Hand-out Rigging Design for Offshore Heavy Lifting Leefmans

HAND-OUT Of the seminar titled

'RIGGING DESIGN for offshore heavy lifting' By W. Leefmans

Held on 7 February 2014 at the Offshore Independents Office Capelle aan den IJssel, Holland

RIGGING DESIGN for offshore heavy lifting

A SEMINAR AT THE ‘OFFSHORE INDEPENDENTS’ OFFICE Capelle aan den IJssel

W. Leefmans

SEMINAR CHAPTERS 1. 2.

3. 4. 5. 6.

CHAPTER 1 INTRODUCTION

CREATING OFFSHORE STRUCTURES 1. 2. 3.

The environment of offshore heavy lifting

An introduction to the art * Road-map from ‘dry weight’ to the ‘hook load’ * Rigging components * The rigging arrangement * The tilt attitude (*) Spreaders (*)

4. 5. 6.

Initiative, studies & engineering Procurement, fabrication & testing Transportation to the field Installation; this includes heavy lifting * Hook-up Commissioning

1

RULES, CRITERIA & GUIDELINES BY:

LIFT OPERATIONS A crane vessel is required * Minor lifts Heavy lifts (dry wt ≥ 50 t) * Pre-rigging at fabricator’s The lift-off * Up-ending a jacket * Setting the module * Many authorities are involved *

1. 2. 3. 4. 5. 6. 7. 8.

CLIENT’S CRITERIA 1. 2. 3. 4. 5. 6. 7.

Safety, timing, environment The best quality for their money Jacket’s location & orientation Jacket’s elevation Jacket’s out-of-levelness Deck elevation Boat-landing elevation

1. 2. 3. 4. 5. 6. 7.

INSURANCE COMPANIES „

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Assume their client’s risks against a premium Risk needs to be classed to assess the premium They rely on the competence of marine warranty surveyors to assess the risk class *

MARINE WARRANTY SURVEYORS (MWS) „ „

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Independent third party Assess and warrant that heavy lifting is kept in the recognized risk class Publish guidelines Verify design criteria Review documents Survey during construction & installation Approvals Etc

Client or ‘Company’ * Marine warranty surveyor * Classification society * Heavy lift contractor * IMCA, API, ISO, etc Others (host country) Design Brief (or Design Basis) *

CLASSIFICATION SOCIETY „ „ „ „ „ „ „ „

Independent third party Core business: class vessels, etc. Sets rules for: steel wire ropes, spreader beams, sister plates, etc. Publish rules Verifies design criteria Document review Survey during construction Etc.

2

HEAVY LIFT CONTRACTOR

DESIGN BRIEF (A basis of understanding) „ „

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Have set standard engineering procedures To solve things the practical way Standards may be issued with their proposal

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Agreed by client, MWS and contractor List of reference documents, by client, warranty surveyors List of standards and codes Weights, COG positions & envelopes * Load spread method * Allowable stress in steel plate parts Dynamic amplification factor (DAF) * Skew load and consequence factors *

VESSEL MOTIONS

CRANE VESSELS „ „ „ „ „ „

Mono-hull types and semi-subs * Main hoist cap. varies from 500 t to 7100 t Vessel is kept stationary during the lift Mooring by anchors Dynamic positioning Operating & stand-off positions; leeward of the target

BALLASTING „ „ „ „ „ „

Changes draught, trim and heel Ballast system includes: tanks, pipelines, pumps, valves & control system ‘Ballasting’, ‘de-ballasting’ & ‘cross filling’ Tanks are either ‘pressed’, ‘slack’ or ‘stripped’ Ballast engineer is in charge for the ballast scenario Pumps run during extreme lifts

Roll: rotations about longitudinal axis Surge: translations along longitudinal axis Pitch: rotations about transversal axis Sway: translations along transversal axis Yaw: rotations about vertical axis Heave: translations along vertical axis Hook motions: we assume but ‘heave’ & ‘horizontal motions’

HLV ‘STANISLAV YUDIN’ „ „ „ „ „ „ „

Monohull vessel Length over all: 185.00 m Breadth: 42.00 m Depth: 12.30 m Operations draught: 7.00 m Main hoist cap. 2500 t at 37.5 m Auxiliary: 500 t

3

HLV ‘THIALF’ „ „ „ „ „ „ „

Semi-sub vessel Length over all: 202.00 m Breadth: 97.00 m Depth: 49.50 m Operations draught: 26.60 m Main hoist cap. 7100 t at 43.00 m Auxiliary: 907 t

FEATURES OF OIL PLATFORMS „ „ „ „ „ „

Installed for an extended period of time In shallow water Location & orientation specified ‘Platform North’ definition Northing & easting >> grid Lowest astronomical tide (LAT) is datum elevation

CRANE MAIN FEATURES 1. 2. 3. 4. 5. 6. 7.

Hoists capacities (fixed figure) Hook lift capacity vs. hook radius * Built-in 10% DAF in the curves Weather limitations Hook elevation vs. hook radius (for vessel at operating draught) * Design hook elevation: deduct 3.00 m The lighter of the two hooks to be applied

TYPICAL MODULES „ „ „ „ „ „ „ „

Jackets * Piles Spacer frames Decks * Box-shaped modules * Bridges * Skids * Towers

JACKET INSTALLATION Transporting method is dictated by the jacket size 1. S : vertical transportation & ditto lift-off 2. M: horizontal transp. & dry up-ending * 3. L : horizontal transp. & wet up-ending * 4. XL: launched jackets & wet up-ending * 5. Setting or docking the jacket

END OF CHAPTER 1 (INTRODUCTION)

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THE ROUTES FOR THE RIGGING DESIGN

CHAPTER 2 THE ROAD-MAP The routes for the design

Main route: From ‘dry weight’ (plus COG position) to the ‘lift weight’ * „ Byway #1: 3 hook load checks * „ Byway #2: verify hook height * „ Byway #3: make tilt prognosis (*) „

DESIGN INPUT

OPTIMUM DESIGN

It is a wee bit of an art A bit more of a science „ Most of all, it is using the common sense

The module’s ‘dry weight’ & the location of its COG * „ Physical limitations „ Available equipment „ Rules, regulations, specifications codes, standards & ‘Design brief’

DESIGN RESULTS

LIFTING AND SAFETY

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What it takes to produce the optimum rigging design: „ „

Applied rules, regulations, codes, specifications, standards & ’Design brief’. „ Dry weight & COG envelope * „ Design wt, lift wt & hook loads * „ Physical limitations made clear „ Design analyses „ Rigging arrangement * & MTO „

We need safety for comfort and assurance, for a low level of risk „ Risk is the probability of a hazard to occur and the consequences „ A hazard could cause harm „ Harm is an undesired event, causing injury, lost of lives, damage, pollution, etc. „

1

ASSESSING SAFETY First we need to define and understand what safety is „ We then assess the safety level for the case, if we can „ Safety is opposite to risk „ So, if one can not assess the safety level, maybe assessing the risk level is possible „

2

The risk assessment matrix: Probability of hazards Likely Reasonably probable Unlikely Remote Extremely remote Theoretically possible

Minor 2 1 0 0 0 0

Consequences CatasSevere Fatal trophic 3 3 3 2 3 3 1 2 3 0 1 2 0 0 1 0 0 0

Disastrous 3 3 3 3 2 1

Offshore heavy lifting

Where the classification of risk can be expressed as: 3 2 1 0

Intolerable risk area. Border area. Tolerable risk area. Low risks area.

The definitions for the level of consequences: Minor Severe (heavy lifting) Fatal (heavy lifting) Catastrophic Disastrous

For an event that causes local damage to the unit or light injuries to personnel. For an event that causes large damage to the unit or serious personnel injuries. For an event threatening the integrity of the unit or causes fatalities. For an event that causes loss of the unit and/or a number of fatalities. For an event that causes loss of the unit and/or a very large number of fatalities.

BUILT-IN REDUNDANCY TO PREVENT A FAILURE „ „ „ „ „

THE PARTIAL COEFFICIENT METHOD

A safety factor is needed for comfort & assurance Factor must cover uncertainties Factor must cover inaccuracies One ‘overall safety factor’ is not appropriate for heavy lifting The ‘partial coefficient method’ is applied *

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Weight factors * Load factors * Safety factor * Factors for structural resistance * This method gives transparency and every factor can be re-calibrated separately

APPLY FACTORS IN THEIR OWN CONTEXT

WEIGHT DEFINITIONS

The product of the ‘partial coefficients’ form the ‘aggregate coefficient’ of the individual system „ One should not go ‘shopping’ for factors

Weight definitions describe the condition with more precision: „ Budget weight (in the contract) „ Dry weights (3 definitions) * „ Design weight * „ Lift weight (i.e. a dynamic load) *

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THREE DRY WEIGHT DEFINITIONS 1.

2.

3.

Dry weight by the fabricators: the bear object for its end-purpose Dry weight for the lift (= #1 + installation aids) * Dry weight for transportation = load-out weight (= #2 + rigging)

DRY WEIGHT ASSESSMENT METHODS 1.

2. 3. 4. 5.

Conceptual stage estimate: initial assessment * Weight control procedure Weight control report MTO (material take-off) used * Weighing the module: final assessment (i.e. ‘the as-weighed weight’)

1

WEIGHT GROWTH FACTORS (to achieve ‘design weight’)

DESIGN WEIGHT DEFINITION „

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Should be made equal to the presumed tolerance of the applied weight assessment method „ Conceptual stage >> 1.25 „ MTO >> 1.10 (structural) & 1.20 (remaining) „ Weighed weight >> 1.03

‘Dry weight’ without any error would do, as being the ‘design weight’; not a realistic option ‘Design weight’ = ‘dry weight’ x ‘weight growth factor’ * Some authorities prefer to work with ‘weight growth allowance’ (+25%), rather than a factor (x1.25)

WEIGHT BUDGET FOR THE RIGGING „ „

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The rigging load includes the weight of rigging itself Rigging weight budget = 3% to 5% of the module’s ‘design weight’ (for simple riggings) ‘Final rigging MTO’ needs to be ≤ ‘budget weight’ Take a closer look at complex arrangements or the longer legs

‘LIFT WEIGHT’ DEFINITION Is a dynamic load ‘Lift weight’ = ‘design wt’ X DAF DAF = dynamic amplification factor DAF varies with the load class of the module *

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D.A.F. PRESUMPTIONS

D.A.F. VARIES WITH THE WEIGHT CLASS Lift by mono-hull vessels offshore: Design wt < 100 t: 100 t – 1000 t

DAF 1.30 1.20

1000 t – 2500 t

1.15

> 2500 t

1.10

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Rigging weight is not factored by DAF DAF maximum to occur during the actual lift-off. Lift-off is rather a ‘smooth ride’ than a ‘jerk’ or a ‘snatch’ load *

2

A 2000 T LIFT-OFF BY ‘STANISLAV YUDIN’

IMPACT DURING LIFT-OFF IS REDUCED, DUE TO: „ „

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Cargo barge emerging Crane vessel immerging, while trim & heel change Rigging legs elongating Hoist wire ropes elongating Elastic deformation of crane parts

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A 200 T LIFT-OFF BY ‘STANISLAV YUDIN’ „ „ „ „ „ „ „

DAF for this load class, to be 1.15 Cargo barge emerging 0.75 m (Barge 91 m x 30 m) Hook drops due to immersion 0.27 m Hook drops due to trim 0.23 m Hook drops due to heel 0.40 m Miscellaneous 0.15 m Total travel of hook 1.80 m

3 HOOK LOAD DEFINITIONS

DAF for this load class, to be 1.20 Cargo barge will emerge 0.08 m (Barge 91 m x 30 m) Hook drops due to immersion 0.03 m Hook drops due to trim 0.02 m Hook drops due to heel 0.04 m Miscellaneous 0.01 m Total travel of hook 0.18 m

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WHEN THE DYNAMIC HOOK LOAD NEEDS TO BE VERIFIED

‘Dry hook load’ = ‘dry wt’ + rigging. (For ballast scenarios, etc.) ‘Static hook load’ = ‘design weight’ + rigging wt. (against hook curve) * ‘Dynamic hook load’ = ‘lift weight’ + rigging wt. (against hook curve +10%) *

HOOK HEIGHT CHECK

Module design weight = 2213 t; Rigging = 100 t Static hook load = 2213 t + 100 t =2313 t Static lift capacity of hook = 2400 t Equation for static is OK (2313t2640t) This lift can NOT be performed.

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3

‘Actual hook height’ at the required hook radius (above operating draught) Deduct 3.00 m, to achieve the ‘design hook height’ (safety margin) Module bottom at least 3.00 m above target Can the module be installed, while sea level is down to LAT? 1

3

END OF CHAPTER 2 (THE ROAD-MAP)

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RIGGING COMPONENTS

CHAPTER 3

1. 2. 3.

TENSILE RIGGING COMPONENTS

4. 5. 6.

FEATURES OF RIGGING COMPONENTS

STEEL WIRE ROPES „

Effective length „ Load capacity „ Stability „ Reliability

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Diameter (d) defines the size Applied in heavy lifting for their flexibility and elasticity. There are two types of wire rope construction : Standard steel wire ropes (up to Ø100 Ø150 mm) * Cable laid ropes (Ø76 mm – Ø600 mm) *

STEEL WIRE ROPE COMPONENTS

STANDARD STEEL WIRE ROPES Lay direction (or ‘twist’) (important feature when making strings) * „ Ordinary lay and Lang’s lay * „ Lay length (L) * „ Lay factor (modulus = L/d) *

Slings * Grommets * Shackles * Sister plates * Bobbins * Spreader elements (*)

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1.

2.

3.

Slings made out of standard steel wire ropes (up to say 150 mm diam.) * Slings made out of cable laid ropes (from 90 mm diam. and up)* Grommets are all made out of cable laid ropes *

1

DESIGN LOADS AND RESISTANCE FACTORS

SLING PARTICULARS „ „ „ „ „ „ „ „ „

EXAMPLE RESISTANCE FACTORS 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

1.

CRBL (= CSBL/Es) Splice efficiency (= Es = 0.75) CSBL (= WLL x Fs) Safety factor (= Fs = 2.25) Workload limit (= WLL) Bearing length Minimum lengths Length tolerances De-rating the WLL for bend *

Sling design load = 147 t Sling ‘work load limit’ to be at least 147 t Minimum CSBL = 147 t x 2.25 = 331 t To be a swaged spliced sling (Es =0.95) CRBL = 331 t/ 0.95 = 348 t Rope ф80 mm chosen: CRBL = 411 t Thence: actual CSBL = 411 t * 0.95 = 390 t Safety factor for heavy lifting = 2.25 WLL = 390 t/ 2.25 = 173 t UC = 147/173 = 0.85 UC is OK

GROMMET’S RATING

2. 3.

4.

5. 6.

LOAD SPREAD OVER TWO PARTS OF THE LEG „

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For a connecting pin that can rotate without friction, the load spread over the parts would be exactly 50%+50% of the leg load. However, pins are fixed bodies The industry assumes a 10% friction for a wire rope at the bend over the bearing area. The extreme load spread over 2 parts then is: 45%+55% Assumed load maximum is 55% in either one of the two standing parts The load spread factor applied then is: 55%/50% = 1.10

GROMMET’S LOAD CAPACITY (worked example) 1.

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Splice efficiency (assumed) = 1.00 CGBL : 12 x ‘strand’s CRBL’ x ‘spinning loss factor’ * 45%+55% load spread over 2 parts De-rate the rope, related to the smaller of the two ‘pin’ radii.

Component’s design load = L Safety factor for heavy lifting = Fs Required minimum sling breaking load = CSBLr = Fs x L Actual minimum breaking load = CSBL (figure from data-base or supplier) WLL = CSBL / Fs ‘Unity check’ = UC = L / WLL

2. 3. 4. 5. 6. 7. 8. 9.

Rope for core and strands Ø = 32 mm Cabled rope Ø = 3 x 32 mm = 96 mm CRBL of the strand ropes = 65.8 t Spinning loss factor = 0.85 CGBL = 12 x 65.8 t x 0.85 = 671 t Nominal WLL = 671 t/2.25 = 298 t Bend efficiency (where D/d = 2.0) = 0.64 Load spread factor = 55%/50% = 1.10 De-rated WLL = 298 x 0.64/1.10 = 173 t

1

GROMMET LENGTH SPECIFICATIONS

GROMMET’S LENGTH DEFINITION 1. 2.

3.

4. 5.

Peripheral length * Nominal bearing length (this is specified on the purchase order) * Applied bearing length (for the conditions of the arrangement) * Length tolerances for individual units Length tolerances for ‘a pair of matched lengths’

Ln

D Lp = ΠD = peripheral length

UNITY CHECK (UC) ANALYSIS Leg design load = 200 t (given) „ Max load in either part = 0.55 x 200t = 110t „ ‘De-rated CSBL’ = 280 t (above slide) „ WLL = 280 t / 2.25 = 124 t „ UC = 110/124 = 0.89

Ln = ‘nominal’ or measured length

La = applied length

DE-RATING A SLING (worked example)

DOUBLE USE SLINGS De-rating the WLL : „ 45% + 55% load spread due to friction at bearing area * „ Factor due to bending* „ Bend efficiency is separate from splice efficiency

La

Bend efficiency is separate from splice efficiency „ CRBL = 400 t (given) „ Splice efficiency = 0.75 (hand splices) „ CSBL = 400 t x 0.75 = 300 t „ Sling doubled > D/d = 2.8 „ Bend efficiency = 0.70 (from diagram) „ ‘De-rated CSBL’ = 400 t x 0.70 = 280 t „

EUROPEAN STANDARDS FOR WIRE ROPE COMPONENTS „

EN 13414-3 (standard in EU member states)

„

Rope Diameter < 60 mm

Coefficient of utilization 5

60 150 mm

3

2

ORDERING NEW SLINGS „ „ „ „ „ „ „

THE SHACKLE

CSBL Diameter (indicative) Nominal bearing length Length of the eyes (In offshore heavy lifting, eyes are of equal lengths) Specify the splice type Standard wire ropes may be ‘swaged spliced’ Cabled ropes may have resin cast splices

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The least complex of all rigging components Suppliers: Green Pin, Le-Béon, Crosby. Specified by its brand, series and load rating: (E.g.: Green Pin, Series P-6036, WLL = 400 t) Standard and ‘Wide body’ shackles * Keep the proper play: radial and axial De-rating for side loads: 70% at 45°; 50% at 90° *

THE BOBBIN „

LIFT POINTS

Increases the radius of the bend in the rope and so improves bend efficiency

Padeyes * „ Padears „ Trunnions (= twin barrels) „ Consequence factor „ Design lift point load „ Orientation & leg angle „ Misalignment „

made out of heavy wall tubing

bobbin pin

4

3

LAMELLAR TEARING „ „

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END OF CHAPTER 3

Defect in rolled steel plating Below welded joints with high stress concentration. Due to poor ‘through–thickness-ductility Z-quality steel plating shall be applied

Load

defect

(TENSILE RIGGING COMPONENTS) 1

3

THE RIGGING ARRANGEMENT

CHAPTER 4

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THE RIGGING ARRANGEMENT

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Simple arrangements: 2, 3 or 4 legs Complex arrangements: spreader components applied ‘Proper fit’ and ‘best fit’ arrangement Data base for rope components MTO Verify if MTO wt ≤ wt. budget

LOAD SPREAD OVER THE LIFT POINTS

A PARADE OF RIGGING ARRANGEMENTS

LIFT POINT LOAD 1 Assess the ‘lift point load’ by: „ ‘Vertical lift point force’ „ Leg angle „ Skew load factor (where applicable) * „ Other factors

Assess ‘vertical lift point force’ by: „ The ‘lift weight’ figure „ The number of lift points „ The COG position (in plan) „ The COG envelope (in plan) „ Lift points locations

LIFT POINT LOAD 2 Vertical lift point force

Lift point load Leg angle

1

THE LIFT POINT DESIGN LOAD

LEG DESIGN LOAD Assess ‘leg design load’ by: „ The ‘lift point load’ „ Add: weight of the leg „ Get: ‘base load’ in the leg „ Apply factor: to achieve the ‘leg design load’

Assess ‘lift point design load’ by: „ The ‘lift point load’ „ Consequence factor: 1.5 >> (1.5 x 100%/66% = 2.25 ) „ Other factors

LEG COMPOSITION & LOAD SPREAD „ Single

part leg (100%) „ Double parts (max = 55%) „ Four parts (max = 30.3%)

COMPONENT DESIGN LOAD „

„ „

The ‘leg design load’ has been assessed The number of leg parts: 1, 2 or 4 The ‘design load’ in one leg part (55% or 30.3%)

LEG DETAILS PARADE OF LEG COMPOSITIONS

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Leg detailed diagram is required to prove clearance margins (where last tucks are clear from pin)

2

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