section 2: Types of Core). 2. STEEL WIRE ROPE CONSTRUCTIONS A steel wire rope is defined not only by its basic elements (wires, strands, core), but also by the way in which the individual wires are laid together to create a strand and the way in which the strands are laid around the core, etc. The steel wire rope's construction is defined when the following criteria have been determined: · Number of wires in a strand. · Type of strand (strand design). · Number of strands. · Type of core. · Lay direction (steel wire rope and strand). · Pre-forming. The steel wire rope is designated according to the number of strands, the number of wires in each strand, the design (type) of the strand, and the type of core. · 6x7 Standard with FC (fibre core). · 8x19 Standard with WSC (steel core). · 8x19 Seale with IWRC (steel core). · 6x36 Warrington Seale with FC (fibre core). Number of Wires in a Strand The number of wires in a strand varies between three and approx. 139, although there are most commonly 7, 19, 24 or 36 wires. The number of wires and their thickness depend on the design of the strand and affects the characteristic of the steel wire rope.
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TEKNISK INFORMATION
Types of Strand (Strand Construction) The type of strand is characterised by the way in which the wires in the strand are arranged. There are four basic types of strand design that are used in all steel wire ropes, either in their original form or as a combination of two or more types. The four basic types are:
Dugttype (dugtdesign) Dugttypen er karakteriseret ved, hvordan trådene i dugten er arrangeret. Der findes fire grundtyper af dugtdesign: · Standard. · Seale. · Filler. · Warrington.
· Standard. · Seale. · Filler. · Warrington.
Disse indgår i alle ståltove, enten rene eller i kombinationer af to eller flere typer.
Standard The Standard construction (fig. 3) is characterised by the fact that all wires are of equal thickness, although the core wire may be thicker. The wires are also laid together in such a way that all of them, with the exception of the centre wire, are of equal length. In this way all the wires are subjected to an equal distribution of load when pulled straight.
Standard Standard konstruktionen (fig. 3) er kendetegnet ved, at alle tråde er lige tykke, dog kan hjertetråden være tykkere. Desuden er trådene slået således sammen, at alle - med undtagelse af centertråden er lige lange. Herved belastes alle trådene ligeligt under lige træk. Den geometriske trådfordeling er én centertråd, hvorpå der lægges ét eller flere lag. Hvert lag fremstilles i hver sin operation. Antallet af tråde stiger med 6 for hvert lag.
Fig. 3
Betegnelsen for en Standard dugt med f.eks. 7 tråde er (6-1), dvs. 1 centertråd med 6 tråde udenom i én operation. Ved 37 tråde er betegnelsen (18/12/6-1), dvs. 1 centertråd med 6 tråde uden om som første operation, 12 tråde lægges herefter uden på i anden operation og 18 tråde i tredje operation. Fig. 4
Centertråden erstattes til tider af flere tråde eller et fiberhjerte (fig. 4).
The geometric wire distribution consists of one centre wire, onto which one or more layers are laid. Each layer is produced in a separate operation. If there are several layers, the number of wires increases by six for each layer. The designation for a Standard strand with e.g. seven wires is (6-1), i.e. one centre wire with six external wires in one operation. If there are 37 wires it is known as (18/12/6-1), i.e. one centre wire with six external wires from the first operation, 12 from the second operation and 18 from the third operation. The centre wire may be replaced by several wires or a fibre core (fig. 4).
Fig. 5
Seale Seale konstruktionen (fig. 5) er kendetegnet ved, at dugten består af to trådlag fremstillet i én operation. Desuden er antallet af tråde i første og andet lag ens.
Seale The Seale construction (fig. 5) is characterised by the way in which the strand consists of two layers of wire produced in one operation. Also, the number of wires in the first and second layer is identical.This construction is somewhat stiffer than a corresponding Standard construction (with the same number of wires). This is because the outer wires in the Seale construction are considerably thicker.
Denne konstruktion er noget stivere end en tilsvarende Standard konstruktion (med samme trådantal). Dette skyldes, at ydertrådene i Seale konstruktionen er væsentlig tykkere.
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TEKNISK INFORMATION Betegnelsen for en Seale dugt med f.eks. 19 tråde er (9-9-1) dvs. 1 centertråd med 9 tråde i første og 9 tråde i andet lag. Centertråden erstattes til tider af flere tråde (fig. 6) eller et fiberhjerte.
A Seale strand with e.g. 19 wires is known as (9-9-1), i.e. one centre wire with nine wires in the first layer and nine wires in the second layer.
Fig. 6
The centre wire may be replaced by several wires or a fibre core (fig. 6).
Filler Filler konstruktionen (fig. 7) er kendetegnet ved, at dugten består af to trådlag fremstillet i én operation. Desuden er antallet af tråde i andet lag dobbelt så stort som første lag. Dette er dog kun muligt, når der indlægges fyldtråde mellem første og andet lag for at forhindre, at dugten bliver kantet. Fig. 7
Denne konstruktion er mere bøjelig end en tilsvarende Standard konstruktion og væsentligt mere bøjelig end en tilsvarende Seale konstruktion (med samme trådantal ekskl. fyldtråde).
Filler The Filler construction (fig. 7) is characterised by a strand consisting of two layers of wires produced in one operation. Also, the number of wires in the second layer is twice the number in the first layer. This is, however, only possible if filler wires are inserted between the first and the second layers, to prevent the strand becoming hexagonal in shape.
This construction is more flexible than a corresponding Standard construction and considerably more flexible than a corresponding Seale construction (with the same number of wires excluding filler wires). A Filler strand with e.g. 25 wires (including 6 filler wires) is known as (12-6F-6-1), i.e. one centre wire with six wires in the first layer and 12 wires in the second layer. There are six filler wires between the first and the second layers.
Betegnelsen for en Filler dugt med f.eks. 25 tråde (inkl. 6 fyldtråde) er (12-6+6F-1), dvs. 1 centertråd med 6 tråde i første lag og 12 tråde i andet lag. Mellem første og andet lag ligger 6 fyldtråde. Centertråden erstattes til tider af flere tråde (fig. 8) eller et fiberhjerte.
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Fig. 8
The centre wire may be replaced by several wires or a fibre core (fig. 8).
Warrington Warrington konstruktionen (fig. 9) er kendetegnet ved, at dugten består af to trådlag fremstillet i én operation. I andet lag (yderlag) indgår to forskellige tråddimensioner, og antallet af tråde i andet lag er dobbelt så stort som det første.
Warrington The Warrington construction (fig. 9) is characterised by a strand consisting of two layers of wire produced in one operation. The second (outer) layer contains wires of two dimensions, and the number of wires in the second layer is twice the number in the first.
Denne konstruktion er meget kompakt og bøjelig. Betegnelsen for en Warrington dugt med f.eks. 19 tråde er (6+6-6-1), dvs. 1 centertråd med 6 tråde i første lag og i alt 12 tråde fordelt på to tråddimensioner i andet lag. Centertråden erstattes til tider af flere tråde (fig. 10) eller et fiberhjerte.
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The centre wire may be replaced by several wires or a fibre core (fig. 10).
Fig. 9
5+5-5-1 Warrington
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This construction is very compact and flexible. A Warrington strand with e.g. 19 wires is known as (6+6-6-1), i.e. one centre wire with six wires in the first layer and a total of 12 wires of two dimensions in the second layer.
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6+6-6-1 Warrington
7+7-7-1 Warrington
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Andre dugttyper Som tidligere nævnt findes der også dugter, der er en kombination af én eller flere af ovenstående fire dugtgrundtyper. En af disse er Warrington Seale (fig. 11). Denne konstruktion er opbygget som en Warrington med et lag mere og Fig.10 hører til en af de mest udbredte. Desuden er den mest bøjelige konstruktion i sammenligning med de fire grundtyper.
Other Types of Strand As previously mentioned, there are also strands that are a combination of one or more of the above four basic types of strand. One of these is the Warrington-Seale (fig. 11). This construction is one of the most widely-used and most flexible constructions compared to the four basic types. The Warrington-Seale construction is characterised by a strand consisting of three layers of wire produced in one operation. The number of wires in the third (outer) layer matches the number of wires in the second layer. Also, the layers below the outer layer are built as a Warrington construction. Fig. 11 A Warrington-Seale strand with e.g. 36 wires is known as (14-7+7-7-1), i.e. one centre wire with seven wires in the first layer, 14 wires made up of two dimensions in the second layer, and 14 wires in the third layer.
Warrington Seale konstruktionen er kendetegnet ved, at dugten består af tre trådlag fremstillet i én operation. Antallet af tråde i tredje lag (yderlag) svarer til antallet af tråde i andet lag. Betegnelsen for en Warrington Seale dugt med f.eks. 36 tråde er (14-7+7-7-1), dvs. 1 centertråd med 7 tråde i første lag, 14 tråde fordelt på to tråddimensioner i andet lag og 14 tråde i tredje lag.
Dugten samt dugtens tråde behøver ikke nødvendigvis at være runde. Eksempler på dette ses af fig. 12. Dugterne er specialdugter (bl.a. med profiltråde) konstrueret til at opfylde helt spe- Fig. 12 cielle krav.
Triangular
The strands and the wires in the strands do not necessarily have to be round. Examples of this are shown in fig. 12. The strands are special strands (i.a. with profiled wire), designed to meet extremely unusual requirements.
Strand constructed of
Strand constructed of
Antal dugter wires including profiled wire profiled wire strand Antallet af dugter i et ståltov varierer fra 3 til ca. 36, mest almindeligt er 6 dugter. Desto flere dugter et Number of Strands ståltov indeholder, desto rundere og mere fleksibelt bliver ståltovet The number of strands in a steel wire rope varies between three and (mindre slidstyrke). approx. 36, although most commonly there are six strands. The more Hjertetype strands a steel wire rope contains, the more rounded and flexible it Som nævnt i afsnittet "Hjerte" findes der to typer hjerter til ståltove: is, although the wires in the strand are also thinner (less durable). · Fiberhjerte (natur- eller kunstfiber). Types of Core · Stålhjerte (WSC eller IWRC). As mentioned in section 1: "Core", there are two types of core for Fiberhjerte steel wire ropes: Fiberhjerte er det mest anvendte, da det udover at give dugterne et · Fibre core (natural or man-made). godt fjedrende underlag også muliggør smøring af ståltovet indefra, · Steel core (WSC or IWRC). idet der under fremstillingen af fiberhjertet kan tilsættes olie og/eller fedt. Desuden reduceres risikoen for rustangreb indefra. Fibre Core Fibre cores are the most commonly used, as not only do they provide a good, elastic base but also enable lubrication of the rope from the inside, since it is possible to add oil and/or grease to the fibre core during production.
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TEKNISK INFORMATION
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Fiberhjertet fremstilles normalt af Polypropylen (PP) eller Sisal. PP kan modstå svage syrer og alkalier, og det rådner ikke. Fordelen ved et sisalhjerte er, at det i større grad kan optage olie/fedt for smøring af ståltovet indefra, og at ståltovet kan anvendes ved en højere temperatur i forhold til PP-hjerte.
This reduces the risk of rust attacking from the inside. The fibre core is normally produced from polypropylene (PP) or sisal. PP can withstand weaker acids and alkalis and it does not rot. The advantage of a sisal core is that it can absorb oil/grease to a greater degree for lubrication of the steel wire rope from the inside.
Anvendelsestemperatur for ståltove med fiberhjerte ses af afsnittet "Ståltovets anvendelsestemperatur".
The maximum operating temperatures for steel wire ropes with a fibre core can be seen in section 9: "Maximum Operating Temperature" and " Minimum Operating Temperature".
Stålhjerte Et stålhjerte er udformet enten som en af dugterne (WSC) eller som et selvstændigt ståltov (IWRC). Randers Reb anbefaler at anvende stålhjerte, hvis det ikke er sikkert, at et fiberhjerte giver dugterne en tilfredsstillende understøtning, f.eks. hvis ståltovet opspoles på en tromle i flere lag under stor belastning eller ved høje temperaturer. Et stålhjerte forøger ståltovets brudstyrke med ca. 10%.
Steel Core A steel core is formed as either one of the strands (WSC) or as an independent steel wire rope (IWRC). Randers Reb recommends the use of a steel core, in the event that it is not certain that a fibre core will provide satisfactory support for the strands, e.g. if the steel wire rope is spooled on to a drum in several layers under a considerable load, or at high temperatures.
Slåningsretninger (ståltov og dugt) A steel core increases the steel wire rope's tensile strength by Ordet slåning bruges i flere betydninger. Dels om selve processen, approx. 10%. der snor tråde og dugter om hinanden, dels for at beskrive det færdige ståltovs udseende. De fire mest Lay Directions (Steel Wire Rope and almindelige betegnelser for ståltoves Strand) Fig. 13 slåninger er: The word "lay" has more than one meaning in this context. It is used to describe Højre krydsslået ståltov. Her er trådene the process of interweaving the wires i dugterne slået modsat retningen af and strands and also to describe the dugterne i tovet. Trådene ligger venstre appearance of the finished steel wire i dugterne, mens dugterne ligger i en rope. The four most common terms to højreskrue i ståltovet (se fig. 13). describe the lay of a steel wire rope are: Right hand regular lay steel wire rope
Venstre krydsslået ståltov. Trådene ligger højre i dugterne, mens dugterne ligger i en venstreskrue i ståltovet (se fig. 14).
Right hand regular lay steel wire rope. In this instance the wires in the strand are laid in the opposite direction to the strands in the rope. The wires are laid helically left, while the strands are laid helically right (see fig. 13).
Fig. 14
Højre Lang's Patent ståltov. Her er trådene i dugterne slået i samme retning som dugterne i tovet. Trådene i dugterne samt dugterne ligger i en højreskrue (se fig. 15). Left hand regular lay steel wire rope
Left hand regular lay steel wire rope. Here the wires in the strand are laid helically right, and the strands helically left (see fig. 14). Right hand Lang lay steel wire rope. Here the wires are laid in the same direction as the strands in the rope. The wires in the strands and the strands are laid helically right (see fig. 15).
Fig. 15
Right hand Lang lay steel wire rope
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Side 7
TEKNISK INFORMATION Venstre Lang's Patent ståltov. Trådene i dugterne samt dugterne ligger i en venstreskrue (se fig. 16). Fig. 16
Left hand Lang lay steel wire rope. The wires in the strands and the strands are laid helically left (see fig. 16).
Venstre Lang's Patent ståltov
Left hand Lang lay steel wire rope
Andre benævnelser er f.eks.: · Spiralslået ståltov (snoningssvagt/-frit ståltov). · Sildebensslået ståltov. Dette ståltov er en kombination af krydsslået og Lang's Patent. · Kabelslået ståltov. Dugterne er normalt 6-slåede ståltove med fibereller stålhjerte. Hjertet kan enten være et fiberhjerte eller et 6-slået ståltov med fiber- eller stålhjerte. · Krydsflettet ståltov. · Fladflettet ståltov. Dette ståltov er fladflettet af dugter eller af paral lelle dugter/ståltove, der er sammenholdt ved syning (bæltestrop). Højre slået ståltov kaldes også Z-slået og venstre slået S-slået. Tilsvarende kaldes en højreslået dugt z-slået og venstre slået sslået. Fig. 17 viser hvorfor. Af de nævnte slåninger er højre krydsslået (sZ) den mest almindelige.
Other terms used are e.g.: · Multi layer steel wire rope (low rotation/rotation resistant). Here there are usually two layers of strands, the inner layer as a rule a left hand Lang lay, while the outer layer is a right hand regular lay. · Alternate lay steel wire rope. This steel wire rope is a combination of regular lay and Lang lay. · Cable laid steel wire rope. The strands are normally 6-lay steel wire rope with a fibre or steel core. The core is a fibre core or a 6-lay steel wire rope with a fibre or steel core. · Square braided steel wire rope. The steel wire rope is square brai ded from strands or steel wire ropes. · Flat braided steel wire rope. This steel wire rope is flat braided from strands or consists of parallel strands or steel wire ropes that are bound together by sewing (belt strap).
Fig. 17
Right hand lay steel wire rope is also known as Z-lay, and left hand as S-lay. Similarly, a right hand lay strand is known as Z-lay and left hand as S-lay. Fig. 17 shows why.
Formlægning I formlagte ståltove har dugterne ved slåningen fået en blivende formændring (se fig. 18), således at de ligger fuldstændig spændingsfrie i det ubelastede ståltov.
Of the types of lay described, right hand regular lay is the most common.
Hvis man tager en dugt ud af ståltovet, vil dugten bevare sin skrueliniefacon, som den havde, da den lå i ståltovet. Z-lay and S-lay steel wire ropes
Fordelene ved et formlagt ståltov er mangfoldige. Bl.a.: · Ved kapning springer ståltovet ikke op. · Lettere at installere, da formlagte ståltove er spæn dingsfrie (døde) - herved ingen tendens til kinkedannelse. · Kan løbe over mindre skiver. · Mindre tilbøjelighed til at dreje omkring sin egen akse - herved mindre slid. · Bedre fordeling af belastningen mellem dugter og tråde. · Ved trådbrud har trådene mindre tilbøjelighed til at rejse sig fra dugten - herved mindre tilbøjelighed til at ødelægge nabotråde og skiver.
Pre-forming
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Pre-Forming "Pre-formed" refers to steel wire ropes in which the strands have been permanently formed during the laying process (see fig. 18), so that they are completely stress-free within the unloaded steel wire rope. If a strand is removed from the steel wire rope, it will retain its helical shape, as though it were still in the steel wire rope. There are many advantages in a pre-formed steel wire rope, such as:
Fig. 18
Alt i alt opnår man en længere levetid med formlagte ståltove i forhold til ikke formlagte ståltove.
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· The steel wire rope will not untwist during cutting. · It is easier to install, as pre-formed steel wire ropes are stress-free. No tendency to form kinks. · It can run over smaller sheaves. · Less tendency to turn on its own axis. Less wear and tear. · Better load distribution between strands and wires. · In the event of a wire breaking, less tendency to protrude from the strand. Less tendency to damage adjacent wires and sheaves.
All in all, pre-formed steel wire ropes can offer a longer life expectancy than steel wire ropes that are not pre-formed.
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TEKNISK INFORMATION Alle Randers Reb ståltove leveres formlagte som standard - på nær nogle enkelte specialkonstruktioner (f.eks. rotationssvage/-frie tove).
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All Randers Reb steel wire ropes are supplied pre-formed, with the exception of certain individual special constructions (e.g. low-rotation/rotation resistant).
3. SPECIELLE STÅLTOVE 3. SPECIAL STEEL WIRE ROPES Som det fremgår af det forudgående er opbygningen/designet af ståltove mangfoldig, hvorfor det er muligt at designe et ståltov, der opfylder specielle krav til anvendelsen. Randers Reb er specialist i at udvikle specielle ståltove, der opfylder netop dine specielle krav. Kontakt os og forhør om mulighederne. Gennem tiderne har Randers Reb fremstillet/udviklet mange specielle ståltove. Nogle af disse ståltove har vi optaget i vores standard program.
As has previously been mentioned, there are many types of construction/design of steel wire ropes, which is why it is also possible to design a steel wire rope that meets the particular requirements for a given application. Randers Reb has specialised in the development of special steel wire ropes that can meet such special requirements. Get in touch with us and find out how we can help solve your problems. Through the years Randers Reb has produced/developed many special steel wire ropes. Some of these special steel wire ropes are now part of our standard product range.
· Compacted ståltov. · Kabelslået ståltov. · Rotationssvage/-frie ståltov. · Forhudet ståltov. · Taifun. · Bloktov. · Ormtov.
· Compacted steel wire rope. · Cable lay steel wire rope. · Low rotation and rotation resistant steel wire rope. · Coated steel wire rope. · Combination rope. · Sisal/Danline clad wire rope. · Cobra.
Compacted ståltov Før slåningen af selve ståltovet bliver dugternes dimension reduceret (compacted), se fig. 19. Der findes forskellige metoder til at reduceFig. 19 re dugtens dimension:
Compacted Steel Wire Rope In compacted steel wire ropes the strand's dimensions are reduced (compacted) before the actual laying of the steel wire rope. There are different ways of reducing the dimension of a strand: I enkelte tilfælde udføres compacteringen først, · By drawing between rollers (compacting). når ståltovet er slået. Herved bliver kun den yder· By drawing between dies (Dyform). ste del af ståltovet compacted. Compacted steel wire rope with fibre core · By beating (hammering). · Trække gennem ruller (Compacting). · Trække gennem dyser (Dyform). · Hamre (Hammering).
De forskellige metoder giver ikke helt samme kvalitet. Den proces der efter Randers Reb's mening giver den bedste kvalitet er trækning af dugter gennem ruller (compacting), hvorefter slåningen af ståltovet foretages.
In individual cases the compacting process is only carried out after the steel wire rope has been laid. In this instance only the outer part of the steel wire rope is compacted (fig. 19).
Compactede ståltove har større slid- og brudstyrke i forhold til ikke compactede ståltove i samme dimension.
The various methods do not all produce the same level of quality. In the opinion of Randers Reb, the best quality is achieved by drawing the strands between rollers, after which the laying process is carried out.
Kabelslået ståltov I et kabelslået ståltov består dugterne af et 6-slået ståltov med WSC (f.eks. 6x7 + WSC eller 6x19 + WSC). Hjertet i det kabelslåede ståltov kan enten være FC eller IWRC (se fig. 20).
Compacted steel wire ropes have greater abrasion resistance and tensile strength than corresponding non-compacted steel wire ropes.
Det samlede antal tråde i en 6x(6x19 + WSC) + IWRC er 931 tråde. De mange tråde bevirker, at ståltovet er utroligt smidigt/fleksibelt og gør det meget velegnet til stropper.
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Cable Laid Steel Wire Rope In a cable laid steel wire rope the strands consist of a 6-lay steel wire rope with WSC (e.g. 6x7 + WSC or 6x19 + WSC). The core in the cable laid steel wire rope can be either FC or IWRC.
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Fig. 20 A 6x(6x19 + WSC) + IWRC contains a total of 931 wires. The high number of wires has the effect of making the steel wire rope incredibly pliable/flexible and thus ideal for slings.
Cable laid steel wire rope
Rotationssvagt/-frit ståltov Ved et rotationssvagt/-frit ståltov forstås et specielt ståltov, der er designet til ikke at dreje op eller rotere, når det belastes (se fig. 21 og 22). Fig. 21
Low-Rotation and Rotation-Resistant Steel Wire Rope A low-rotation or rotation-resistant steel wire rope is a special steel wire rope designed not to turn or rotate when bearing a load. Fig. 22
Examples of low-rotation and rotation-resistant steel wire ropes
Der leveres to typer af rotationssvage/-frie ståltove:
Examples of rotation in ordinary steel wire rope and in low-rotation and rotation-resistant steel wire ropes
· Ståltove med ét lag dugter. Antallet af dugter er normalt tre. Ståltovet er uden hjerte eller med et fiberhjerte.
There are two types of low-rotation and rotation-resistant steel wire ropes available:
· Ståltove med to eller flere lag dugter (spiralslået). Antallet af yder dugter er normalt mellem 8 og 20. Hjertet kan være af fiber eller stål.
· One layer of strands. There are three or four strands. The steel wire rope has either no core or a fibre core. · Spiral lay, i.e. two or more layers of strands. The number of outer strands is normally between eight and 20. The core may be either fibre or steel.
Disse ståltove anvendes normalt i enstrengede anlæg eller som flerstrenget ved tunge byrder og/eller store løftehøjder. Det specielle design gør, at anvendelsesmulighederne for tovene er begrænsede. Desuden kræves specielle håndteringskrav f.eks.: · Større skiver end ved normale ståltove. · Mindre fladetryk. · Optimale spor i skiver. · Lille indløbsvinkel på spil. · Helst ét lag på spiltromlen. · Anvendelse af svirvler ofte nødvendigt. · Større sikkerhedsfaktor. · Ståltovene er normalt ikke formlagte, hvorfor disse skal brændes over (tilspidses) eller takles før overskæring for at undgå, at ståltovet springer op og ødelægger balancen i ståltovet. · Under installationen skal man være meget opmærksom på, at der ikke tilføres ståltovet spændinger, f.eks. hvis tovet drejes/twistes.
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These steel wire ropes are normally used in single-strand units, or in multi-strand units for heavy loads and/or significant lifting heights. The special design results in limited applications for this type of rope and imposes special handling requirements, such as: · Larger sheaves than for normal steel wire ropes. · Less surface pressure. · Optimal grooves in sheaves. · Small fleet angle on winch. · Preferably one layer on the drum. · Use of swivels is often necessary. · Increased safety factor. · The steel wire ropes are normally not pre-formed. Consequently the wire rope has to be seized before cutting (alternatively welded ends) to avoid the steel wire rope unwinding (destroying the balance in the rope).
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Hvis du er i tvivl om anvendelsen af rotationssvage/-frie ståltov, så kontakt din konsulent eller vores tekniske afdeling.
· During installation great care must be taken not to subject the steel wire rope to tension, e.g. caused by turning/twisting.
Forhudet ståltov Ved et forhudet ståltov forstås et ståltov, der er belagt (coated) med et plastmateriale f.eks. PP, PE, PVC eller PA alt efter anvendelsesområde (se fig. 23).
If you are in any doubt as to the use of low-rotation and rotationresistant steel wire ropes, please contact your local salesman or our Technical Department. Fig. 23
Coated Steel Wire Rope A coated steel wire rope is one that has been coated with a plastic material such as PP, PE, PVC or PA, depending on its intended application (fig. 23).
Forhudningen beskytter ståltovet mod rust og slid. Andre fordele er f.eks., at levetiden ved kørsel over skiver forlænges væsentligt. Desuden vil eventuelle trådbrud ikke ødelægge ting, som ståltovet kommer i nærheden af. Taifun Taifun er Randers Reb's handelsbetegnelse for et specielt ståltov, hvor ståldugterne er omviklet med fibergarner (se fig. 24). Taifuner fremstilles med FC eller IWRC.
Coated Steel Wire Rope
Taifunen anvendes primært som forstærkning i fiskenet, men kan også anvendes til gyngetove, klatrenet og hvor der i industri eller landbrug bl.a. stilles specielle krav til slidstyrken.
Combination Rope Taifun is Randers Reb's trade name for a special combination rope, in which the steel strands are wrapped up in fibre threads. Combination rope is produced with FC or IWRC.
Fig. 24
Taifuner forener egenskaber fra fibertove og ståltov: Styrke og lille forlængelse fra ståltovet, "blød" overflade og fleksibilitet fra fibertovet.
Combination rope with FC
Taifuner fremstilles normalt som et 6-slået tov, men kan også laves med 3, 4 eller 8 dugter. Bloktov Bloktov er Randers Reb's handelsbetegnelse for et specielt ståltov, hvor ståldugterne er omviklet dels med fibergarner (Danline), dels med sisalgarner. Bloktovet fremstilles primært med FC (se fig. 25), men kan også fremstilles med IWRC. Sisalgarnerne udvider sig, når de bliver våde, hvorved Bloktovet i større grad kan fastholde ting/emner, der er bundet til tovet. Ellers har Bloktovet samme egenskaber som Taifunen.
Sisal/Danline clad wire rope
Bloktove fremstilles normalt som et 6-slået tov, men kan også laves med 3, 4 eller 8 dugter. Ormtov Ormtov er Randers Reb's handelsbetegnelse for et specielt kabelslået ståltov, hvor dugterne er et 6-slået tov med FC. Tre af dugterne er af stål og de resterende tre dugter er af fiber. Ormtovet fremstilles primært med FC (se fig. 26), men kan også fremstilles med IWRC.
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Combination rope combines the properties of fibre ropes and steel wire ropes: The strength and minimal elongation of the steel wire rope, and the "soft" surface and flexibility of the fibre rope. Combination rope is used primarily for strengthening fishing nets, but may also be used for swings, climbing ropes and for applications in industry/farming that require particularly durable ropes.
Fig. 25
Bloktove anvendes som forstærkning i fiskenet.
The coating protects the steel wire rope against rust and wear and tear. Other advantages are e.g. that its life expectancy when running over the sheaves is increased significantly. Furthermore, any wires that might break will not cause damage to objects in the proximity of the steel wire rope.
Sisal/Danline clad wire rope Sisal/Danline clad wire rope is a special steel wire rope in which the steel strands are wrapped in a combination of fibre threads (Danline) and sisal threads. Sisal/Danline clad wire rope is produced primarily with FC, but can also be produced with IWRC.
The sisal threads expand when wet, causing the Sisal/Danline clad wire rope to have increased ability to secure objects/materials that are tied to the rope. In other respects the Sisal/Danline clad wire rope has the same properties as the combination rope. Fig. 26
Cobra
The Sisal/Danline clad wire rope is used to strengthen fishing nets. Cobra Cobra is Randers Reb's trade name for a special spring lay wire rope in which the strands are 6-lay rope with FC. Three of the strands are steel, and the other three strands are fibre rope. Cobra is produced
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Den specielle opbygning af dugterne gør, at tovet har en noget større brudforlængelse end almindelige ståltove og Taifuner, hvilket gør Ormtovet velegnet som træktove på slæbebåde.
primarily with FC, but can also be produced with IWRC. The special construction of the strands means that the rope has a greater tensile elongation than standard steel wire ropes and combination rope, which makes Cobra ideal as a mooring rope on a tug boat.
4. EKSEMPLER PÅ ANVENDELSE AF STÅLTOVE
4. USE OF STEEL WIRE ROPE
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Fig. 27
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5. VALG AF DET RETTE STÅLTOV
5. SELECTING THE RIGHT STEEL WIRE ROPE
Ved valget af det rette ståltov til et givent formål skal der tages hensyn til de forskellige ståltoves egenskaber, som f.eks.:
In selecting the right steel wire rope, the properties of the various types of steel wire rope must be considered, e.g.:
· Brudstyrke. · Slidstyrke. · Fleksibilitet/bøjningsudmattelsesstyrke. · Korrosionsmodstand. · Forlængelse. · Rotationsmodstand. · Knusningsmodstand. · Vibrationsudmattelsesstyrke. · Pulsationsudmattelsesstyrke. · Krydsslået eller Lang's Patent.
· Tensile strength. · Abrasion resistance · Bending fatique resistance · Corrosion resistance. · Elongation. · Rotation resistance. · Crushing resistance. · Vibration resistance. · Pulsation resistance. · Regular lay or Lang lay.
Ved udvælgelsen af det rette ståltov er det vigtigt at fastlægge, hvor vigtige de forskellige egenskaber er for anvendelsen og derefter få dem prioriteret. Desuden er det også vigtigt, at man er opmærksom på relevante standarder og regulativer.
In selecting the right steel wire rope, it is important to determine how important the various properties are in relation to the application and then to assign priorities to these. It is also important to be aware of the relevant standards and regulations. If you are in any doubt, please contact our sales consultants or our Technical Department.
Hvis du er i tvivl, så kontakt din konsulent eller vores tekniske afdeling. Brudstyrke Brudstyrken på ståltovet afhænger af tovets dimension, trådbrudstyrke og konstruktion. Minimum garanteret brudstyrke for de forskellige tovtyper er angivet på vores datablade.
A steel wire rope should never be subjected to a load exceeding 50% of its breaking load.
Belast aldrig et ståltov til mere end 50% af brudstyrken. Selve designet af dugterne påvirker ikke brudstyrken væsentligt (max. ca. 5%). En ændring af hjertetypen fra fiber til stål giver lidt større ændring (ca. 10%). Den største ændring fås ved at ændre dimension eller trådbrudstyrke (se også fig. 28). Ståltove må kun belastes til en given SWL-værdi (Safe Working Load), også kaldet WLL-værdi (Working Load Limit). Hermed forstås ståltovets brudstyrke divideret med den for anvendelsen krævede sikkerhedsfaktor (se tabel 1). Tabel 1
Forskellige sikkerhedsfaktorer De angivne faktorer er kun vejledende
Jan 2002
The design of the steel wire rope does not significantly affect the tensile strength (up to approx. 5%). A change of core from fibre to steel makes slightly more difference (approx. 10%). The greatest change is achieved by changing the dimensions or the tensile strength of the wires (see also fig. 28). It is often required that the steel wire rope must have a specific SWL value (Safe Working Load), also known as a WLL value (Working Load Limit). This means the steel wire rope's tensile strength divided by the safety factor required for the relevant application.
Table 1 Various safety factors. NB: These factors are only intended as guidelines
Til mange formål er der udarbejdet nationale og internationale normer og standarder, der fastsætter minimumskravet til sikkerhedsfaktoren.
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Tensile Strength The tensile strength of the steel wire rope depends on the rope's dimensions, the tensile strength of the wires and the construction. The minimum guaranteed tensile strength for the different kinds of rope is shown in the Randers Reb product catalogue.
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NB: There are a number of national and international norms and standards that define the minimum requirements for the safety factor.
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TEKNISK INFORMATION Slidstyrke Ståltove med tykke ydertråde (f.eks. 6x7 Standard eller 6x19 Seale) giver en god slidstyrke. Lang's Patent tove giver bedre slidstyrke end krydsslåede ståltove (se også fig. 28). Desuden kan slidstyrken øges ved at anvende større trådbrudstyrke. Bøjningsudmattelsesstyrke Desto flere tråde der er i dugten, desto større bliver bøjningsudmattelsesstyrken og fleksibiliteten. Lang's Patent tove giver bedre bøjningsudmattelsesstyrke end krydsslåede ståltove. Desuden kan bøjningsudmattelsesstyrken øges ved at anvende formlagte ståltove (se også fig. 28). Korrosionsmodstand Galvaniserede og rustfrie tråde giver en glimrende beskyttelse mod korrosion. Indfedtning med specielle fedt- eller olietyper vil også øge korrosionsmodstanden. Hvis ståltovet er udsat for kraftig korroderende påvirkning, anbefales det at anvende dugter med tykke ydertråde. Forlængelse Ståltove med få tråde (f.eks. 1x7 Standard og 1x19 Standard) forlænger sig mindst (har størst elasticitetsmodul). Denne type ståltov er velegnet til barduner, men egner sig ikke til at køre over skiver/blokke. Hvis der ønskes lille forlængelse samtidig med kørsel over skiver, bør ståltovsklasse 6x7 eller 6x19 (begge med stålhjerte) eller visse specialkonstruktioner anvendes. Ved større ståltovsdimensioner kan ståltovsklasse 6x36 med stålhjerte også anvendes (se også afsnittet "Ståltovsforlængelse"). Rotationsmodstand Almindelige 6- og 8-slåede ståltove vil dreje op, når de hænger frit under belastning. Krydsslåede ståltove giver mere modstand mod opdrejning end Lang's Patent ståltove. Et ståltov med stålhjerte drejer mindre end et ståltov med fiberhjerte. Den type ståltove, der har størst modstand mod opdrejning, er rotationsfrie/-svage ståltove (specialkonstruktioner, se også afsnittet "Rotationssvagt/-frit ståltov). Knusningsmodstand Et stålhjerte giver bedre understøtning til dugterne end et fiberhjerte, hvorfor risikoen for fladtrykning er mindre på et ståltov med stålhjerte. Dugter med tykke og få tråde har større modstand mod fladtrykning/knusning. Desuden har et 6-slået ståltov større knusningsmodstand end et 8-slået (se også fig. 27). Vibrationsudmattelsesstyrke Vibrationer, hvor end de kommer fra, sender chokbølger gennem og absorberes af ståltovet, hvorved der er mulighed for lokalt at ødelægge ståltovet (ikke nødvendigvis udvendigt på ståltovet). Der er her tale om steder, hvor f.eks. ståltovet har kontakt med en skive/blok eller går ind på spiltromlen eller ved fastgørelsen.
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Abrasion resistance Steel wire ropes with thick outer wires (e.g. 6x7 Standard or 6x19 Seale) provide good abrasion resistance. Lang lay ropes provide better abrasion resistance than regular lay steel wire ropes (see also fig. 27). Abrasion resistance can also be increased by using wires with greater tensile strength. Bending fatique resistance The greater the number of wires in the strand, the greater the bending fatique resistance and flexibility. Lang lay ropes provide better bending fatique resistance than regular lay steel wire ropes. Bending fatique resistance can also be increased by using pre-formed steel wire ropes (see also fig. 28). Corrosion Resistance Galvanised and rustproof wires provide excellent protection against corrosion. Lubrication with special types of grease or oil will also increase resistance to corrosion. If the steel wire rope is subjected to significant corrosive influences, it is recommended that strands with thick outer wires are used. Elongation Steel wire ropes with fewer wires (e.g. 1x7 Standard and 1x19 Standard) are subject to the least elongation (have the greatest elasticity modulus). This type of steel wire rope is ideally suited for guy ropes, but is not suitable to be run over sheaves/blocks. If only a small degree of elongation when running over sheaves is required, 6x7 or 6x19 steel wire rope should be used, in each case with a steel core or with certain special constructions. For larger dimensions, 6x36 steel wire rope with a steel core can also be used. Rotation Resistance Standard 6-lay and 8-lay steel wire ropes will rotate when they hang free and carry a load. Regular lay steel wire rope provides greater resistance to rotation than lang lay steel wire rope. A steel wire rope with a steel core rotates less than a steel wire rope with a fibre core. The type of rope that provides greatest resistance to rotation is, as the name suggests, low-rotation and rotation-resistant steel wire rope (special constructions, see also section 3:"Low-Rotation and Rotation-Resistant Steel Wire Rope"). Crushing resistance A steel core provides better support for the strands than a fibre core, which is why the risk of flattening is less in a steel wire rope with a steel core. Strands with fewer, thicker wires have greater resistance to flattening/crushing. Also, a 6-lay steel wire rope has greater crushing resistance than an 8-lay rope (see also fig. 28). Vibration resistance Vibrations, from wherever they might come, send shock waves through the steel wire rope, which will be absorbed by the steel wire rope at some point, and in some cases they may cause localised destruction of the steel wire rope (not necessarily on the outside).
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TEKNISK INFORMATION Generelt har ståltove med størst fleksibilitet også størst vibrationudmattelsesstyrke. Pulsationsudmattelsesstyrke Vekslende træk i et ståltov vil nedsætte levetiden på ståltovet, dog afhængigt af kraften og frekvensen.
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This may, for example, be at places where the steel wire rope comes into contact with a sheaf/block, or enters the drum, and by the end terminals. In general, those steel wire ropes with the greatest flexibility also have the greatest vibration resistance.
Generelt kan ståltove med størst fleksibilitet bedre optage den pulsePulsation resistance rende belastning. Man bør være meget opmærksom på, hvilke endeChanges in the tension of a steel wire rope, depending on the size terminaler eller fittings der anvendes, idet disses pulsationsudmatteland frequency, will reduce the rope's life expectancy. sesstyrke er lige så vigtige som valget af det rette ståltov. Fig. 28
Abrasion resistance, crushing resistance, tensile strength and bending fatique resistance of various steel wire ropes Forskellige ståltovs slidstyrke, knusningsmodstandsevne, brudstyrke, bøjningsudmattelsesstyrke Krydsslået eller Lang's Patent Lang's Patent ståltove er den ståltovstype, der bedst kan tåle at køre over skiver samt har den bedste slidstyrke. Men for at kunne anvende et Lang's Patent ståltov kræves tre ting: · Ståltovet skal være låst i begge ender, da det ellers vil dreje op. Ståltovet har næsten ingen modstand mod opdrejning. · Ståltovet må kun køre op i ét lag på spiltromlen, da det ellers let ødelægger sig selv. · Ståltovet må ikke køre over små skiver, da konstruktionen herved kommer i ubalance.
Fig. 29
In general, steel wire ropes with the greatest flexibility can cope better with intermittent loading. Great care should be taken in the use of end terminals or fittings, as their pulsation resistance is equally as important as the selection of the right steel wire rope. Regular Lay or Lang Lay Lang lay steel wire ropes are the ones most suited to running over sheaves and are the most durable, but if they are to be used, three things must be observed: - Lang lay steel wire ropes must be secured at both ends, otherwise the rope will rotate. The steel wire rope has no resistance to rotation. · Lang lay steel wire ropes may only be reeled on to the drum in a single layer, as they can easily destroy themselves. · Lang lay steel wire ropes may not run over small sheaves, as the construction will become unbalanced.
Wear marks on a regular lay (on the left) and a Lang lay (on the right) steel wire rope respectively
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TEKNISK INFORMATION Lang's Patent ståltoves gode slid- og bøjeegenskaber skyldes, at trådene påvirkes/belastes anderledes og har en større bæreflade end krydsslåede ståltove (se fig. 29). Slidmærker på henholdsvis krydsslået (til venstre) og Lang's Patent (til højre) ståltov
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The reason for Lang lay steel wire ropes' excellent qualities of abrasion resistance and pliability is that the wires are affected/loaded in a different way and have a larger load-bearing surface than a regular lay steel wire rope (see fig. 29). Note that the largest wearing surface is on the Lang lay steel wire rope.
Den største slidflade er på Lang's Patent slået ståltov. 6. BESTILLING AF STÅLTOVE
6. ORDERING STEEL WIRE ROPE
Ved bestilling af ståltove er det vigtigt at gøre beskrivelsen af ståltovet så nøjagtig som mulig. En korrekt bestilling bør indeholde følgende:
When ordering steel wire rope, it is important to describe the steel wire rope as accurately as possible. A correct order should contain the following information: Description of steel wire rope:
· Diameter. · Konstruktion. · Slåningsretning. · Slåningstype. · Hjerte. · Trådbrudstyrke og/eller ståltovets brudstyrke. · Tråd overfladebeskyttelse (galvaniseret/ugalvaniseret). · Indfedtningstype. · Længde. · Specielle tolerancekrav. · Antal enheder. · Bearbejdning af ståltovsenderne (endebefæstigelser). · Emballage (kvejl, kryds, tromler mm.).
· Diameter. · Construction. · Direction of lay. · Type of lay. · Core. · Wire tensile strength. · Surface protection of wire (galvanised/ungalvanised) · Type of lubrication. · Length. · Quantity. · Processing of steel wire rope ends (end fittings). · Packaging (coil, crosses, reels, etc.).
Kontakt os, hvis du er i tvivl om, hvilken type ståltov der skal anvendes.
If you are in any doubt as to the type of steel wire rope to be used, please contact us and we will try to find the best solution.
Hvis slåningsretning og/eller specifik hjertetype ikke er aftalt mellem kunde og Randers Reb, leverer Randers Reb et kryds højreslået ståltov med en hjertetype, der er standard for Randers Reb. Typen vil fremgå af ordrebekræftelsen.
If the direction of lay and/or specific type of core is not agreed between the customer and Randers Reb, Randers Reb will supply a right hand regular lay steel wire rope with a core type that is standard for Randers Reb. This will be indicated on the order confirmation form.
7. STÅLTOVSTOLERANCER 7. STEEL WIRE ROPE TOLERANCES Længdetolerancer Indtil 400 m: Over 400 m og til og med 1.000 m: Over 1.000 m:
- 0 + 5%. - 0 + 20 m. - 0 + 2%.
Hvor der kræves mindre længdetolerancer, skal dette specificeres i ordren.
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Length Tolerances Up to 400 m: Over 400 m up to and including 1,000 m: Over 1,000 m:
- 0 + 5% - 0 + 20 m - 0 + 2%
For steel wire ropes requiring smaller length tolerances, agreement must be reached between the customer and Fyns Kran Udstyr.
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TEKNISK INFORMATION Dimensionstolerancer og ovalitet
Tabel 3
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Dimension tolerances and ovalness
Dimensionstolerancer og ovalitet på ståltove Dimension tolerances and ovalness of steel wire ropes
Ovenstående er gældende, hvis intet andet er aftalt mellem kunde og Fyns Kran Udstyr eller angivet på datablad. Værdierne er baseret på et forslag til EN-norm. Randers Reb arbejder i øjeblikket på at tilpasse alle ståltove dette forslag. Måling af ståltovsdimension og ovalitet se afsnittet "Kontrol af dimensionen". Vægttolerancer De i katalogbladene angivne vægte er teoretiske værdier. Vægttolerancen er ca. +/- 5%.
NB: The above figures apply unless otherwise agreed between the customer and Fyns Kran udstyr, or otherwise specified on a data sheet. The values are based on a proposed EN standard. Randers Reb is currently working on adapting all steel wire ropes to conform to this proposal. Measurement of steel wire rope dimension and ovalness. (See section:"Inspection of Dimensions"). Weight Tolerances The weights mentioned in the catalogue are theoretical values. The weight tolerance is approx. ± 5%.
8. HÅNDTERING OG INDKØRING 8. HANDLING, INSPECTION AND INSTALLATION Modtagelse, kontrol og opbevaring Ved modtagelsen kontrolleres om produktet svarer til det bestilte. Hvis ståltovet ikke skal anvendes med det samme, skal ståltovet opbevares tørt. Ved længere tids opbevaring skal man ind imellem kontrollere, om ståltovet skal eftersmøres (se også afsnittet "Vedligeholdelse af ståltovet"). Kontrol af dimensionen Inden installeringen skal dimensionen på ståltovet kontrolleres og dimensionen skal passe til det udstyr, som ståltovet skal anvendes i (se også afsnittet "Dimensionstolerancer og ovalitet"). Korrekt måling af dimensionen (ISO 3178) foretages med skydelære,
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Receiving, Inspection and Storage On receipt the product should be inspected to confirm that it corresponds to the one ordered. If the steel wire rope is not to be used immediately, it must be stored in a dry place. If it is to be stored for a longer period, it must be checked regularly to determine whether it requires lubrication (see also section: "Maintenance of Steel Wire Rope"). Inspection of Dimensions It is important that the steel wire rope's dimension is checked before installation, and that it is checked that the dimension matches the equipment with which the steel wire rope is to be used (see also section 7: "Dimension Tolerances and Ovalness").
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TEKNISK INFORMATION der er forsynet med brede kæber, der skal dække over mindst to dugter (se fig. 31). Målingen foretages to steder med mindst en meters afstand på et lige stykke uden belastning. Hvert sted foretages to målinger 90° forskudt. Gennemsnittet af disse fire målinger angiver diameteren på ståltovet. Ståltovets ovalitet er største forskel mellem de fire målinger angivet som % af ståltovets nominelle diameter.
Fig. 31
Correct measurement of dimensions (ISO 3178) is undertaken with a calliper gauge equipped with a broad enough jaw to cover at least two strands (see fig. 31).
Korrekt udstyr og måling af ståltov Correct equipment and measurement of steel wire rope
Kontrol af føringsudstyr Inden ståltovet monteres, er det vigtigt at sikre sig, at alle dele, som ståltovet kommer i kontakt med, er i orden og passer til ståltovet. Ting som f.eks.: · Spiltromle. · Afstand mellem spiltromle og første skive/ledeskive. · Styreruller. · Skiver. Hvis udstyret ikke er i orden, er der stor risiko for, at ståltovet får et unormalt stort slid og derved en kort levetid. Spiltromle Undersøg om tromledimensionen og eventuelle tovriller passer til ståltovet samt standen af tromlen. Randers Reb anbefaler, at korrekte riller på tromlen skal have følgende udseende (se fig. 32): B = rillediameter = 1,06 x d. A = stigningen på rillesporet = 1,08 x d. C = rilledybden = 0,30 x d. R = topradius = ca. 0,15 x d.
Inspection of Guidance Equipment Before the steel wire rope is fitted, it is important to ensure that all parts that will come into contact with the steel wire rope are in good condition and match the steel wire rope, e.g.: · Drum. · Distance between drum and first sheaf or lead sheaf. · Guide roll. · Sheaves. If the equipment is not suitable, there is a significant risk that the steel wire rope will suffer unusually great wear and tear and will thus have a shorter life expectancy. Drum Check that the drum dimensions and possible rope grooves match the steel wire rope, and check the condition of the drum.
B = diameter of groove = 1.06 x d A = elevation of groove = 1.08 x d C = depth of groove = 0.30 x d R = upper radius = approx. 0.15 x d
Hvis tovrillerne ikke passer til ståltovet, får ståltovet et unormalt stort slid og der tilføres spændinger.
Fig. 32
where d = steel wire rope's nominal diameter If the rope grooves do not match the steel wire rope, the rope will suffer unusually high wear and tear, stresses will be introduced and the grooves will have to be repaired.
Vær opmærksom på, at der ofte stilles specielle krav til tromlediameter m.m. i normer og standarder. Levetiden på ståltovet er bl.a. meget afhængig af dimensionen på tromlen. Desto større tromle, desto længere levetid (se også afsnittet "Skiver og blokke").
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The measurement is undertaken at two places at least one metre apart on a straight section without any load. At each place two measurements are made at 90° angles. The average of these four measurements defines the diameter of the steel wire rope. The degree of ovalness in the steel wire rope is the greatest difference between the four measurements, expressed as a percentage of the nominal diameter of the steel wire rope.
Randers Reb recommends that correct rope grooves are as follows:
hvor d = ståltovets nominelle diameter.
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Please note that norms and standards often impose special requirements in respect of drum diameters, etc. The steel wire rope's life expectancy depends to a great extent on the drum's dimensions, among other things. The larger the drum, the longer the life expectancy (see also section 6: "Sheaves/Blocks").
Rope grooves on the drum
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Afstand mellem spiltromle og første skive/ledeskive Distance between Drum and First Sheaf or Lead Sheaf Afstanden fra spillet til den første skive eller ledeskive har betydning The distance from the winch to the first sheaf is of importance for the for ensartetheden af opspolingen samt utilsigtet tilførsel af spændingconsistency of the winding process. er i ståltovet. Fig. 33 Randers Reb recommends that Randers Reb anbefaler, at afstanden L eller indløbsvinklen b skal være (se fig. 33):
the distance L or the fleet angle ß should be:
· For tromler uden sporriller: Lmax = 115 x tromlebredde.
- For drums without rope grooves: Lmin = 115 x drum width.
Lmin = 15 x tromlebredde. · For tromler med sporriller : Lmax = 115 x tromlebredde.
Lmax = 15 x drum width. - For drums with rope grooves Lmin = 115 x drum width.
Lmin = 20 x tromlebredde.
Distance between drum and lead sheaf (L), and fleet angle (ß)
(115 x tromlebredde ~ b = 0,25°, 15 x tromlebredde ~ b = 2° og 20 x tromlebredde ~ b = 1,5°). Hvis afstanden ikke passer, får ståltovet et unormalt stort slid, hvorfor afstanden skal ændres. Styreruller Undersøg om styreruller er slidt, f.eks. på spillet. Hvis de er, får ståltovet et unormalt stort slid, hvorfor styrerullen skal udskiftes eller repareres. Hvis styrerullen repareres ved svejsning, skal man sørge for, at hårdheden på svejsematerialet er ca. 300 Brinel, således at man få sliddet på styrerullen i stedet for på ståltovet. Skiver/blokke Undersøg om skivediameteren og skivespor passer til ståltovet. Desuden skal skiverne let kunne dreje. Når et ståltov bøjes over f.eks. en skive, opstår der nogle ret komplicerede spændinger (kombination af bøje-, træk- og trykspændinger) i trådene. De største spændinger forekommer i de tråde, der ligger længst væk fra ståltovets bøjningscenter. Efter gentagede bøjninger vil der opstå udmattelsesbrud i disse tråde. Hvornår der opstår udmattelsesbrud i trådene afhænger bl.a. af konstruktionen, belastningen samt hvor store skiverne er. Nedenstående kurve (fig. 34) viser skiveforholdet DSk/d (skivediameter/ståltovsdiameter) indflydelse på ståltovets levetid for forskellige ståltovskonstruktioner.
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Lmax = 20 x drum width.
(115 x drum width ~ ß = 0.25º, 15 x drum width ~ ß = 2º, and 20 x drum width ~ ß = 1.5º). If the distance does not match these figures, the steel wire rope will be subject to unusually significant wear and tear; the distance should therefore be changed. Guide Rolls Check whether the guide rolls, e.g. those on the winch, are worn. If they are, the steel wire rope will be subject to unusually significant wear and tear; the guide rolls should therefore be replaced or repaired. If the guide roll is repaired by welding, care should be taken to ensure that the hardness of the welding material is approx. 300 Brinel, and that it is the guide roll that is worn, and not the steel wire rope. Sheaves/Blocks Check that the sheaf diameter and sheaf groove match the steel wire rope. The sheaves must also be able to turn freely. When a steel wire rope is fed over e.g. a sheaf and bends, certain complex tensions (a combination of bending, tensile and compression stress) are generated in the wires. The greatest tensions occur in the wires furthest away from the steel wire rope's bending centre. After repeated bends, stress failure will occur in these wires. The steel wire rope construction and the size of the sheaves are decisive in determining when wire fracture occurs. The curve below shows the influence of the D/d ratio (sheaf diameter/nominal steel wire rope diameter) on the life expectancy of steel wire rope of different types.
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Levetidsfaktor
Fig. 34
Skiveforholdet DSk/d
Ståltovets levetid som funktion af skiveforholdet DSk/d (skivediameter/ståltovsdiameter) for div. konstruktioner
Life expectancy of steel wire rope of different types expressed as a function of the D/d ratio (sheaf diameter/steel wire rope diameter
Vær opmærksom på, at der ofte stilles specielle krav til skive-/tromlediameter i normer og standarder. Hvis dette ikke er tilfældet, anbefales minimum DSk/d = 25 for 6x7 ståltovsklassen og minimum DSk/d = 20 for 6x19 og 6x36 ståltovsklasserne.
Please note that norms and standards often impose special requirements in respect of sheaf/drum diameters. If this is not the case, a minimum D/d = 25 is recommended for 6x7 steel wire ropes, and a minimum D/d = 20 for 6x19 and 6x36.
Hvis det er muligt, skal man undgå S-bøjning dvs. fra f.eks. underside på én skive til overside på den næste skive. S-bøjning giver tidligere udmattelsesbrud, hvorfor skiveforholdet (se nedenfor) bør øges med mindst 25% i forhold til samme retningsændring. Problemet er specielt stort, når skiverne er tæt på hinanden.
If at all possible, S-bends (where the steel wire rope runs from the lower side of one sheaf to the upper side of the next) should be avoided. Such bends result in premature damage. The sheaf ratio (see below) should thus be increased by at least 25% in relation to the same change of direction. The problem is particularly great when the sheaves are placed close to each other.
Sporet i skiven har også stor indflydelse på levetiden af ståltovet. Sporet må hverken være for stort eller for lille - sporet Fig. 35
The groove in the sheaf also has a significant influence on the steel wire rope's life expectancy. The groove must be neither too large nor
Correct groove diameter
Groove diameter too small Fig. 36
skal passe til ståltovsdimensionen (se fig. 35).
too small - the groove must match the steel wire rope's dimensions.
Randers Reb anbefaler, at et korrekt skivespor understøtter ståltovet på ca. 1/3 af omkredsen (~ 120°) og har en spordiameter på DSp = 1,06 x ståltovets nominelle diameter (se fig. 36). Spordiameteren må under ingen omstændigheder være under aktuel ståltovsdiameter. Correct figure of groove in sheave
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Groove diameter too large
Randers Reb recommends that a correct sheaf groove should support approx. 1/3 of the circumference of the steel wire rope (~120 °C) and have a groove diameter of Dsp = 1.06 x the steel wire rope's nominal diameter (see fig. 36). The groove diameter may under no circumstances be less than the relevant steel wire rope's diameter.
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TEKNISK INFORMATION Nedenstående kurve (fig. 37) viser sporforholdet DSp/d (spordiameter/ståltovsdiameter) indflydelse på ståltovets levetid. Inspicér løbende skiver/blokke for bl.a. slidte lejer, slidte skivespor og slid på kanter. Hvis disse forhold ikke er optimale, slides ståltovet unormalt hurtigt, og ståltovet tilføres spændinger. Defekte skiver/blokke skal udskiftes eller repareres omgående. Hvis sporet repareres ved svejsning, anbefaler Randers Reb, at hårdheden på svejsematerialet er ca. 300 Brinel, således at man får sliddet på skiven i stedet for på ståltovet.
Fig. 37
The curve in the diagram below indicates the effect of the D/d ratio (sheaf diameter/steel wire rope diameter) on the steel wire rope's life expectancy. Always check whether the sheaf groove is worn at the base and along the edges. If it is not, the steel wire rope will be subject to unusually significant wear and tear and stresses will be introduced into the rope. Defect sheaves/blocks should therefore be replaced or repaired immediately.
Life expectancy as a function of the Dsp/d ratio (sheaf diameter/steel wire rope diameter)
Størrelsen af ståltovets anlægsvinkel a (vinkelændring) på skiven har også indflydelse på ståltovets levetid (se fig. 38). Fig. 38
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If the groove is repaired by welding, Randers Reb recommends that the hardness of the welding material is approx. 300 Brinel, so that it is the sheaf that is worn, and not the steel wire rope.
The size of the steel wire rope's contact angle a (angle change) on the sheaf also has an effect on the steel wire rope's life expectancy (see fig. 38).
Life expectancy as a function of the contact angle a
Hvis det er nødvendigt at ændre retningen på ståltovet, anbefaler Randers Reb at undgå retningsændringer mellem 5° og 45°.
If the steel wire rope has to change direction, Randers Reb recommends avoiding changes in direction between 5° and 45°.
Installering af ståltovet Randers Reb ståltove er fremstillet på en sådan måde, at de i ubelastet tilstand er spændingsfrie. Ståltovet leveres enten på tromler eller i kvejl. For at undgå at tilføre ståltovet spændinger og kinker under installationen, er det nødvendigt at anbringe tromlen/kvejlen på en drejeskive eller i en buk. Hvis dette ikke er muligt, kan ståltovet rulles ud på jorden, mens ståltovsenden fastholdes (se fig. 39).
Installation of Steel Wire Rope Steel wire rope from Randers Reb is produced in such a way that in an unloaded state it is tension-free. The steel wire rope is supplied either on reels or in coils. To avoid creating tension or kinks in the steel wire rope during installation, it is necessary to place the coil/reel on a revolving platform, or as shown in fig. 39. If this is not possible, the steel wire rope can be rolled out on the ground while the end of the rope is held in place.
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TEKNISK INFORMATION
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Fig. 39
Correct ways to remove steel wire rope from a coil or reel Husk at sikre ståltovsenden mod opdrejning uanset om ståltovet er formlagt eller ej. Dette kan f.eks. gøres ved overbrænding (tilspidsning), påsvejsning af trækøje eller omvikling med ståltråd/jernbindsel (se også afsnittet "Kapning og takling af ståltov").
Remember to secure the end of the steel wire rope against opening, regardless of whether or not it is pre-formed. This can be done by such means as tapered and welded ends, beckets, or seizing with soft or annealed wire or strand (see also section 6: "Cutting and Seizing of Steel Wire Ropes").
Under afspolingen må ståltovet ikke: During the unwinding of the steel wire rope, it must not: · På nogen måde aftages over kanten på tromlen eller tages fra en kvejl, der ligger på jorden, idet der herved opstår kinker på ståltovet (se fig. 40). · Slæbes hen over en hård overflade, der kan beskadige trådene. · Trækkes gennem jord, sand og grus, idet slidpartikler vil fæstne sig til den fedtede ståltovsoverflade.
· In any way pass over the edge of the reel or be taken from a coil on the ground, as this will create kinks in the steel wire rope (see fig. 40). · Be dragged over a hard surface that can damage the wires. · Be dragged through earth, sand or gravel, as abrasive particles will attach themselves to the greased surface of the steel wire rope. Fig. 40
Incorrect ways to remove steel wire rope from a coil or reel
Spoling fra tromle til spiltromle Når ståltovet under installeringen kører direkte fra tromle til spiltromle, skal man sikre sig, at afløbstromlen løber samme vej som optagertromlen (se fig. 41). Fig. 41 Hvis det gøres forkert, tilføCorrect res ståltovet spændinger.
Winding from Reel to Drum During installation, when the steel wire rope is running directly from the reel to the drum, care must be taken to ensure that the reel is running in the same direction as the drum. Incorrect
If this is done incorrectly, the steel wire rope is subjected to tension.
For at opnå en problemløs In order to achieve problem-free opspoling ved flerlagswinding in multi-layer winding, it is opspoling er det af stor vigextremely important that that the tighed, at ståltovet køres op steel wire rope is under tension på tromlen med forspænwhen applied to the drum. If the ding. Hvis lagene er for løse, layers are too loose, the upper Correct/incorrect winding from Reel to drum kan ovenliggende lag under layers can damage or cut into the belastning trække/skære sig layers below when tension is applined i underliggende lag, hvorved ståltovet ødelægges. Ståltovet skal ed, resulting in damage to the steel wire rope. The rope must be køres på tromlen med minimum 2% af ståltovets brudstyrke. wound onto the drum at a tension corresponding to at least 2% of the tensile strength of the rope.
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TEKNISK INFORMATION Afbremsningen af aftagertromlen kan gøres på flere måder (se af fig. 42). Man må under ingen omstændigheder forsøge at klemme ståltovet mellem to træplader, idet ståltovet herved bliver varigt ødelagt.
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Braking of the drum can be done in several ways (see fig. 42). Please note: Steel wire rope should never be pressed between two wooden plates, as this will result in permanent damage to the rope.
Fig. 42 Correct
Correct
Incorrect
Examples of correct/incorrect ways to brake a reel Korrekt montering på spiltromlen Nedenstående figur (fig. 43) illustrerer korrekt fastgørelse og opspoling på spiltromlen af henholdsvis højre- og venstreslået ståltov.
Correct Fitting to Drum Fig. 43 below illustrates the correct way of installing and winding on to the drum for right and left hand laid steel wire rope respectively.
Fig. 43
Kapning og takling af ståltov Forudsat at ståltovet ikke brændes over (tilspidses), anbefaler Randers Reb, at ståltovet takles inden kapning. Følgende metode til takling skal anvendes (se fig. 44):
Cutting and Seizing of Steel Wire Rope Randers Reb recommends that, as long as the steel wire rope does not have welded ends, it has to be seized before being cut. The following seizing method must be used: Fig. 44
Rotationssvage/-frie ståltove skal mindst have fire taklinger på hver side af kappestedet.
Please note that low-rotation and rotation-resistant steel wire ropes must have at least four seizings on each side of the cutting point.
Correct cutting and seizing of steel wire rope
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TEKNISK INFORMATION Indkøring af ståltovet Efter montering af ståltovet anbefaler Randers Reb, at ståltovet køres gennem anlægget flere gange under lav hastighed og moderat belastning (f.eks. 5% af brudstyrken). Herved tilpasser ståltovet sig gradvist de nye forhold. Dugterne sætter sig, ståltovet forlænger sig. Desuden formindskes diameteren lidt, da dugterne og hjertet presses sammen. Ståltovet vil således være mindre udsat for skader, når maksimal belastning anvendes. Den tid, der benyttes til indkøringen af ståltovet, bliver tjent ind igen mange gange, idet ståltovet får længere levetid. Vedligeholdelse af føringsudstyr Ordentlig vedligeholdelse af udstyret, som ståltovet har kontakt med, har stor betydning for ståltovets levetid. Slidte skivespor, styreruller mm., skæve skiver og fastsiddende lejer resulterer bl.a. i chokbelastning og vibrationer i ståltovet, hvilket har en ødelæggende effekt på ståltovet med unormalt slid og udmattelse til følge. Udstyr, som ståltovet har kontakt med, skal inspiceres regelmæssigt. Hvis udstyret ikke er i orden, skal det omgående udskiftes evt. repareres. Ved reparation af føringsudstyret ved svejsning skal man sørge for, at hårdheden på svejsematerialet er ca. 300 Brinel, således at man får sliddet på føringsudstyret i stedet for på ståltovet (se også afsnittet "Kontrol af føringsudstyr"). 9. KONTROL OG VEDLIGEHOLDELSE Vedligeholdelse af ståltovet Den olie/fedt, som ståltovet tilføres under fremstillingen, beskytter kun ståltovet under opbevaringen og den første tids brug. Ståltovet skal derfor eftersmøres regelmæssigt. Ordentlig eftersmøring er meget vigtig for ståltovet levetid, idet smøringen har til formål dels at beskytte ståltovet mod rust, dels at reducere friktionen mellem trådene og dugterne i ståltovet. Desuden nedsættes friktionen mellem ståltovet og de flader, som ståltovet berører. Smøremidlet, der skal anvendes til eftersmøringen, skal være fri for syrer og må ikke have skadelig indvirkning på hverken ståltråde og/eller fiberhjertet samt miljø. Smøremidlet skal have en konsistens som gør, at smøremidlet trænger ind i hjertet og dugten. Ståltovet skal rengøres før eftersmøringen. For opnåelse af maksimal eftersmøring skal smøremidlet påføres under kørsel og ved en skive eller på tromlen, idet ståltovet her vil åbne sig. Smøremidlet kan herved lettere trænge ind. Randers Reb har udviklet en speciel eftersmøringsolie - Randers WIRE OLIE type 01- der tilfredsstiller de specielle krav, der stilles til eftersmøring af ståltove. Olien har en god indtrængnings- og smøreevne. Desuden er olien vandfortrængende og tilsat additiver, der er rustopløsende og stopper yderligere rustdannelse under lagring og brug.
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Running in Steel Wire Rope After the steel wire rope has been installed, Randers Reb recommends that it is run through the system several times at low speed and moderate loading (e.g. 5% of tensile strength). In this way the steel wire rope will gradually become accustomed to the new conditions. The strands will settle, the steel wire rope will lengthen and the diameter will decrease a little due to the fact that the strands and the core are compressed. The steel wire rope will thus be less susceptible to damage when maximum load is applied. The time spent "running-in" the steel wire rope will be earned many time over, as the steel wire rope will thus have a longer life expectancy. Maintenance of Guidance Equipment Thorough maintenance of the equipment that the steel wire rope will come into contact with is of great significance for the steel wire rope's life expectancy. Worn sheaf grooves, guide rolls, etc., crooked sheaves and jammed bearings all result in such effects as shock load and vibrations in the steel wire rope, which have a destructive effect on the steel wire rope, resulting in exaggerated wear and tear and fatigue. Equipment that the steel wire rope comes into contact with must be inspected regularly. If there is a problem with the equipment, it must be replaced or repaired immediately. If the guidance equipment is repaired by welding, care should be taken to ensure that hardness of the welding material is approx. 300 Brinel, so that it is the sheaf that is worn, and not the steel wire rope (see also section 6: "Inspection of Guidance Equipment"). 9. INSPECTION AND MAINTENANCE Maintenance of Steel Wire Rope The oil/grease that is added to the steel wire rope during production is only sufficient to protect the steel wire rope during the storage period and initial use. The steel wire rope must be lubricated regularly. Thorough lubrication is extremely important for the steel wire rope's life expectancy, as the purpose of lubrication is partly to protect the steel wire rope against rust, and partly to reduce friction between the wires and the strands in the steel wire rope. Friction is also thereby reduced between the steel wire rope and the surfaces with which it comes into contact. The lubricant used must be free of acids and must not have a destructive effect on the steel wires, the fibre core and the environment. The lubricant must have a consistency that enables it to penetrate the core and the strands. The steel wire rope must be cleaned before lubrication. To achieve maximum lubrication effect, the lubricant should be applied during operation, at a sheaf or on the drum, as this is where the steel wire rope opens up and makes it easier for the lubricant to penetrate.
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TEKNISK INFORMATION Olien kan let påføres med pensel. Se også vort Produktinformation's blad "Smøring og vedligeholdelse af ståltove". Kontrol af ståltovet Følgende er en vejledning på mulige kontrolpunkter i forbindelse med inspektion/kontrol af et ståltov - ikke en komplet manual eller erstatning for krav angivet i tilhørende normer og standarder. Slid Ståltovet skal udskiftes,, når den nominelle diameter er reduceret med 10%. Forlængelse Alle ståltove forlænger sig ved belastning (se også afsnittet "Ståltovsforlængelse"). Ståltovets forlængelse over levetiden kan opdeles i tre faser. · Fase 1: Under den første tids brug forlænger det nye ståltov sig helt naturligt. Dels p.g.a. belastningen, dels p.g.a. at ståltovet sætter sig. · Fase 2: Når ståltovet har sat sig. Under det meste af sin levetid for længer ståltovet sig ikke ret meget. Forlængelsen under denne fase skyldes primært slid. · Fase 3: Under denne fase nedbrydes ståltovet hurtigt og forlænger sig uden yderligere påvirkning, hvilket bl.a. skyldes fremskredent slid. Ståltovet skal udskiftes omgående. Reduktion af dimensionen Enhver mærkbar reduktion af ståltovsdimensionen i forhold til den oprindelige dimension indikerer nedbrydelse af ståltovet. Reduktionen kan bl.a. skyldes: · Udvendigt/indvendigt slid. · Sammenklemning af dugt og/eller hjerte. · Udvendig/indvendig rustdannelse. · Forlængelse.
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Randers Reb has developed a special lubricating oil, Randers WIRE OIL Type 01, which satisfies the special requirements for lubrication of steel wire ropes. The oil has excellent penetrative and lubrication qualities. It is also water-resistant and contains additives that dissolve rust and prevent further formation of rust during storage and operation. The oil is easily applied with a brush. See also our Product Information leaflet, "Lubrication and Maintenance of Steel Wire Ropes". Inspection of Steel Wire Rope The following guidelines cover possible points that should be checked in conjunction with the inspection of steel wire rope. This is not a complete manual, nor is it an alternative to the relevant norms and standards. Wear and Tear As a rule, a steel wire rope should be replaced when the outer wires are worn down to 1/3 of the original wire dimension. Elongation All steel wire ropes become elongated when loaded (see also section 9: "Steel Wire Rope Elongation"). The elongation of a steel wire rope during its lifetime can be divided into three phases: - Phase 1: The new steel wire rope becomes longer quite naturally during its initial period of use. This partly because of the loading, and partly because the steel wire rope settles. - Phase 2: When the steel wire rope has settled and for most of its lifetime, the steel wire rope does not become much longer.Elongation during this phase is mainly due to wear. - Phase 3: The steel wire rope suddenly becomes longer very quickly. This means that the steel wire rope is deteriorating rapidly due to such causes as advanced wear and fatigue. The steel wire rope must be replaced immediately. Reduction of Dimensions Every noticeable reduction of the steel wire rope's dimensions in comparison with its original dimensions indicates a deterioration in the steel wire rope. The reduction may be due to such causes as:
Rust Rust er mindst lige så vigtig en faktor som slid i forbindelse med vurderingen af ståltovets stand. Rust stammer normalt fra dårlig vedligeholdelse af ståltovet og bevirker hurtigere udmattelse af trådene (skørhed/revnedannelse). Kinker Kinker forårsager permanent ødelæggelse af ståltovet. Kinker dannes pga. udtrækning af løkker. Ståltovet skal udskiftes omgående.
- External/internal wear and tear. - Compression of strands and/or core. - External/internal formation of rust. - Elongation. Rust Rust is just as important a factor as wear and tear in terms of evaluating the steel wire rope's condition. Rust is normally caused by poor maintenance of the steel wire rope and promotes quicker fatigue in the wires (fragility/creation of cracks). Kinks Kinks cause permanent damage to the steel wire rope. Kinks are formed due to extraction of loops. The steel wire rope must be replaced immediately.
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TEKNISK INFORMATION Fuglerede En fuglerede (dugterne rejser sig samme sted) opstår bl.a., hvis ståltovet f.eks. er tilført torsion (drejet op), oplever pludselig aflastning, køres gennem for små skivespor og/eller spoles op på for lille tromle (fig. 44).
Bird's Nest A "bird's nest" (the strands rising in the same place) is created by such actions as the steel wire rope being subjected to torsion (rotated), sudden unloading, running through sheaf grooves that are too small and/or winding on a drum that is too small.
Fig. 44
Ståltovet skal udskiftes omgående.
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The steel wire rope must be replaced immediately.
Lokalt slid/ødelæggelse Lokalt slid på ståltovet skyldes som oftest dårlig spoling. Alle fittings og splejsninger skal undersøges for slid eller trådbrud, løse eller knækkede dugter, slid eller revner på/i fittings mm.
Local Wear and Tear/Damage Local wear and tear is most often caused by poor winding. All fittings and splicings must also be inspected for wear or broken wires, loose or split strands, wear or cracks in fittings, etc.
Brandskader Efter brand eller påvirkning af høje temperaturer kan der opstå metalskader, tab af olie/fedt og ødelæggelse af stål- eller fiberhjerte mm.
Fire Damage After a fire or exposure to high temperatures, metal damage, loss of oil/grease and destruction of fibre core, etc., may occur.
Bird's nests
Ståltovet skal udskiftes omgående.
The steel wire rope must be replaced immediately.
Hjertet kommer ud mellem dugterne Uafhængigt af årsagen til at hjertet kommer ud mellem dugterne, skal ståltovet udskiftes omgående.
Core Protruding between the Strands Regardless of the cause of the core protruding between the strands, the steel wire rope must be replaced immediately.
Trådbrud Trådbrud kan opstå af mange forskellige årsager. Nogle alvorlige, andre ubetydelige.
Wire Fracture A wire fracture may result from many different causes, some serious, others insignificant.
Hvis trådbruddene er alvorlige, skal ståltovet udskiftes omgående.
If the wire fractures are serious, the steel wire rope must be replaced immediately.
Hvis du er i tvivl om, hvorvidt ståltovet skal kasseres eller ej, så kontakt din konsulent eller vores tekniske afdeling hurtigst muligt.
If you are in any doubt as to whether the steel wire rope should be scrapped or not, please contact your local salesman or our Technical Department as soon as possible.
10. FORLÆNGELSE OG FORSTRÆKNING Ståltovsforlængelser Når et ståltov belastes, forlænger det sig. Forlængelsen består af to typer forlængelser - sætningsforlængelse (blivende) og elastisk forlængelse. Forlængelse p.g.a. overbelastning (f.eks. flydning) eller opdrejning vil ikke blive omtalt. Sætningsforlængelse Når et nyt ståltov belastes, bliver dugter og hjerte mindre (komprimeres). Desuden klemmer dugterne hårdere på hjertet - konstruktionen sætter sig. Dette medfører, at ståltovsdimensionen bliver lidt mindre, hvorved ståltovet forlænger sig. Denne forlængelse kaldes sætningsforlængelse og vedbliver, indtil ståltovet flere gange har været belastet ved normal drift. Hvis ståltovet på et senere tidspunkt belastes med en større kraft end under normal drift, vil ståltovet sandsynligvis forlænge sig yderligere.
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10. ELONGATION AND PRE-STRETCHING Steel Wire Rope Elongation When a steel wire rope is loaded it becomes longer. This elongation consists of two types of elongation - construction elongation (permanent) and elastic elongation. Elongation due to overloading (yielding) or due to rotation are not dealt with here. Constructional Elongation When a new steel wire rope is subjected to a load, the strands and the core decrease in size (are compacted). In addition, the strands are squeezing more tightly around the core. The construction settles. This means that the steel wire rope's dimension becomes slightly smaller, causing the steel wire rope to become longer. This elongation is known as constructional elongation and remains in place until the steel wire rope has been subjected to loads several times in normal operation. If the steel wire rope is at a later date subjected to a
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TEKNISK INFORMATION Sætningsforlængelse er afhængig af:
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greater force than that experienced under normal operating conditions, the steel wire rope will probably become a little longer.
· Hjertetype. · Ståltovskonstruktionen. · Slåstigningen. · Materialet. · Belastningen. Ståltove med stålhjerte har mindre sætningsforlængelse end ståltove med fiberhjerte. Da ståltoves sætningsforlængelse er afhængig af flere faktorer, kan en entydig sætningsforlængelse ikke angives. Tabel 4 er vejledende: Tabel 4
Constructional elongation is dependent on: · Type of core · Steel wire rope construction · Elevation (the length a strand passes to wrap once around the core) · Material · Load Steel wire ropes with steel cores have less constructional elongation than steel wire ropes with fibre cores. Since the construction elongation of steel wire ropes is dependent on a number of factors, it is not possible to give a clear definition of construction elongation. Table 4 is intended to provide guidelines.
Guidelines for constructional elongation in steel wire ropes Elastisk forlængelse (E-modul). Elastisk forlængelse er ikke kun afhængig af belastningen, men også af konstruktionen, hvorfor ståltove ikke følger Young's E-modul. Tabel 5 angiver forskellige ståltovskonstruktioners E-modul. Tabellen er vejledende.
Elastic Elongation (Modulus of elasticity) Elastic elongation is not only dependent on the load on the steel wires, but also on the construction, which is why steel wire ropes do not follow Young's modulus. It is therefore not possible to produce an unequivocal Modulus of elasticity for steel wire ropes. Table 5 is intended as a guide only.
Tabel 5
Guidelines for Modulus of elasticity on steel wire ropes
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TEKNISK INFORMATION
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Den elastiske forlængelse på ståltovet beregnes ud fra følgende formel:
The elastic elongation in a steel rope is calculated according to the following formula:
Elastisk forlængelse (mm) = W * L / (E * A), hvor: W = belastningen (kp) L = ståltovets længde (mm) E = E-modulet (kp/mm2) A = stålarealet (mm2)
Elastic elongation (mm) = W x L / (E x A) Where W = Load L = Length of steel wire rope E = Modulus of elasticity A = Steel area
Hvis et mere præcist E-modul er nødvendigt, skal man måle E-modulet på det aktuelle ståltov.
If a more accurate Modulus of elasticity is required, it must be measured in the actual steel wire rope in question.
Varmeudvidelse Et ståltov ændrer længde, når temperaturen ændres. Længdeændringen beregnes ud fra følgende formel:
Heat Expansion A steel wire rope will change its length when the temperature changes. Changes in length are according to the following formula:
Længdeændring (m) = a * L * Dt
Change in length (m) = a x L x Dt
hvor: a = Lineære varmeudvidelseskoef. = 11 x 10-6 m/m pr. ° C i området 0° C til ca. 100° C. L = Ståltovets længde (m). Dt = Ændring af temperatur (° C).
Where: a = linear heat expansion coefficient = 11 x 10-6 m/m per °C in area 0 to approx. 100° C. L = Length of steel wire rope (m). Dt = Change in temperature (°C).
Når temperaturen falder, bliver ståltovet kortere. Når temperaturen øges, forlænges ståltovet.
When the temperature drops, the steel wire rope will become shorter, whereas it will become longer if the temperature rises.
Forstrækning Ved forstrækning belastes ståltovet indtil flere gange med ca. 45% af ståltovets nominelle brudstyrke, hvorved ståltovets sætningsforlængelse fjernes.
Pre-stretching By pre-stretching, the steel wire rope is loaded to approx. 45% of its nominal tensile strength, during the course of which the steel wire rope's construction elongation is removed.
Fjernelsen af sætningsforlængelse forudsætter, at ståltovet ikke yderligere håndteres. Ved yderligere håndtering falder wiren mere eller mindre tilbage til dens oprindelige form, men forstrækning er i mange tilfælde alligevel en god ting, idet ståltovet væsentlig hurtigere stopper sin sætningsforlængelse. Dette medfører, at ståltovet ikke skal efterspændes så mange gange.
The removal of the construction elongation pre-supposes that the steel wire rope is not subjected to further treatment! If there is further treatment, the steel wire rope will more or less return to its original form. However, pre-stretching is in many cases a good idea anyway as it means that the steel wire rope more rapidly ceases its constructional elongation.
11. ANVENDELSESTEMPERATURER Maksimum anvendelsestemperatur · Zinken på galvaniserede tråde smelter ved 419° C. Ved 300° C begynder zinken at blive blød. · En opvarmning selv på et relativt kort stykke af wiren til over 300° C - samtidig med at opvarmningen sker et stykke inde i wiren - bevirker, at wiren kommer i ubalance og evt. låses. Tråd-/wirebrud opstår herefter hurtigere. · Trådenes mekaniske egenskaber, f.eks. brudstyrke og bøjestyrke, ændrer sig ved opvarmning. Opvarmning i f.eks. en time ved 200° C bevirker et fald i trådenes bøjestyrke.
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(kp) (mm) (kp/mm²) (mm²)
However, in many instances pre-stretching can still be beneficial, as the steel wire rope's constructional elongation will thus be completed much more quickly. This in turn means that the steel wire rope does not need to be re-tightened many times. 11. OPERATING TEMPERATURES Maximum Operating Temperature · Zinc on galvanised wires melts at 419 °C. At 300 °C the zinc begins to soften. · If a relatively short piece of cable is heated to more than 300 °C, the heating affects the inside of the wire rope, the wire rope will become unbalanced and may become locked, causing fractures in the cable/wires to occur more quickly.
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TEKNISK INFORMATION · Et kunstfiberhjerte begynder at blive blødt ved 80° C - 100° C. Et blødt hjerte bevirker, at understøtningen for dugterne forsvinder og stålwiren kommer i ubalance. Tråd-/wirebrud vil hurtigere forekomme. · Sisalhjerter kan tåle væsentligt højere temperaturer end ståltov med kunstfiberhjerte. Da brudstyrke og bøjelighed/fleksibilitet ofte er vigtige mekaniske egenskaber for et ståltov, kan Randers Reb ikke anbefale, at:
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· The wires' mechanical properties, e.g. tensile strength and bending strength, change when the temperature rises. A temperature of e.g. 200 °C for 1 hour will reduce the wires' bending strength. · An artificial fibre core starts to soften at 80-100 °C. A soft core means that the support for the strands disappears and the steel wire rope will become unbalanced, causing fractures in the cable/wires to occur more quickly. · Sisal cores can tolerate significantly higher temperatures than steel wire rope with artificial fibre cores.
· Ståltov med stålhjerte opvarmes til over 200° C gennem længere tid. · Ståltov med sisalhjerte opvarmes til over 200° C gennem længere tid. · Ståltov med kunstfiberhjerte opvarmes til over 75° C gennem længere tid.
Since tensile strength and pliability/flexibility are often important mechanical properties for a steel wire rope, Randers Reb does not recommend that a steel wire rope with:
Overfladetemperaturen kan i en kort periode accepteres at stige til 400° C.
· A sisal core is subjected to temperatures above 200 °C for a longer period of time.
Minimum anvendelsestemperatur Stålet, der anvendes i ståltovet, kan anvendes ned til meget lave temperaturer (minus 200° C evt. lavere), uden at stålets egenskaber forringes væsentligt. Derimod vil olie/fedt ved minus 25° C - 50° C miste sin smørende og rustbeskyttende virkning. Desuden vil fiberhjerter let kunne knuses ved lave temperaturer.
· An artificial fibre core is subjected to temperatures above 75 °C for a longer period of time.
Forudsat at stålwiren ikke indeholder fiberhjerter og at eventuelt olie/fedt ikke skal rustbeskytte og/eller have en smørende virkning, kan ståltovet anvendes ned til ca. minus 200° C. I modsat fald ned til ca. minus 25° C.
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· A steel core is subjected to temperatures above 200 °C for a longer period of time.
For a short period of time it can be acceptable for the surface tem perature to reach 400 °C. Minimum Operating Temperature The steel that is used in steel wire rope can be used at extremely low temperatures (minus 200 °C or less) without any significant effect on the characteristics of the steel. However, at temperatures of only minus 25-50 °C oil and grease will lose their ability to serve as lubricants and protect against rust. This makes the fibre cores easy to damage. Provided that the steel wire rope does not have a fibre core and that oil and grease are not required as protection against rust or as lubrication, such rope can be used in operating temperatures of approx. minus 200 °C. If these conditions cannot be met, the minimum temperature is approx. minus 25 °C.
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TEKNISK INFORMATION
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12. MARTENSIT
12. MARTENSITE FORMATION
Martensitdannelse Martensit er en strukturændring, der sker i trådmaterialet ved høj friktionsvarme (se fig. 45) som f.eks. ved dårlig spoling på spil, hvor de yderste ståltovslag presses ned i de underliggende lag under en sådan belastning, at gnistdannelse opstår med efterfølgende hurtig afkøling (se fig. 46). Fig. 45
Martensite formation Martensite is a structural change in the wire material caused by a very sudden cooling of the rope after a strong local heating generated by friction. The friction may be caused by e.g. bad winding of the wire rope on winches.
Martensite spots in fishing rope which has been used under bad conditions Fig. 47
Fig. 46
Flattened wire showing martensite structure
The brittle layer of martensite shows clearly
Denne strukturændring giver en hård men skør overflade, og under normal belastning eller ved splejsning kan trådbrud opstå, selvom der ikke har været nævneværdigt ydre slid (se fig. 47).
The martensite structure is very brittle and may cause fractures during normal operation or when spliced, even though the wire rope does not show any visible signs of external wear.
Forholdsregler mod martensitdannelse:
Precautions against martensite:
· Blokkene må ikke være nedslidte og bør kunne dreje let.
· The blocks must not be worn down and should turn easily. · When a wire rope is wound on a drum, it should be in tight wraps without the layers crossing each other in order to prevent the top layer from cutting into the underlying layers.
· Spoling på tromlen bør ligge i tætte vindinger uden krydsninger, så det overliggende lag under belastning ikke skærer sig ned i de underliggende lag. · Ståltovet bør eftersmøres, således at friktionen mellem tråde og dugter er mindst mulig.
· The wire rope should be lubricated at regular intervals in order to minimise the friction between wires and strands.
· Kontrollér ståltovet for sammentrykninger, små revner og mekaniske skader, som kan være tegn på martensitdannelse.
· The wire rope should be checked at regular intervals for crushing, minor cracks and mechanical damages, all of which might indicate martensite spots.
Hvis en stålwire er strømførende, eller ståltovet spoles op i flere lag under stor belastning, vil der ofte opstå gnister. Overfladetemperaturen, hvor gnisten opstår, er over 800° C, hvorfor sandsynligheden for dannelse af martensit er relativ stor. Hvis forekomsten af gnister er stor, opstår der hurtigt trådbrud og evt. wirebrud.
If a steel cable carries a current, there will often be sparks. The surface temperature where the sparks appear will be over 800 °C, making it quite probable that Martensite will be formed. If there is a strong probability of sparks appearing, wire and cable fractures may occur quickly.
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TEKNISK INFORMATION 13. ENDEBEFÆSTIGELSER
13. END TERMINATIONS
Endebefæstigelser.
End terminations
I fig. 48 ses eksempler på endebefæstigelser.
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Type of end terminations. Degree of efficiency
Fig. 48
Wire rope socket, resin poured
Wedge socket
Wire rope socket, swaged
Clips
Hand-spliced with thimble
Mechanical splice with thimble and Talurit
Eksempler på endebefæstigelser på ståltove Examples of end terminations on steel wire ropes En endebefæstigelse nedsætter normalt brudstyrken på ståltovet. Tabel 6 angiver virkningsgrad (tilnærmet) for de forskellige typer endebefæstigelser.
End terminations normally reduce the tensile strength of steel wire rope. Table 6 shows the approximate effect of the different types of end terminations.
Tabel 6
Clips Wedge socket Hand-spliced Mechanical splice with ferrule Wire rope socket, swaged Wire rope socket, resin poured
Degree of efficiency for different types of end terminations Fig. 49 viser eksempler på rigtig og forkert montering af wirelås.
Fig. 49 Examples of correct and incorrect attachment of wire rope clips. Fig. 49 Right way
Wrong way
Wrong way
Examples of correct and incorrect ways of attachment of dead end on different kinds of wedge sockets
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TEKNISK INFORMATION
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Fig. 50
14. ISTØBNING MED WIRELOCK
14. SOCKETING (WIRELOCK)
Istøbning (Wirelock) Hvis intet andet er aftalt mellem kunde og Fyns Kran Udstyr, så udfører Fyns Kran Udstyr istøbning af tovpære med Wirelock - er en speciel stærk 2-komponent støbemasse. Wirelock anvendes i større og større grad i stedet for zink bl.a. p.g.a. :
Unless otherwise agreed between the customer and Fyns Kran Udstyr, Fyns Kran Udstyr will undertake socketing with Wirelock. Wirelock is an especially strong twin-component moulding material. Wirelock is increasingly being used instead of zinc, e.g. because:
· at varmeudviklingen er væsentlig lavere i forhold til zinkstøbning. Herved elimineres risikoen for hærdning af ståltrådene med udmattelsesbrud til følge. Desuden undgår man at fedtet forsvinder (bortsmelter) i overgangszonen ved tovpærehalsen. · Wirelock kræver ikke opvarmning af tovpære forudsat, at denne ikke har en temperatur på under 10 °C. · Wirelock tillader fuld belastning 1 - 2 time efter støbningen. · Wirelock kræver ingen specielle hjælpemidler i.f.m. istøbningen. · Wirelock er modstandsdygtig overfor syre, saltvand, olie og fedt. · Wirelock tåler chokbelastning og stød. · Wirelock kan anvendes til alle former for istøbning. · Wirelock trænger bedre ind mellem trådene end zink. · Wirelock kan anvendes op til 115 °C Wirelock er bl.a. godkendt af Arbejdstilsynet, Det Norske Veritas og Lloyd's Register of Shipping.
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· Heat generation is much lower than with a zinc seal. The risk of hardening of the steel wires, causing stress fractures, is thus eliminated. The disappearance (melting away) of grease is also avoided at the junction by the base of socket. · Wirelock does not require heating of the rope socket, as long as its temperature is not below 10 °C. · Wirelock permits full loading 1-2 hours after the sealing process. · Wirelock does not require any special ancillary tools in connection with the sealing process. · Wirelock is resistant to acid, salt water, oil and grease. · Wirelock tolerates shock loading and impact. · Wirelock can be used for all types of seal. · Wirelock penetrates further in between the wires than zinc. · Wirelock can be used in temperatures of up to 115 °C. Wirelock has been approved by such bodies as the Danish Directorate of Labour Inspection, Det Norske Veritas and Lloyd's Register of Shipping.
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TEKNISK INFORMATION Vejledning for istøbning af ståltove 1. Ståltovsenden indføre i tovpæren, hvoref ter ståltovet takles. Afstanden fra tovenden til den øverste kant af taklingen (L) skal svare til længden på den koniske del af tovpæren minus ståltovsdiameter (d). Længden på taklingen (l) skal være minimum 1,5 x d. 2. Opsplitning af de enkelte tråde i dugterne kan herefter ske. Hvis ståltovet indeholder et stålhjerte skal dette også splittes op. Eventuelle fiberhjerter kappes over taklingen. Opsplitningen skal være ensartet og gå helt ned til taklingen.
Guidelines for Socketing with Wirelock 1. Insert the end of the steel wire rope into the rope socket, and fasten the steel wire rope. The distance from the end of the rope to the uppermost part of the rigging (L) must correspond to the length of the conical part of the rope socket minus the diameter of the steel wire rope (d). The length of the rigging (l) must be at least 1.5 x d.
Fig. 1
Placing and size of rope sockets
Fig. 2 Hvis ståltovet kun består af 19 tråde eller mindre, skal trådene i toppen ombukkes. HUSK at tillægge længden af ombukket til længden af det opsplittede stykke. 1) Den opsplittede del af ståltovet (kosten) rengøres/affedtes f.eks. i en sodaopløsning. Ved afrensningen og en efterfølgende skylning skal ståltovet vende nedad således, at væsken ikke trænger ned ståltovet.
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2. The individual wires in the strands can be split after this. If the steel wire rope contains a steel core, this must also be split open. If there are any fibre cores, they may be cut above the rigging. The split must be clean and go as far down as the rigging. If the steel wire rope only consists of 19 wires or less, the wires at the top must be doubled up. Remember to add the length of the doubled section to the length of the split section.
Splitting the steel wire rope and removing the fibre core
2) Træk tovpæren op over kosten indtil trå dene er i niveau med overkanten af tovpæren. Kontroller, at et stykke (ca. 0,5 x d) af den øverste del af taklingen befinder sig i den koniske del af tovpæren.
2) Pull the rope socket over the brush until the wires level with the upper edge of the rope socket. Check that a part (min. 0.5 x d) of the upper section of the rigging is in the conical part of the rope socket.
Fig. 3
Ståltovet fastgøres, så det står lodret samtidig med, at et stykke (ca. 25 x d) af ståltovet hænger lodret. Herefter tætnes tovpærehalsen med f.eks. kit for at forhindre udtrængning af Wirelock under istøbingen.
1) Clean/de-grease the split section of the steel wire rope (the brush), e.g. in a soda solution. When being cleaned and then rinsed off, the steel wire rope must be facing downwards so that the solution does not penetrate the rope.
Fasten the steel wire rope so that it is vertical, while a piece (approx. 25 x d) of the steel wire rope is hanging vertically. Pack the base of socket with e.g. putty to prevent any Wirelock escaping during the sealing process. Correct location of the rope socket and packing with putty
3) Bland de to komponenter sammen i en plasticspand eller lignende (komponenterne skal have en temperatur på mellem 10 °C og max. 25 °C). Blandingen omrøres grundigt i ca. 2 minutter. Ved en lufttemperaturer under 10 °C bør een pose "booster" (accelerator) tilsættes før omrøring.
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3) Mix the two components together in e.g. a plastic bucket. The components must have a temperature of 10-25 °C. Stir the mixture thoroughly for around two minutes. If the air temperature (sealing temperature) is below 10 °C, a bag of "booster" (accelerator) should be added before stirring.
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TEKNISK INFORMATION På posen er angivet, til hvilken mængde Wirelock den skal anvendes. Under 3 °C bør to poser booster tilsættes. Istøbingen kan godt foretages i frostgrader, blot man sørger for, at Wirelock massen ikke kommer under 10 °C under hele istøbningsprocessen. BEMÆRK : Blandingsforholdet mellem de enkelte komponenter er nøje afstemt og må ikke deles.
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The bag provides instructions about how much Wirelock must be used. Below 3 °C two bags should be added. The sealing process can be undertaken at temperatures below 0 °C, as long as measures are taken to ensure that the Wirelock putty itself does not come under 10 °C at any time during the process. NB: The mix ratio between the individual components is precisely calculated and should not be divided.
Forbruget af Wirelock ses af tabel 1. Tabel 1
The following table shows how Wirelock should be applied.
Number of seals per litre Wirelock 4) Blandingen hældes i tovpæren, indtil tovpæren er fyldt helt op. For at forhindre dannelsen af luftbobler skal en let "piskning" med et stykke ståltråd foretages nede mellem ståltovets tråde. Flere istøbninger kan godt foretages forudsat, at ihældning sker lige efter hinanden.Evt. overskydende Wirelock kan ikke gemmes, men skal kasseres.
4) Pour the mixture into the rope socket until the rope socket is full. To prevent air bubbles forming, a piece of steel wire should be used to "whip" gently between the wires in the steel wire rope. Several applications may be made at a time, provided that they are done in quick succession. Any surplus Wirelock must be disposed of.
BEMÆRK : Blandingsmassen starter med at være tykflydende. Herefter bliver massen tyndere og tyndere indtil et vist punkt, hvorefter selve hærdeprocessen går igang. Wirelock skal ihældes, inden massen når sit tyndeste punkt.
NB: At the outset the mixture has a thick, liquid consistency. It then becomes thinner until a certain point at which the hardening process begins. The Wirelock must be poured before the mixture reaches its thinnest state.
5) Wirelock er fremstillet således, at hærdetiden er 10 minutter i tem peraturområdet 18 °C til 24 °C. Det bør dog bemærkes, at produktets hærdetid er meget følsom overfor temperaturen på Wirelock, f.eks. er hærdetiden kun ca. 5 minutter ved 30 °C og ca. 20 minutter ved 10 °C. Hærdetiden har ingen indflydelse på kvaliteten af hærdningen. Tovpæren må belastes 1 time efter, at Wirelock er hård i overfladen (se også afsnit 9.8.2).
5) Wirelock is produced in such a way that its hardening time is 10 minutes in the 18-24 °C temperature range. It should, however, be noted that the product's hardening time is very sensitive to the temperature of the Wirelock, e.g. it is only approx. 5 minutes at 30 °C and approx. 20 minutes at 10 °C. The hardening time has no effect on the quality of the hardening. Loads can be applied to the rope socket one hour after the Wirelock is hard on the surface.
6) Kit fjernes. Specielt når tovpærehalsen hænger opad under brugen, anbefaler Fyns Kran Udstyr, at tovpærehalsen fyldes op med vandfortrængende olie/fedt for at minimere risikoen for rustdannelse på dette kritiske sted (hulrummet fyldes med vand).
6) Putty must be removed. Particularly in cases where the unit is to be used with the base of socket upwards, Fyns Kran Udstyr recommends that the base of socket be filled up with water-repellent oil/grease in order to minimise the risk of rust at this critical point due to penetration of water.
Kontrol af istøbning a) Hvis man ridser med en skruetrækker i støbemassen i tovpæreåb ningen, og der fremkommer en hvid stribe, er hærdningen foregået, som den skal.
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Seal Inspection a) If a screwdriver is used to scratch the Wirelock at the opening of the rope socket and a white stripe appears, the hardening process has been completed correctly.
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b) Desto mørkere Wirelock er, desto højere temperatur har hærde processen opnået. Den mørke farve opnås p.g.a korrekte temperaturforhold. Hvis farven er blågrøn, er dette ensbetydende med en "kold" støbning/hærdning. Istøbningen kan kun godkendes, hvis skruetrækkerprøven er O.K. (se punkt a).
b) The darker the Wirelock, the higher the temperature during the hardening process. The dark colour is achieved due to correct hardening conditions. If the colour is bluish-green, it indicates a "cold" sealing/hardening process. The sealing process may only be approved if the screwdriver test has been passed.
Genbrug af tovpærer Fjernelse af Wirelock i brugte tovpærer kan ske ved opvarmning til 250 °C i ovn, hvorefter støbemassen krakelerer ved slag og kan fjernes med dorn. For at undgå opvarmning af tovpæren er det bedre blot at presse materialet ud med specialværktøj.
Re-use of sockets Dismantling of Wirelock in used rope sockets can be undertaken by means of heating in a furnace to a temperature of 250 °C, after which the seal cracks when struck and can be removed with a mandrel. To avoid heating up the rope socket, it is recommended that the material be pressed out using special equipment.
BEMÆRK: Tovpæren må under ingen omstændigheder opvarmes til mere end 250 °C forudsat, at leverandøren af tovpærerne ikke har angivet andet. BEMÆRKNINGER: a) Tovpære og tov skal jævnligt kontrolleres for brud/beskadigelse, specielt i og ved tovpærehalsen. b) Undgå brug af åben ild under blandingen og istøbning med Wirelock. Hærderen indeholder styren, hvis flammepunkt er ca. 30 °C. c) Der skal anvendes beskyttelsesbriller og hansker ved istøbning. Hvis det foregår indendørs, skal der være lokal udsugning. d) Wirelock må ikke komme i forbindelse med stærke alkaliske opløsninger som acetone og lignende, da disse stoffer kan nedbryde Wirelock. e) Hvis tovpæren har en temperatur på under 10 °C, bør denne opvarmes f.eks. ved at lægge den i en spand varmt vand. f) En forudsætning for at sidste anvendelsesdato gælder er, at Wirelock opbevares mellem 10 °C og max. 25 °C. Ved hver leverance medsendes "Leverandør Brugsanvisning" på Wirelock. Fyns Kran Udstyr foretager gerne istøbningen med Wirelock enten hos dig eller i vort splejseri. Fyns Kran Udstyr er også leveringsdygtig i såvel tovpærer samt andre typer fittings.
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Note: a) Rope and rope socket must be inspected regularly for fractures, especially in and around the base of socket. b) Avoid using an open flame during the mixing and sealing process with Wirelock. The hardening agent contains an acid that is flammable at approx. 30 °C. c) Protective glasses and gloves must be worn during the sealing process. If undertaken indoors, air extraction equipment must be used. d) Wirelock must not come into contact with strong alkaline solutions such as acetone, as these substances can cause the Wirelock to disintegrate. e) If the rope socket has a temperature of below 10 °C, it should be warmed up, e.g. by placing it in a bucket of warm water. f) The "use before" date presupposes that the Wirelock is stored at 10-25 °C. g) Every consignment is accompanied by "Supplier's Directions for Use" of Wirelock. Fyns Kran Udstyr will be pleased to carry out the sealing process with Wirelock either on your premises or in our own splicing shop. Fyns Kran Udstyr is also a supplier of rope sockets and other types of fittings.
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TEKNISK INFORMATION 15. TROMLEKAPACITET
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15. DRUM CAPACITY Max. drum capacity (in metres) is = A x C x (A + B) x p / d², where A, B and C are expressed in cm. D = steel wire rope's diameter in mm. p = pi = 3.14
Fig. 51 Drum Capacity
16. KLASSIFICERING AF STÅLTOVE
16. CLASSIFICATION AND USE OF STEEL WIRE ROPE
Ståltovsklasser (eksempler på ståltove) De forskellige ståltove kan inddeles i forskellige klasser. Inden for hver klasse er fastlagt antallet af dugter samt antallet af ydertråde i hver dugt. Der findes forskellige systemer/regler for klassificering af ståltovene (ISO, DIN, amerikanske). Randers Reb har valgt at anvende den klassificering, der gælder for EU (EN-norm) (se tabel 2).
Classification of Steel Wire Rope The different kinds of steel wire rope can be divided up into distinct classes. The number of strands and the number of outer wires in each strand is laid down for each class of steel wire rope. The different systems and sets of rules for this classification include ISO, DIN and American. Randers Reb has chosen to employ the set of classifications used by the EU (the EN norm).
Tabel 2
Class
Number of outer strands
Number of wires in strand
Number of outer wires in strand
Number of layers of wire in strand
Eksempler på ståltovsklasser (se også fig. 52) Examples of different classes of steel wire rope (see also fig. 52)
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Eksempler på anvendelse af ståltove
Examples of the use of Steel Wire Rope
Fig. 52 viser eksempler på ståltove i de mest anvendte ståltovsklasser.
Fig. 52 shows examples of steel wire rope in the most common categories of steel wire rope.
Fig. 52
Examples of steel wire rope in the most common categories of steel wire rope 17. TOVVÆRK
17. ROPES
Tabel 8
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TEKNISK INFORMATION Tovværk fremstilles primært af syntetiske materialer som f.eks. PE, PP, PA og polyester. Tovværk af naturfibre som sisal, hamp, manila og papir produceres stadigvæk, men udbudet er ikke ret stort. Årsagen hertil er, at det syntetiske tovværk generelt har en større slidstyrke, ikke suger vand og ikke rådner. Tovværk fremstilles primært som 3- og 4-slået, krydsflettet, rundflettet og kvadratflettet.
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Ropes are primarily made of synthetic materials such as PE, PP , PA and polyester. Ropes of natural fibre are still manufactured, but only in small quantities, as synthetic ropes are more wear-resistant and do not absorb water or rot. Ropes are primarily manufactured as 3- and 4-strand, crossbraided, roundbraided and plaited. 18. CHAINS AND LIFTING COMPONENTS
18. KÆDER OG KOMPONENTER Gunnebo - din partner i sikkert løft Tænk Gunnebo ved valg af løftekæder og komponenter. Gunnebo er kendt for kvalitet, helt ned til den mindste komponent som et resultat af mere en 200 års erfaring, systematisk kvalitetskontrol, forskning og udvikling. Kæder og komponenter laves af sejhærdet legeret stål. En garanti for meget høj styrke, lav vægt, høj slidstyrke og lang levetid. Alle Gunnebo G8 komponenter er mærket ensartet med tilsvarende kædestørrelse, klasse og producentens betegnelse for positiv identifikation. Kvalitet i henhold til internationale standarder Gunnebo arbejder tæt sammen med sine stålleverandører for at sikre, at råmaterialerne opfylder de strenge kvalitetskrav. Gunnebo arbejder også tæt sammen med sit verdensmarked og har officielle godkendelser fra vigtigste nationale og internationale myndigheder inklusiv MOD, NATO, BG og mange andre. Gunnebo G8 klasse 8 kæde er produceret og testet i henhold til kravene i ISO 1834 & 3076, 1984 og EN 818-1, & 2. Alle komponenter opfylder de relevante prEN og EN-standarder. Alle Gunnebo's produktionsenheder er godkendte af Lloyd's (LRQA) for kvalitetssikkerhed i henhold til ISO 9001. Denne godkendelse kombinerer også den nye europæiske standard EN 29001. Gunnebo's kvalitetskontrol dækker alle produktionsaspekter fra råmateriale til leveret produkt. LRQA godkendelse for systemet inkluderer design, udvikling, produktion, markedsføring og distribution af løftekæder og tilhørende komponenter. Testcertifikater leveres på forespørgsel. Gunnebo giver dig flere valgmuligheder Gunnebo G8 er mere end blot endnu et kædeslingsystem. Det er et totalt løftekoncept i legeret stål af høj kvalitet til tunge løft. Kæderne og komponenterne i G8 og SK sortimenterne er designet til at give mere fleksibilitet og flere valgmuligheder og dermed løse næsten ethvert løfteproblem, hvor der skal bruges kædesling - hvad enten det drejer sig om kæde-, wire- eller kædesling. Da BK sikkerhedskrogen blev introduceret for ca. 30 år siden, blev den industrielle sikkerhed på arbejdspladser over hele verden forhøjet betydeligt. Den nye generation i sikkerhedskroge - OBK/GBK - er en mere kompakt version af den velkendte BK-krog. Modificeringen af sikkerhedspalen giver bedre sidestabilitet og krogen har nu forbedret nagling. Endnu en nyskabelse fra Gunnebo, der viser vejen.
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Gunnebo - your partner in safe lifting Think Gunnebo when selecting lifting chain and components. Gunnebo has become known for quality, down to the smallest component, as a result of over 200 years experience, systematic quality control, research and development. Chain and components are made from quenched and tempered alloy steel. A guarantee for very high strength, low weight, high wear resistance and long life. All Gunnebo G8 components are uniformly marked with equivalent chain size, grade and manufacturer's designation for positive identification. Quality to international standards Gunnebo work closely with their steel suppliers to ensure that the raw material meets their stringent specification. They also work closely with their world markets and have official approval by the main national and international authorities including MOD, NATO, BG and many others. Gunnebo G8 Grade 8 chain is manufactured and tested to the requirements of ISO 1834 & 3076, 1984 and EN 818-1, & 2. All components match the relevant prEN- and EN-standards. All Gunnebo productions units are approved by Lloyds (LRQA) for quality assurance to ISO 9001. This approval also combines the new European standard EN 29001. Their quality management covers all aspects of production from raw material to delivered product. LRQA approval for their system includes design, development, manufacture, marketing and distribution of lifting chains and associated components. Full test certification is supplied on request. Gunnebo gives you more options Gunnebo G8 is more than just another chain sling system. It is a total lifting concept in high grade alloy steel for heavy lifting. The chain and components in the G8 and SK ranges are designed to give more flexibility, more options to meet almost any lifting problem involving slings - whether chain, steel wire rope or soft slings. When introduced around 30 years ago, the BK Safety Hook dramatically increased industrial safety on sites all over the world. The new generation safety hooks - OBK/GBK - provide a more compact version of the well-known BK-hook. The grip latch modification gives better side stability and the hook now has improved riveting. Once again, Gunnebo innovation leads the way.
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TEKNISK INFORMATION Sikkert design ned til lastdetaljen BK/OBK/GBK sikkerhedskrogene opfylder to vigtige krav. Det ene er, at lasten forbliver i krogen. Palen lukker automatisk, så snart krogen bliver belastet. Den kan ikke åbnes utilsigtet under last. Udløseren kan kun betjenes, når lasten er sikkert afsat. Det andet er, at krogen ikke så let hænger fast under løft p.g.a. dens bløde profil. Gunnebo sikkerhedskrogene er designet til arbejde. Det er let at betjene udløseren selv med arbejdshandsker på. Den forbliver åben, så begge hænder er fri til at belaste krogen. Sikkerhedskrogene fås fra WLL 1,25 - 25 ton. Anvendelse · Opret et kartotek over alle kæder, der er i brug. · Løft aldrig med en vredet kæde. · Kædesling skal opkortes med en opkorterkrog - der må aldrig slås knuder på kæden. · Beskyt kæden mod skarpe kanter ved at lægge et mellemlag imellem. · Belast aldrig en krog i spidsen - lasten skal altid ligge korrekt i bunden af krogen. · Brug altid den korrekte størrelse kæde til lasten under hensyntagen til vinkel og muligheden for ulige belastning. · Topøjet skal altid kunne hænge frit i krankrogen. · Undgå altid belastning i ryk. Vedligeholdelse Mindst hver 6. måned eller oftere i henhold til lovmæssige bestemmelser, type af anvendelse og tidligere erfaring skal der udføres en omhyggelige kontrol. · Kæder med bøjede, revnede eller udhulede led skal udskiftes, ligesom deformerede komponenter så som bøjede ovalringe, åbne kroge og enhver komponent, der viser tegn på slitage. · Slitagen på kæden og komponenterne må ingen steder overstige 10% af de oprindelige dimensioner. Slitagen på kædeled - max. 10% - er defineret som den gennemsnitlige diameter af materialet målt i 2 retninger. · Overbelastede kædesling skal tages ud af brug.
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Safe design down to the load detail Gunnebo BK/OBK/GBK Safety Hooks fulfil two important requirements. One is that the load stays put in the hook. The latch closes automatically as soon as the hook is loaded. It cannot be opened under load accidentally. The release trigger will only operate when the load is safely grounded. The other is that the hook will not easily snag during lifting because of its smooth profile. Gunnebo Safety Hooks are designed for work. It is easy to operate the release trigger even with working gloves on. It stays open so that both hands are free to load the hook. Gunnebo Safety Hooks are available for Working Load Limits 1.25 to 25 tonnes. Use · Keep a register of all chains in use. · Never lift with a twisted chain · Chain slings should be shortened with at shortening hook, never by knotting. · Never point load a hook - the load should always seat correctly in the bowl of the hook. · Always use the correct size sling for the load allowing for the inclu ded angle and the possibility of unequal loading. · The master link should always be able to move freely on the crane hook. · Avoid snatch-loading at all times. Maintenance Periodic through examination must be carried out at least every six months or more frequently according to statutory regulations, type of use and past experience. · Chain with bent, cracked or gouged links should be replaced, as should deformed components such as bent master links, opened up hooks and any fitting showing signs of damage. · The wear of the chain and components shall in no place exceed 10% of the original dimensions. The chain link wear - max. 10% - is defined as the reduction of the mean diameter of the material measured in two directions. · Overloaded chain slings must be taken out of service.
I Danmark kræver Arbejdstilsynet, at alt løftegrej skal kontrolleres mindst én gang om året. Fyns Kran Udstyr tilbyder at udføre test direkte hos kunden (se afsnit 9).
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TEKNISK INFORMATION 19. TEKNISKE OMREGNINGSTABELLER
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19. TECHNICAL CONVERSION TABLES Fig. 9
Omsætning mellem diverse enheder
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TEKNISK INFORMATION Testcertifikat for stålwirer
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Test and Examination Certificate for Wire Rope
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TEKNISK INFORMATION Certifikat for test af løftegrej
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Certificate for test of Lifting Gear
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TEKNISK INFORMATION Certifikat for test af faldsikringsudstyr
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Certificate for test of Fall Arrest Equipment
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TEKNISK INFORMATION Certifikat for test af El-taljer
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Certificate for test of Electric Chain Hoists
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TEKNISK INFORMATION Certifikat for test af Vakuumløfteåg
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Certificate for test of Vacuum Lifters
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TEKNISK INFORMATION Certifikat for test af kædetaljer, wiretaljer, løbekatte, løftekløer, spil og donkrafte
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Repair Certificate for Chain Hoists, Pull-Lift Trolleys, Lifting Clamps and Jacks
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Fyns Kran Udstyr A/S ISO 9002 certifikat
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Fyns Kran Udstyr A/S ISO 9002 certificate
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10
MTC
Anchor Handling Course
SWIVEL As a safety precaution, a swivel is inserted in the system to release stress, turns and torsion in steel wires. The swivel is inserted between the dead man wire and the PCP, to ensure no stress, turns and / or torsion in the wire, enabling the deck crew to safely disconnect the systems. Use of swivel can however give a reduction in the breaking load with up to app. 30%, depending on the type of swivel in use. It is strongly recommended not to use a swivel with too low friction coefficient allowing the wire end to freely rotate during normal operation. This will decrease the fatigue life dramatically. The MoorLink swivel has a high friction coefficient and will not allow the wire to rotate when under load. T.O. has delivered a MoorLink swivel to all AHTS vessels. Please observe the enclosed table / drawing (page 5) showing breaking strength when the swivels are on wire drums and stern rollers. Please read the following pages together with chapter 8 for further information.
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MoorLink Swivel Subject: Theory - Swivels versus Wire torque ____________________________________________________________________________
Background Six-stranded wire rope behaves different in different applications or operations, which could lead to potential problems for the user. In theory a six stranded rope should not be allowed to open up (swivel) under load to achieve longest lifetime of the rope. This is normally only possible in a perfect world, where no external operational criteria are present. An all wire moored drilling or accommodation rig might achieve this by perfect anchor handling and spooling off / on from / to a winch. In reality the winches are not spooling perfectly and if the wire is dragged over or in seabed the geometry of the wire could lead to induced torque.
Safety Torque can cause severe damages to personnel and equipment. This normally occurs when an anchor handling wire is spooled in with high tension and disconnection shall occur. The torque has been transferred to the end of the rope disconnection can be impossible or lead to a kink in the rope. This also happens during cross over operations on combination mooring systems.
Combination Mooring Systems For drilling rigs equipped with combination chain /wire system swivels would assist during the cross over operation and bolstering of anchors. When hauling in the wire, the torque moves towards the end of the rope. In order to remove the torque from the wire to prior to disconnection the swivel positioned in the cross over point should absorb the torque at a relative low tension. It is strongly recommended not to use a swivel with too low friction coefficient allowing the wire end to freely rotate during normal operation (when moored). This will decrease the fatigue life dramatically. The wire also introduces twist to the chain during normal operation and when hauling in anchors. The chain has a relative high torsion stiffness when under tension (nil when stored in a pile onshore or in the chain locker). This means that the wire will induce a number of turns over the length of the chain, which is not causing any damages to the chain. However, when the chain is hauled in and the AHT is coming closer to the bolster these turns will be present on a short piece of chain, potentially leading to problems bolstering the anchor properly. By installing a swivel close to the anchor end this torque could be absorbed.
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Anchor handling Anchor handling can be divided into two different main categories: 1. 2.
The usage of vessel’s own anchor handling wire or tow wire, which is permanently installed (and replaced when damaged) and kept with high tension on the drum. The usage of external supplied anchor-handling wires (normal for deep-water operations). These wires are normally not spooled on to the winches with any high tension before commencement of work.
The problem that occurs during anchor handling is that the torque induced in the wire is transferred to the end of the rope and if the axial stiffness in the connected part is low the torque is transferred further. This means that a swivel can absorb the torque and avoid any twist to be transferred.
Bearing Systems 1.
Slide Bearing System
Bearing system is bronze aluminium type running on a polished stain less steel washer. The material is often used in high load / low speed bearings in many offshore applications (very good corrosion and wear resistance in seawater). The bearing is self-lubricating with embedded sold lubricant. The base material is high-grade bronze alloys and has finely finished surface with pockets in which a specially formulated solid lubricant is embedded. During operation a very fine, but very strong lubricating film is deposited automatically over the complete moving area. This film remains intact at all times, even immediately upon starting. The construction is also being equipped with grease inlets in order to secure and guarantees a well-lubricated moving surface. 2.
Roller Bearing System
The roller bearing swivels are equipped with a cylindrical thrust roller bearing system (either single or double row).
Summary What is best? The usage of roller or slide bearing swivel? It depends on your operation. The main issue is that most operations are different. The operation can be normal anchor handling, or installation of chain, polyester ropes or spiral strand, anchor proof loading, towing etc.
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Anchor Handling Course
The slide-bearing swivel should not rotate under tension until the induced torque is exceeding the start friction. This enhances the fatigue life of the wire. Typical operation is anchor handling and inserts in combination mooring systems The roller bearing systems would rotate under tension, as the friction moment is lower than the induced torque. This could be benefit if you do not want to transfer the torque from your wire to the object lowered. Bear in mind, fatigue life of the wire will decrease after continuos use of roller bearing swivels. Typical operation is installation of sub sea equipment, anchors or proof loading of anchors.
Theory of Torque versus Friction: Based on our past experience and information provided by two large steel-wire rope manufacturers: ScanRope and Haggie Rand the induced torque by a six-stranded wire rope is: 6-8% of the diameter of rope x tensions. Example Induced torque: Wire size: Tension:
89mm 200 tonnes
Resulted induced torque:
0.07 x 0.089 x 200.000 x 9,81 = 12.223 Nm
Break Out Torque Comparison: 1.
Friction moment Roller Bearing System:
0.015 (0.005 in rolling mode)
Average Diameter of bearing:
0.20 m
Break-out Torque: 2.
0.5 x 0.20 m x 0.015 x 200.000 x 9.81 = 2.943 Nm
Friction moment Slide Bearing System:
0.12 (0.10 in gliding mode)
Average Diameter:
0.20 m
Break-out Torque:
0.5 x 0.20 m x 0.12 x 200.000 x 9.81 = 23.544 Nm
As can be seen above the resistance (friction moment) in the slide bearing system is HIGHER than the induced torque in the wire. The swivel will not rotate when the tension is increased.
M:\ANCHOR HANDLING\Course Material\Training Manual New\Chapter 09\1.0 Swivel.doc
Chapter 09
Page 4
MTC
M:\ANCHOR HANDLING\Course Material\Training Manual New\Chapter 09\1.0 Swivel.doc
Anchor Handling Course
Chapter 09
Page 5
MTC
Anchor Handling Course
Pin Extractor As torsion tension builds up in wires that have been under heavy load this will result in violent movement of the wires when disconnected. Removing of pins, in shackles, dismantling of other connecting links e.g. Pear – and Kenter link, from systems that have been under tension and where torsion is likely, should only take place by use of a tugger or capstan wire together with a chain - / wire sling or a Pin Extractor. Occasionally people have been injured when a crowbar has been used for this action, so that is why a crowbar never should be used to punch pins out of shackles where the wire has been under tension. When using the tugger or capstan wire together with a sling or Pin Extractor, the safety is considerably improved. See the Pin Extractor in use on an 85 T shackle on the following page. The wire from either the tugger or the capstan is fixed on the Extractor, which is hooked on to the shackle pin. The pin is now easily pulled out by use of a tugger or capstan.
M:\ANCHOR HANDLING\Course Material\Training Manual New\Chapter 09\2.0 Pin Extractor.doc
Chapter 09
Page 1
Maersk E-procurement Training Centre work group A/S
Pin Extractor in use on a 85 T Shackle
Anchor Handling Equipment, chapter 9
MTC
Anchor Handling Course
Socket Bench As mentioned in the APM Procedures 15, 16 and 15, 259, that we now and then have to resocket the wires used for anchor handling and towing. These re-socketing are often carried out by the ship’s crew and in this connection occurs the problem how to clean out used wire sockets. The only applicable method for removing the old piece of wire is to squeeze the compound out of the socket. For this purpose you can use a hydraulic jack. The same method is used on workshops ashore. The method with using heat on the socket in order to get the used socket cleaned is not applicable for following two reasons. 1. You can easily change the steel structure of the socket, which afterwards under load can brake. 2. There can be a pocket of air inside the socket/compound. When the air pocket becomes superheated this can result in an unexpected explosion of compound. The attached picture on the following page illustrates how a hydraulic jack can be used to squeeze out the old compound.
M:\ANCHOR HANDLING\Course Material\Training Manual New\Chapter 09\4.0 Socket Bench.doc
Chapter 09
Page 1
Maersk E-procurement Training Centre work group A/S
Socket Bench Hydraulic Jack in use - squeezing out the old compound
Anchor Handling Equipment, chapter 9
CHAINS & FITTINGS
SECTION 2
CHAINS AND FITTINGS Introduction There are currently two types of chain in common use within the marine industry. Studlink chain which is the most popular is used by the shipping and the oil Industry. Open link, which has no studs, is generally used in special mooring applications such as permanent moorings for FPSO’s for the larger diameter chains and buoy and marine moorings for the small diameters. Chain is normally supplied in 27.5 metre lengths but the oil industry uses chain of much longer lengths up to about 1370 feet (4,500 metres). Long lengths of chain mean no joining links, which may be the weakest links, but shipping and handling can be a problem. Chain size is generally expressed as the diameter of the steel at the bending area. This can mean that steel bars of 78-79mm may be used to manufacture chain of 76mm diameter. Chain can be fitted with open end links to enable shackle connections to be made. These end links are normally forged to the chain using an intermediate link also known as an enlarged link. These links are larger than the diameter of the chain to take into account the differing radii and the reduced strength of the links due the end link being studless. Chain strengths are expressed as grades followed by a number. The letter used varies with countries but the strength of the chain remains the same. The United Kingdom used “U”, France and Spain used “Q” and the Scandinavian countries use “K”. The number relates to the type and hence the strength of the steel. U1 grade is mild steel, U2 is a high tensile steel and U3 is a special heat treated steel. These grades are normally only used within the shipping industry as the oil industry demands even greater strengths for the chain used. The original grade designed for the offshore industry was ORQ (Oil Rig Quality). Although this chain is still in use it has been superseded by new grades such as Rig Quality 3 and Rig Quality 4. These grades were introduced by the classification societies in order to standardise quality. The same grades also apply to the joining links that may be used with the chain. Tables showing the various strengths of chain are shown overleaf. Offshore Industry dictates that chain must be periodically inspected for wear and defects. The level of inspection and the intervals of these surveys are laid down by the classification authorities. Balmoral can carry out such inspections in line with relevant classification society requirements.
2.1
CHAINS & FITTINGS
STUD LINK MOORING CHAIN
3.6d
6d
4d
6.5d
6.75d
ENLARGED LINK
Common Link
2.2
1.2d
1.1d
1d COMMON LINK
4d
Enlarged Link
END LINK
End Link
CHAINS & FITTINGS
STUD LINK CHAIN Shot = 90 ft = 27.5 m U2 Weight Kg/shot incl. Kenter
222 A 306 418 C 497 652 E 734 826 H 919 1105 1209 1437 1555 1809 1946 2100 2253 2573 2742 3097 3374 3681 4187 4832 5385 5723 6613
9.81 kN P.L. B.L.
mm
142019 22 172026 28 210032 34 264036 38 42 44 48 50 54 56 58 60 64 66 70 73 76 81 87 92 95 102
= = =
in
1240 3/4280 7/8 1370 1480 1 1/8 18201 1/4530 1 5/16 1 7/16660 2500 1 1/2 1 5/8 1 3/4 1 7/8 2 2 1/8 2 3/16 2 5/16 2 3/8 2 1/2 2 5/8 2 3/4 2 7/8 3 3 3/16 3 7/16 3 5/8 3 3/4 4
P.L. kN
150 935 200 278 1129 321 417 1391 468 523 1815 581 703 769 908 981 1140 1220 1290 1380 1560 1660 1840 1990 2150 2410 2750 3040 3230 3660
U3 B.L. kN
870 211590 280 1040 389720 449 1270 583 910 655 1660 732 1050 812 981 1080 1280 1370 1590 1710 1810 1940 2190 2310 2580 2790 3010 3380 3850 4260 4510 5120
ORQ
P.L. kN
B.L. kN
P.L. kN
B.L. kN
211 30 280 389 40 449 583 65 655 732 75 812 981 1080 1280 1370 1590 1710 1810 1940 2190 2310 2580 2790 3010 3380 3850 4260 4510 5120
301 401 556 642 833 937 1050 1160 1400 1540 1810 1960 2270 2430 2600 2770 3130 3300 3690 3990 4300 4820 5500 6080 6440 7320
1400 1620 1746 1854 1976 2230 2361 2634 2846 3066 3453 3924 4342 4599 5220
2110 2441 2639 2797 2978 3360 3559 3970 4291 4621 5209 5916 6544 6932 7868
1 Tonne Proof Load Breaking Load
2.3
CHAINS & FITTINGS
STUD LINK/STUDLESS CHAIN – OIL INDUSTRY GRADES Break Load Dia
R4-RQ4
mm
kN
66 68 70 73 76 78 81 84 87 90 92 95 97 100 102 105 107 111 114 117 120 122 124 127 130 132 137 142 147 152 157 162 165 168 171 175 178
2.4
4621 4885 5156 5572 6001 6295 6745 7208 7682 8167 8497 9001 9343 9864 10217 10754 11118 11856 12420 12993 13573 13964 14358 14955 15559 15965 16992 18033 19089 20156 21234 22320 22976 23633 24292 25174 25836
R3S R3 Stud and Studless kN
4200 4440 4685 5064 5454 5720 6130 6550 6981 7422 7722 8180 8490 8964 9285 9773 10103 10775 11287 11807 12334 12690 13048 13591 14139 14508 15441 16388 17347 18317 19297 20284 20879 21477 22076 22877 23479
kN
3761 3976 4196 4535 4884 5123 5490 5866 6252 6647 6916 7326 7604 8028 8315 8753 9048 9650 10109 10574 11047 11365 11686 12171 12663 12993 13829 14677 15536 16405 17282 18166 18699 19234 19771 20488 21027
RQ3-API kN
3559 3762 3970 4291 4621 4847 5194 5550 5916 6289 6544 6932 7195 7596 7868 8282 8561 9130 9565 10005 10452 10753 11057 11516 11981 12294 13085 13887 14700 15522 16352 17188 17693 18199 18707 19386 19896
Weight Stud
Studless
kgs/m
kgs/m
95 101 107 117 126 133 144 155 166 177 185 198 206 219 228 241 251 270 285 300 315 326 337 353 370 382 411 442 473 506 540 575 596 618 640 671 694
87 92 98 107 116 122 131 141 151 162 169 181 188 200 208 221 229 246 260 274 288 298 308 323 338 348 375 403 432 462 493 525 545 564 585 613 634
CHAINS & FITTINGS
Proof Load R4-RQ4
Dia
mm
66 68 70 73 76 78 81 84 87 90 92 95 97 100 102 105 107 111 114 117 120 122 124 127 130 132 137 142 147 152 157 162 165 168 171 175 178
R3S
Stud
Studless
Stud
Studless
kN
kN
kN
kN
3643 3851 4064 4392 4731 4962 5317 5682 6056 6439 6699 7096 7365 7776 8054 8478 8764 9347 9791 10242 10700 11008 11319 11789 12265 12585 13395 14216 15048 15890 16739 17596 18112 18631 19150 19845 20367
3238 3423 3613 3904 4205 4411 4726 5051 5383 5723 5954 6307 6547 6912 7159 7536 7790 8308 8703 9104 9511 9785 10061 10479 10903 11187 11906 12637 13376 14124 14879 15641 16100 16560 17022 17640 18104
3036 3209 3387 3660 3942 4135 4431 4735 5046 5365 5582 5913 6138 6480 6712 7065 7304 7789 8159 8535 8916 9173 9432 9824 10221 10488 11162 11847 12540 13241 13949 14663 15094 15525 15959 16538 16972
2935 3102 3274 3538 3811 3997 4283 4577 4878 5187 5396 5716 5933 6264 6488 6829 7060 7529 7887 8251 8619 8868 9118 9497 9880 10138 10790 11452 12122 12800 13484 14174 14590 15008 15427 15986 16407
Weight
R3
RQ3-API
Stud Studless kN
Stud Studless kN
Stud
Studless
kgs/m
kgs/m
2631 2782 2935 3172 3417 3548 3840 4104 4374 4650 4838 5125 5319 5616 5817 6123 6330 6750 7071 7397 7728 7950 8175 8515 8858 9089 9674 10267 10868 11476 12089 12708 13081 13455 13831 14333 14709
2361 2496 2634 2847 3066 3216 3446 3683 3925 4173 4342 4599 4774 5040 5220 5495 5681 6058 6346 6639 6935 7135 7336 7641 7950 8157 8682 9214 9753 10299 10850 11405 11739 12075 12412 12863 13201
95 101 107 117 126 133 144 155 166 177 185 198 206 219 228 241 251 270 285 300 315 326 337 353 370 382 411 442 473 506 540 575 596 618 640 671 694
87 92 98 107 116 122 131 141 151 162 169 181 188 200 208 221 229 246 260 274 288 298 308 323 338 348 375 403 432 462 493 525 545 564 585 613 634
2.5
CHAINS & FITTINGS
OPEN LINK MOORING CHAIN
LONG LINK (MILD STEEL)
d 3.5d 6d Size
mm
ins
13 16 19 22 26
1/2 5/8 3/4 7/8 1
Weight
Proof Load
kg/m
kg
3.34 5.06 7.14 10.46 13.38
3190 4830 6820 10000 12770
MEDIUM LINK (MILD STEEL)
Minimum Breaking Load kg
7970 12090 17050 24990 31940
d 3.5d
5.5d Size mm
13 16 19 22 25 28 32 34 38 42 44 48 51
2.6
Weight ins
1/2 5/8 3/4 7/8 1 1 1/8 1 1/4 1 3/8 1 1/2 1 5/8 1 3/4 1 7/8 2
kg/m
3.50 5.20 7.40 10.00 12.80 16.50 21.00 23.50 29.50 36.00 39.50 47.00 53.00
Proof Load kg
3200 4800 6800 9100 11800 14800 19400 21800 27300 33300 36600 43500 49200
Minimum Breaking Load kg
6400 9600 13600 18200 23600 29500 38700 43600 54600 66600 73200 87000 98300
CHAINS & FITTINGS
OPEN LINK MOORING CHAIN
SHORT LINK (MILD STEEL)
d 3.5d 5d
Size mm
6 7 8 10 11 13 16 19
Weight
Proof Load
ins
kg/m
kg
1/4 9/32 5/16 3/8 7/16 1/2 5/8 3/4
0.89 1.13 1.39 1.95 2.67 3.72 5.64 7.96
700 900 1250 2000 2240 3200 5000 6820
Minimum Breaking Load kg
1400 1800 2500 4000 4480 6400 10000 3640
2.7
CHAINS & FITTINGS
KENTER JOINING LINKS
Size mm
Weight kg
19 22 26 30 32 34 38 41 44 48 52 54 57 60 64 67 70 73 76 79 83 86 89 92 95 98 102 105 108 110 114 120
1.0 1.6 2.6 3.5 4.8 6.5 8.4 11.0 13.5 16.5 20 24 28 32 39 45 52 60 67 77 86 93 101 112 123 137 151 158 163 171 180 230
d
6d
4d
4.2d
TYPICAL APPLICATION
Smaller diameters Grade 3, ORQ Larger diameters Grade ORQ, R3 R4 All dimensions given are approximate
2.8
1.5d
Kenter Joining Link Common Link Common Link
CHAINS & FITTINGS
PEAR SHAPE ANCHOR CONNECTING LINK
G D J
C
F
A K
E H
B Anchor Shank
Anchor Shackle
Common Links
No
Chain size in mm
4 5 6 7 8 9 10 No
4 5 6 7 8 9 10
A mm
B mm
C mm
D mm
E mm
F mm
32-40 42-51 52-60 62-79 81-92 94-95 97-102
298 378 454 562 654 692 889
206 260 313 376 419 435 571
59 76 92 117 133 146 190
40 51 60 79 92 98 121
48 64 76 95 124 130 165
83 100 121 149 149 159 190
G
H
40 x 44 56 51 x 60 74 62 x 73 88 85 x 79 111 111 x 102 130 x 133 124 x 137 141 130 181
J
26 32 37 48 54 57 73
K
Weight in kg
43 52 64 76 79 83 108
13 27 49 94 149 236 386
Smaller diameters Grade 3, ORQ Larger diameters Grade ORQ, R3 R4 All dimensions given are approximate 2.9
CHAINS & FITTINGS
DETACHABLE CONNECTING LINK
E
D
C F
E
B
G
A
Chain size in mm
A
B
C
D
E
F
G
weight in Kg
30-32 33-35 36-38 40-42 43-44 46-48 50-51 52-54 56-58 59-60 62-64 66-67 68-70 71-73 74-76 78-79 81-83 84-86 87-89 90-92 94-95 97-98 100-102
190.5 210 229 248 267 286 305 324 343 362 381 400 419 438 457 476 495 514 537 552 571 590 607
127 140 152 165 190 194 197 210 221 234 246 246 275 283 295 308 320 332 350 356 368 381 394
44 49 53 57 62 64 64 67 71 78 79 83 92 94 95 102 103 107 116 119 122 127 132
32 35 38 41 44 48 51 54 57 60 64 67 73 73 76 79 83 86 92 92 95 98 102
35 39 43 50 51 55 59 64 67 70 73 78 83 85 90 92 92 100 105 106 114 117 119
39 42 46 50 56 60 64 67 71 75 78 79 90 93 94 96 103 107 114 116 119 121 122
21 23 25 27 30 31 33 36 38 40 42 44 46 48 50 52 55 57 59 61 62 67 68
4.5 6.0 7.8 10.0 12.5 14.5 16.5 20.0 23.5 27.5 32.0 37.0 45.5 48.5 54.5 62.5 73.0 80.5 93.5 97.5 116.0 123.0 130.0
Smaller diameters Grade 3, ORQ Larger diameters Grade ORQ, R3 R4 All dimensions given are approximate 2.10
CHAINS & FITTINGS
D’ TYPE JOINING SHACKLES
Size mm
Weight kg
19 22 26 30 32 34 38 41 44 48 52 54 57 60 64 67 70 73 76 79 83 86 89 92 95 98 102 105 108 110 114 120
1.7 2.7 4.3 7 7.8 8.5 13.8 18 22 27 29 39 46 52 64 74 84 98 110 122 134 144 154 168 184 200 220 230 264 285 320 340
3.4d
7.1d
1.2d 1.6d
1.3d
1.4d
1.3d
2.8d
4d Enlarged Link
Common Link
Joining Shackle
End Link
End Link
Enlarged Link
Common Link
2.11
CHAINS & FITTINGS
‘D’ TYPE ANCHOR SHACKLES
Size mm
Weight kg
19 22 26 30 32 34 38 41 44 48 52 54 57 60 64 67 70 73 76 79 83 86 89 92 95 98 102 105 108 110 114 120
2.5 3.8 6.0 9 11.3 14 19.8 26 32 39 48 57 67 80 93 106 121 141 159 172 189 200 230 258 290 301 344 390 422 431 475 530
4d
8.7d
1.8d 1.4d
2.4d 5.2d
Enlarged Link
1.4d
3.1d
Anchor Shackle
Swivel End Link
Smaller diameters Grade 3, ORQ Larger diameters Grade ORQ, R3 R4 All dimensions give are approximate
2.12
1.3d
Anchor Shank
Clenched Anchor Shackle
CHAINS & FITTINGS
SHACKLES BOW AND ‘D’ SCREW PIN SHACKLES UP TO 120 tonne SWL
BOW SCREW PIN
'D' SCREW PIN Size
Inside Length
Gap
SWL Tonnes
Size mm
Pin Dia mm
Gap mm
O/Dia Eye mm
2 3.25 4.75 6.5 8.5 9.5 12 13.5 17 25 35 55 85 120
13 16 19 22 25 29 32 35 38 44 51 64 76 89
16 19 22 25 29 32 35 38 41 51 57 70 83 95
19 26 32 35 42 45 51 57 60 73 83 105 127 140
32 41 48 54 60 67 76 85 92 111 127 152 165 203
Outside of Eye
Pin Dia
Inside Weight Weight Length Safety Screw Pin mm kg kg
48 61 70 83 95 108 118 133 149 178 197 267 330 381
0.36 0.72 1.3 1.8 2.6 3.6 5.1 6.9 9.0 14.2 21.0 43 66 114
0.36 0.68 1.0 1.5 2.4 3.4 3.9 5.9 7.9 12.7 18.7 38.0 59 102
2.13
CHAINS & FITTINGS BOW AND ‘D’ SAFETY PIN SHACKLES UP TO 100 tonne SWL
2.14
SWL Tonne
Size mm
Pin Dia mm
Gap mm
O/Dia Eye mm
2 3.25 4.75 6.5 8.5 9.5 12 13.5 17 25 35 50-55 75-85 100
13 16 19 22 25 29 32 35 38 44 51 64 76 89
16 19 22 25 29 32 35 38 41 51 57 70 83 95
19 26 32 35 42 45 51 57 60 73 83 105 127 149
32 41 48 54 60 67 76 85 92 111 127 152 165 203
Inside Weight Weight Length Safety Screw Pin mm kg kg
41 51 60 70 80 89 99 111 124 149 171 203 229 267
0.36 0.67 0.72 1.7 2.4 3.3 4.7 6.1 8.4 13.0 19.0 38.0 56.0 99.0
0.3 0.55 0.6 1.4 2.1 3.0 4.1 5.5 7.4 16.0 16.5 33.7 49.0 86.0
CHAINS & FITTINGS
SHACKLES, BOW & ‘D’ SAFETY BOW SAFETY
'D' SAFETY Size
Inside Length
Outside of Eye
Gap
Pin Dia
GREEN PIN SWL Tonnes
Size mm
Pin Dia mm
Gap mm
120 150 200 250 300 400 500 600 700 800 900 1000
89 102 120 125 135 165 175 195 205 210 220 230
95 108 130 140 150 175 185 205 215 220 230 240
146 165 175 200 200 225 250 275 300 300 320 340
Inside Weight Length Safety mm kg
381 400 500 540 600 650 700 700 700 700 700 700
120 160 235 285 340 560 685 880 980 1100 1280 1460
CROSBY SWL Tonnes
Size mm
Pin Dia mm
Gap mm
Inside Length mm
O/Dia Eye mm
Weight kg
120 150 200 250 300 400 500 600
89 102 108 121 130 149 155 178
95 108 121 127 152 178 190 210
133 140 184 216 216 210 219 235
371 368 394 508 495 571 641 810
203 229 268 305 305 356 381 432
120 153 204 272 352 499 704 863
2.15
CHAINS & FITTINGS
JAW & JAW SWIVELS
Size mm
Weight kg
54 57 60 64 68 70 73 76 84 90 95 102 105 108 114 120
120 156 200 258 303 330 361 394 493 600 700 970 1060 1170 1440 1650
1.4d
1.3d
1.3d 12.7d
7.7d
2.2d
c 1.7d Anchor Shank
1.7d 4d
5.6d End Link
Enlarged Link Common Link Anchor Shank
Common Link
Enlarged Link
End Link
Anchor Shackle
TYPICAL APPLICATION
2.16
CHAINS & FITTINGS
BOW & EYE SWIVELS
3.6d
1.1d
1.4d 9.3d 6.3d
4.7d
1.2d 3.4d Swivel
End Link
End Link
Enlarged Link
Enlarged Link End Link
Size mm
Weight kg
19 22 26 30 32 34 38 41 44 48 52 54 57 60 64 67 70 73 76 79 83 86 89 92 95 98 102 105 108 110 114 120
2.8 4.4 6.8 9.4 12.7 17.5 22 29 36 43 54 64 75 78 90 104 114 134 152 171 189 196 217 256 275 300 342 387 420 450 520 620
Common Link
Enlarged Link
Swivel
Enlarged Link
TYPICAL SWIVEL ASSEMBLIES
2.17
CHAINS & FITTINGS
MOORING RINGS
7.5d
2d
TYPICAL APPLICATION
Ring Shackles Sinker
2.18
Size mm
Weight kg
19 25 32 38 44 51 57 64 70 76 83 89 95 102
6 12 24 40 63 98 136 193 252 323 421 518 630 780
CHAINS & FITTINGS
FISH PLATES
C B
D D
A
Chain Size mm
A mm
B mm
C mm
D mm
38 48 58 70 76 83 95 102
320 360 430 506 550 600 685 736
168 184 225 266 290 316 361 388
50 60 80 90 90 100 120 120
76 88 102 120 130 142 162 174
Proof Breaking Load Load Weight Tonnes Tonnes kg
81.2 127 190 270 313 356 508 594
106 181 287 404 472 549 794 910
13 25 50 81 96 127 199 230
2.19
CHAINS & FITTINGS
PELICAN HOOKS
C D E
A B Chain
Pelican Hook Deck Padeye TYPICAL APPLICATION
2.20
Chain Size mm
A mm
B mm
C mm
D mm
E mm
25-28 32 34-42 44-48 51-58 60-64 67-70 76-83
90 100 110 120 135 150 170 200
35 40 45 50 60 70 80 100
38 45 55 60 75 86 90 105
30 35 42 50 60 70 80 100
358 390 430 475 525 600 705 880
S.W.L. Weight Tonnes kg
10 15 25 35 50 60 75 100
24 35 50 70 98 150 230 430
CHAINS & FITTINGS
SLIP HOOKS
Size mm
19 22 25 29 32 35 38 41 44 48 51 54 57 60 64 67 70 73 76 79 83 86 89 92 95 98 102
Weight kg
4.3 6.6 10 14 19 27 34 44 55 66 82 98 115 137 159 183 208 241 272 312 348 394 437 483 532 593 649
13d 0.6d 1.3d
2.5d
6.7d 1.3d 4.4d
1.3d
4d
10.4d
2.21
CHASERS & GRAPNELS ‘J’ CHASERS BEL 101 ’J’ CHAIN CHASER Safe Working Load: Proof Test Load: Weight:
ø3.38
86
4.88 124
100 Tonnes 250 Tonnes 1882 Kg
96.00 2438
50 27. 699
72.00 1829
12.00 305
CHAIN CHASERS Chain chasers were developed to overcome the problems of recovering rig anchors when anchor pendant lines failed in service. The operational sequence of chasing is shown below. Stage 1
Wire Rope from Anchor Handling Vessel Anchor
Chain Chaser Mooring Chain
3.2
Stage 2
Stage 3
CHASERS & GRAPNELS BEL 109 GRAPNEL
ø3.38 86
Safe Working Load: 100 Tonnes Proof Test Load: 150 Tonnes Weight: 1351 Kg
4.50 114
70.00 1778
4.00 102
3.00 76 54.00 1372
GRAPNELS The grapnel was designed as a “fishing” tool primarily for the purpose of recovering an anchor and chain which has become detached and has fallen to the sea bed. The operational sequence is as follows: Stage 1
Stage 2
Recovery Wire Rope
Broken Chain
Recovery Wire Rope
Broken Chain
3.3
CHASERS & GRAPNELS
GRAPNELS BEL 139 GRAPNEL Safe Working Load: 250 Tonnes Proof Test Load: 350 Tonnes Weight: 2630 Kg
ø5.25 133
7.5 191
66.00 1676 7.88 200 3.94 100
8.5 216
3.4
66.5 1689 ø3.50 89
78.5 1994 50.5 1283
5.0 127
Continuous Fillet Weld
1.5 38
3.94 100
CHASERS & GRAPNELS
PERMANENT CHASERS BEL 102 - 106 - 110
G Hø
A C F D B
Type
S.W.L.
Proof Test
A
B
C
D
45.00 39.00 30.00 991 762 1143 in 67.00 46.00 39.00 30.00 BEL 130 250 106 Tonnes Tonnes mm 1702 1168 991 762 in 73.50 49.00 44.50 33.00 130 250 BEL 110 Tonnes Tonnes mm 1867 1245 1130 838 in 65.25 250 BEL 100 102 Tonnes Tonnes mm 1657
Weight:
BEL 102 BEL 106 BEL 110
E
E
F
G
H
12.00 305 15.00 381 13.00 330
7.50 191 8.00 203 8.00 203
4.88 124 5.13 130 5.13 130
3.38 86 3.88 99 3.88 99
1088 Kg 1451 Kg 1433 Kg
Lifting eye dimensions shown are standard for each type. Specials can be made to suit customer requirements.
3.5
CHASERS & GRAPNELS
DETACHABLE PERMANENT CHAIN CHASERS BEL 107 - 108 - 111
G Hø
A
C
F D B
Type
S.W.L.
Proof Test
in 76.00 BEL 130 250 108 Tonnes Tonnes mm 1931 in 78.50 130 250 BEL 111 Tonnes Tonnes mm 1994
Weight:
BEL 107 BEL 108 BEL 111
B
C
D
E
F
G
H
45.00 1143 46.00 1168 49.00 1245
42.50 1080 42.00 1067 44.50 1130
30.00 762 30.00 762 33.00 838
12.00 305 15.00 381 13.00 330
7.50 191 8.00 203 8.00 203
4.88 124 5.13 130 5.13 130
3.38 86 3.88 99 3.88 99
A
in 74.25 250 BEL 100 107 Tonnes Tonnes mm 1886
E
1238 Kg 1656 Kg 1742 Kg
Lifting eye dimensions shown are standard for each type. Specials can be made to suit customer requirements.
3.6
CHASERS & GRAPNELS
PERMANENT WIRE CHASERS BEL 210 - 213 - 214 - 215
A
C
F
D B
Type
BEL 210 BEL 213 BEL 214 BEL 215
Weight:
Proof S.W.L. Test Tonnes Tonnes
130 130 130 250
BEL BEL BEL BEL
250 250 250 400
210 213 214 215
A
mm 2073 mm 1962 mm 2318 mm 2051
1959 1846 2530 2495
B
C
1245 1203 1099 1086 1308 1397 1168 1060
Hø
E
G
D
E
F
G
838 692 902 711
330 330 330 356
432 445 508 445
130 130 130 178
H
99 99 99 127
kg kg kg kg
Lifting eye dimensions shown are standard for each type. Specials can be made to suit customer requirements.
3.7
CHASERS & GRAPNELS
‘J’ LOCK CHAIN CHASERS BEL 115
4.88 124
82.00 2083
3.38 86
12.00 305
ø28.00 711
21.00 533
1
1
BEL 115/35 for chain 2 /2 inch to 3 /2 inch. BEL 115/45 for chain 3 Safe Working Load: Proof Test Load: Weight:
3.8
3
/4
1
inch to 4 /2 inch. 100 Tonnes 250 Tonnes 1778 Kg
58.50 1486
MTC
Anchor Handling Course
Breaking the anchor off the bottom: Breaking out anchors takes its time mainly because: Breaking out forces is caused by the volume of the soil on the fluke and the sucking or under pressure below it. Pulling up the anchor increases the soil resistance due to the dilatant behaviour of the soil. This resistance decreases with time, reducing the negative pressure and thus easing the break out. For most anchors the following guide is useful: 1. In sandy soil the break out force will be between 12 and 17% of the anchor's test load. 2. In clay soil the break out force will be about 60% of the anchor’s test load. 3. In sticky soft soil the break out force can exceed 100% of the anchor’s test load. As the typical test tension of the anchor is around 1/3 break strain of the chain or wire in use, the following table is a summary of the forces: Chain type 76 mm U3 76 mm ORQ 76 mm K4
1/3 Break load 143 154 200
Sandy 17% 24 26 34
Clay 60%
Soft Soil 100%
86 93 120
143+ 154+ 200+
Breaking the anchor off the bottom is very likely the operation where there has been most loss of time and equipment. It is a very time-consuming and hard job to get the anchor up, when the connection between the anchor and the vessel is broken. Wrong use of equipment and wrong technique gives many possibilities of damaging the work and or the pennant wire, other anchor handling equipment i.e. the swivel and especially maybe also the winch. One of these possibilities must here be mentioned: The mentioned possibility of damaging the wire is overload on the wire during the work with breaking the anchor loose from the bottom. A very common but inappropriate method is to shorten up on the work wire - heave in on the winch – and keep on going until the stern roller is above the anchor position and the anchor will break loose or the wire / equipment will break. See fig 1, page 2, chapter 11. Shorten up on the work wire might help breaking loose the anchor in many situations, but on the other hand there is a high risk for overloading your equipment. The tension, which during the above mentioned method is used on the wire, is depended on following circumstances: 1. Winch pull force 2. Vessel’s displacement 3. Nature of the sea / sea state
M:\ANCHOR HANDLING\Course Material\Training Manual New\Chapter 11\Breaking the anchor off the bottom.doc
Chapter 11
Page 1
MTC
Anchor Handling Course
Pt. 1 is depending on the size of the winch and which layer you are working on. If you are using one of the bigger winch sizes you are able to exceed the breaking load of the wire. Pt. 2 and pt. 3 can easily by many times exceed the breaking load of the wire regardless the size of winch – small or large.
D B
B A
C
A
Fig 1
•
“A” is the break loose force, indicating the best direction and size of tension to be used for breaking loose the anchor.
•
“B” will be the tension you will get in your work wire in order to obtain the required force “A”, if position of the stern roller is above the anchor,
•
“D” is water depth plus penetration of anchor.
Anchors in very soft clay can be buried very deep. A penetration of 60 meters is mentioned. Another fact is that the soil aft of the anchor is disturbed due to the penetration of the anchor. While the soil above the anchor might be intact and has probably been it for several thousand years. The forces illustrated on fig 1 are the same if position of chaser collar is on top of the anchor shank as e.g. on a Stevpris. (Illustrated with green arrows on fig 1)
M:\ANCHOR HANDLING\Course Material\Training Manual New\Chapter 11\Breaking the anchor off the bottom.doc
Chapter 11
Page 2
MTC
Anchor Handling Course
The way to break the anchor loose of the bottom is therefore: Slowly to increase power in a direction away from the rig (pull the anchor out backwards) until the above mentioned “breaking loose force” and then holding this power to let the under pressure or “suction force” be reduced / equalised so as to ease the break out. If the anchor is not loosened after 30 to 40 minutes (a mater of estimate), then slowly increase 10% and so on. An example from the North See: The anchor was buried 60 meter. Maximum allowed tension on the system, 130 T. The AH-vessel used 18 hours to break loose the anchor – but it came, without breaking anything. Changing the heading of the vessel might also help to break the anchor loose, but before this is performed it has to be verified with the rig, as going off line with the vessel gives a high risk of bending the shank of the anchor. The forces on the wire might be considerably increased if there is significant swell as the boat heaves up and down. It is very important during the “Breaking loose operation” to keep the actual tension on every piece of equipment in use, i.e. wires, swivel, connecting links and winch, below allowed maximum working load. Below is a bad example of a written procedure about how to retrieve the anchor:
“When the boat has the chaser at the anchor, it will increase power and maintain app. 50% bollard pull for 15 minutes. If no appreciable forward movement is recognised, the boat will reduce bollard pull to 30% and
shorten work wire length to water depth plus 30 meters! The boat will break the anchor off-bottom by increasing power until the anchor is free from the seabed but will exercise caution not to exceed 200 metric tons work wire tension unless approved by the rig’s OIM and or barge master.” As mentioned in the Vryhof Anchor Manual: “Anchors in very soft clay can be buried very deep. Have patience, take your time and be gentle with the equipment; the anchor will come.”
M:\ANCHOR HANDLING\Course Material\Training Manual New\Chapter 11\Breaking the anchor off the bottom.doc
Chapter 11
Page 3
Anchor deployment, example of
DANMARK
Polaris
1 JK MultiMedie +45 6474 1995
Anchor deployment, example of • The Maersk Trainer will back up to rig. • Rig passes over PCP to deck of the Maersk Trainer using rig crane.
AHTS backs up to rig to recieve PCP on deck POLARIS
DANMARK
POLARIS
15 mt Stewpris anchor
PCP (w/ chaser)
AHTS MAERSK TRAINER
2 JK MultiMedie +45 6474 1995
Anchor deployment, example of
POLARIS
DANMARK
POLARIS AHTS MAERSK TRAINER
3 JK MultiMedie +45 6474 1995
Anchor deployment, example of • The rig will commence paying out all chain. • The Maersk Trainer will be instructed to increase power to prevent mooring chain from rubbing on the rig’s anchor bolster.
~ 573 m (Fairlead to stern roller horizontal distance)
~57 mt POLARIS
DANMARK
~77 mt @ stern
~75 mt @ fairlead
Polaris
41.18°
Maersk Trainer
3 9⁄16" dia. x 609 m rig chain
4 JK MultiMedie +45 6474 1995
Anchor deployment, example of • The Rig will pay out additional 500 meters of mooring wire and stop while AHTS keeps wire off bolster.
~ 1727 m (Fairlead to stern roller horizontal distance)
~58 mt POLARIS
DANMARK
~118 mt @ stern
~91 mt @ fairlead
Polaris
~41.74°
AHTS Maersk Trainer
3 1⁄2"dia. rig wire (~1000 m outboard)
3 9⁄16 dia. x 609 m rig chain
5 JK MultiMedie +45 6474 1995
Anchor deployment, example of • The Maersk Trainer pays 500 meters of work wire and keeps tension on system.
~ 1727 m (Fairlead to stern roller horizontal distance)
~58 mt POLARIS
DANMARK
~118 mt @ stern
~91 mt @ fairlead
Polaris
~41.74°
AHTS Maersk Trainer
3" dia. work wire (~500 m outboard)
3 1⁄2"dia. rig wire (~1000 m outboard)
15 mt Stewpris anchor
3 9⁄16 dia. x 609 m rig chain
5A JK MultiMedie +45 6474 1995
Anchor deployment, example of • The Maersk Trainer will reduce power and pay out additional work wire equal to a total of 1.3 times the anchors water depth.
POLARIS
DANMARK
AHTS Maersk Trainer
Polaris
3" dia. work wire (~1638 m outboard)
3 1⁄2"dia. rig wire (~1981 m outboard)
3 9⁄16 dia. x 609 m rig chain
15 mt Stewpris anchor
6 JK MultiMedie +45 6474 1995
Anchor deployment, example of • The Maersk Trainer will again increase power sufficiently to stretch mooring line to appox. 91 mt bollard pull. • When the Rig has determined the mooring line has been stretched, the AHTS will be instructed to reduce power rapidly, thereby setting the anchor on bottom.
~ 3341 m (Fairlead to stern roller horizontal distance)
POLARIS
DANMARK
AHTS Maersk Trainer
Polaris
3" dia. work wire (~1638 m outboard) 3 1⁄2"dia. rig wire (~1981 m outboard)
Water Depth 1300 m 3 9⁄16 dia. x 609 m rig chain
15 mt Stewpris anchor
7 JK MultiMedie +45 6474 1995
Anchor deployment, example of • The Maersk Trainer returns to the rig with the PCP
POLARIS
DANMARK
8 JK MultiMedie +45 6474 1995
Anchor deployment, example of
POLARIS
DANMARK
9 JK MultiMedie +45 6474 1995
Anchor deployment, example of • Pee Wee anchor pandant socket.
10 JK MultiMedie +45 6474 1995
vryhof anchor manual 2000
1
ACCREDITED BY THE DUTCH COUNCIL FOR CERTIFICATION Reg. No 24
ISO-9001CERTIFICATED FIRM DET NORSKE VERITAS INDUSTRY B.V., THE NETHERLANDS
Copyright © Vryhof anchors b.v., krimpen a/d yssel, the netherlands 1999. No part of this book may be reproduced in any form, by print, copy or in any other way without written permission of vryhof. Vryhof, Stevin Mk3, Stevpris, Stevshark and Stevmanta are registered trade marks. Vryhof reserves all intellectual and industrial property rights such as any and all of their patent, trademark, design, manufacturing, reproduction, use and sales rights thereto and to any article disclosed therein. All information in this manual is subject to change without prior notice. Vryhof anchors is not liable and/or responsible in any way for the information provided in this manual. First edition published 1984. Print run 7,500 copies. Second edition published 1990. Print run 7,500 copies. Reprint second edition print run 5,000 copies. Third edition published 2000. Print run 2,500 copies.
Table of contents Introduction
2
6
1. General Mooring systems Mooring components Mooring line Chain Wire rope Synthetic fibre rope Connectors Shackles Connecting link kenter type Connecting link pear shaped Connecting link c type Swivels Anchoring point Dead weight Drag embedment anchor Pile Suction anchor Vertical load anchor History of drag embedment anchors Characteristics of anchor types History of vryhof anchor designs
9 11 11 11 11 11 12 12 12 12 12 13 13 13 13 14 14 14 15 16 18
2. Theory Introduction Criteria for anchor holding capacity Streamlining of the anchor Shank shape Mooring line Criteria for good anchor design Aspects of soil mechanics in anchor design Soil classification Fluke/shank angle Fluke area Strength of an anchor design During proof loading While embedded in the seabed During anchor handling Strength of the shank
23 24 24 24 25 26 27 28 30 31 32 32 32 32 33
Table of contents Strength of the fluke Strength in extremely hard soils Anchor loads and safety factors Anchor behaviour in the soil Drag embedment anchors The set-up and consolidation effect The rate effect Vertical load anchors Proof loads for high holding power anchors Quality control Anchor tests Introduction Reading test curves Test results Norwegian Contractors (1984) Large scale anchor tests in the Gulf of Mexico Uplift Cyclic effect factor Tests with Stevmanta anchors Soil table 3. Practice Introduction Soil survey Pile or anchor Setting the fluke/shank angle Introduction Changing the fluke/shank angle on the Stevpris Mk3 Changing the fluke/shank angle on the Stevpris Mk5 Connecting a swivel to the Stevpris anchor Chasers Chasers and their application Chaser types The J-chaser The permanent chain chaser The detachable chain chaser The permanent wire chaser The J-lock chaser Stevpris installation
33 34 35 37 37 37 38 38 39 41 42 42 43 44 44 45 45 46 46 48
51 52 53 54 54 54 55 56 58 58 60 60 60 61 61 62 63
3
Table of contents
4
Stevpris deployment for modus Introduction Laying anchors Retrieving anchors Anchor orientation Decking the Stevpris anchor What not to do! Racking the Stevpris Deploying the Stevpris from the anchor rack Boarding the anchor in deep water Ballast in fluke Chaser equilibrium Deployment for permanent moorings Piggy-backing Introduction Piggy-back methods Piggy-backing involving hinging anchors Piggy-backing with two Stevpris anchors Piggy-backing by using a chaser Stevmanta VLA installation Introduction Single line installation procedure Installation procedure Stevmanta retrieval Double line installation procedure Stevmanta retrieval Double line installation procedure with Stevtensioner The Stevtensioner Introduction The working principle of the tensioner Measurement of the tensions applied Duration of pretensioning anchors and piles Handling the Stevtensioner Stevtensioner product range Supply vessels/anchor handling vessels
63 63 63 65 66 66 68 69 69 70 71 72 73 74 74 75 75 76 77 78 78 78 79 80 82 83 84 88 88 88 90 91 92 93 94
Table of contents 4. Product data Introduction Dimensions of vryhof anchor types Stevin Mk3 Stevpris Mk5 Stevshark Mk5 Stevmanta VLA Dimensions of other anchor types Proof load test for HHP anchors Dimensions of vryhof tensioner Proof load/break load of chains Chain components and forerunners Connecting links Conversion table Mooring line catenary Mooring line holding capacity Shackles Wire rope Wire rope sockets Thimbles Synthetic ropes Mooring hawsers Main dimensions chasers Stevin Mk3 UHC chart Stevin Mk3 drag and penetration chart Stevpris Mk5 UHC chart Stevpris Mk5 drag and penetration chart Stevmanta VLA UPC chart
97 98 98 99 100 101 102 104 106 108 110 112 113 114 115 116 118 120 123 124 126 128 130 131 132 133 134
5
Introduction A stone and something that looked like a rope. For millennia this was the typical anchor. Over the last 25 years of more recent history, vryhof has brought the art to a more mature status. They have grown into a world leader in engineering and manufacturing of mooring systems for all kinds of floating structures. In doing so the company has secured numerous anchor and ancillary equipment patents, and shared its experience with others.
6
The company understands that the needs of the industry can not be satisfied by the supply of standard hard-ware only. Universal and tailored solutions rooted in proven engineering should be based on long practical experience. Vryhof has been and will be introducing new and original anchor designs well into the 21st century. With their products, advice and this manual, it shares this knowledge with those who are daily faced with complex mooring situations. This manual is intended as a means of reference for all who purchase, use, maintain, repair or are in any way involved with anchors. Though written from one anchor manufacturer’s standpoint, the information contained herein is applicable to many types of anchors. Total objectivity is, of course, impossible. It is hoped this manual will contribute to the work and success of all who work with anchors. They are the only fixed reference point for many of the floating structures on the world’s often turbulent waters.
1
General
Mooring systems Mooring systems have been around just as long as man has felt the need for anchoring a vessel at sea. These systems were used, and are still used, on ships and consisted of one or more lines connected to the bow or stern of the ship. Generally the ships stayed moored for a short duration of time (days). When the exploration and production of oil and gas started offshore, a need for more permanent mooring systems became apparent. Numerous different mooring systems have been developed over the years, of which a short selection is presented here. semi-sub mooring
Semi-submersible drilling rig - generally the semisubmersibles are moored using an eight point mooring. Two mooring lines come together at each of the columns of the semi-submersible. 9 CALM buoy - generally the buoy will be moored using four or more mooring lines at equally spaced angles. The mooring lines generally have a catenary shape. The vessel connects to the buoy with a single line and is free to weathervane around the buoy. typical turret mooring
SALM buoy - these types of buoys have a mooring that consists of a single mooring line attached to an anchor point on the seabed, underneath the buoy. The anchor point may be gravity based or piled. Turret mooring - this type of mooring is generally used on FPSOs and FSOs in more harsh environments. Multiple mooring lines are used, which come together at the turntable built into the FPSO or FSO. The FPSO or FSO is able to rotate around the turret to obtain an optimal orientation relative to the prevailing weather conditions. Spread mooring - generally used on FPSOs and FSOs in milder environments. The mooring lines are directly connected to the FPSO or FSO at both the stern and bow of the vessel.
Mooring systems When oil and gas exploration and production was conducted in shallow to deep water, the most common mooring line configuration was the catenary mooring line consisting of chain or wire rope. For exploration and production in deep to ultra-deep water, the weight of the mooring line starts to become a limiting factor in the design of the floater. To overcome this problem new solutions were developed consisting of synthetic ropes in the mooring line (less weight) and/or a taut leg mooring system (fig. 1-01 and fig. 1-02).
10
The major difference between a catenary mooring and a taut leg mooring is that where the catenary mooring arrives at the seabed horizontally, the taut leg mooring arrives at the seabed at an angle. This means that in a taut leg mooring the anchor point has to be capable of resisting both horizontal and vertical forces, while in a catenary mooring the anchor point is only subjected to horizontal forces. In a catenary mooring, most of the restoring forces are generated by the weight of the mooring line. In a taut leg mooring, the restoring forces are generated by the elasticity of the mooring line. An advantage of a taut leg mooring over the catenary mooring is that the footprint of the taut leg mooring is smaller than the footprint of the catenary mooring, i.e. the mooring radius of the taut leg mooring will be smaller than the mooring radius of a catenary mooring for a similar application.
catenary system
fig. 1-01
taut leg system
fig. 1-02
Mooring components A typical mooring system can be divided in three different components, the mooring line, the connectors and the anchor point.
Mooring line Chain The most common product used for mooring lines is chain which is available in different diameters and grades. Two different designs of chain are used frequently, studlink and studless chain. The studlink chain is most commonly used for moorings that have to be reset numerous times during their lifetime, for instance semi-submersibles, while studless link chain is often used for permanent moorings (FPSOs, buoys, FSOs). A chain mooring line can be terminated in either a common link or an end link (fig. 1-03). Wire rope When compared to chain, wire rope has a lower weight than chain, for the same breaking load and a higher elasticity. Common wire ropes used in offshore mooring lines are six strand and spiral strand. The wire rope is terminated with a socket (for instance open spelter, closed spelter, CR) for connection to the other components in the mooring system. Generally wire rope is more prone to damage and corrosion than chain (fig. 1-04). Synthetic fibre rope A recent development is the use of synthetic fibre ropes as mooring line. Typical materials that can be used are polyester and high modulus polyethylene (Dyneema). The major advantage of synthetic fibre ropes is the light weight of the material and the high elasticity. The synthetic fibre rope is generally terminated with a special spool and shackle for connection to the other components in the mooring system.
fig. 1-03
fig. 1-04
11
Mooring components Connectors Shackles The shackle is a connector that is very common in the offshore industry. It consists of a bow, which is closed by a pin. Many different types of shackles are available, depending on the application. The shackle can be used in both temporary and permanent moorings (fig. 1-05).
12
Connecting link kenter type The connecting link kenter type is most commonly used for the connection of two pieces of chain mooring line, where the terminations of the two pieces have the same dimensions. The connecting link kenter type has the same outside length as a chain link of the same diameter. Generally connecting links kenter type are not used in permanent mooring systems, as they have a shorter fatigue life than the chain (fig. 1-06). Connecting link pear shaped The pear shaped connecting link is similar to the connecting link kenter type, except that it is used for the connection of two pieces of mooring line with terminations that have different dimensions. Like the connecting link kenter type, the pear shaped connecting links are not used in permanent mooring systems (fig. 1-07). Connecting link c type Like the connecting link kenter type, the connecting link c type is used for the connection of two pieces of mooring line with terminations that have the same dimensions. The major difference between the kenter type and the c type is the way that the connector is opened and closed. This connector is generally not used in permanent moorings (fig. 1-08).
fig. 1-05
fig. 1-06
fig. 1-07
fig. 1-08
Mooring components Swivels A swivel is used in a mooring system, generally of a temporary type, to relieve the twist and torque that builds up in the mooring line. The swivel is often placed a few links from the anchor point, although it can also be placed between a section of chain and a section of wire rope. There are many different types of swivels available, although a disadvantage of most common swivels is that they may not function while under load, which is caused by high friction inside the turning mechanism. A new development is swivels that are capable of swivelling under load, due to special bearing surfaces inside the mechanism (fig. 1-09).
fig. 1-09
Anchoring point Dead weight The dead weight is probably the oldest anchor in existence. The holding capacity is generated by the weight of the material used and partly by the friction between the dead weight and the seabed. Common materials in use today for dead weights are steel and concrete (fig. 1-10). Drag embedment anchor This is the most popular type of anchoring point available today. The drag embedment anchor has been designed to penetrate into the seabed, either partly of fully. The holding capacity of the drag embedment anchor is generated by the resistance of the soil in front of the anchor. The drag embedment anchor is very well suited for resisting large horizontal loads, but not for large vertical loads although there are some drag embedment anchors available on the market today that can resist significant vertical loads (fig. 1-11).
13
fig. 1-10
fig. 1-11
Mooring components Pile The pile is a hollow steel pipe that is installed into the seabed by means of a piling hammer or vibrator. The holding capacity of the pile is generated by the friction of the soil along the pile and lateral soil resistance. Generally the pile has to be installed at great depth below seabed to obtain the required holding capacity. The pile is capable of resisting both horizontal and vertical loads (fig. 1-12).
14
Suction anchor Like the pile, the suction anchor is a hollow steel pipe, although the diameter of the pipe is much larger than that of the pile. The suction anchor is forced into the seabed by means of a pump connected to the top of the pipe, creating a pressure difference. When pressure inside the pipe is lower than outside, the pipe is sucked into the seabed. After installation the pump is removed. The holding capacity of the suction anchor is generated by the friction of the soil along the suction anchor and lateral soil resistance. The suction anchor is capable of withstanding both horizontal and vertical loads (fig. 1-13).
fig. 1-12
fig. 1-13
Vertical load anchor A new development is the vertical load anchor (VLA). The vertical load anchor is installed like a conventional drag embedment anchor, but penetrates much deeper. When the anchor mode is changed from the installation mode to the vertical (normal) loading mode, the anchor can withstand both horizontal and vertical loads (fig. 1-14).
fig. 1-14
History of drag embedment anchors History traces the use of anchors to China as far back as 2,000 BC, though it is quite probable that they were used prior to this. At that time the general tendency was to use large stones, baskets of stones, bags of sand or even logs of wood loaded with lead which were then fastened to lines. It was this weight as well as a certain degree of friction on the bottom which secured a vessel in position. With the introduction of iron into anchor construction, teeth or flukes were built on the anchor, allowing penetration into the seabed, thus offering additional stability. Yet these primitive anchors were of poor construction and often broke under pressure. Curved arms were introduced in 1813, and from 1852, the so-called ‘Admiralty Anchor’ was used for ships of the Royal Navy. Another refinement in the 19th century was the elimination of the stock, the crosspiece at the top of an anchor which ensured that the positioning of the anchor would allow the flukes to penetrate the soil. A stockless anchor was invented in 1821 and became popular, primarily as a result of the ease of handling and stowing, qualities still valued today. A large number of anchor types has been designed and commercialised over the years. Some have prospered, others not. The most recent designs are the results of vast experience and extensive testing, and are far more efficient than their historical predecessors. A short overview of the anchors in use today, is presented on the following pages.
15
Characteristics of anchor types Based upon certain charateristics such as fluke area, shank, stabilisers, it is possible to classify the various anchor types. To allow a rough comparison of anchor type efficiency, an indication (*) is provided for a 10 t anchor as (HOLDING CAPACITY = WEIGHT * EFFICIENCY).
Class A
Stevpris
Class B
Bruce SS
Class C
Stevin
Class D
Danforth
Class E
AC14
Class F
US Navy Stockless
Class G
Single Fluke Stock
Class A efficiency range *33 to 55 slender anchors with ultra-penetration. Class B efficiency range *17 to 25 anchors with ‘elbowed’ shank, allowing for improved penetration.
16
Class C efficiency range *14 to 26 anchors with open crown hinge near the centre of gravity and relatively short shank and stabilisers or built-in stabilisers. Class D efficiency range *8 to 15 anchors with hinge and stabilisers at the rear and relatively long shanks and stabilisers. Class E efficiency range *8 to 11 anchors with very short, thick stabilisers; hinge at the rear and a relatively short, more or less square-shaped shank. Class F efficiency range *4 to 6 anchors with square shank, no stock stabilisers. The stabilising resistance is built-in the crown. Class G efficiency range * - 200 mm
Soil description Clay Fine Silt Medium Silt Coarse Silt Fine Sand Medium Sand Coarse Sand Fine Gravel Medium Gravel Coarse Gravel Cobbles Boulders
In general, the soil types encountered in anchor design are sand and clay (Grain diameter from 0.1 µm to 2 mm). However, mooring locations consisting of soils with grain sizes above 2 mm, such as gravel, cobbles, boulders, rock and such, also occur. Clay type soils are generally characterised by the undrained shear strength, the submerged unit weight, the water content and the plasticity parameters. The consistency of clays is related to the undrained shear strength. However, American (ASTM) and British (BS) standards do not use identical values. The undrained shear strength values Su can be derived in the laboratory from unconfined unconsolidated tests (UU) (table B). On site the values can be estimated from the results of the Standard Penetration Test (SPT) or Cone Penetrometer Test (CPT). An approximate relation between shear strength and the test values are shown in table C.
Undrained Shear Strength (kPa) Consistency of Clay Very soft Soft Firm Stiff Very stiff Hard Very hard
ASTM D-2488
BS CP-2004
0 - 13 13 - 25 25 - 50 50 - 100 100 - 200 200 - 400 > 400
0 - 20 20 - 40 40 - 75 75 - 150 150 - 300 300 - 600 > 600
table B
Su kPa
UCT kPa
SPT N
CPT MPa
0 - 13 13 - 25 25 - 50 50 - 100 100 - 200 > 200
0 - 25 25 - 50 50 - 100 100 - 200 200 - 400 > 400
0- 2 2- 4 4- 8 6 - 15 15 - 30 >-30
0.0 - 0.2 0.2 - 0.4 0.4 - 0.7 0.7 - 1.5 1.5 - 3.0 >3.0
table C
Soil classification
The mechanical resistance of sandy soils is predominantly characterised by the submerged unit weight and the angle of internal friction, ϕ. These parameters are established in the laboratory. An approximate correlation between the angle ϕ and the relative density of fine to medium sand is give in table D. The undrained shear strength of clayey soil can also be estimated based on manual tests.
Descriptive term
Relative Density
A classification system for soil based on the carbonate content and grain size of the soil (Clark and Walker), is shown on page 48 of this chapter.
SPT N
CPT MPa 0- 5 5 - 10 10 - 15 15 - 20 > 20
table D
Descriptive term
The rock strength can generally be described by its compressive strength (table E).
ϕ
Very loose < 0.15 < 30 0- 4 Loose 0.15 - 0.35 30 - 32 4 - 10 Medium dense 0.35 - 0.65 32 - 35 10 - 30 Dense 0.65 - 0.85 35 - 38 30 - 50 Very dense > 0.85 > 38 > 50
• In soft clay the thumb will easily penetrate several inches, indicating an undrained shear strength smaller than 25 kPa. • In firm (medium) clay the thumb will penetrate several inches with moderate effort, indicating an undrained shear strength between 25 kPa and 50 kPa. • Stiff clay will be easily indented with the thumb but penetration will require great effort, indicating an undrained shear strength between 50 kPa and 100 kPa. • Very stiff clay is easily indented with the thumbnail, indicating an undrained shear strength between 100 kPa and 200 kPa. • Hard clay is indented with difficulty with the thumbnail, indicating an undrained shear strength larger than 200 kPa.
Angle
Very weak Weak Moderately weak Moderately strong Strong Very strong Extremely strong table E
Compressive strength qu [MPa]
1.25 5 12.5 50 100
< 1.25 – 5 – 12.5 – 50 – 100 – 200 > 200
29
Fluke/shank angle The penetration of an anchor into a certain soil type is greatly influenced by the selected fluke/shank angle. For hinging anchor types (Stevin, Danforth etc.) the fluke/shank angle is the angle between the anchor shackle, the hinge and the fluke tip. The method for measuring the fluke/shank angle for fixed shank anchors (Stevpris, FFTS, etc.) is not well defined. Often it is the angle between the anchor shackle, the rear of the fluke and the fluke tip, but not all anchor manufacturers use the same definition.
fig. 2-09
The recommended fluke/shank angles for different soil conditions are presented in table F:
30
Some modern anchors, like the Stevpris Mk5, have an additional intermediate fluke/shank angle of 41 o, which can be used in intermediate or more complex soil conditions. For instance at a location where the anchor has to pass through a layer of soft clay before penetrating into a layer of sand. If an anchor is used with an incorrect fluke/shank angle, it will negatively influence performance. This is the case for all anchor types. In hard soil, an anchor with a fluke/shank angle of 320 will give the highest holding power. If an anchor is used with the fluke/shank angle set at 500, the anchor will fail to penetrate into the seabed and will begin to trip, fall aside and slide along the seabed (Fig. 2-9 and 2-10). If an anchor is used in very soft clay (mud) with the fluke/shank angle set at 32o, the anchor will penetrate into the seabed, however the penetration will be less than when a fluke/shank angle of 50o is used. Consequently the holding capacity will be lower when the fluke/shank angle is set at 32o, and the drag length longer (Fig. 2-11).
fig. 2-10
sand angle mud angle fig. 2-11
Soil type
Very soft clay Medium clay Hard clay and sand table F
Approximate fluke/shank angle 50˚ 32˚ 32˚
Fluke area Because the fluke area of an anchor is of great influence on the holding capacity, it can be useful to compare the fluke area of different anchor types that are available on the market today. In general, it can be stated that two anchors of the same weight but of different type (for instance a Stevin anchor and a Stevpris Mk5 anchor), do not necessarily have the same fluke area. Consequently, two anchors of the same weight but different type, will have different holding capacities. Some examples:
fig. 2-12
Fig. 2-12 shows a Stevpris Mk5 anchor and a Moorfast anchor, both of identical weight. It demonstrates that in spite of being the same weight, the fluke areas differ substantially. The ultimate holding capacity of the Stevpris Mk5 anchor is 4 to 8.5 times higher than that of the same weight Moorfast anchor. Fig. 2-13 illustrates the difference in fluke area of the Stevpris Mk5 anchor in comparison with the Bruce FFTS Mk4 anchor, both of which have identical weight.
31
fig. 2-13
Strength of an anchor design Anchors should be designed to withstand the loads applied on them in the different loading situations. Typical loading situations and areas of special attention for anchors are: • During the proof loading of the anchors in the factory, after construction has been completed. On basis of the proof load results, the classification societies issue the approval certificate.
32
While embedded in the seabed Depending on the soil conditions, different loading • situations can occur on the anchor. In sands and clays, the load tends to be spread equally over the anchor, which generally presents no problems. Retrieval is also very simple, without excessive loads placed on the anchor. • In very hard soils, the anchor has to be able to withstand the load with only one or two of the fluke tips buried in the soil, as penetration in very hard soil conditions is generally shallow. In • very soft clays (mud) penetration of the anchor is uncomplicated. However, recovery of the anchor can cause high loads, sometimes exceeding the load that was used to install the anchor. Sidewards forces on the top of (shallow) buried • anchors can be so extreme that no anchor is capable of resisting them. During anchor handling
• Care should be taken during the handling of the anchors, as the loads exerted by the winches, vessels and chain can sometimes exceed the structural strength of the anchor and cause damage. Anchor designers attempt to design the anchors for these high loads, however this is not always possible due to variations in the magnitude of the loads during handling operations. • Large forces can be exerted on the anchor when high winch power is used, the anchor is caught on the anchor rack or caught behind the stern roller of the AHV.
Strength of an anchor design • The use of an improper anchor/chaser combination. When a chaser is used that is either too small or too large, the chaser could jam on the shank of the anchor and cause damage. The strength of the Stevpris anchor is now more closely examined in the light of the remarks made before. Strength of the shank The prismatic shape of the Stevpris anchor not only ensures optimal penetration of the soil but also guarantees maximum strength. Although the Stevpris design also has limitations, it is one of the better designs to withstand sideward forces on the shank, a frequent occurrence in practice. When using an anchor in very soft clay (mud), the bending moment on the shank is low during the installation and when the anchor is in the soil. However, during the breaking out of the anchor, high bending moments could be introduced in the shank due to the high retrieval forces required in very soft clay. In extremely sticky soils, the breaking out force of the anchor can rise to 80% or 90% of applied anchor load; in certain instances, it can even exceed 100%. To reduce these forces the breaking out procedure is undertaken at low speed to allow time for the anchor to break out. Strength of the fluke The strength of the fluke and especially the fluke points of an anchor are very important when working in extremely hard soils such as coral, limestone and other rock types. It is possible in such instances that the total holding capacity of the anchor will have to be sustained by the fluke points alone. This means the structure must be strong enough to withstand extreme bending forces. Loading in normal soil conditions is not a problem due to the fact that the load is equally spread over the fluke.
33
Strength of an anchor design In fig. 2-14, the different force points are shown for varying soil conditions. The location on the fluke where the proofload is applied, is also indicated. Strength in extremely hard soils In very hard soils such as calcarenite, coral and limestone, an anchor will not penetrate very deeply. Consequently the load applied to the anchor has to be held by the fluke tips of the anchor and a small portion of the fluke. This means that extremely high loads will be applied to the fluke tips, compared to normal soil conditions such as sand and clay.
34
For use in very hard soil conditions, vryhof has designed the Stevshark anchor, a modified version of the Stevpris anchor. To create the Stevshark, the Stevpris anchor has been strengthened, consequently a Stevshark anchor having the same outside dimensions and holding capacity as a Stevpris anchor will be heavier. Strength calculations of the Stevshark design have been made to guarantee sufficient strength in the fluke points. The Stevshark anchor is designed to withstand the application of the main part of the load on just its fluke tips. To promote penetration, the Stevshark anchor has a serrated shank and can be provided with cutter points on the fluke tips. Ballast weight can also be added inside the hollow flukes of the anchor, up to 35% of the anchor weight. This is important when working in very hard soil, where the anchor weight pressing on the fluke tips promotes penetration, i.e. increased bearing pressure.
clay sand
fig. 2-14
proofload rock
Anchor loads and safety factors The loads in a mooring system are caused by the wind, waves and current acting on the floater. Depending on the location of the floater in the world, different metocean conditions will prevail. In the table below, some extreme metocean conditions are presented for different areas.
4000
3895 Total dynamic
Load in kN
3000
Quasi static 2342
2000
1000
0
8300
8400
8500
8600
On top of this quasi-static load there are the individual wave forces causing a high frequency motion. The high frequency motion causes dynamic shock loads with a period of 10 to 14 seconds due to the rolling of the vessel and the movements of the anchor lines through the water. The quasi-static load plus the individual wave forces is called the total dynamic load. Generally the quasi-static loads will be equal to 50% to 90% of the total dynamic load. See Fig. 2-15 for an example of the difference between the quasi-static load and the total dynamic load.
Location
Wave period s
Windspeed m/s
Current m/s
Campos Basin Gulf of Mexico Northern North Sea
8 – 10 11 15 - 16
12 - 15 14 15 - 17
25 44 - 48 38 - 39
1 1 0.9– 1.2
Porcupine Basin Vorine Basin West of Africa West of Shetlands
16 14 4 15
16 16 10 16
39 - 41 37 - 39 20 39 - 41
1.0 – 1.5 1.0 – 1.5 1 1.0 – 3.0
18 15 6 17
-
8800
9800
35
Waveheight m
-
8700
Time in seconds
fig. 2-15
The loads induced in the mooring system can be divided into quasi-static loads and total dynamic loads. The quasi static load is the load due to the swell, wind, current and the frequency of the system. For quasi-static loads, the systems tend to move at a low frequency, generally with a period of 140 to 200 seconds.
20 17 16 19
Anchor loads and safety factors The quasi-static and total dynamic loads are generally calculated for the intact and damaged load condition. The intact load condition is the condition in which all the mooring lines are intact. The damaged load conditions is the condition in which one of the mooring lines has broken. From the quasi-static load and the total dynamic load, the required holding capacity of the anchor can be calculated. This is called the ultimate holding capacity (UHC) for drag embedment anchors and the ultimate pull-out capacity (UPC) for VLAs. The required holding capacity is calculated by applying the factors of safety specified by the classification societies.
36
In the tables G and H, the factors of safety are presented for the different load conditions for drag embedment anchors (for instance the Stevpris Mk5 anchor), according to API RP 2SK. The factors of safety used by the major classification societies are generally similar to those given in API RP 2SK (2nd edition, 1996). For VLAs, the recently used factors of safety suggested by ABS, are presented in table I. The factors of safety for VLAs are higher than the factors of safety required for drag embedment anchors, due to the difference in failure mechanisms. When a drag embedment anchor reaches its ultimate holding capacity, it will continuously drag through the soil without generating additional holding capacity, i.e. the load will stay equal to the UHC. When a VLA exceeds its ultimate pullout capacity, it will slowly be pulled out of the soil.
Permanent mooring Intact load condition Damaged condition
Quasi-static Total dynamic load load 1.8 1.2
1.5 1.0
table G
Temporary mooring
Quasi-static Total dynamic load load
Intact load condition 1.0 Damaged condition Not required
0.8 Not required
table H
VLA
Intact load condition Damaged condition table I
Total dynamic load 2.0 1.5
Anchor behaviour in the soil Drag embedment anchors Drag embedment anchors are generally installed by applying a load equal to the maximum intact load. The anchor will then have penetrated to a certain depth, but will still be capable of further penetration because the ultimate holding capacity has not been reached. The anchor will also have travelled a certain horizontal distance, called the drag length. After installation the anchor is capable of resisting loads equal to the installation load without further penetration and drag. When the installation load is exceeded, the anchor will continue to penetrate and drag until the soil is capable of providing sufficient resistance or the ultimate holding capacity has been reached. However, there are certain effects which allow the anchor to withstand forces larger than the installation load without further penetration and drag. These are: The set-up and consolidation effect Set-up and consolidation mainly occur in clayey soils. The penetrating anchor disturbs the soil and the soil temporarily loses strength. With time, the disturbed clay reconsolidates to its initial shear strength, this takes from a few hours up to 1 month, depending on the soil type. Because not all the soil around the anchor is disturbed, the set-up effect factor is less than the sensitivity index indicates. The disturbance mainly reduces the soil resistance parallel to the fluke. On reloading, the parallel soil resistance gains strength, it takes a larger load to move the anchor again. Equilibrium dictates that also the normal load, i.e. the bearing soil resistance to the fluke, increases; consequently the load at the shackle increases also with the set-up factor. Observations on anchors for drilling rigs and theoretical considerations for a 3 to 4 week consolidation time demonstrate a typical set-up effect factor =1.5.
37
Anchor behaviour in the soil
38
Using the rate effect and set-up factors, the behaviour of the anchor after installation can be predicted more accurately. Vertical Load Anchors A VLA is installed just like a conventional drag embedment anchor. During installation (pull-in mode) the load arrives at an angle of approximately 45 to 500 to the fluke. After triggering the anchor to the normal load position, the load always arrives perpendicular to the fluke. This change in load direction generates 2.5 to 3 times more holding capacity in relation to the installation load. This means that once the required UPC of the VLA is known, the required installation load for the VLA is also known, being 33% to 40% of the required UPC. As a VLA is deeply embedded and always loaded in a direction normal to the fluke, the load can be applied in any direction. Consequently the anchor is ideal for taut-leg mooring systems, where generally the load angle varies from 25 to 450.
0
Rate effect factor
The rate effect An increased rate of loading increases the soil resistance, consequently the anchor holding capacity increases. This must be taken into account with respect to total dynamic loads. For anchor behaviour the rate effect factor indicates how much higher the dynamic high frequency load may be without causing extra movement of the anchor once installed at the installation load. The rate of loading influences pore pressure variations, viscous inter-granular forces and inertia forces. Typical rate effect factors are 1.1 to 1.3 for total dynamic loads, see Fig. 2-16 where the rate effect is presented for two different soil conditions (Su = 10 kPa and Su = 50 kPa).
1.2 1.1 1 0.9 0.8 0
200
400
600
800
1000
Time factor St fig. 2-16
Su=10 kPa
Su=50 kPa
Proof loads for high holding power anchors The proof load according to Classification Societies’ rules is applied at 1/3rd of the fluke length and is carried out immediately on fabrication of the anchor. It is obtained by placing the anchor in a test yoke in which a hydraulic cylinder applies the test loads, controlled by a calibrated manometer (fig. 2-17). The vryhof anchor types have been approved by the following Classification Societies: • The American Bureau of Shipping • Bureau Veritas • Det Norske Veritas • Germanischer Lloyd • Lloyd’s Register of Shipping • Registro Italiano Navale • USSR Register of Shipping • Nippon Kaiji Kyokai • Norwegian Maritime Directorate In the early days there were no specific regulations regarding the holding power and strength of mooring anchors. The rules which did exist were often followed regardless of the type of vessel. Some anchors were approved as ‘high holding power’ anchors. This so-called HHP approval was obtained after carrying out field tests in various types of soil in which it had to be shown that an anchor provided a holding power of at least twice that of a standard stockless anchor. If an HHP anchor was requested by the owner, the anchor has proof tested in strict accordance with the rules, nothing more. See table J for some examples of HHP anchor proof loads. A more detailed overview of HHP anchor proof loads is given in the product data section.
fig. 2-17
Anchor weight 1 5 7 10 15 20 table J
t t t t t t
Proof Load factor 26 79 99 119 155 187
t t t t t t
Anchor weight 26 15 14 12 10 9
x x x x x x
39
Proof loads for high holding power anchors The use of the specified proof loads for HHP anchors can lead to situations where different types of anchors with the same holding capacity are proof loaded at different loads, see fig. 2-18. From this figure it can be concluded that the proof load of the anchors should preferably be related to the breakload of the mooring line on the vessel.
Proofload HHP anchors, UHC=250 t. 29 t Danforth
10 t Stevin Mk3
4.5 t Stevshark Mk5
4 t Stevpris Mk5 0
50
100
Nowadays the rules and regulations are far more rigid, and the requirements have been substantially increased. There are now special rules for ‘mobile offshore units’ and ‘permanently moored structures’.
150
200
250
Proofload in t
fig. 2-18
Balanced mooring system API RP 2SK Breakload chain Ultimate holding capacity anchor Damaged load floater Proofload chain Pretension load anchor
If anchors need mobile offshore units certification, the following properties may be required:
Intact load floater Proofload anchor
0
fig. 2-19
40
• Proof load of the anchors at 50% of the breaking load of the chain. • Submission of a strength calculation of the anchor to the classification society prior to commencing anchor production: this includes determining the mechanical strength of the anchor as well as proving that the applied material can withstand the proofload. • A statement of documented holding power from the anchor supplier. • Submittal of a Quality Assurance/Quality Control Manual. In fig. 2-19, a mooring system is shown in which all of the components are balanced. The strength of the mooring line, holding capacity of the anchor and strength of the anchor are all in the correct proportion and comply with the rules.
10
20
30
40
50
60
Load in %
70
80
90
100
Quality control The application of more advanced and complex technology in anchor construction has brought about requirements for a systematic approach to quality. Initiated by various authorities they are continuously refined and followed up by operating companies such as vryhof anchor. Like other companies, vryhof has become increasingly aware of the vital importance of managerial aspects and their influence on the total quality-assurance and control system. Design and fabrication of anchors for permanent moorings are in accordance with the quality requirements of the Rules NS/ISO 9001 as described in our Quality Assurance Manual. Vryhof anchors obtained the ISO 9001 certificate No. QSC 3189 issued by Det Norske Veritas for ‘Design, Manufacture of anchors, and Sales of anchors and mooring components’. Quality control is maintained throughout production. A compilation of certificates is presented to a client upon completion of a project.
ACCREDITED BY THE DUTCH COUNCIL FOR CERTIFICATION Reg. No 24
ISO-9001CERTIFICATED FIRM DET NORSKE VERITAS INDUSTRY B.V., THE NETHERLANDS
41
Anchor tests Introduction In addition to practical experience of users and associates, anchor tests are one of the most reliable means of forecasting anchor performance and thus making a proper choice of anchor type and size.
42
Examining anchor tests that have been carried out in the past, certain conclusions can be made: • Many tests were undertaken in which the results were recorded accurately. Detailed reports, however, have not been very • common. • Anchor tests of the past are not always easy to interpret or compare because of different soil and anchor types. • Test results have not always been interpreted independently. The more tests results are strictly compared to • practical results, the better one can forecast the holding power and general behaviour in practice. Vryhof is in the perfect situation of having detailed test data available together with extensive practical data obtained during installation and use of anchors on projects on site. Research into anchor behaviour and the ultimate holding capacity of anchors is often carried out by testing a model anchor, preferably followed by a fullscale test in the field. The optimal anchor test consists of model tests with 10 kg anchors, followed by fullscale tests with 1 t and 10 t anchors. The anchors should be pulled until the ultimate holding capacity is reached. It is obvious that full-scale testing of anchors can be expensive. Large AHVs, strong winches and strong mooring lines are required, which are not always available. For example, a 5 t Stevpris Mk5 anchor, deployed in sand, is capable of stopping a modern AHV at its full bollard pull. Testing a 10 t Stevpris Mk5
anchor to its ultimate holding capacity in sand would require a horizontal pulling capacity of approximately 600 t. If anchor tests are to be comparable, the testing program should preferably meet, as a minimum, the following criteria: • An accurate and sophisticated measuring system should be used. • The anchors should be tested up to their ultimate holding capacity. • Drag and penetration of the anchor should be recorded during testing. • The anchor should be held under tension with a blocked winch for 15 minutes, to investigate any drop in holding capacity.
Holding Capacity
Anchor tests
A
G
B C D E F
fig. 2-20
Drag
43 Reading test curves The behaviour of an anchor during tensioning can be accurately interpreted from the holding capacity versus drag curve. Sample test curves are presented in Fig. 2-20. Properly interpreted performance curves can explain a lot about anchor behaviour.
• Curve A is very steep and represents a streamlined anchor in very stiff soil.
• Curve B is a normal curve for anchors in sand and medium clay. • Curve C is a curve of an unstable anchor. This can be caused by a wrong fluke/shank angle setting, a short stabiliser or a fluke that is too long. • Curve D is a normal curve for an anchor in very soft clay. • Curve E is an anchor with a 32o fluke/shank angle in very soft clay. • Curve F represents an anchor that is turning continuously. This can be caused by the absence of stabilisers, a too large fluke/shank angle or a low efficiency anchor at continuous drag. • Curve G represents an anchor penetrating in a layer of stiff clay overlain by very soft clay.
Curves A, B, D, E and G show a very stable rising line, which indicates that the anchor builds up its holding capacity constantly until the ultimate holding capacity has been reached, after which the anchor shows continuous drag. The other curves are largely selfexplanatory.
Holding capacity in t
Anchor tests
150
Sand 100
50
soft clay
25
0
44
10
20
30
40
Drag in meters
fig. 2-21
Full scale Gullfaks A anchors 800 700
Holding capacity in t
Test results Vryhof’s extensive database of test results with different anchor types, sizes and soil conditions, has been frequently used in anchor design. Data has been obtained from practice, scale models and from third parties. The data has been interpreted and afterwards incorporated in the ultimate holding capacity, drag and penetration graphs of the Stevin Mk3 and Stevpris Mk5 anchor as well as in the ultimate pullout capacity graph of the Stevmanta VLA.
8 m soft clay on rock
600
B*
A
C
500 400 300
Survival load = 1500 ton 200
A = 40 t Stevpris in sand B = 60 t Stevshark in mud on rock C = 65 t Stevpris in mud
100
* Final pretension load on site 0 20
Norwegian Contractors (1984) In 1984 Norwegian Contractors carried out tests at Digernessundet, Stord, Norway. The purpose of these tests was to determine the correct anchor type and size for the mooring system of the Gullfaks A platform during the construction of the platform at Digernessundet. Although the construction would took place at one location, it was know that three different types of soil conditions would be encountered: sand, soft mud and an 8 m mud layer on rock. After the initial trials the Stevpris anchor was selected for further testing. The 3 t Stevpris anchor that was used for the tests at a 3.30 pulling angle, produced a maximum holding capacity of 150 t in the sand, 102 t in the very soft clay and 150 t in the layer of mud on rock. As the mooring system required a survival load of 1500 t, a 65 t Stevpris (mud location), 40 t Stevpris (sand location) and 60 t Stevshark (mud on rock location) were selected for the final mooring. Fig. 2-21 shows the test results of the 3 t Stevpris anchor, while fig. 2-22 shows the result of the tensioning of the final anchors with a load of 820 t.
fig. 2-22
40
Drag in meters
60
80
Anchor tests Large scale anchor tests in the Gulf of Mexico In 1990, tests were performed with 2 t and 7 t Stevpris Mk5 anchors, as part of an anchor test Joint Industry Project (JIP). The anchors were tested using a wire rope forerunner.
Large scale anchor test jip - 7 & 2 t
Horizontal load in kips
700
The 2 t Stevpris anchor was tested up to its ultimate holding capacity of 107 t (235 kips). Due to insufficient pulling capacity, the 7 t Stevpris anchor could not be pulled up to its ultimate holding capacity. Based on the results of tests, the ultimate holding capacity of the 7 t Stevpris anchor was calculated to be larger than 338 t (745 kips) (fig. 2-23).
600
7-3 500
7-2
400
2-1
200
2-2
100
0
50
100
150
200
50
25 000
40
20 000 30 15 000 20
10 000
18˚ 10
5 000 0
0
fig. 2-24
100
150
200
Line length pulled in feet
250
300
Line angle vs mudine
Line load in lbs
60
= dyn load = pull angle
50
300
350
400
450
500
45
35 000
0
250
Drag distance in feet
fig. 2-23
Uplift Stevpris anchors are well capable of resisting uplift loads when they are deeply embedded. Anchors in sand and firm to hard clays do not penetrate very deeply and only take small uplift loads. Stevpris anchors installed in very soft clay and mud penetrate deeply, a typical penetration for a 15 t anchor is 15 to 25 meters. Due to the inverse catenary in the soil, the anchor line arrives at the anchor shackle at an angle of 20o to 30o with the mud line. Once the anchor is installed, a load making an angle up to 20o with the horizontal at mud line will not change the loading direction at the anchor! A Stevpris anchor has been tested in the Gulf of Mexico with gradually increasing pull angle (fig. 2-24). The maximum resistance was obtained for 18o uplift at mud line.
30 000
7-4 7-1
300
Anchor tests Cyclic effect factor The loading at the anchor is cyclic. Exxon performed cyclic tests on anchors reported by Dunnavent and Kwan, 1993. Although the maximum cyclic load was less than the initial installation load, the static load applied after the cycling phase revealed 25 to 50% larger anchor resistance than the initial installation load (fig. 2-25). This effect is explained by further penetration of the anchor. Applying this knowledge to the anchors, the static anchor resistance after some storm loading improves by the cyclic effect factor of 1.25 to 1.5.
Anchor resistance in kN
Increased capacity vs initial static
Initial static capacity 0.15
Cycling
0.1
0.0
0
50
100
150
200
250
300
350
Time in seconds
fig. 2-25 200
Line load in %
46
Tests with Stevmanta anchors Tests have been performed in the Gulf of Mexico and offshore Brazil. The Stevmanta anchor being pulled in with a load equal to F, accepted a vertical load to the anchor of up to 2 times F! Amongst the many tests the anchor relaxation was measured. The anchor with a fluke area of 0.13 m2 was pulled in at 0o pull angle (fig. 2-26), then loaded vertically to a load equal 1.6 times the maximum installation load. At this load the winch was blocked.
100
Change from pull-in to normal mode
50
0 20.00
fig. 2-27
Block winch
150
22.00
0.00
2.00
Time in seconds
4.00
6.00
8.00
Anchor tests This permitted the monitoring of the load with time (fig. 2-27) as what would be expected in real circumstances at a constant loaded anchor line. The results show that the holding capacity of the anchor does not change significantly during continuous loading, as the observed decrease in tension was due to movement of the winch. The subsequent pulling at 7:00 AM showed that for only a small movement, the full plate capacity (2 x installation load) could be reached. Continuous pulling caused the anchor to loose resistance and break out. To demonstrate that the feature of these anchors is not only a vertical resistance, the anchor was installed with a horizontal pull, the mode changed to the normal (vertical) mode and the anchor subsequently pulled with an uplift angle of 30o (fig. 2-28). The behaviour is similar to the earlier vertical pull test. However, for the 30o pull angle the anchor did not break out but moved slowly along the pulling direction through the soil. The graphs clearly show this effect and that the anchor can be used for substantial horizontal loads.
47
Line load in %
200
Block winch 150
Change mode
100
50
0 0
5
10
15
20
25
30
35
Line length pulled in feet
fig. 2-26
Line load in %
200
150
100
Change from pull-in to normal mode
50
0 0
fig. 2-28
5
10
15
20
25
Line length pulled in feet
30
35
40
Soil table
Approx. Rock strength
Cementation of soil
Increasing grain size of particulate deposits
0.002 mm
2 mm
60 mm
Carbonate silt
Carbonate sand
Carbonate gravel
Siliceous carbonate
Siliceous carbonate
silt
sand
Calcareous clay
Calcareous silica silt
Calcareous silica sand
Clay
Silica silt
Silica sand
Carbonate clay
90
50 Mixed carbonate and non-carbonate gravel 10
Silica gravel
Weak to moderately weak
Well cemented soil
Calcilutite
Calcisiltite (carb.
Calcarenite (carb.
Calcirudite (carb.
(carb. Calystone)
Siltstone)
Sandstone)
Conglom. Or Breccia
Clayey calcilutute
Siliceous calcisiltite
Siliceous calcarenite
Conglomeratic calcirudite
50
Calcareous sandstone
Calcareous conglomerate
10
Sandstone
Conglomerate or breccia
Calcareaous claystone Calcareous siltstone
Claystone
Siltstone
Strong to extemely strong
(well cemented) rock
Moderately strong to strong
Fine-grained limestone
Detrital limestone
Conglomerat limestone
Fine-grained
Fine-grained siliceous
Siliceous detrital
Conglomerate
agrillaceous limestone
limestone
limestone
limestone
Calcareous claystone
Calcareous siltstone
Calcareous sandstone
Calcareous conglomerate
Claystone
Siltstone
Sandstone
Conglomerate of Breccia
Crystalline limestone or marble
Conventional metamorphic nomenclature applies in this section
90
90
50
10
50
Total carbonate content %
Very weak
Very weak to firmly cemented soil
Increasing lithification
48
0.063 mm
3
Practice
Introduction Practice Although theoretical knowledge of anchors is essential for good anchor design and selection, the practical issues are just as important. The handling of an anchor and the selection and use of support equipment is of equal importance. Anchor handling is a critically important and often complicated process. It is influenced by such factors as the weight and shape of the anchor, the nature of the soil, the depth of the water, the weather conditions, the available handling equipment and the type and weight of mooring line. It is for these reasons that anchor handling is a subject which requires careful consideration. Without proper anchor handling, optimal performance of an anchor is not possible. In the process of handling anchors, various types of support equipment are necessary or beneficial. An anchor manual would be incomplete without consideration of these auxiliary items, the reasons for their use, their operation and the advantages and drawbacks involved. This chapter gives an overview of the recommended procedures that should be followed for anchor handling and the types and use of the support equipment during the handling operations. The following handling procedures are by no means complete, but they do give some suggestions which can be applied to each anchor handling procedure and adapted for specific circumstances and locations. Some of the topics covered in this chapter are: requirements for a soil survey, connection of the anchor to the mooring line, chasers, handling the Stevpris anchor, handling the Stevmanta anchor, the Stevtensioner, anchor handling/supply vessels.
51
Soil survey For the dimensioning of drag embedment anchors, the availability of site-specific soil data is important. For advice on specifying drag embedment anchor type/size and calculating expected behaviour, the site-specific soil data should be compared with soil data of previous drag embedment anchor (test) sites. The soil survey requirement for the design of drag embedment anchors usually consists of only shallow boreholes, while in anchor pile design deep boreholes are required. For suction anchor design therefore a more extensive soil investigation is generally required when compared to drag embedment anchors. When choosing between anchor pile, suction anchor and drag embedment anchor the financial implications of the soil survey should be taken into account. 52 A typical soil survey for drag embedment anchor design requires a survey depth of twice the length of the fluke in sand and 8 times the fluke length in very soft clay. In most cases a depth of 8 to 10 meters is sufficient, although in very soft clay a reconnaissance depth of 20 to 30 meters should be considered. For optimal drag embedment anchor dimensioning, each anchor location should ideally be surveyed. The soil investigation can consist of boreholes, vibrocores, cone penetration tests or a combination of these. Cone penetration tests including sleeve friction are preferred, but they should be accompanied by at least one vibrocore or sample borehole per site to obtain a description of the soil. Depending upon the type of survey performed and the soil conditions encountered, the survey report should present the test results obtained on site and in the laboratory including the points as shown in table K. It is possible to dimension the drag embedment anchors based on limited soil information (for instance fewer boreholes). The ‘lack’ of soil data can be compensated by choosing a conservative (larger) anchor size.
Typical contents survey report • Cone penetration resistance. • Sleeve friction. • Pore pressure. • SPT values. • Granulometry and percentage fines. • Wet and dry densities. • Water content. • Drained and undrained triaxal tests. • Undrained shear strength, also remoulded. • Unconfined compression tests. • Plasticity limits. • Specific gravity. • CaCO3 content. • Shell grading. • Angularity and porosity. • Compressibility. • Cementation. • Normalised rock hardness test (point load test). • RQD index, rock quality designation. table K
Pile or anchor The choice between piles and anchors is only possible for permanent systems. Piles are not a good investment when an anchored entity must be moved. But the choice is often made for piles on emotional grounds; a pile does not drag! However, anchors that are properly pre-tensioned on site will also not drag. While it is a psychologically loaded subject, experience has shown that the choice between anchor and pile is merely a matter of economics. The required pile weight for a system is equal to the required weight of a Stevpris anchor. Piles cost about 40% of equivalent capability anchors. However, the installation costs for piles are much higher. Piles require a follower and a pile hammer. The installation spread for piles is much more significant; a crane barge with support spread versus the two anchor handling vessels. The weather downtime for a spread involving a crane vessel is much longer than when AHVs are used. To allow drag of the anchors during pretensioning, extra chain length is required. Sometimes the pretension load for piles is much less than for anchors. The survey work for anchors is generally much simpler than for piles. When abandoning a field, anchor removal is much cheaper than removal of installed piles. The choice between piles and anchors strongly depends upon the circumstances. The table L can help in estimating the costs for the two alternatives. Suction piles are an alternative for drag embedment anchors and piles, also for MODU applications. The advantage is the accurate positioning of the suction piles. The disadvantage is the cost of the pile itself and the cost of the installation. Also many soil types do not allow suction pile applications, whereas drag embedment anchors can be used in any soil type.
Description
Pile
Soil survey Procurement Installation spread Installation time Pile hammer Follower Pump unit Pretensioning Extra chain Rest value pile/anchor Removal of anchor point ROV + less expensive
+ + + + +
Suction Anchor pile + + + + + -
+ + + + + + + + +
- more expensive
table L
53
Setting the fluke/shank angle Introduction In soil such as sand and medium to hard clay, an anchor with a fluke/shank angle of 32o will give the highest holding power. An anchor with a 50 o fluke/shank angle in this soil will not penetrate but will drag along the seabed. If used in mud a 50o fluke/shank angle is appropriate. An anchor with a 32 o fluke/shank angle will penetrate less and generate lower holding capacity in mud(fig. 3-01).
fluke angle too large in hard soil !
no penetration ! fig. 3-01
change from mud to sand angle
The Stevpris Mk5 anchor has an additional fluke/ shank angle setting of 41o, which can be adopted in certain layered soil conditions (table M).
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Changing the fluke/shank angle on the Stevpris Mk3 This can be carried out within half an hour with the Stevpris anchor upside down on deck. Secure the anchor on deck. Connect a tugger wire (C) to the holes (D) on the bottom side of the fluke. Change from mud to sand angle by removing the locking plates and the two rear pins in (B), decrease the fluke/shank angle by hauling the cable (C). Reinstall the pins and locking plates in (A). Seal weld the locking plates, do not weld them to the pins (fig. 3-02).
fig. 3-02
Soil type
Optimal fluke/shank angle setting
Very soft clay (mud) Certain layered soils Medium to hard clay or sand
500 410 *
* Stevpris Mk5 only table M
320
Setting the fluke/shank angle Change from sand to the mud position, increase angle by veering (C), change over pin and locking plates from (A) to (B). No special welding requirements (fig. 3-03). Changing the fluke/shank angle on the Stevpris Mk5 Changing the fluke/shank angle on the Stevpris Mk5 anchor is even quicker. No welding required. Veering and hauling (C) to change the fluke/shank angle as above, the pin however remains in (A), the locking plate is secured by means of a cotter pin (fig. 3-04).
change from sand to mud angle
fig. 3-03
change fluke/shank angle Stevpris Mk5
fig. 3-04
55
Connecting a swivel to the Stevpris anchor To connect a swivel to the Stevpris anchor, several different configurations are possible. These are:
56
Type I - The swivel is connected directly to the shank of the anchor thus omitting the anchor shackle (fig. 3-05). J swivel shackle, C end link, B enlarged link, A common link Type II - The swivel is connected to the anchor shackle (fig. 3-06). J swivel shackle, C end link, B enlarged link, A common link Type III - The swivel is connected to the anchor shackle via a special design end link (fig. 3-07). K special end link, J swivel, C end link, B enlarged link, A common link Type IV - The swivel is part of a forerunner connected to the anchor shackle, for instance the forerunners VA02, VA04 and VA 06 described in the product data section (fig. 3-08). PL pear link, A common link, B enlarged link, H swivel. When a chaser is used in combination with the Stevpris and swivel, some of the configurations mentioned above are more suitable than others. In general, swivels are only designed to withstand longitudinal forces, and are usually not designed for use in combination with chasers. The design of the chaser tends to stop it at the swivel. Consequently, there will be high bending forces on the swivel, which can result in damage or even breakage.
J
C
A
fig. 3-05
J
C
B
A
C
B
fig. 3-06
K
J
A
fig. 3-07
PL
fig. 3-08 damage possible!
Generally, it is best when the swivel is fitted some distance from the anchor when a chaser is used. The chaser can then pass the swivel and stop on the anchor shank. When a load is applied to the chaser, the swivel is only loaded longitudinally. This means that in combination with the use of a chaser, the configuration type III and type IV are preferred.
B
NO !
fig. 3-09
A
B
H
B
A
Connecting a swivel to the Stevpris anchor When the swivel (or swivel forerunner) is connected to the anchor shackle by means of an end shackle and a chaser is used, the end shackle and the anchor shackle should be connected bow through bow instead of pin through bow as is normal practice. This to minimise the chance of damage to the shackles. The illustrations fig. 3-09 through fig. 3-14 show how and how not to connect the swivel to the Stevpris anchor when using a chaser.
fig. 3-10 damage possible!
NO ! The best method for chasing with a swivel in the system is to maintain the tension of the anchor line as much as possible during chasing. This will make the chaser pass more easily over the swivel. fig. 3-11
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fig. 3-12 damage possible!
NO !
fig. 3-13
fig. 3-14
Chasers Chasers and their application To facilitate handling, pendant wires may be applied to retrieve the anchor. These wires are connected to a pendant eye situated on the anchor and equipped with a buoy for picking up. In deeper water higher anchor break-out forces are encountered, resulting in longer, heavier pendant wires and consequently larger buoys. Due to wear caused by the continuous movement of the buoy by the waves, these pendants will break close to the buoy. The buoys would then float free and the anchors are much more difficult to recover.
58
To overcome this, chasers were introduced. These were rings ‘chased’ along the cable towards the anchor and back again to a rig or handling vessel. Their function was to ensure both installation and break-out of the anchor without having to use a pendant line/buoy. The chaser system thus totally eliminates buoys, partly eliminates cables and reduces wear on the system. The cost of a chaser is small when compared to the cost of a mooring line. It is therefore extremely important from an operator’s viewpoint that chasers do not inflict damage to the mooring lines. Towing a chaser along mooring lines with, at times, high interface pressures, must result in wear. It is thus essential that such wear is taken by the chaser and not the mooring line. The chasers vryhof recommends are manufactured in a material that is softer than the steel used for the mooring line. Chaser wear is induced by the application of high interface pressure between the mooring line and the chaser. High interface pressure can arise from:
• Pulling the chaser along a slack mooring line. • Maintaining high tension in the chaser workwire when chasing a tensioned mooring line.
Chasers Chasing operations are best carried out on mooring lines which are fully tensioned. There is little need for the application of high interface pressure while chasing, the permanent chaser is captive on the mooring line and, unlike the J-chaser, will not become disengaged due to a slack work wire. For optimum chasing operations, the length of the chaser pendant line should be at least 1.5 times the waterdepth. There are many different types of chaser available on the market today. A selection of the different chaser types is described in more detail on the following pages.
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Chaser types The J-chaser The J-chaser (fig. 3-15) is used on mooring lines where the anchor has to be recovered and no permanent chaser has been installed, or the normal recovery mechanism has failed. In other cases the J-chaser is used simply to keep a chain free from a pipeline during deployment of the anchors. The chaser is deployed over the stern roller of an AHV at approximately 1/3 of the water depth. The chaser is towed across the mooring catenary until it catches the chain. It is then towed into contact with the anchor shank/fluke for anchor break-out and retrieval.
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The permanent chain chaser As a practical alternative to the buoy and pendant, the permanent chain chaser (fig. 3-16) was introduced. Originally, simple shackles were used; these were followed by special cast oval rings which were attached to a pendant by a ‘bight’ of chain and shackle. Very soon afterwards the pear-shaped chaser with shackle eye was introduced. The design of these chasers offers superior sliding and penetration properties.
fig. 3-15
fig. 3-16
Chaser types The detachable chain chaser For rigs in service it is sometimes preferred to equip the mooring with a chaser which does not require the anchor chain to be broken and re-made. Detachable chain chasers (fig. 3-17) were introduced to satisfy this need. The withdrawal and replacement of the single bolt permits easy assembly of the chaser on the mooring cable. The permanent wire chaser The permanent wire chaser (fig. 3-18) was introduced when rigs moved to deeper waters, and composite wire/chain mooring systems became necessary. The chaser incorporates a ‘rocker’ which is centrally mounted on a hinge bolt. The rocker has two opposing grooves, and when the chaser is engaged with the mooring line, the wire slides through one of these grooves irrespective of the angle which the chaser makes with the mooring. The large radius at the base of the groove assists in reducing wear of the rocker and avoids severe ‘opening’ of the lay of the wire if a loop of wire is pulled during the handling process. The material of the rocker is not as hard as the material of the wire. This means that wear is taken by the rocker without damage to the wire and, because the rocker is easily removable, replacement is relatively inexpensive. The permanent wire chaser is easily detachable by removal and re-assembly of the hinge bolt and rocker. Some designs of wire chaser incorporate fully rotating rollers over which the mooring wire passes. To be effective such rollers need to be of a large diameter and require to be supported by bearings. They are consequently larger, heavier and much more costly than the permanent wire chasers discussed above, and because of their size, they require more power at the AHV to penetrate the seabed and reach the anchor.
fig. 3-17
fig. 3-18
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Chaser types The J-lock chaser. The J-lock chaser (fig. 3-19) has been designed so that it can slide along the chain in one direction and when the pulling direction is reversed, the chaser locks on the chain and does not slide any further. This means that the tension in the mooring line can be wholly transferred from the rig to the chaser. The J-shape permits catching the anchor chain after the anchor has been installed. This means that this chaser can be used to assist in unforeseen circumstances. The wellbalanced and ‘guiding’ design of the chaser enables catching the chain when the chaser approaches a mooring at a point where the catenary angle is as high as 450.
62
When a normal permanent chaser is used under unforeseen conditions, there is the chance that the AHV cannot break out the anchor by means of the chaser. The J-lock chaser can help in such an instance. It is released from a second AHV and slides along the chain towards the anchor. The design prevents the J-lock chaser from sliding back. The J-lock chaser is stopped at the permanent chaser. If the winch pull of both tugs is now increased, the J-lock chaser prevents the permanent chaser from sliding away from the anchor. Consequently, the forces required do not increase, and the anchor can easily be broken out. After this operation, the J-lock chaser can be released again. This chaser can also be used when a very heavy chain has to be installed. It assists during installation by lifting the chain.
fig. 3-19
Stevpris installation Stevpris deployment for MODUs chaser
Introduction Typical methods for deployment and retrieval of Stevpris anchors with an anchor handling vessel (AHV) are described, focusing on the use of chasers for handling the anchor (fig. 3-20). This is the most common practice on mobile drilling rigs (MODUs). Handling using permanent pendant lines is similar. Deployment procedures for the Stevpris anchor will also be given for permanent moorings where chasers are normally not used. Laying anchors It is preferred, and by some operators required, to deck the anchor before run out to check the jewellery. Run the anchor line out the full distance with anchor on deck or on roller, with the chain between the flukes (fig. 3-21). Boat increases power until anchor line tension rises on rig winch tension meter. When rig gives order to lower the anchor, veer pendant till anchor arrives at roller. Allow the anchor some speed to negotiate the bump at the change-over from the deck on to the roller (fig. 3-22). If anchor is kept on roller, keep triangular plates below the main shackle on the drum for stability of the anchor. Alternatively the chaser can be kept on deck/roller. In this situation the propeller thrust passes underneath the anchor and does not influence the fluke (fig. 3-23).
fig. 3-20
always deck anchor with chain between flukes fig. 3-21
63
quickly pass drum fig. 3-22
triangular plates on drum fig. 3-23
Stevpris installation Reduce propulsion momentarily when anchor passes the propeller thrust, keep chaser on anchor head for control of anchor orientation and lower anchor (fig. 3-24).
64
Once below the propeller wash zone, reactivate and maintain propeller thrust to well above 30 tons. Keep constant tension in order to ensure anchor does not fall through chaser, i.e. anchor remains in the chaser and orientation of the anchor is correct (fig. 3-25). Note: In some circumstances AHVs prefer to run the anchor hanging from the pendant line below the propeller wash approximately 60 to 80 meter above the seabed. This method requires less power on the winch during the actual laying of the anchor. If this method is employed, make sure that at all times the anchor is correctly oriented in the chaser. Keep constant tension in the pendant line to prevent the anchor from falling through the chaser and possibly turn. Stop lowering when anchor hangs 10 to 15 meter above the bottom and advise rig. Rig now instructs AHV to pay out until pendant line is 1.4 to 1.5 times the water depth in shallow water (100m) and 1.3 to 1.4 times in deeper water. AHV increases power till tension is again seen to rise at the rig, i.e. the load in the line is larger than the chain-soil friction (fig. 3-26). Rig commences to pull in slowly. AHV further increases power until tension rises further at rig winch. At this moment rig orders AHV to lay the anchor. AHV immediately stops the propulsion and is consequently pulled backwards. AHV pays out pendant and maintains paying out pendant after anchor has landed on the bottom till a wire length of 1.5 to 2 times the water depth is out. Enough slack wire must be paid out not to disturb the anchor during buoying off or waiting. Stay above or behind the anchor. Rig continues heaving the cable to a sufficient load, equal to the total chain/soil friction plus 50 t to embed the anchor fully and create confidence in good setting.
STOP !
fig. 3-24
fig. 3-25
wait for signal rig fig. 3-26
Stevpris installation This also gives stability to the anchor when the AHV strips the chaser back or buoys off the pendant. Now the AHV can retrieve the chaser and return to the rig. If circumstances allow, the rig can tension up to the full pretension load directly (fig. 3-27). No extra pull after landing! It is customary with older anchors such as Danforth, Moorfast, etc. to give another pull once the anchor is on bottom. Do not do this with Stevpris anchors. Once the anchor hits bottom, AHV should not pull again. Pendant line must remain slack, otherwise anchor could land upside down! (fig. 3-28). Suggestion: pre-load the anchors to the maximum required pretension load as soon as the chaser is 100 meter or more ahead of the anchor, i.e. do not wait. If anchor has not been laid correctly, a rerun can be made immediately. Retrieving anchors The chaser should be brought to the anchor with a pendant of at least the length of 1.5 to 2 times the water depth, measured from the stern roller. Chaser should hang freely down from the anchor line till the bottom is reached, i.e. slack in the pendant line. A too short pendant and/or too little tension in the cable results in a situation as sketched (fig. 3-29). While chasing, the rig should maintain tension of 60 to 70% of the pre-load tension. No tension in pendant to ensure smooth passing over the chain. When chaser is pulled into contact with anchor shank, increase thrust and keep thrust while heaving, especially in rough water (fig. 3-30).
rig hauls AHV slacks fig. 3-27
do not pull after landing ! fig. 3-28
65 wrong ! keep cable under tension
fig. 3-29
patience in very soft soils !
fig. 3-30
Stevpris installation The motion of the vessel itself now helps gradually to break the anchor loose. Sequentially with the vessels motion the pendant is shortened gradually. Anchors in very soft clay can be buried very deep. Have patience, take your time and be gentle with the equipment; the anchor will come. The rig can help and speed-up the operation by hauling the anchor line at the same time! Once the anchor is off bottom, keep the chaser in contact with the bow shackle by maintaining sufficient thrust (fig. 3-31). Anchor orientation The anchor flukes are always oriented towards the rig, on deck the anchor lays on its back with shackle towards AHVs bow and cable between the upwards directed fluke points. Check jewelry (fig. 3-32).
rig hauls
keep pulling
fig. 3-31
always deck anchor with chain between flukes fig. 3-32
66 It is important to control the anchor orientation at all times for easy racking, laying and decking of the anchor, i.e. keep pendant line under tension while working the anchor. If the anchor slides through the chaser, the anchor has to be pulled back to the stern roller and orientation checked (fig. 3-33).
keep tension ! fig. 3-33
Decking the Stevpris anchor If anchor is not correctly oriented, reduce propulsion and let anchor slide down through the chaser. Rotation is easier while near the rig where all loads are lower (fig. 3-34). wrong ! anchor cannot deck ! fig. 3-34
Stevpris installation Turn the anchor with a shot of propeller wash. Then pay out pendant, make sure anchor is below the propeller wash away from the propeller influence zone (fig. 3-35). Increase propulsion moving AHV forward pulling chaser in contact with the anchor. Make sure the stern roller is perpendicular to the chain, the chain directing between the fluke points (fig. 3-36). With sufficient bollard pull haul pendant, stop/reduce thrust for only a few seconds when anchor passes the propeller wash onto the drum. Pull anchor on the drum, allow the anchor to turn with its back on the roller, fluke points up. Then pull further on deck (fig. 3-37).
fig. 3-35
turn
fig. 3-36
67 With little tension in the line, the chain hangs steep against the fluke points and anchor cannot rotate easily (A). Before rotating the anchor, pull on the cable, the anchor will be free to turn (B) and (C) (fig. 3-38). With anchor on the stern roller reactivate propulsion. For inspection anchor can be pulled on deck. If required, change fluke angle to 32 degrees for hard soil or to 50 degrees for very soft soil. Mind, every anchor type will be unstable and drag in hard soil, stiff clay or sand with a fluke angle set for mud! (fig. 3-39).
STOP !
fig. 3-37
fig. 3-38
fig. 3-39
stop / reduce propulsion
Stevpris installation What not to do! The anchor is approaching the drum. If the AHV maintains thrust, the water flow will push the fluke (fig. 3-40). If the propeller is not stopped, the thrust risks turning the anchor around the cable then acting as a shaft (fig. 3-41).
thrust on anchor makes it swing ! fig. 3-40
The relative weight of the anchor increased by the thrust force on the fluke will cause the anchor and the cable to slide down through the chaser and control of anchor orientation is lost (fig. 3-42).
68
When the thrust is maintained while hauling in the chaser, the cable prevents the anchor to turn on its back at the stern roller. Boarding will be difficult now. The anchor could pass the stern roller on its side and get damaged! So stop/reduce the thrust just before the anchor passes the propeller wash (fig. 3-43).
and rotate ! fig. 3-41
anchor slides through chaser fig. 3-42
damage ! fig. 3-43
Stevpris installation Racking the Stevpris Rig heaves in anchor line, pulling AHV towards it. AHV keeps sufficient tension in pendant, chaser remains in tight contact with anchor, anchor remains correctly oriented (fig. 3-44). At some distance from the rig, AHV pays out winch wire while keeping sufficient bollard pull (at least 1.5 times anchor weight) to keep chaser on anchor head. Anchor flukes point towards the rig. Rig hauls, AHV veers while keeping some tension in the pendant line transferring the anchor to the bolster. The direction of the anchor cable must now be perpendicular to the rack (fig. 3-45).
keep tension ! fig. 3-44
keep tension !
When anchor arrives at bolster, reduce tension to 15 tons. As soon as anchor is resting on bolsters, slack pendant wire completely. If tension is not sufficient, anchor falls out of control of the chaser and might rotate and make racking difficult. If this occurs, bring anchor to the stern of the AHV, rotate anchor with fluke points directing outwards and keep chaser tight on the anchor (fig. 3-46).
fig. 3-45
69
wrong ! risk losing control over anchor orientation fig. 3-46
Deploying Stevpris from the anchor rack AHV receives pendant from rig and connects to AHV winch wire. AHV moves to a position at a good distance but less than the water depth (for instance 50 meter dependent on weather) from the rig. Stop winch and keep sufficient tension, 20 to 30 tons or more as required to maintain the chaser on the head of the anchor. Only now rig pays out cable while AHV hauls in on the winch. The AHV maintains sufficient tension while pulling the anchor to the stern roller. Reduce the power of the propeller as anchor passes the wash zone and bring anchor on roller for inspection and reactivate thrust (fig. 3-47).
keep tension ! fig. 3-47
Stevpris installation Boarding the anchor in deep water In deep water the weight of the anchor line becomes of predominant importance. For line loads larger than 8 times the anchor weight the anchor could be pulled against the chaser as illustrated, it could even position itself upside down! In such cases boarding the anchor is difficult and damage might occur (fig. 3-48).
70
The best and preferred solution is to pull the anchor from the bottom and have the rig haul the anchor line, allowing the boarding of the anchor near the rig where loads are smaller. If this is not possible or allowed for some reason, another solution is to reduce the weight that is hanging from the anchor. This can be done by lifting the anchor line using a lock chaser or grapnel handled by a second vessel (fig. 3-49).
anchor weight high tension fig. 3-48
lock chaser
fig. 3-49
It is recommended to board the anchor with the chain between the fluke. The anchor fluke is generally designed to withstand loads up to 8 times the anchor weight (fig. 3-50).
8 x anchor weight fig. 3-50
It happens that the anchor is accidentally pulled over the roller on its side. Due to the large forces damage to shank and fluke might occur when the chain is hanging over the anchor (fig. 3-51).
large weight fig. 3-51
Stevpris installation If boarding the anchor on its side is inevitable, make sure that before boarding, the vessel is turned to free the anchor line from the anchor and haul gently. The chain will pass the stern roller next to the anchor. However, this situation should be avoided as damage may occur (fig. 3-52). Ballast In fluke Using a wire rope forerunner and ballast material placed inside the hollow fluke, the anchor may not topple over with the fluke points directed downwards. A wire anchor line might be too light to position the anchor correctly and the anchor may not topple over, the anchor could skid over the seabed and prevent penetration. When the fluke is ballasted, the weight of a chain forerunner will cause the shackle to nose down and bring the fluke in penetration position (fig. 3-53).
fig. 3-52
wire
chain
with ballast in fluke use chain forerunner fig. 3-53
71
Stevpris installation Chaser equilibrium To control the anchor, the chaser collar must always be on the anchor head. The tension in the anchor cable must be equal or larger than 1.5 times the weight of the anchor. If not, the anchor slides through the chaser and the orientation is not controlled (fig. 3-54).
pendant line force
anchor line tension
anchor weight fig. 3-54
Equilibrium forces determine if chaser is in contact with the anchor. Near bottom, the vertical load at the chaser from the anchor line Flv is small. The chaser remains only in contact with the anchor if the bollard pull Fph is larger than the horizontal line load Flh which in turn must be larger than the anchor weight W (if not the anchor will slide down). The angle of the pendant line must be larger than 45° (fig. 3-55).
Fp
Fpv
Flh Fph Flv fig. 3-55
W
72 Recommendation: Bollard pull must always be equal or larger than the line tension, i.e. use a minimum bollard pull of 20 to 30 tons for a 12 to 15 ton anchor. Use a minimum pendant line length of 1.4 to 1.5 times the water depth in shallow water (100m) and 1.3 to 1.4 times the depth in deeper water (fig. 3-56).
chaser
fig. 3-56
Fl
Stevpris installation Deployment for permanent moorings The simplest deployment procedure for the Stevpris anchor is to lower the anchor to the seabed using the mooring line. When the anchor is nearly on the seabed, the AHV should start moving slowly forward to ensure that the anchor lands correctly on the seabed (fig. 3-57). Another option for the deployment of the Stevpris anchor is to connect a temporary installation bridle (wire rope) to the anchor. The bridle is connected to the padeyes situated at the back of the shank of the anchor. The AHV then lowers the anchor overboard while paying out the mooring line and the bridle simultaneously (fig. 3-58).
fig. 3-57
temporary bridle mooring line
fig. 3-58
73 To recover a Stevpris anchor after it has been installed, the AHV should take the mooring line and pull it in the opposite direction that the anchor was installed in, generally away from the centre of the mooring. The AHV should recover the mooring line till a length of approximately 1.5 times the water depth is still overboard. When only 1.5 times the water depth of mooring line is left overboard, the AHV should block the winch and keep a constant tension on the mooring line equal to the pre-load tension. Once the anchor starts to move in the soil, a lower tension in the mooring line can be used (fig. 3-59).
fig. 3-59
Piggy-backing Introduction Piggy-back is the practice of using two or more anchors in order to obtain holding power greater than can be achieved with one only. Piggy-backing is used when anchors are employed with insufficient holding capacity. This can be caused by improper design for the particular environment or insufficient anchor size. In some soil conditions, the use of two smaller anchors in piggy-back can offer an advantage over the use of one larger anchor. This can be the case when the anchor has to hold in a certain layer and holding capacity in the underlying layer is uncertain.
74
Considerations to remember on piggy-backing: • Installing a piggy-back system is more costly than the installation of a single anchor. • If the mooring line of the second anchor is connected to the rear of the first anchor, the stability, penetration and holding capacity of the first anchor may be less than is the case for a single anchor. The force from the second anchor may tend to pull the fluke of the first anchor closed (hinging type anchors). • If the piggy-back anchor is connected to the first anchor by means of a chaser, the chaser may obstruct penetration of the first anchor. • Both anchors must be exactly in line with the mooring line load. The lead anchor may become unstable if a lateral load is applied. • Two hinging anchors in piggy-back do not provide 2 times but only 1 to 1.6 times the individual holding capacity of the two anchors, for reasons described in second point above. • If the first anchor is not influenced by the pull from the second anchor, and the second anchor (fixed fluke/shank type anchors) is connected at 3 to 4 shank lengths distance from the first anchor, the holding capacity of the 2 anchors may be up to 2.5 times the holding capacity of the individual anchors, due to the extra penetration of the second anchor.
Piggy-back methods Piggy-backing involving hinging anchors Since there is little difference between handling one hinging anchor or two, the first method is described with a Stevin anchor (hinging) in combination with a Stevpris anchor (non-hinging). Here, the Stevpris is main anchor and the Stevin is back-up. This is the best solution when using a fixed shank anchor as the fluke of the Stevpris anchor can not be pulled closed. The pendant line is connected to the padeye near the anchor shackle so performance is not reduced. Note: if the piggy-back anchor can not be laid in line with the mooring load, the piggy-back anchor makes the main anchor unstable. In such a case the Stevpris can better be placed as the second anchor. For optimal performance of the combination, the pendant line between the two anchors should be wire rope, to promote penetration and obtain better holding capacity (fig. 3-60). The installation procedure is described as follows: • Pay out the main anchor as usual. • Tension the mooring line until the anchor slips. • Connect the second anchor to the pendant line. • Bring the anchor to its location. • Lower the piggy-back anchor and tension the mooring line again. • Provide the pendant of the second anchor with a buoy for easy retrieval.
fig. 3-60
75
Piggy-back methods
76
Piggy-backing with two Stevpris anchors When two Stevpris anchors are used in piggy-back, the holding capacity of the combination may be equal or higher than the sum of the individual holding capacities of the anchors. The installation procedure of two Stevpris anchors in piggy-back (fig. 3-61) is as follows: • Pay out the main Stevpris anchor, with the mooring line connected to the anchor shackle and the pendant line (wire rope for optimal performance and approximately three times the shank length of the first Stevpris anchor) connected to the padeye behind the anchor shackle. • Connect the other end of the pendant line to the anchor shackle of the second Stevpris anchor. • To lower the second Stevpris anchor to the seabed, a second pendant line is connected to the padeye behind the anchor shackle. • Using the second pendant line, the Stevpris anchors are lowered to the seabed and positioned and buoyed off. The Stevpris anchors are then tensioned by pulling • on the mooring line (fig. 3-62).
fig. 3-61
fig. 3-62
Piggy-back methods Piggy-backing by using a chaser Sometimes chasers are used to connect the piggyback anchor to the first anchor (fig. 3-63), although a pendant line connected directly to the padeye behind the main anchor shackle of the first anchor is prefered. The installation procedure described for two Stevpris anchors is also applicable when a chaser is used for the connection. During the deployment of the piggy-back combination, care must be taken that anchors are installed in line with the load.
77
fig. 3-63
Stevmanta VLA installation Introduction The Stevmanta VLA consists of an anchor fluke which is connected with wires to the angle adjuster. The angle adjuster is responsible for changing the anchor from the installation mode to the vertical (or normal) loading mode.
78
installation mode shear pin
There are many options to install VLA anchors. The most efficient methods are based on two different principles: • Double line installation method using the fixed angle adjuster. • Single line installation method using the shear pin angle adjuster.
fig. 3-64
The double line installation method is typically used when it is preferable to install the anchor with a steel wire rope installation line instead of using the actual mooring line (for example polyester).
fig. 3-65
The following three typical methods for installing the Stevmanta VLA are discussed: • Single line installation method. • Double line installation method. • Double line installation method using the Stevtensioner. It is also possible to use the Stevtensioner with the single line installation method, however because this is very similar to the double line installation method with Stevtensioner, it is not presented here. Single line installation procedure This procedure requires only one AHV for installation of the Stevmanta. The Stevmanta is deployed with the shearpin angle adjuster. The mode of the anchor changes when the shearpin breaks at a load equal to the required installation load. When the shear pin breaks, the Stevmanta changes from the installation mode to the normal (vertical) loading mode (fig. 3-64 and fig. 3-65).
normal mode
Stevmanta VLA installation Installation procedure In the installation procedure an optional tail has been included on the Stevmanta. The tail assists in orient ation of the Stevmanta on the seabed. Connect the installation/mooring line to the angle adjuster on the Stevmanta on the AHV. Lower the Stevmanta overboard. The Stevmanta will decend tail first, i.e. the tail will be the first part to reach the seabed (fig. 3-66). When the Stevmanta is on the seabed, an ROV can optionally inspect the anchor (position and orientation). The AHV starts paying out the installation/ mooring line while slowly sailing away from the Stevmanta (fig. 3-67).
tail for orientation recovery
fig. 3-66
When enough of the installation/mooring line has been paid out, the AHV starts increasing the tension in the installation line. The Stevmanta will start to embed into the seabed (fig. 3-68).
79
ROV
fig. 3-67
fig. 3-68
Stevmanta VLA installation When the predetermined installation load has been reached with the AHVs bollard pull, the shearpin in the angle adjuster fails, triggering the Stevmanta into the normal (vertical) loading mode. This can be clearly noticed on board the AHV, as the AHV will stop moving forward due to the sudden increase in holding capacity. Now that the Stevmanta is in the normal (vertical) loading mode, the AHV can continue to increase the tension in the (taut-leg) installation/mooring line up to the required proof tension load (fig. 3-69). fig. 3-69
80
After the Stevmanta has been proof tensioned to the required load, the installation/mooring line can be attached to the floater. In case of a pre-laid mooring, the mooring line can be buoyed off, for easy connection later on (fig. 3-70). Stevmanta retrieval The Stevmanta is easily retrieved by pulling on the ‘tail’. Connection to the tail can be achieved either with a grapnel or by using an ROV (fig. 3-71). fig. 3-70
fig. 3-71
Stevmanta VLA installation Alternatively the Stevmanta can be equipped with an optional recovery system. The recovery system consists of two special sockets which connect the front wires to the fluke. To recover the anchor, the mooring line is pulled backwards, i.e. away from the centre of the mooring. Once the mooring line has been pulled back, the front sockets will disconnect from the fluke (fig. 3-72).
pull for retrieval
fig. 3-72
retrieval
The Stevmanta VLA is now pulled out of the soil using just the rear wires. This reduces the resistance of the anchor, so that it can be retrieved with a load equal to about half the installation load (fig. 3-73).
fig. 3-73
81
Stevmanta VLA installation Double line installation procedure This procedure requires two AHVs. The Stevmanta is deployed with the fixed angle adjuster. The mode of the anchor (installation mode or normal (vertical) loading mode) is chosen by pulling on either the installation line or the mooring line. The Stevmanta is in the installation mode when the installation line is tensioned, i.e. the line on the front of the angle adjuster (fig. 3-74).
installation mode mooring line installation line
fig. 3-74
normal mode mooring line
The Stevmanta is in the normal (vertical) loading mode when the mooring line is tensioned, i.e. the line on the rear of the angle adjuster (fig. 3-75).
82
During the installation AHV1 handles the steel installation line and AHV2 handles the mooring line, for instance polyester (fig. 3-76). In the installation procedure an optional subsea recovery buoy can be included in the installation line. The recovery buoy is connected to the installation line via a delta plate at approximately 90 m from the Stevmanta (fig. 3-77). Connect the installation line to the angle adjuster on the Stevmanta on board AHV1. Pass the mooring line from AHV2 to AHV 1 and connect it to the angle adjuster. Lower the Stevmanta VLA overboard by keeping tension on both the installation line (AHV1) and the mooring line (AHV2). When the Stevmanta is on the seabed, an ROV can inspect the anchor’s position and orientation. AHV2 slackens the tension in the mooring line and AHV1 starts paying out the installation line while slowly sailing away from the Stevmanta (fig. 3-78).
installation line fig. 3-75
AHV2
AHV1
fig. 3-76
AHV2
AHV1
AHV2
AHV1
fig. 3-77
fig. 3-78
Stevmanta VLA installation When enough of the installation line has been paid out, AHV1 starts increasing the tension. The Stevmanta will start to embed into the seabed. AHV2 keeps the mooring line slack by keeping the same distance from AHV1. If more bollard pull is required than one AHV can deliver, AHV2 can buoy off the mooring line and pull with AHV1 in tandem.
AHV2
AHV1
break link breaks
fig. 3-79
When the predetermined installation load has been reached, the breaking device in the installation line fails (break shackle connecting the installation line to the delta plate), freeing the installation line from the Stevmanta (fig. 3-79). If the optional recovery buoy is used, the breaking device is placed on the delta plate connecting it to the installation line and AHV1. AHV1 is now no longer connected to the Stevmanta and the installation line can be recovered on deck (fig. 3-80). AHV2 can now start increasing the tension in the mooring line. If AHV2 can not generate enough bollard pull to reach the required proof tension load, AHV1 can be connected in tandem to AHV2 to generate additional bollard pull.
AHV2
pretension load recovery line fig. 3-80
AHV2
fig. 3-81
AHV2
After the Stevmanta has been proof tensioned to the required load, the mooring line can be attached to the floater. In case of a pre-laid mooring, the mooring line can be buoyed off, for easy connection later on (fig. 3-81). fig. 3-82
Stevmanta retrieval The Stevmanta is recovered from the seabed by returning to ‘installation mode’ instead of the normal (vertical) loading mode. The AHV picks up the recovery buoy from the seabed and by pulling vertically on the installation line, the anchor is retrieved easily (fig. 3-82).
83
Stevmanta VLA installation Double line installation with Stevtensioner The Stevmanta is deployed with the fixed angle adjuster. The mode of the anchor (installation mode or normal (vertical) loading mode) is chosen by pulling on either the installation line or the mooring line. The Stevmanta is in the installation mode when the installation line is tensioned, i.e. the line on the front of the angle adjuster (fig. 3-83).
installation mode mooring line installation line
fig. 3-83
normal mode
The Stevmanta is in the normal (vertical) loading mode when the mooring line is tensioned, i.e. the line at the rear of the angle adjuster. During the installation AHV1 handles the installation line (preferably chain and steel wire) and AHV2 handles the mooring line, for instance polyester (fig. 3-84).
mooring line
installation line fig. 3-84
84
The installation procedure with the Stevtensioner requires a reaction anchor (the typical use of the Stevtensioner is presented in the next chapter). In this case the reaction anchor can be either a Stevpris or Stevmanta. For now a Stevpris is shown as reaction anchor and is to be on the active side of the Stevtensioner. Connect the installation line to the angle adjuster on the Stevmanta on AHV1. Pass the mooring line from AHV2 to AHV1 and connect it to the angle adjuster. Lower the Stevmanta to the seabed by keeping tension on both the installation line and mooring line. Connect the installation line to the passive side of the Stevtensioner. A break link can be installed between the Stevtensioner and the installation line on the passive side (fig. 3-85).
AHV2
tensioner
AHV1
fig. 3-85
AHV2
Connect the installation line to the reaction anchor. Pass the installation line through the Stevtensioner (fig. 3-86). fig. 3-86
work chain stopper
AHV1
Stevmanta VLA installation Sail to set-down position of the reaction anchor (AHV1 only). AHV2 stays above the Stevmanta. During the movement of AHV1, the installation line of the Stevmanta has to be paid out (fig. 3-87). Lower the Stevtensioner and reaction anchor to the seabed (fig. 3-88). Buoy off the retrieval line (or mooring line) of the reaction anchor. AHV1 sails to tensioning point and starts taking in the slack of the tensioning line (fig. 3-89).
AHV2
shark jaws
85
AHV1
wire stopper tensioner
chain
fig. 3-87
AHV2
AHV1
wire stopper tensioner
stopper chain
fig. 3-88
AHV2
AHV1
wire stopper tensioner
fig. 3-89
stopper chain
Stevmanta VLA installation Start the tensioning procedure (yo-yoing) (fig. 3-90). The break link will break on the Stevmanta when the required installation load has been reached (fig. 3-91). Recover the Stevtensioner, the installation line and the reaction anchor to AHV1. AHV2 can now proof tension the Stevmanta and then buoy off the mooring line. Installation of the Stevmanta is now complete (fig. 3-92).
86
Instead of using a reaction anchor, two Stevmantas can also be installed at the same time. After completion of the tensioning (yo-yoing), AHV2 proof tensions one Stevmanta while AHV1 recovers the Stevtensioner and disconnects it from the installation line of the other Stevmanta. This Stevmanta can then also be proof tensioned (fig. 3-93).
Stevmanta VLA installation
AHV2
AHV1 wire stopper tensioner chain
stopper
fig. 3-90
AHV2
AHV1 wire stopper tensioner break link breaks
chain
stopper
fig. 3-91
chain
AHV2
wire
AHV1
tensioner
pretension load
stopper
fig. 3-92
AHV2
AHV1
wire stopper tensioner
fig. 3-93
stopper chain
87
The Stevtensioner Introduction The Stevtensioner is used for cross tensioning of diametrically opposed anchor legs moored by drag anchors or anchor piles. The Stevtensioner is generally used for the installation of (semi) permanent floating structures such as the SPM buoy, STL, TLP, FPS, FPSO, etc. After the tensioning operations the Stevtensioner is demobilised and ready for the next project. The Stevtensioner can however also be used for permanent tensioning purposes, becoming a part of the mooring system.
88
The Stevtensioner can be deployed from a crane barge, AHV or any vessel having enough crane/winch capacity to pull the required vertical force. The existing models VA220 and VA500 were designed for handling a single size of chain. The new Stevtensioner models VA600, VA1000 and VA1250 can handle chain diameter ranging from 76 mm up to 152 mm. Because of this variety in chain sizes additional work chain may not be required (fig. 3-94). The working principle of the tensioner The Stevtensioner is based on the principle that a vertical load to a horizontal string causes high horizontal loads. To achieve the required horizontal pretension load at the anchor points, the vertical pulling force only needs to be 40% of this pretension. The anchor line tension is measured by a measuring pin located inside the Stevtensioner and as such well protected against damage caused by handling and lifting operations (fig. 3-95).
2V H
fig. 3-95
fig. 3-94
The new Stevtensioner models offer the following features: • Smaller dimensions, reduced weight and improved handling, but heavy enough to easilty slide down the mooring line. • Designed to smoothly guide at least 5 links and therefore prevent chain getting stuck inside. • Due to economical volume/weight ratio, the new Stevtensioner models allow for containerised freight by either sea or, for rush deliveries, by air. • The integrated shape allows for smooth passage over stern roller. • Load measuring pin is equipped with two independent sets of strain gauges. The umbilical cable connections are protected against handling and lifting operations. These connections may be used for acoustic transfer of the signals.
The Stevtensioner One anchor line (passive line) is attached to the tension measuring pin at the Stevtensioner. The opposite anchor line (active line) passes through the Stevtensioner. Tensioning starts by applying the yo-yo movement to the active line (fig. 3-96). When the Stevtensioner is lifted by the active chain, it blocks the chain. When the Stevtensioner is lifted from the seabed, the passive and active mooring lines are also lifted. Consequently the anchors or piles are loaded and cause an inverse catenary of the mooring line in the soil, as well as causing the anchor to drag and embed. In other words: chain length is gained. Lowering the Stevtensioner slackens the anchor lines and allows it to slide down over the active chain. By repeating this several times (called the yo-yo movement), the horizontal load on the anchor points increases. Generally the required horizontal load is achieved after 5 to 7 steps. Once tensioning is completed, the Stevtensioner is recovered by pulling the lifting/pennant wire making it disengage. This allows the Stevtensioner to slide up along the active chain to the surface (fig. 3-97).
passive chain
89
active chain
fig. 3-96
chain locks
fig. 3-97
The Stevtensioner Measurement of the tensions applied Fig. 3-98 shows the curve recorded during tensioning of chains connected to piles for the Coveñas Pipeline Project in Colombia. The graph shows a total of 5 heaves (yo-y’s), each resulting in a higher tension.
Different methods can be applied to verify the tension in the chain. These are discussed below. Computer calculations The tension in the chain can be calculated by means of computer catenary calculations. Besides known parameters such as submerged chain weight, and the length of the mooring line, other parameters measured during tensioning need to be incorporated in the calculation: • Height Stevtensioner above seabed. • Vertical pulling load.
tension force in t
90
When the Stevtensioner is lifted from the seabed, the passive and active mooring lines are also lifted from the seabed. Consequently the anchors or piles are loaded. The loading causes an inverse catenary of the mooring line in the soil, and also causes the anchor to drag and embed; in other words: chain length is gained. When lowering to seabed the gain in chain length (slack) is won by the Stevtensioner sliding down the chain (approximately 5 to 8 links). The next heave (yo-yo) will therefore create a higher tension in the system. In practise a total of 5 to 7 yo-yos are required to reach the required proof tension load.
tension on anchor lifting force
250 125 0 0
fig. 3-98
30 time in minutes
60
90
120
The Stevtensioner By using this method the tension in the chain can be calculated at any height of the Stevtensioner above seabed. This method is independent of the waterdepth. Umbilical cable and measuring pin The chain tension can be measured with a measuring pin. The pin is part of the Stevtensioner housing and is equipped with strain gauges. The pin is connected to a tension read-out unit on the installation vessel by using an umbilical cable. The pin is connected to the passive chain. All tensioning data are measured on deck and presented during tensioning on a chart recorder. A hand winch with sliding contacts is used to veer and haul the umbilical without disconnecting the umbilical from the registration equipment. The measurement is insensitive for variations in cable length. The use of an umbilical is an effective method in waterdepths down to approximately 200 meters. Beyond this depth it becomes more efficient to use either an acoustic system or computer calculations. Break - link The passive chain can be attached to the Stevtensioner by a break link. When, during the tensioning operation, a predetermined load has been reached, the link breaks. Consequently the passive chain falls to the bottom, and the Stevtensioner can be retrieved. Duration of pretensioning anchors and piles Once the required tension has been achieved, the tension has to be maintained for a certain duration. This period is described in the table below for various Certification Authorities. Certification Authority
Required duration of maintaining tension Lloyds Register of Shipping 20 minutes American Bureau of Shipping 30 minutes Det Norske Veritas (NMD) 15 minutes
91
The Stevtensioner Handling the Stevtensioner Handling operations can generally be described as follows:
• Positioning the anchors and paying out the chain • Hook-up all necessary hardware for tensioning
92
operations on deck of barge or AHV • Deployment Stevtensioner to the seabed and positioning of the installation vessel • First lift (yo-yo) • Series of yo-yos • Maintain required tension for a specified period of time • Retrieve the Stevtensioner and disconnect • Prepare for next tensioning A Stevtensioner can be deployed from a crane barge, Anchor Handling Vessel or any vessel having enough crane/winch capacity to lift the required vertical force. General tensioning procedures General tensioning procedures using crane barge or AHV for Stevtensioner models VA1000 and VA1250 are presented in fig. 3-99 and 3-100. Hook-up Pass the active chain (2) through the tensioner (1) on deck. Connect passive chain (3) to measuring pin shackle (9). Connect dislock wire (5) to shackle (4). Connect umbilical cable (7) to read-out system on deck and to the measuring pin (6). Lowering Fix active chain (2) to winch or crane hook. Slack dislock wire (5) and lower Stevtensioner to seabed. Stevtensioner will pass over active chain (2). Tensioning mode When Stevtensioner is on seabed, slack dislock wire (5) before the first yo-yo, and keep slack during all yo-yos!
fig. 3-99
The Stevtensioner Tensioning is achieved by pulling on active chain (2). The mooring lines will be lifted from the seabed causing the anchors or piles to be loaded. After each yoyo active chain is gained. The active chain can only pass through the Stevtensioner in one direction. Approximately 4 to 7 yo-yos are required to obtain the required pretension load (fig. 3-100).
2 7 5
4
8 3 6
fig. 3-100
Retrieving When tensioning is completed be sure to lower the Stevtensioner to seabed and slack off active chain (2) before retrieving Stevtensioner with dislock wire (5). Pull on dislock wire (5). Stevtensioner will pass over chain (2). Disconnect Stevtensioner on deck of the barge or AHV. Stevtensioner Product Range The following Stevtensioners are available from vryhof anchors.
Stevtensioner model
Maximum horizontal load [t]
VA 220 VA 500 VA 600 VA1000 VA1250
220 500 600 1000 1250
Suitable* for chain Suitable* for chain size with Kenter size without Kenter shackle [mm] shackle [mm] 50 102 76 - 84 102 - 117 114 - 132
60 112 76 - 87 102 - 135 114 - 152
93
Size Stevtensioner lxhxw [m] 2.6 5.4 2.2 3.1 3.5
x x x x x
1.2 2.6 0.9 1.2 1.4
x x x x x
1.0 2.4 0.6 0.8 0.9
Weight Stevtensioner [t] 5 20 2.5 6 9
* The suitability only refers to the section of chain passing through the Stevtensioner. Chain or wire not passing through the Stevtensioner may have any dimension. table N
Supply vessels/anchor handling vessels Drilling rigs are generally moored with 8 to 12 anchors. These are laid in a mooring pattern. Originally normal tugs were used for these operations, but very soon, there was a call for specialised vessels. For anchor handling vesselss, it is very important to be able to work quickly and effectively. Much depends on the expertise of the captain and crew. The equipment and its design are also extremely important. Engine power has to be sufficient to handle chain and/or wire and anchors at the water depth concerned. The newest generation of AHVs has bollard pulls far in excess of 200 t.
These specialised anchor handling vessels (AHVs) now have: • A large deck space. • Powerful winches, with auxiliary winches to reel extra wires. • Large chain lockers, for storage of the chain. • Large wire storage capacity. • An adapted seaworthy design and very manoeuvrable with bow and stern thrusters. Some even with a dynamic positioning system. • Space for drilling mud and fuel tanks for supply to drilling rigs. • Small auxiliary cranes. • One or two sets of towing pins and shark jaws. • A stern roller that sometimes consists of two individually rotating drums. table O
94
Care should be given to the rated maximum bollard pull which in reality might be less, depending on the use of other power consuming equipment such as bow (and sometimes) stern thrusters, winches, etc. The winch often causes confusion. An AHV owner demonstrates maximum pulling capacity at the bare drum during the maiden trip, but a contractor requires high winch output when the drum is 70 to 100% wound with wire under working conditions. It is also possible that an owner limits the pressure of the hydraulic system below factory limits, to reduce winch wear and repair costs. The dynamic capacity of the winch brake is particularly important when a long heavy chain must be deployed. Hydraulically and electrically braked drums are more efficient than band brakes. For handling chain, many supply vessels have chain lockers below decks and a wildcat above the chain locker. To ensure easy handling of chain and wire, simple, well-constructed tools are necessary. An experienced crew will also make the handling easier.
4
Product data
Introduction Product Data
In this editon of the vryhof anchor manual, we have given the reader as much information and data as we imagined would normally be needed. Undoubtedly some is missing. This can be vryhof-specific or general information. Vryhof-specific, information can be related to brochures, detailed handling recommendations and product data. This can be obtained on request, while general information will also be provided if available. To make the next edition of the anchor manual suit the requirements of the reader even better than this one, your suggestions of comments are much appreciated. 97
Dimensions of vryhof anchor types
Stevin Mk3
B D
S 98
C A
E L K Main dimensions Stevin Mk3 dimensions in mm anchor weight in kg weight
1000
1500
3000
5000
7000
9000
12000
15000
20000
30000
A B C D E K L S
2429 2654 1559 2023 737 1010 412 60
2774 3038 1785 2316 843 1156 471 65
3493 3828 2249 2918 1063 1456 594 80
4120 4538 2667 3460 1260 1727 704 80
4602 5077 2983 3871 1409 1932 788 90
5012 5521 3244 4209 1533 2100 857 100
5516 6076 3570 4632 1687 2312 943 110
5942 6545 3846 4990 1817 2490 1016 120
6372 6986 4100 5324 2048 2674 1083 160
7289 7997 4694 6094 2345 3061 1240 180
Note: The dimensions of the Stevin Mk3 anchor may be changed for specific applications
Dimensions of vryhof anchor types
Stevpris Mk5
B
H
C
99
A
S E sand
T
F mud
Main dimensions Stevpris Mk5 dimensions in mm anchor weight in kg weight
1500
3000
5000
8000
10000
12000
15000
18000
20000
22000
25000
30000
65000
A B C E F H T S
2954 3184 1812 1505 271 1230 493 80
3721 4011 2283 1896 342 1550 622 90
4412 4756 2707 2248 406 1837 738 110
5161 5563 3166 2629 474 2149 862 130
5559 5992 3410 2832 511 2315 929 140
5908 6368 3624 3010 543 2460 988 150
6364 6860 3904 3242 585 2650 1064 170
6763 7290 4149 3446 622 2816 1131 180
7004 7550 4297 3569 644 2917 1171 190
7230 7794 4436 3684 665 3011 1209 200
7545 8133 4629 3844 694 3142 1262 200
8018 8643 4919 4085 737 3339 1341 220
10375 11184 6365 5286 954 4321 1736 300
Note: The dimensions of the Stevpris Mk5 anchor may be changed for specific applications
Dimensions of vryhof anchor types
Stevshark Mk5
H
B
C
100
A
S E sand
T
F mud
Main dimensions Stevshark Mk5 dimensions in mm anchor weight in kg weight
1500
3000
5000
8000
10000
12000
15000
18000
20000
22000
25000
30000
65000
A B C E F H T S
2862 3085 1755 1458 263 1192 478 80
3605 3886 2212 1837 332 1502 603 90
4275 4608 2622 2178 393 1780 715 110
4999 5389 3067 2547 460 2082 836 130
5385 5805 3304 2743 495 2243 900 140
5723 6169 3511 2915 526 2383 957 150
6165 6645 3782 3140 567 2567 1031 160
6551 7062 4019 3337 602 2728 1095 170
6785 7314 4163 3457 624 2826 1135 180
7004 7550 4297 3568 644 2917 1171 190
7309 7879 4484 3723 672 3044 1222 200
7767 8373 4765 3957 714 3235 1299 210
10051 10834 6166 5120 924 4186 1681 300
Note: The dimensions of the Stevshark Mk5 anchor may be changed for specific applications
Dimensions of vryhof anchor types
Stevmanta VLA
H
B D
101
C
E1
E0
T F
Main dimensions Stevmanta VLA dimensions in mm. Area in m2 area
5
8
10
12
15
17
20
B C D E0 E1 F H T
3143 2976 1945 3075 3371 172 1459 639
3975 3765 2460 3890 4264 217 1845 809
4445 4209 2750 4349 4767 243 2063 904
4869 4611 3013 4764 5222 266 2260 991
5443 5155 3368 5326 5839 298 2527 1107
5795 5488 3586 5670 6216 317 2690 1179
6286 5953 3890 6150 6742 344 2918 1279
Note: The dimensions of the Stevmanta VLA anchor may be changed for specific applications
Dimensions of other anchor types
A
A D
D
B
C
C
B
102
FLIPPER DELTA weight lb. kg 2205 1000 5512 2500 11023 5000 16535 7500 22046 10000 26455 12000 33069 15000 44092 20000 71650 32500 88185 40000
A mm 2605 3150 3945 4565 5040 5335 5735 6405 7320 7850
B mm 1960 2660 3300 3850 4270 4530 4845 5410 6200 6650
C mm 740 1005 1260 1435 1600 1705 1830 2010 2310 2480
D mm 1560 2130 2660 3080 3400 3600 3875 4320 4930 5290
DANFORTH weight lb. kg 1000 454 2500 1134 5000 2268 10000 4536 12000 5443 14000 6350 16000 7257 20000 9072 25000 11340 30000 13608
A mm 1830 2260 2780 3510 3730 3920 4100 4370 4710 5000
B mm 1580 2140 2700 3330 3540 3720 4000 4150 4470 4750
D mm 940 1549 2032 2159 2388 2591 2997 3226 3353 3556
C
LWT kg 454 2268 4536 6804 9072 11340 13608 15876 18144 27216
C
B
lb. 1000 5000 10000 15000 20000 25000 30000 35000 40000 60000
C mm 483 787 1041 1092 1219 1295 1499 1600 1676 1778
D
D
weight
D mm 1100 1350 1650 2100 2240 2360 2470 2620 2820 3000
A
A
B
C mm 410 560 710 890 945 995 1040 1110 1195 1270
A mm 1905 2997 3658 3988 4394 4851 5029 5283 5537 6350
B mm 1803 2845 3480 3791 4166 4521 4801 5055 6096 7061
C mm 622 984 1245 1362 1499 1708 1715 1803 1905 2184
D mm 1168 1829 2235 2438 2692 2946 3073 3226 3327 3810
MOORFAST weight lb. kg 1000 454 6000 2722 10000 4536 12000 5443 16000 7257 20000 9072 30000 13608 40000 18144 50000 22680 60000 27216
A mm 1549 2565 3327 3531 3886 4166 4801 5436 5639 5893
B mm 1905 3632 3988 4242 4750 4978 5512 6299 6528 6883
Dimensions of other anchor types
A
A
D
D
B
C C
B STATO weight lb. kg 3000 1361 6000 2722 9000 4082 15000 6804 20000 9072 25000 11340 30000 13608 35000 15876 40000 18144 60000 27216
A mm 3277 3658 4064 5182 5334 5740 5969 6299 6553 7540
B mm 2769 3632 4318 5690 5842 6248 6528 6883 7188 8120
C mm 860 960 1090 1370 1420 1540 1570 1670 1750 2000
D mm 1829 2337 2540 3200 3277 3480 3683 3886 4064 4570
A D
B
US NAVY STOCKLESS weight A lb. kg mm 1000 454 1072 5000 2268 1854 10000 4536 2337 15000 6804 2680 20000 9072 2946 25000 11340 3175 30000 13608 3372 35000 15876 3550 40000 18144 3708 60000 27216 4775
C
B mm 841 1437 1810 2089 2280 2456 2608 2743 2872 3194
C mm 521 889 1121 1295 1413 1522 1616 1703 1778 2218
D mm 772 1319 1661 1861 2094 2256 2394 2523 2619 3375
AC14 weight lb. kg 2844 1290 4630 2100 6746 3060 12368 5610 18298 8300 23149 10500 29762 13500 41447 18800 44092 20000 50706 23000
A mm 2730 3210 3640 4460 5080 5500 5980 6670 6810 7140
B mm 980 1150 1310 1600 1830 1970 2150 2400 2450 2570
C mm 470 550 620 760 870 940 1020 1140 1170 1220
D mm 1060 1250 1420 1740 1980 2140 2330 2600 2660 2780
103
Proof load test for HHP anchors (US units)
104
Anchor weight lbs
proof load kips
Anchor weight lbs
proof load kips
Anchor weight lbs
proof load kips
100 125 150 175 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 3900 4000
6.2 7.3 8.2 9.1 9.9 11.5 12.9 14.2 15.5 16.7 18.1 19.2 20.5 21.7 23 24.3 25.5 26.6 27.8 28.9 29.8 32.1 34.5 36.8 39.1 41.3 43.5 45.8 48.2 50.3 52.3 54.5 56.6 58.6 60.8 62.8 64.8 66.8 68.8 70.7 72.6 74.5 76.4 78.3 80.1 81.9 83.7 85.5 87.2 89 90.7
4100 4200 4300 4400 4500 4600 4700 4800 4900 5000 5100 5200 5300 5400 5500 5600 5700 5800 5900 6000 6100 6200 6300 6400 6500 6600 6700 6800 6900 7000 7100 7200 7300 7400 7500 7600 7700 7800 7900 8000 8100 8200 8300 8400 8500 8600 8700 8800 8900 9000 9500
92.5 94.2 95.9 97.5 99.1 100.7 102.3 103.9 105.5 107 108.5 110 111.4 112.9 114.4 115.9 117.4 118.7 120 121.4 122.7 124.1 125.4 126.8 128.2 129.5 130.8 132 133.2 134.4 135.7 136.9 138.1 139.3 140.6 141.6 142.7 143.7 144.7 145.7 146.8 147.9 149 150 151.1 152.2 153.2 154.3 155.2 156.2 161.1
10000 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000 24000 25000 26000 27000 28000 29000 30000 31000 32000 33000 34000 35000 36000 37000 38000 39000 40000 42000 44000 46000 48000 50000 52000 54000 56000 58000 60000 62000 64000 66000 68000 70000 75000 80000 82500
165.8 174.5 184.8 194.7 205.2 214.3 222.9 230.9 239 245 250.4 256.7 263.5 270.9 277.2 282.8 289.2 296.7 304.9 312.3 318.9 326.9 333.7 341.2 348 354.8 361.6 368.4 375.2 382 388.8 400.6 411.5 425.1 437 449.1 460.4 472 484.3 496.5 508.4 519.3 530.2 541 551.9 562.8 590 617 630
Proof load test for HHP anchors (SI units) Anchor weight kg
proof load kN
Anchor weight kg
proof load kN
Anchor weight kg
proof load kN
50 55 60 65 70 75 80 90 100 120 140 160 180 200 225 250 275 300 325 350 375 400 425 450 475 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1600 1700 1800 1900
29.7 31.7 34 35.3 37 39 40.7 44 47.3 53 58.3 63.7 68.4 73.3 80 85.7 91.7 98 104.3 110.3 116 122 127.3 132 137.3 143 155 166 177.3 188 199 210.7 221.3 231 241.7 252.3 262 272.7 282.7 292 302 311.7 321 330.3 339.7 349 366.7 384 401 418.3
2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 3900 4000 4100 4200 4300 4400 4500 4600 4700 4800 4900 5000 5100 5200 5300 5400 5500 5600 5700 5800 5900 6000 6100 6200 6300 6400 6500 6600 6700 6800 6900
434.3 450 466 480.7 495 509.7 524.3 537 550.3 563.7 577 589 601 613 625 635.7 645 655.7 666.3 677 687 696.3 706 715.7 725.7 735 742.3 751.7 760 769 777 786 797.3 808.7 818 827.3 836.3 845 855.7 866.3 877 887 897.3 908 917.3 926.7 936 944.7 953 961
7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 9600 9800 10000 10500 11000 11500 12000 12500 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500 20000 21000 22000 23000 24000 25000 26000 27000 28000 29000 30000 31000 32000 34000 36000
970.3 987 1002 1018 1034 1050 1066 1078 1088.7 1099.3 1110 1120.7 1132 1148 1162.7 1173.3 1210 1240 1266.7 1300 1340 1380 1410 1450 1483.3 1520 1553.3 1586.7 1620 1653.3 1686.7 1720 1753.3 1780 1800 1833.3 1900 1956.7 2016.7 2070 2130 2190 2250 2303.3 2356.7 2410 2463.3 2516.7 2623.3 2730
105
Dimensions of vryhof tensioners
H
L
106
Main dimensions Stevtensioner dimensions in m. weight in t Stevtensioner model VA220 VA500
L 2.6 5.4
B 1.0 2.4
H 1.2 2.6
weight 5 20
B
Dimensions of vryhof tensioners
H
L
107
Main dimensions Stevtensioner dimensions in m. weight in t Stevtensioner model VA600 VA1000 VA1250
L 2.2 3.1 3.5
B 0.6 0.8 0.9
H 0.9 1.2 1.4
weight 2.5 6 9
B
Proof load/break load of chains (in US units)
diameter
Proof load R4-RQ4
108
inches 3 /4 1 3/16 1 1 1/8 1 1/4 1 3/8 1 1/2 1 5/8 1 3/4 1 7/8 2 2 1/16 2 1/8 2 3/16 2 1/4 2 5/16 2 3/8 2 1/2 2 5/8 2 11/16 2 3/4 2 7/8 3 3 1/16 3 1/8 3 3/16 3 1/4 3 5/16 3 3/8 3 1/2 3 9/16 3 5/8 3 3/4 3 13/16 3 7/8 3 15/16 4 4 1/8 4 1/4 4 3/8 4 1/2 4 5/8 4 3/4 4 7/8 5 5 1/8 5 1/4 5 3/8 5 1/2 5 5/8 5 3/4 5 7/8 6 6 1/8 6 1/4 6 3/8 6 1/2 6 5/8 6 3/4 6 7/8 7 7 1/8 7 1/4
R3 S
Break load R3
stud
studless
stud
studless
kips 75 88 131 165 203 244 289 337 388 443 500 531 561 593 625 658 692 762 835 872 910 988 1069 1110 1152 1194 1237 1281 1325 1416 1462 1508 1603 1651 1699 1749 1798 1899 2001 2105 2211 2319 2428 2538 2650 2764 2878 2994 3111 3228 3347 3467 3587 3709 3830 3953 4076 4199 4323 4447 4571 4695 4820
kips 66 77 116 146 179 216 255 298 343 391 443 469 496 524 553 582 612 674 738 771 805 874 945 982 1019 1056 1094 1133 1172 1252 1292 1334 1417 1460 1503 1546 1590 1679 1770 1862 1955 2050 2147 2245 2344 2444 2545 2647 2751 2855 2960 3066 3172 3279 3387 3495 3604 3713 3822 3932 4042 4152 4262
kips 62 73 110 138 169 203 241 281 323 369 417 442 468 494 521 549 577 635 696 727 758 823 891 925 960 995 1031 1068 1105 1180 1218 1257 1336 1376 1416 1457 1498 1582 1668 1754 1843 1932 2023 2115 2209 2303 2398 2495 2592 2690 2789 2889 2989 3090 3192 3294 3396 3499 3602 3706 3809 3913 4016
kips 60 71 106 133 163 197 233 271 313 357 403 427 452 478 504 530 558 614 672 702 733 796 861 894 928 962 997 1032 1068 1140 1177 1215 1291 1330 1369 1409 1448 1529 1612 1696 1781 1868 1956 2045 2135 2226 2319 2412 2506 2601 2696 2793 2890 2987 3086 3184 3283 3383 3482 3582 3682 3782 3882
RQ3-API
stud stud studless studless kips kips 54 49 63 57 95 85 119 107 147 132 176 158 208 187 243 218 280 252 320 287 361 324 383 344 405 364 428 384 452 405 476 427 500 449 550 494 603 541 630 565 657 590 714 640 772 693 802 719 832 747 863 774 894 802 925 830 957 859 1022 918 1056 947 1089 977 1158 1039 1192 1070 1227 1101 1263 1133 1299 1165 1371 1231 1445 1297 1521 1365 1597 1433 1675 1503 1753 1574 1833 1645 1914 1718 1996 1791 2079 1865 2162 1940 2247 2016 2332 2093 2417 2170 2504 2247 2591 2325 2678 2404 2766 2483 2855 2562 2944 2642 3033 2722 3122 2802 3211 2882 3301 2963 3391 3043 3481 3124
R4-RQ4
R3 S
R3
Weight RQ3-API
stud and studlless kips 95 111 167 210 257 310 366 427 492 562 635 673 712 752 793 835 878 967 1059 1106 1154 1253 1356 1408 1461 1515 1570 1625 1681 1796 1854 1913 2033 2094 2156 2218 2281 2409 2538 2671 2805 2941 3080 3220 3362 3506 3651 3798 3946 4095 4246 4398 4551 4704 4859 5014 5170 5327 5483 5641 5798 5956 6114
kips 86 101 152 191 234 281 333 388 447 510 577 612 647 684 721 759 798 878 962 1005 1049 1139 1232 1280 1328 1377 1427 1477 1528 1632 1685 1739 1848 1903 1959 2016 2073 2189 2307 2427 2549 2673 2799 2926 3055 3186 3318 3451 3586 3722 3859 3997 4135 4275 4416 4557 4698 4841 4983 5126 5269 5412 5556
kips 77 90 136 171 210 252 298 348 401 457 517 548 580 612 646 680 715 787 862 900 940 1020 1103 1146 1189 1233 1278 1323 1368 1462 1509 1557 1655 1704 1754 1805 1856 1960 2066 2174 2283 2394 2507 2621 2736 2853 2971 3091 3211 3333 3456 3579 3704 3829 3954 4081 4208 4335 4463 4591 4719 4847 4976
kips 73 86 128 162 198 238 282 329 379 432 489 518 548 579 611 643 676 744 815 852 889 965 1044 1084 1125 1167 1209 1251 1295 1383 1428 1473 1566 1613 1660 1708 1756 1855 1955 2057 2160 2265 2372 2480 2589 2700 2812 2925 3039 3154 3270 3387 3504 3623 3742 3861 3981 4102 4223 4344 4465 4586 4708
stud
studless
lbs/ft 5 6 10 12 15 18 21 25 29 33 38 40 43 45 48 51 54 59 65 69 72 79 86 89 93 97 100 104 108 116 121 125 134 138 143 147 152 162 172 182 192 203 214 226 238 250 262 274 287 301 314 328 342 356 371 386 401 417 433 449 466 482 500
lbs/ft 5 6 9 11 14 16 20 23 27 31 35 37 39 42 44 46 49 54 60 63 66 72 78 81 85 88 92 95 99 106 110 114 122 126 130 135 139 148 157 166 176 186 196 206 217 228 239 251 262 275 287 299 312 325 339 353 367 381 395 410 425 440 456
Proof load/break load of chains (in SI units)
diameter
Proof load R4-RQ4
mm 19 20.5 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 73 76 78 81 84 87 90 92 95 97 100 102 105 107 111 114 117 120 122 124 127 130 132 137 142 147 152 157 162 165 168 171 175 178 180 185
R3 S
stud
studless
stud
studless
kN 331 385 442 524 612 707 809 917 1031 1151 1278 1410 1548 1693 1843 1999 2160 2327 2499 2677 2860 3048 3242 3440 3643 3851 4064 4392 4731 4962 5317 5682 6056 6439 6699 7096 7365 7776 8054 8478 8764 9347 9791 10242 10700 11008 11319 11789 12265 12585 13395 14216 15048 15890 16739 17596 18112 18631 19150 19845 20367 20715 21586
kN 293 340 390 463 541 625 715 811 911 1018 1130 1247 1369 1497 1630 1767 1910 2058 2210 2367 2529 2695 2866 3042 3221 3406 3594 3884 4183 4388 4702 5024 5355 5693 5923 6275 6513 6876 7122 7497 7750 8265 8658 9057 9461 9734 10009 10425 10846 11129 11844 12571 13306 14051 14802 15559 16016 16474 16934 17548 18010 18318 19088
kN 276 320 368 436 510 589 674 764 859 959 1065 1175 1290 1411 1536 1666 1800 1939 2083 2231 2383 2540 2701 2867 3036 3209 3387 3660 3942 4135 4431 4735 5046 5365 5582 5913 6138 6480 6712 7065 7304 7789 8159 8535 8916 9173 9432 9824 10221 10488 11162 11847 12540 13241 13949 14663 15094 15525 15959 16538 16972 17263 17989
kN 267 310 356 422 493 570 651 738 830 927 1029 1136 1247 1364 1485 1610 1740 1874 2013 2156 2304 2455 2611 2771 2935 3102 3274 3538 3811 3997 4283 4577 4878 5187 5396 5716 5933 6264 6488 6829 7060 7529 7887 8251 8619 8868 9118 9497 9880 10138 10790 11452 12122 12800 13484 14174 14590 15008 15427 15986 16407 16687 17389
Break load R3
RQ3-API
R4-RQ4
R3S
studstudstud and studless studless kN kN kN kN 239 215 420 382 278 249 488 443 319 286 560 509 378 339 664 604 442 397 776 706 511 458 897 815 584 524 1026 932 662 594 1163 1057 744 668 1308 1188 831 746 1460 1327 923 828 1621 1473 1018 914 1789 1625 1118 1004 1964 1785 1223 1097 2147 1951 1331 1194 2338 2124 1443 1295 2535 2304 1560 1400 2740 2490 1681 1508 2952 2682 1805 1620 3170 2881 1933 1735 3396 3086 2066 1854 3628 3297 2201 1976 3867 3514 2341 2101 4112 3737 2484 2230 4364 3965 2631 2361 4621 4200 2782 2496 4885 4440 2935 2634 5156 4685 3172 2847 5572 5064 3417 3066 6001 5454 3584 3216 6295 5720 3840 3446 6745 6130 4104 3683 7208 6550 4374 3925 7682 6981 4650 4173 8167 7422 4838 4342 8497 7722 5125 4599 9001 8180 5319 4774 9343 8490 5616 5040 9864 8964 5817 5220 10217 9285 6123 5495 10754 9773 6330 5681 11118 10103 6750 6058 11856 10775 7071 6346 12420 11287 7397 6639 12993 11807 7728 6935 13573 12334 7950 7135 13964 12690 8175 7336 14358 13048 8515 7641 14955 13591 8858 7950 15559 14139 9089 8157 15965 14508 9674 8682 16992 15441 10267 9214 18033 16388 10868 9753 19089 17347 11476 10299 20156 18317 12089 10850 21234 19297 12708 11405 22320 20284 13081 11739 22976 20879 13455 12075 23633 21477 13831 12412 24292 22076 14333 12863 25174 22877 14709 13201 25836 23479 14961 13427 26278 23880 15590 13991 27383 24884
R3
Weight RQ3-API
studlless kN 342 397 456 541 632 730 835 946 1064 1188 1319 1456 1599 1748 1903 2063 2230 2402 2580 2764 2953 3147 3347 3551 3761 3976 4196 4535 4884 5123 5490 5866 6252 6647 6916 7326 7604 8028 8315 8753 9048 9650 10109 10574 11047 11365 11686 12171 12663 12993 13829 14677 15536 16405 17282 18166 18699 19234 19771 20488 21027 21387 22286
kN 324 376 431 511 598 691 790 895 1007 1124 1248 1377 1513 1654 1800 1952 2110 2273 2441 2615 2794 2978 3166 3360 3559 3762 3970 4291 4621 4847 5194 5550 5916 6289 6544 6932 7195 7596 7868 8282 8561 9130 9565 10005 10452 10753 11057 11516 11981 12294 13085 13887 14700 15522 16352 17188 17693 18199 18707 19386 19896 20236 21087
stud
studless
kg/m 8 9 11 13 15 17 20 22 25 28 32 35 39 42 46 50 55 59 64 69 74 79 84 90 95 101 107 117 126 133 144 155 166 177 185 198 206 219 228 241 251 270 285 300 315 326 337 353 370 382 411 442 473 506 540 575 596 618 640 671 694 710 750
kg/m 7 8 10 12 14 16 18 20 23 26 29 32 35 39 42 46 50 54 58 63 67 72 77 82 87 92 98 107 116 122 131 141 151 162 169 181 188 200 208 221 229 246 260 274 288 298 308 323 338 348 375 403 432 462 493 525 545 564 585 613 634 648 685
109
Chain components and forerunners 4D
A
3.6D
F
C
B
A
E
A
A
A
A
A
D
4.4D
3.96D
F
C
B
H
B
A
E
A
A
A
B
1.1D
4.35D
C
4D
110 PL
A
A
A
A
A
A
A
A
A
1.2D
4D
E
4.2D
PL
A
B
H
B
A
E
A
A
A
1.52D
D
C
B D K
C
B
A
E
A
A
A
A
A
PL
E A
X
Y
K
C
B
H
B
A
E
A
A
A
Z
K
Chain components and forerunners 6.3D
13.2D
3.8D
4.7D
9.7D
4.15D
3.3D
H
1.2D
I 5.15D
1.2D 3.8D
2.2D
1.45D 4D
1.7D 2.2D
1.65D 1.35D 8D
3.4D
0.8D
1.4D 4D
7.1D
G
111
1.6D 1.2D 2.8D
1.3D
4.6D
1.8D
2.4D 5.2D
8.7D
1.4D
F 1.8D 1.4D 3.1D
A = B = C = E = F = G = PL = H = I = K =
common link enlarged link end link joining schackle kenter type anchor shackle D type joining shackle D type pear link swivel swivel shackle special end link
Connecting links C F H
G B
J
K
D E A
Pear shaped anchor connecting link (pearlink) dimensions in mm
112
NO
chain size
4 5 6 7 8 9 10 11
32 42 52 62 81 94 97 103
- 40 - 51 - 60 - 79 - 92 - 95 - 102 - 108
D
A
B
C
D
E
F
298 378 454 562 654 692 889 940
206 260 313 376 419 435 571 610
59 76 92 117 133 146 190 203
40 51 60 79 92 98 121 127
48 64 76 95 124 130 165 175
83 100 121 149 149 159 190 203
G
H
44x 44 56 51x 60 74 62x 73 88 85x 79 111 111x 102 130x133 124x 137 141 130 181 156 200
J
K
kg
26 32 37 48 54 57 73 76
43 52 64 76 79 83 108 111
13 27 49 94 149 236 386 418
C
E
F
E
B G
A
Detachable chain connecting link (C-connector) dimensions in mm chain size
A
B
C
D
E
F
G
weight kg
30 - 32 33 - 35 36 - 38 40 - 42 43 - 44 46 - 48 50 - 51 52 - 54 56 - 58 59 - 60 62 - 64 66 - 67 68 - 70 71 - 73 74 - 76 78 - 79 81 - 83 84 - 86 87 - 89 90 - 92 94 - 95 97 - 98 100 - 102
190.5 210 229 248 267 286 305 324 343 362 381 400 419 438 457 476 495 514 537 552 571 590 607
127 140 152 165 190 184 197 210 221 234 246 246 275 283 295 308 320 332 350 356 368 381 394
44 49 53 57 62 64 64 67 71 78 79 83 92 94 95 102 103 107 116 119 122 127 132
32 35 38 41 44 48 51 54 57 60 64 67 73 73 76 79 83 86 92 92 95 98 102
35 39 43 50 51 55 59 64 67 70 73 78 83 85 90 92 92 100 105 106 114 117 119
39 42 46 50 56 60 64 67 71 75 78 79 90 93 94 96 103 107 114 116 119 121 122
21 23 25 27 30 31 33 36 38 40 42 44 46 48 50 52 55 57 59 61 62 67 68
4.5 6.0 7.8 10.0 12.5 14.5 16.5 20.0 23.5 27.5 32.0 37.0 45.5 48.5 54.5 62.5 73.0 80.5 93.5 97.5 116.0 123.0 130.0
Conversion table to convert from length
multiply by
millimetres mm
0.03937
metres m kilometres km kilometres km
0.30480
miles mi
1.60934
square millimetres mm2
square kilometres km
2
square inches in square feet ft
10.76391
square feet ft2
0.38610
square miles mi2 square millimetres mm2 square metres m2
0.06102
cubic inches in3
square kilometres km2
0.26417
gallons (US) gal
cubic metres m3
35.31467
cubic feet ft3
cubic inches in
16.38706
millilitres ml
3
gallons (US) gal
3.78541
cubic feet ft3
0.02832
kilograms kg
2.20462 1.10231 0.45359
kilograms per cubic metre kg/m3 pounds per cubic foot lb/ft
3
0.90718 0.06243 16.01846
kilonewtons kN
0.22481
kilonewtons kN
0.10197
metric tons t kips kip metric tons t
litres l cubic metres m3 pounds lb short tons US ton kilograms kg metric tons t pounds per cubic foot lb/ft3 kilograms per cubic metre kg/m3 kips kip metric tons t
2.20462
kips kip
4.44822
kilonewtons kN
9.80665
kilonewtons kN
kips kip
0.45359
kilopascals kPa
20.88555
pounds per square foot psf
metric tons t
megapascals MPa
0.14504
kips per square inch ksi
pounds per square foot psf
0.04788
kilopascals kPa
kips per square inch ksi
6.89472
megapascals MPa
metres per second m/s
1.94384
metres per second m/s
2.23694
knots kn miles per hour mph temperature
kilometres km square inches in2
millilitres ml
pounds lb
velocity
metres m kilometres km
2.58999
short tons US ton
pressure or stress
millimetres mm
square miles mi
metric tons t
force or weight
nautical miles nmile
0.00155
0.09290
2
litres l
density
1.852
645.16
2
2
mass
miles mi
feet ft
square metres m2
volume
feet ft
0.62137
25.4
nautical miles nmile area
inches in
3.28084
0.53996
inches in
to obtain
degrees celsius ˚C degrees fahrenheit ˚F
0.51444 0.44704 multiply by 1.8 then add 32 subtract 32 then multiply by 0.555
knots kn miles per hour mph metres per second m/s metres per second m/s degrees fahrenheit ˚F degrees celsius ˚C
113
Mooring line catenary When the mooring line of a floater is deployed, part of the mooring line will lay on the seabed and part of the mooring line will be suspended in the water. The part of the mooring line that is suspended in the water will take on a catenary shape. Depending on the waterdepth, the weight of the mooring line and the force applied to the mooring line at the fairlead, the length of the suspended mooring line (S in [m]) can be calculated with:
F X
s
d
v
j
fig. 4-01
114
√dx{2xF
}
-d W with d : the waterdepth plus the distance between sealevel and the fairlead in [m] F : the force applied to the mooring line at the fairlead in [t] and w : the unit weight of the mooring line in water in [t/m] The horizontal distance (X in [m]) between the fairlead and the touchdown point of the mooring line on the seabed can be calculated with:
X=
{ }
{ wF -d} x log e
S + F w F - d w
The weight of the suspended chain (V in [t]) is given by: V=wxS
1200
800
400
0 0
100
200
300
400
500
depth in meters fig. 4-03 S, F = 50 t
S, F = 100 t
S, F = 150 t
S, F = 200 t
S, F = 100 t
S, F = 300 t
X, F = 50 t
X, F = 100 t
X, F = 150 t
X, F = 200 t
X, F = 250 t
X, F = 300 t
180
weight catenary chain in t
S=
length S and X in meters
1600
140
100
60
20 0 0
100
200
300
400
500
depth in meters
See fig. 4-01 for a clarification of the symbols used. The angle is the angle between the mooring line at the fairlead and the horizontal. Example. In fig. 4-02, the suspended length S and the horizontal distance X are plotted for a 76 mm chain for different loads F (ranging from 50 t to 300 t). The suspended weight of the mooring line is plotted in fig. 4-03. The submerged unit weight of the 76 mm chain is 0.110 t/m.
fig. 4-02 F = 50 t
F = 100 t
F = 250 t
F = 300 t
F = 150 t
F = 200 t
Mooring line holding capacity Holding capacity of the mooring line on the seabed. The holding capacity (P) in [t] of the part of the mooring line that is laying on the seabed, can be estimated with the following equation: P=fxlxw with f : friction coefficient between the mooring line and the seabed l : the length of the mooring line laying on the seabed in [m] w : the unit weight of the mooring line in water in [t/m] If no detailed information on the friction coefficient is available, the following values can be used:
mooring line type chain wire rope
friction coefficient starting sliding 1.0 0.7 0.6 0.25
The values for the friction coefficient given under starting can be used to calculate the holding capacity of the mooring line, while the values given under sliding can be used to calculate the forces during deployment of the mooring line.
115
Shackles A
A
O
D
D
B
B C
E
C
Chain shackle
E
Anchor shackle
chain shackle and anchor shackle According to U.S. federal specification (RR-C-271) dimensions in mm
116
SWL t
A
B
C
2 3.25 4.75 6.5 8.5 9.5 12 13.5 17 25 35 42.5 55 85 120 150 200 250 300 400 500 600 700 800 900 1000 1200 1500
13 16 19 22 25 28 32 35 38 45 50 57 65 75 89 102 120 125 135 165 175 195 205 210 220 230 250 260
16 19 22 25 28 32 35 38 42 50 57 65 70 80 95 108 130 140 150 175 185 205 215 220 230 240 280 325
22 27 31 36 43 47 51 57 60 74 83 95 105 127 146 165 175 200 200 225 250 275 300 300 320 340 400 460
D chain shackle 43 51 59 73 85 90 94 115 127 149 171 190 203 230 267 400 500 540 600 650 700 700 730 730 750 750 840 840
D anchor shackle 51 64 76 83 95 108 115 133 146 178 197 222 254 330 381 400 500 540 600 650 700 700 730 730 750 750 840 870
E
32 38 44 50 56 64 70 76 84 100 114 130 140 160 190 216 260 280 300 350 370 410 430 440 460 480 560 650
O anchor shackle 32 43 51 58 68 75 83 92 99 126 138 160 180 190 238 275 290 305 305 325 350 375 400 400 420 420 500 600
Weight Chain shackle KG 0.38 0.66 1.05 1.46 2.59 3.34 4.74 6.19 7.6 12.82 18.16 27.8 35.1 60 93 145 180 225 305 540 580 850 920 990 1165 1315 1700 2500
Weight anchor shackle KG 0.44 0.79 1.26 1.88 2.79 3.8 5.26 7 8.8 15 20.65 29.3 41 62.3 109.5 160 235 285 340 570 685 880 980 1110 1295 1475 1900 2800
Shackles A
D
G
B C F
E
heavy duty shackle double nut dimensions in mm SWL t
rope dia inch 12-13” 14-15” 16-18” 19-21” 22-23” 24”->
60 85 110 130 175 225
A
B
C
D
E
F
G
weight kg
65 80 90 100 125 130
76 90 102 114 133 146
175 220 254 280 300 333
350 390 430 480 600 720
165 178 210 235 265 305
305 380 434 480 550 593
535.5 604 676 754.5 924 1075.5
65 87 146 194 354 410
F
E
D
B A
C
A
sling shackle dimensions in mm SWL t
A
B
C
D
E
F
weight kg
75 125 150 200 250 300 400 500 600 700 800 900 1000 1250 1500
70 85 89 100 110 122 145 160 170 190 200 220 240 260 280
70 80 95 105 120 134 160 180 200 215 230 255 270 300 320
105 130 140 150 170 185 220 250 275 300 325 350 380 430 460
290 365 390 480 540 600 575 630 700 735 750 755 760 930 950
186 220 250 276 300 350 370 450 490 540 554 584 614 644 680
120 150 170 205 240 265 320 340 370 400 420 440 460 530 560
67 110 160 220 320 350 635 803 980 1260 1430 1650 2120 2400 2980
117
Wire Rope Depending on the required service life of the mooring system, the following types of wire rope are recommended: Design life Up to 6 years Up to 8 years Up to 10 years 10 years plus 15 years plus 20 years plus
118
Recommended product type Six strand Six strand c/w zinc anodes Six strand c/w ‘A’ galvanised outer wires & zinc anodes Spiral strand Spiral strand c/w Galfan coated outer wires Spiral strand c/w HDPE sheathing
The two rope constructions have differing properties. The advantages of each of the rope types are presented in the following table: Spiral strand Higher strength/weight ratio Higher strength/diameter ratio Torsionally balanced Higher corrosion resistance Higher fatigue resistance
Six strand Higher elasticity Greater flexibility Lower axial stiffness
Properties of spiral stand wire rope Diameter mm (inch) 76 84 90 96 102 108 114 121 127 133 140 146 151
(3) (3.25) (3.5) (3.75) (4) (4.25) (4.5) (4.75) (5) (5.25) (5.5) (5.75) (6)
MBL t
Axial Stiffness (EA) [MN]
525 640 720 825 965 1075 1180 1300 1455 1595 1775 1895 2020
520 610 700 810 910 1030 1170 1300 1430 1600 1720 1870 2030
Weight in air Unsheathed kg/m 28 35.2 39.5 45 51 57 65 71 80 88 96 106 114
Sheathed kg/m 31 38.7 42.5 49.5 54 62 70 76 85 94 101 111 120
Submerged weight kg/m 24 30.5 33.5 38 43 48 55 60 67 74 81 89 96
Nominal steel area mm2
Sheathing Thickness mm
3465 4220 4750 5435 6350 7055 7775 8550 9596 10490 11675 12470 13270
8 8 10 10 11 11 11 11 11 11 11 11 11
Wire Rope Properties of six strand wire rope Diameter mm (inch)
77 83 90 96 103 109 115 122 128 135 140 146 152
(3) (3.25) (3.5) (3.75) (4) (4.25) (4.5) (4.75) (5) (5.25) (5.5) (5.75) (6)
Construction Axial Stiffness (EA) [MN]
6*36 6*47 6*47 6*52 6*52 6*52 6*76 6*76 6*76 6*95 6*95 6*95 6*95
API 9A-EIPS Minimum Breaking load t
MBL t
Weight in air kg/m
347 402 460 516 582 652 725 801 880 915 995 1078 1165
425 475 575 625 680 740 844 950 1025 1110 1220 1310 1410
25 29 35 37.5 43.5 49 56 64 69 75 80 88 97
320 370 445 470 555 630 680 770 875 915 1020 1100 1200
Installation of sheathed spiral strand. The limiting factors for the installation of a sheathed spiral strand are defined by the properties of the sheathing. The maximum bearing pressure (_b) on the sheath is limited to 21 N/mm2 to avoid permanent deformation. The minimum bending diameter permitted can be calculated using the following formula: D = (4 x W) / (π x σb x {d x 0.15 x t}0.5) Where : D = sheave diameter mm W = line load N d = sheathed cable diameter mm t = sheathing radial thickness mm σb = maximum bearing pressure N/mm2 The above formula ensures no damage to the sheathing through bending. In addition to prevent damage to the cable within the sheathing, the minimum bending diameter is 24 times the unsheathed cable diameter., i.e. D > 24 x (d – 2 x t).
Submerged weight kg/m 20.5 24.5 29.5 31.5 36.5 41.5 47 54 58 63 67 74 81.5
Nominal steel area mm2 2835 3285 3950 4185 4925 5575 6050 6810 7760 8095 9025 9815 10650
119
Wire rope sockets G D1 B A
X
Closed spelter socket dimensions in mm NO
MBL t
428 430 431 433 440 445 450
650 820 1000 1200 1500 1700 1900
F E
120
for wire dia. mm 75 - 84 85 - 94 95 - 104 105 - 114 115 - 130 131 - 144 145 - 160
A
B
D1
F
G
X
360 400 425 500 580 625 700
375 410 450 500 570 630 700
150 175 205 230 260 300 325
350 380 400 500 600 680 725
150 170 200 210 225 240 275
1110 1250 1400 1570 1800 1940 2150
F E
G
C
C
B
B
A
A
D
G
D
Closed spelter socket dimensions in mm NO 201 204 207 212 215 217 219 221 222 223 224 225 226 227 228 229 230 231 240 250 260
SWL t 6.3 10 14 17 20 28 40 40 45 50 60 60 75 80 90 100 115 160 225 270 320
for wire dia. mm 20 - 22 24 - 27 27 - 30 31 - 36 37 - 39 40 - 42 43 - 48 49 - 53 49 - 54 54 - 59 55 - 60 60 - 65 61 - 68 69 - 75 76 - 80 81 - 86 87 - 93 94 - 102 122 - 130 140 - 155 158 - 167
A
B
C
D
E
F
G
type
101 114 127 139 152 165 190 195 216 215 228 235 248 279 305 330 356 381 500 580 675
90 103 116 130 155 171 198 225 224 235 247 245 270 286 298 311 330 356 475 550 600
33 36 39 43 51 54 55 54 62 58 73 62 79 76 83 102 102 108 120 150 175
24 28 32 38 41 44 51 56 57 62 63 68 73 79 86 92 99 108 138 160 175
47 57 63 70 79 82 89 100 96 110 108 120 140 159 171 184 197 216 260 300 325
92 104 114 127 136 146 171 190 193 210 216 230 241 273 292 311 330 362 515 510 600
38 44 51 57 63 70 76 90 82 100 92 110 102 124 133 146 159 178 210 250 300
A A A A A A A B A B A B A A A A A A A A A
Wire rope sockets C
J
D1 B A
X
Open spelter socket dimensions in mm NO
MBL t
338 340 344 346 350 370 380
650 820 1000 1200 1500 1700 1900
L2 K J K
for wire dia. mm 75 - 84 85 - 94 95 - 104 105 - 114 115 - 130 131 - 144 145 - 160
A
B
C
D1
J
X
375 410 425 500 580 625 700
298 320 343 500 580 625 700
296 340 362 440 580 625 680
140 152 178 200 250 280 300
159 171 191 200 220 230 250
1050 1170 1300 1570 1800 1940 2150
L2 K J K
C
121
C D1
D1
B
B L1
L1 A
A
D
D Open spelter socket dimensions in mm NO 100 101 104 108 111 112 115 118 120 121 125 128 130 132 135 138 140 142 144 146 150 160 170
SWL t
for wire dia. mm 5 18 - 19 3 14 - 16 6.3 20 - 22 10 23 - 26 14 27 - 30 10 31 - 34 17 31 - 36 20 37 - 39 28 40 - 42 16 39 - 43 40 43 - 48 45 49 - 54 60 55 - 60 75 61 - 68 80 69 - 75 90 76 - 80 100 81 - 86 115 87 - 93 160 94 - 102 200 108 - 115 225 122 - 130 270 140 - 155 320 158 - 167
A
B
C
D
D1
J
K
89 115 101 114 127 190 139 152 165 220 190 216 228 248 279 305 330 356 381 460 500 580 675
76 62 89 101 114 114 127 162 165 142 178 228 250 273 279 286 298 318 343 480 500 500 600
80 70 90 120 130 127 144 160 176 157 200 216 236 264 276 284 296 340 362 440 560 600 650
21 18 24 28 32 36 38 41 44 45 51 57 63 73 79 86 92 99 108 125 138 160 175
35 28 41 51 57 50 63 70 76 63 89 95 108 121 127 133 140 152 178 190 250 275 290
38 36 44 51 57 60 63 76 76 74 89 101 113 127 133 146 159 171 191 208 210 230 250
16 16 19 22 25 32 28 30 33 38 39 46 53 60 73 76 79 83 89 101 120 140 175
L1 205 212 235 275 306 367.5 338 394 418 440.5 468 552 596 653 696 733 776 844 905 1160 1280 1380 1600
L2
type
70 68 82 95 107 124 119 136 142 150 167 193 219 247 279 298 317 337 369 410 450 510 600
C A C C C A C C C A C C C C C C C C C C C C C
Wire rope sockets F E
C
B
A
D CR-socket dimensions in mm
122
NO
MBL t
522 524 526 527 528 529 530 531 533
250 300 400 500 600 700 800 900 1000
rope dia mm 49 - 54 55 - 60 61 - 68 69 - 75 76 - 80 81 - 86 87 - 93 94 - 102 108 - 115
A
B
C
D
E
215 230 250 280 310 340 360 380 450
125 145 160 175 190 205 220 240 260
55 65 75 80 85 100 105 110 125
57 63 73 79 86 92 99 108 120
115 135 150 165 175 200 205 225 240
Advantages of the CR socket. – Guaranteed high breaking load. – Integrated non rotating stopper system which prevents the tamp from turning or slipping out of the cone. – An open-widow side for easy rope handling. – A high performance connection for the right combination with a detachable link. – No rings in the cone to a give a maximum rope/socket connection. – Impact value of min. 27 Joule at -40˚C. A
B C
X
Y Forged eye socket Dimension A B C X Y
Size 1.7 D According to insulating tube thickness 1.4 D According to wire rope diameter According to wire rope diameter
Note : D is the nominal diameter of the chain that connects to the socket.
F 200 230 270 300 325 350 360 380 420
weight kg 30 46 62 87 110 135 160 208 270
Thimbles
F E K
D C
A
B
main dimensions bellmouth thimble dimensions in mm For wire dia. 10”-12” 15”-16” 18”-21”
A 366 440 454
B 606 746 844
C 277 352 352
D 480 608 660
E 195 248 300
F 166 191 226
K 85 105 118
weight kg 80 125 175
123
H2 H1
A
C X E D
F B
G
main dimensions tubular thimble dimensions in mm For wire dia. 12” 15” 18” 21” 24” 27”
A
B
C
D
E
F
G
H1
H2
X
521 625 727 829 930 1035
420 510 610 740 880 1020
260 312 368 415 465 517
194 194 219 219 273 273
144 144 169 169 201 201
130 150 175 200 225 250
20 25 30 30 30 30
130 158 183 206 229 260
140 168 194 219 245 273
10 40 40 40 40 40
weight kg 50 80 140 180 260 380
Synthetic ropes Material properties
Material Construction Specific gravity of core Melting point Range for use UV resistance Rot / mildew resistance Cold water shrinkage Water absorption fibres Water adhesion Approximate elongation at first loading (broken- in rope, dry and wet condition) At 20% of MBL At 50% of MBL At break
124
Polyester
HMPE
High tenacity polyester Parallel strand with braided jacket ± 1.38 > 250˚C -40˚C - +120˚C Excellent 100% < 0.5% < 0.5% ± 30%
High modulus gel spun polyethylene Parallel strand with braided jacket ± 0.99 (floating) 144˚ / 152˚C -30˚C - +100˚C Conform BS 4928 / BS 5053 100% 0% Nil 45%
± 3% ± 6% ± 12%
± 0.8% ± 2% ± 4%
Production and construction in accordance with BS4928 / BS5053 (1985). The dry breaking strength is equal to the wet breaking strength. The properties of the different rope sizes are presented in the following tables. HMPE Circ. inch 2 21/2 3 31/2 4 41/2 5 51/2 6 61/2 7 71/2 8 81/2 9 91/2 10 11 12 13 14 15 16 17 18 19 20 21
Diameter mm
MBL t
Weight kg/m
16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 88 96 104 112 120 128 136 144 152 160 168
16 25 36 47 62 77 95 115 131 152 174 198 222 248 274 301 330 390 462 530 600 686 777 868 966 1066 1170 1280
0.1 0.2 0.3 0.4 0.5 0.6 0.8 0.9 1.1 1.3 1.5 1.7 2.0 2.2 2.5 2.8 3.1 3.7 4.5 5.1 6.1 7.0 7.9 8.9 10.0 11.2 12.4 13.9
Note : MBL in unspliced (new) conditions, MBL spliced -/- 10%.
Polyester Circ. inch
Diameter mm
MBL t
Weight kg/m
15 17 191/2 201/2 22 23 241/2 251/2 261/2
120 137 156 166 176 186 199 205 213
400 500 600 700 800 900 1000 1100 1200
9.5 13.0 15.8 17.3 19.4 21.7 23.8 26.3 28.3
Note : MBL in spliced condition.
Synthetic ropes Recommended practise for handling fibre rope mooring lines before and during installation. • Ropes should not be permanently installed around bollards or fairleads. • A minimum bending radius should be observed. The minimum bend radius (D/d) with very low line tensions should be larger than 6. • When unreeling the rope, maximum line tension should be observed, to avoid pulling the rope into the underlying layer. Torque or twist in the rope should be avoided. • Fibre ropes should not be run over surfaces which have • sharp edges, grooves, nicks or other abrasive features. • Care should be taken when applying shearing forces to the rope. • There should be no “hot work” such as welding in the vicinity of the rope. • Frictional heat from excessive slippage of the fibre rope over a capstan, drum, etc. must be avoided. • Care should be taken that ropes do not get knotted or tangled. • Rope contact with sharp gritty materials should be avoided. • Abrasion or fouling of the mooring line with other anchoring equipment such as anchor, steel wire rope, chain and connectors must be avoided. • Chasers should not be used on fibre ropes. • Shark jaw stoppers designed for use with steel wire rope or chain should not be used for handling fibre ropes. • It should be avoided that the ropes undergo more than 1000 loadcycles with a line tension smaller than 5% of the MBL. • Pre-deployed lines should not be left buoyed at the surface waiting connection to the platform, unless a minimum line tension of 5% (for polyester) of the MBL is maintained. • If the fibre rope is laid on the seabed, it must be protected against external abrasion and ingress of abrasive particles.
125
Mooring hawsers Double braided nylon
Circular braided nylon
Diameter mm
Ndbs t
Nwbs t
weight kg/m
Ndbs t
Nwbs t
weight kg/m
Ndbs = nwbs t
weight kg/m
12 13 14 15 16 17 18 19 20 21
96 104 112 120 128 136 144 152 160 168
208 249 288 327 368 419 470 521 577 635
198 236 273 311 349 398 446 495 548 603
5.7 6.7 7.8 8.9 10.2 11.4 12.8 14.3 15.8 17.4
205 256 307 358 406 454 501 547 597 644
195 244 292 341 387 433 477 521 569 614
5.0 6.0 7.3 8.4 9.5 10.7 12.0 13.2 14.4 15.7
217 258 297 339 378 423 468 523 578 636
5.7 6.7 7.8 8.9 10.2 11.5 12.8 14.3 15.9 16.9
Specific gravity Melting point
1.14 250˚C
1.14 215˚C
Note : ndbs = new dry break strength in spliced condition nwbs = new wet break strength in spliced condition Deltaflex 2000 in 8 strand plaited construction.
126
Deltaflex 2000
Circ. inch
Approximate elongation at first loading (brokenin rope, dry and wet condition) At 20% of MBL At 50% of MBL At break
Circular braided nylon (double braided is similar)
Deltaflex 2000
± 16% ± 22% ± >40%
± 19% ± 26% ± 33%
1.14 260˚C
Mooring hawsers Double braided construction versus circular braided construction The circular braided construction can be defined as a recent alternative for the double braided construction. The elongation and TCLL values of both construction types are the same. The efficiency (breaking load/raw material) of the circular braided construction is however much higher, which means that the circular braided construction can be more budgetary attractive. Both construction types have an overbraided jacket as part of their construction, but the important difference is that where the overbraiding of the double braided construction is load bearing, the overbraiding of the circular braided construction is just there for protection. This means that when the overbraiding is damaged due to chafing or other reasons, the stability and break load of the circular braided construction will remain unchanged, while the double braided construction should be considered as structurally damaged (loss of stability and a lower break load). Advantages of Deltaflex 2000 When compared to nylon hawsers, a Deltaflex 2000 hawser has the folowing advantages: • Equal strength in dry and wet conditions. • Strength is 10% to 20% higher than wet double braided nylon. • High energy absorption and elastic recovery. • No water absorption. • One of the highest TCLL (thousand cycle load level) values of all sysnthetic ropes.
127
Main dimensions chasers G
G
F
H
G
G
H
H
D
A
D
A
A
B B
C
E D B
E
J-Chaser VA 101
J-Lock Chaser VA 115
E
Permanent Wire Chaser VA 210-213-214-215
G
G
H
H
128 A
A C
C
F
F D B
D B
E
Permanent Chain Chaser VA 102-106-110-112
E
Detachable Chain Chaser VA 107-108-111
main dimensions chasers dimensions in mm Type VA VA VA VA VA VA VA VA VA VA VA VA VA
101 102 106 107 108 110 111 112 115 210 213 214 215
A
B
C
D
E
F
G
H
proofload t
weight kg
2483 1657 1702 1886 1931 1867 1994 2210 2083 2073 1962 2318 2051
1829 1143 1168 1143 1168 1245 1245 1384 1486 1245 1099 1308 1168
991 991 1080 1067 1130 1130 1397 1203 1086 1397 1060
699 762 762 762 762 838 838 953 711 838 692 902 711
305 305 381 305 381 330 330 356 533 432 445 508 445
191 203 191 203 203 203 260 305 330 330 330 356
124 124 130 124 130 130 130 130 124 130 130 130 178
86 86 99 86 99 99 99 99 86 99 99 99 127
250 250 250 250 250 250 250 250 250 250 250 250 400
1882 1088 1451 1238 1656 1433 1742 2064 1778 1959 1846 2530 2495
Main dimensions chasers Note: the VA115 is available in two versions: the VA 115/35 for 21/2” to 31/2” chain and the VA115/45 for 33/4” to 41/2” chain. Restoration of worn chaser profiles. Worn profiles may be restored by application of a weld deposit. Care must be taken to ensure a satisfactory bond between parent material and the weld deposit and to avoid the generation of a brittle structure in the area of repair. The following procedure is recommended: • The area to be welded must be cleaned to a bright metal finish. • Prior to the commencement of welding, the parent material should be pre-heated to 180-200 ˚C and the pre-heat temperature is to be maintained during welding. • The initial layer of weld deposit should be effected by a high nickel electrode such as: Metrode C.I. softlow nickel – N.I.O. 8C.2FE A.W.S. No.A5.15.ENI-CL. • Subsequent layers of welding may be laid using a less noble electrode such as: Metrode CI special cast Ni Fe – FE.55.NI-1.3.C A.W.S. No. A5.15.ENI.FE.CI. • Each successive layer of weld must be cleaned and hammered. • On completion of welding, the built-up zone and surrounding area should be insulation wrapped to permit slow cooling.
129
Stevin Mk3 UHC chart
y
d ar
h
an
nd
sa
um
y
cla
i
ed
m
ry
y
la
tc
f so
ve
130
typical Ultimate Holding Capacity (UHC) in t
d
cla
Ultimate Holding Capacity The prediction lines above represent the equation UHC= A*(W)0.92 with UHC as the Ultimate Holding Capacity in tonnes and A a parameter depending on soil, anchor and anchor line with values between 16 and 31.
Stevin Mk3 size in t
The Stevin Mk3 design line very soft clay represent soils such as very soft clays (mud), and loose and weak silts. The line is applicable in soil that can be described by an undrained shear strength of 4 kPa at the surface increasing by 1.5 kPa per meter depth or in the equation Su = 4+1.5*z. with Su in kPa and z being the depth in meters below seabed. In very soft soils the optimum fluke/shank angle is typically 50 deg.
The design line sand represents competent soils, such as medium dense sands and stiff to hard clays and is based on a silica sand of medium density. In sand and hard clay the optimal fluke/shank angle is 32°. The medium clay design line represents soils such as silt and firm to stiff clays. The fluke/shank angle should be set at 32° for optimal performance.
Stevin Mk3 drag and penetration chart
g
ery in v
dra
soft
clay
lay
mc
ediu
nm ag i
nd
in sa
drag
tion
etra
pen
soft
ery in v
ium
ion
t etra
pen
ion trat
ed in m
clay
clay
and
in s
e pen
Stevin Mk3 size in t
drag
penetration
anchor load as % of UHC 70 60 50 40 30
drag % max drag 48 37 27 18 9
penetration as % max penetration 80 68 55 42 23
Example: loading 70% of ultimate holding capacity corresponds with 48% of maximum drag and 80% of maximum penetration at ultimate holding capacity.
typical drag and penetration in meters anchor loaded to ultimate holding capacity (UHC)
dr
131
Stevpris Mk5 UHC chart
y
rd
d an
nd
sa
um
cla
ha
y
cla
i
ed
m
ry
y
la
tc
f so
typical Ultimate Holding Capacity (UHC) in t
ve
132
Ultimate Holding Capacity The prediction lines above represent the equation UHC= A*(W)0.92 with UHC as the Ultimate Holding Capacity in tonnes and A a parameter depending on soil, anchor and anchor line with values between 24 and 110.
Stevpris Mk5 size in t
The Stevpris Mk5 design line very soft clay represent soils such as very soft clays (mud), and loose and weak silts. The line is applicable in soil that can be described by an undrained shear strength of 4 kPa at the surface increasing by 1.5 kPa per meter depth or in the equation Su = 4+1.5*z. with Su in kPa and z being the depth in meters below seabed. In very soft soils the optimum fluke/shank angle is typically 50 deg.
The design line sand represents competent soils, such as medium dense sands and stiff to hard clays and is based on a silica sand of medium density. In sand and hard clay the optimal fluke/shank angle is 32°. The medium clay design line represents soils such as silt and firm to stiff clays. The fluke/shank angle should be set at 32° for optimal performance.
Stevpris Mk5 drag and penetration chart
ay
ft cl
ry so n ve
i
ium
drag
ed in m
in sa
drag
nd nd a
tion
etra
pen
clay
hard
ry in ve
clay
soft
clay
ay
m cl
ion trat
in
iu med
in
an sand
e pen
tion
etra
pen
lay
rd c
d ha
Stevpris Mk5 size in t
drag
penetration
anchor load as % of UHC 70 60 50 40 30
drag % max drag 48 37 27 18 9
penetration as % max penetration 80 68 55 42 23
Example: loading 70% of ultimate holding capacity corresponds with 48% of maximum drag and 80% of maximum penetration at ultimate holding capacity.
typical drag and penetration in meters anchor loaded to ultimate holding capacity (UHC)
drag
133
Stevmanta VLA UPC chart 2000
600
1800
134
500 1400
400
1200
1000 300 800
C 200
600
typical installation load in t
typical UPC - Ultimate Pull-out Capacity in t
1600
400 100
B
200
A 0
0 5
0
10
15
20
25
30
Stevmanta Fluke Area (m2) Mooring lines in diameters; A
ø 76 mm
B
ø 121 mm
C
Six strand & spiral strand
ø 151 mm Spiral strand
Typical Ultimate Pull-out Capacity (UPC) The prediction lines on the “UPC chart” can be expressed in the equations as stated below:
D
= 1.5 *k0.6 *d-0.7 *A0.3 *tan1.7 (α)
where, D = Stevmanta penetration depth [m] k = quotient Undrained Shear Strength clay [kPA] and depth [m] d = mooring line or installation line diameter [m] A = Stevmanta fluke area [m2] α = Stevmanta fluke / shank angle [deg]
UPC = Nc *Su *A where, UPC = Nc = Su = A =
Ultimate Pull-out Capacity [kN] Bearing Capacity Factor (k *D), Undrained Shear Strength clay [kPa] Stevmanta fluke area [m2]
The UPC graph incorporates a Nc- value of 10, α-value of 50 degrees and k-value of 2. The graph clearly illustrates the influence of the diameter of the mooring line or installation line, and whether six strand or spiral strand is used. The typical installation load to obtain a specified UPC is presented on the right vertical axis of the graph.
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Introduction The forces acting upon a ship determine her movement. Some of these forces are controllable and some are not. Some of them can we measure and some we can not. The ship is subjected to the forces from the wind, waves and current and in shallow water and narrow waterways by the interaction from the bottom, banks or sides of the channel. Close approach to other vessels generates intership action, and wash from propellers/thrusters from another vessel will also affect our ship. Some of these forces will vary in size depending on the speed of our, or the other ship, whereas other forces are affecting us all the time. Forces from pulling an anchor-wire-towing-cable etc, is also an important factor. This chapter will explain some basis knowledge to Ship handling and Manoeuvring theory but the most important factor in Ship handling is experience. It is therefore essential that navigators do practice handling of their ship when there are a chance to do so. Propulsion system Most vessels do have diesel engines, which through a gear rotate the aft propeller, and an electrical power system generation power to the thrusters. But some special vessels can have a system with electrical propellers/thrusters, and maybe only having azimuth thrusters whiteout any rudders. Depending on the layout of your propellers/thrusters/rudders the ship handling can be quite different from one ship type to another. A continued research and development is taking place within the maritime technology and new engines, propeller and rudder types are invented every year. This chapter will therefore concentrate on some basis knowledge regarding propellers and rudders.
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Propellers A propeller can be a fixed propeller, which mean that the propeller blades are fixed, which again mean that changing from ahead and astern can only be done by stopping the rotation and then rotate the propeller the opposite way. In our business we use propellers with variable pitch, where the propeller blades can turn, changing the pitch. From neutral where the propeller is rotating but without moving any water, to full pitch ahead or astern. The variable pitch propeller will always rotate and can very fast go from full ahead to full astern. If we look at the propeller seen from the aft and the propeller rotate clockwise when sailing ahead we call it a right-handed propeller and left-handed if rotating anti clockwise. When the propeller rotate and special when we do not make any headway water flow to the propeller are less compared to when making headway. The water pressure on the top blades is lower compared with the blades in their lower position. The lower blades will therefore have a better grip, and a right-handed propeller going ahead will push the stern towards starboard (ship’s heading turning port). With a variable pitch propeller the propeller is always turning the same way and the movement of the stern will always be to port (rotation clockwise) whether we are going ahead or astern. If we place the propeller inside a nozzle we eliminate this force and direct the water flow from the propeller in one direction. The direction of the trust is determined by the direction of the water flow and by the direction the water flow pass the rudder. Thrusters Thrusters are propellers placed inside a tunnel in the ship or outside as an azimuth thruster. The tunnel thruster can push the ship in two directions whereas the azimuth thruster can rotate and apply force in all 360°. Most thrusters are constructed with an electrical motor inside the ship with a vertical shaft down to a gear in the thruster, which again rotate the propeller blades. All thrusters do have variable pitch propellers. Be aware of that your azimuth thruster can give full thrust in one direction and 15 -20 % less thrust in the opposite direction (because of the big gearbox). And also remember that high speed through the water can empty the tunnel from water, and overheat the gear, if used. Turbulence and air in the water can during powerful astern manoeuvre also result in air in the stern thruster.
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Rudders The rudder is a passive steering system, which only can work if water is passing the rudder. The rudder is constructed like a wing on a plane, wide in the front and slim aft. When turning the rudder the flow of water will on the backside create a low pressure and on the front a high pressure. The low pressure or suction creates 75% of the turning force, whereas the high-pressure side only 25%. That is why a traditional rudder looses steering moment when turned more than 40-50 degrees. With high angles there will be turbulence on the backside killing the suction force. The Becker rudder is constructed as a normal rudder, but with an extra small rudder flap on the edge. This flap turn twice the angle of the rudder, and the water on the high-pressure side will be directed more or less side wards creating big side wards thrust. The Schilling rudder has a rotating cylinder built into the front of the rudder, rotating in a direction moving water towards the backside of the rudder. A Shiller rudder can therefore turn up to 70 degree. The Jastram rudder is an asymmetric constructed rudder designed special for the particular ship and propeller, and can also turn up to 70 degree. If water do not pass the rudder, the rudder do not have any affect, which many navigators know from their experience with variable pitch propellers. When the pitch is placed in neutral the rotating propeller stops the water flow, and the rudder can not be used. When the propellers are going astern, the water passing the rudder is poor, and the effect from the rudder is very low. But with a high speed astern the rudder will help, as there will be water passing the rudder.
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Manoeuvring When talking about manoeuvring our ship, we need to look at how the ship is responding to different forces, and what happen when we apply forces as well. A ship lying still in the water is exposed to forces from the current and wind. Swell and waves do not move the ship, but close to an offshore installation, swell and waves can push us into or away from the installation. Current The current moves the water we sail in and the ship will be set in the same direction and with the same speed as well. We can calculate the force depending on the angle the current attacking the ship, where current abeam can be very high, special with water depth lower than twice the draft. Turning a ship (80m long draft 8 meter) on a river with 2 knots current and water depth of 12 meter will when the ship is across the river give a force of 60 tons. If we have a lot of water below the keel the force will be 21 tons in above example, but when the water depth are lower the force will increase rapidly, and with only 2 meter below the keel the force will be 78 tons; a significant force. Wind We can do the same calculation with the wind, but the force from the wind moving the supply ship is not a considerable force, where big containerships, car-carriers, bulkers and tankers in ballast have to do their wind calculations. The problem with wind in our business is the turning moment created by the wind. With our big wind area in the front of the ship and none in the aft, the ship will turn up in the wind or away from the wind, depending on the shape of the hull and accommodation and the direction of the wind. We can however use the force from the current and wind in an active way. Instead of fighting against the force, turn the ship and use the current or wind to keep you steady in a position or on a steady heading. When operating close to FPSO, drill ships or other installations with a big underwater shape or hull, this can result in different forces and direction of the current and wind compared to observations done just 10 meters away. Other forces Forces between two ships passing each other can also be a considerable affect special if the speed is high. In front of a ship steaming ahead there is an overpressure, and along the sides a low pressure. If a big ship pass us this pressure system can move or turn our ship, and if the big ship do have a high speed (30 knots) you can feel that effect up to ½ mile away.
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Turning point (Pivot point) When a ship is stopped in the water and we use our thrusters to turn the ship, it will normally turn around the Centre of the ship, depending on the underwater shape of the hull. When sailing this point will move ahead and the ship will turn around the Pivot point now approximately 1/3 to 1/6 from the front. Our bow thruster will therefore loose some of the turning moment as it must now move the hole ship in the desired direction, whereas the stern thruster, and also the rudders, do have a long arm and thereby giving a big turning moment of the stern of the ship. It will be the opposite when going astern, the pivot point moving aft and in this case our bow thruster having a long arm and a very big moment. The Pivot point must not be confused with the turning point we can choose on our Joystick; this is a computer-calculated turning point. But think about it, when you next time have chosen turning point aft and you are sailing ahead with 5 knots and the ship seems reluctant in retrieving a high turning rate. Forces from cable lying, wire/chain from tow and anchor handling, special if there is a big force in the system, will also have a significant effect on our ship. Some times it can be very difficult to turn a ship as the Pivot point can move outside the ship. As the pull from these systems mostly is very big, we need to use high engine/thruster power to obtain the desired movement. Ship handling With a basis knowledge of the different forces acting on our ship. Special whether it is a big or a small force, knowledge of how our propellers, rudders and thrusters are working and how the ship react on above, we can gain a better and quicker experience in ship handling of the particular ship we are on right now. You will see experienced navigators using split-rudder, where one rudder have one angle and the other rudder having another angle. Going for and back on the engine you can control the aft end of the shipside wards without moving ahead or astern. But again other navigators will get the same result by using the rudders in parallel drive and turn the rudders from side to side, and still use the engine to control the movement side wards and ahead or astern. The best way is like mentioned in the beginning of this chapter, to practice manoeuvring of your particular ship, using the information mentioned in this chapter.
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General layout Jack-Up drilling unit: A Jack-up drilling unit is designed for drilling in water depth up to 150 metres. A jack-up is standing on 3 legs, each leg ending in a footing; these footings are called spud cans. The derrick is normally situated on a cantilever, in drilling position the cantilever is skidded out so the derrick is extracted over the rig’s stern. The Blow Out Preventer (BOP) is placed under the rig floor, the tubular from the BOP to seabed is called the conductor pipe. At production platforms a Jack-up is placed very close to the platform and the cantilever is skidded over the platform. Before rig move, the rig has to be prepared for towing, all pipe from the derrick are laid down on deck and secured. Risers and BOP is retrieved and secured. Watertight integrity is checked, and the cantilever skidded in, flush with aft end of rig and secured. Deck cargo secured, cranes laid down and secured. Stability is calculated, ballast distributed for the rig to float at even keel, in this situation the rig will not accept cargo handling, as the calculations are done, and cargo secured on deck. Weather conditions for rig move of jack-up rigs are normally 15-20 knots of wind, sea/swell less than 1.5 metres, weather window more than 24 hours. A tow master is normally in charge of operations. A rig move starts with jacking down to 2 metre draft and checking for watertight condition. All overboard valves are checked for leaks. At this same time one or more boats for towing will be connected to the tow bridle. Then the rig is jacked down to calculated draft, boats ordered to pull minimum power. Due to the considerable size of spud cans, the rig will jack further down to break suction of the spud cans. This is called freeing legs and can take hours depending of the amount penetration of spud cans into the seabed. When the rig float free, the legs are jacked up, flush with bottom of hull and the tow begins. During the tow a jack-up rig afloat is very sensible to roll and pitch period, the long legs can cause a whipping effect, and therefore the roll and pitch period has to be more than 10 seconds. Severe rolling with short rolling period will cause structural damage at jacking houses and is known to have caused loss of rigs. In the rigs operational manual limits for roll and pitch are given. At the new location the rig will lower legs and tag bottom, jack the hull free of the water and preload. Preloading takes several hours and is a process where the rig is ballasted corresponding to maximum environmental conditions, normally a 100 years wind condition. Again operational manual will give the precise procedure. During preload no cargo operations are allowed to take place.
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When preload is completed, tugs are released and the rig jacked to working air gap, and the cantilever skidded out. Now drilling and cargo operations can begin. A Jack-up drilling rig is fitted with an anchoring system consisting of 4 anchors. These anchors are light anchors, connected to wire of diameters less than 3”. In some cases anchor handling will take place with jack ups. The jack-up will jack down close to location, run out anchors, and use the anchor system to move in close to platforms or sub sea production well heads. The tugs will be connected up, but will only use little or no power. To receive anchors, the A/HV will move close to the rig, and the rig’s crane will first lower the anchor buoy and pennant wire, and then lower the anchor to the deck. The anchor is then run out to position, lowered in the pennant wire, pennant wire connected to anchor buoy, then the buoy is launched. To retrieve the anchor, the AHV will move in stern to the buoy, catch the buoy, disconnect the pennant wire from the buoy, connect work wire to pennant wire, then break the anchor loose of seabed, take anchor on deck, return the anchor, buoy and pennant to the rig.
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General information about a Semi Submersible drilling unit: A semi submersible-drilling unit (semi) is designed to drill at water depth more than 100 metres. A semi is floating on stability columns and has low GMT, and therefore a slow rolling period. This makes the semi an acceptable working platform as regards to crane operation etc. Generally a semi is anchored in a mooring spread of 8 anchors, 30/60 degrees; another number of anchor is used, but not very often. Heading into the prevailing weather. Forward end is defined with heli-deck and accommodations. On rigs with 8 anchors, the anchors are numbered clockwise with anchor no.1 forward starboard. The BOP is placed on the seabed, connecting with risers up to the rig. Between BOP and riser a flexible joint is installed. The purpose for a flex joint is to allow some movement of the rig due to the elasticity of the mooring spread. At 90 metres this elasticity is greater than the flexibility of the flex joint, this is therefore a critical depth. A riser angle of up to 10 degree from vertical is maximum allowable. In case of severe weather, where the riser angle increases to maximum allowable the rig can disconnect from the BOP, and connect when the weather improves. At sea level a slip joint is installed in the riser system. The purpose of a slip joint is to allow the rig to heave. At the slip joint the riser tensioning system keeps tension on the riser, this is to carry the weight of the riser. Slip joints has a stroke of 50 feet. Just under the rig floor a ball joint is installed. The purpose of a ball joint is to allow the rig to roll and pitch. The last component here to be mentioned is the drill string compensator. This purpose of a compensator is to allow the rig to heave and still keep the same weight on the drill string; the motion compensator has a stroke of 20 feet. To prepare a semi for tow, pipe is paid down on deck and secured, deck cargo is secured. The last operations before a rig move is to retrieve the risers and the BOP, secure these items on deck, and de-ballast the rig to transit draft. At transit draft the bolsters are visible. Sequences for retrieving anchors are given in the procedure for rig move. Breast anchors, which are number 2,3,6,7, are retrieved first, then a tug is made fast to the tow bridle, and then the last anchors can be retrieved. During the tow the rig has a good stability, and can endure severe weather. In some weather conditions the rig will ballast to survival draft.
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At the new location the sequence will be to run anchors (no 4 &5) first, then anchors no 1 and 8, disconnect vessel from tow bridle, then run breast anchors. When all anchors are run and confirmed in the correct position (bearing and distance from rig) the anchors will pre-tensioned to an agreed load, corresponding to 100 years weather condition. In some cases the combination seabed and anchor system cannot hold the pre-tensioning. In that case piggyback anchor will be set. Piggyback are anchors in tandem. Anchor spread can extent far from the semi, with piggyback anchors the distance to the rig can be 2 miles.
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