ASME Vessel Standard - Suncor
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0601
Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
Revision:
9
Rev
Revision History
9
This revision is a complete reformat to Std 0601 Rev 8 and includes requirements for pressure vessels to ASME Section VIII, Div. 2 that was previously contained in Std 0602 Rev 1.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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TABLE OF CONTENTS PURPOSE AND SCOPE.............................................................................................................................. 5 RESPONSIBILITIES..................................................................................................................................... 5 REFERENCED STANDARDS...................................................................................................................... 5 DEFINITIONS AND ACRONYMS ................................................................................................................ 8 STANDARD .................................................................................................................................................. 9 5.1. General .................................................................................................................................................. 9 5.2. Design Requirements........................................................................................................................... 10 5.3. Materials............................................................................................................................................... 27 5.4. Fabrication ........................................................................................................................................... 30 5.5. Inspection And Testing......................................................................................................................... 32 5.6. Documentation and Approval Requirements ....................................................................................... 36 5.7. Special Service Requirements............................................................................................................. 37 6. IMPLEMENTATION.................................................................................................................................... 41 7. INTERPRETATION AND UPDATING ........................................................................................................ 41 8. LIST OF APPENDICES.............................................................................................................................. 41 9. ADDENDA .................................................................................................................................................. 41 10. APPROVED BY .......................................................................................................................................... 41 APPENDIX A – TYPICAL FABRICATION MATERIALS ......................................................................................... 42 APPENDIX B – SUPPLEMENTARY REQUIREMENTS FOR VESSELS FABRICATED OF 1 Cr-½ Mo and 1¼ Cr-½ Mo STEELS.................................................................................................................... 44 APPENDIX C – SUPPLEMENTARY REQUIREMENTS FOR VESSELS FABRICATED OF 2¼ Cr-1 Mo, 2¼ Cr-1 Mo-¼ V, 3 Cr-1 Mo and 3 Cr-1 Mo-¼ V STEELS ........................................................... 49 APPENDIX D – SUPPLEMENTARY REQUIREMENTS FOR HEAVY WALL VESSELS ...................................... 58 APPENDIX E – NOZZLE LOADS FOR VESSELS FABRICATED FROM STEEL ................................................. 60 APPENDIX F – INTERPRETATIONS ..................................................................................................................... 64 1. 2. 3. 4. 5.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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1. PURPOSE AND SCOPE 1.1.
The Standard is issued to establish uniform procedures and requirements for design, material selection, fabrication, inspection, and testing of pressure vessels fabricated in accordance with ASME Code Section VIII Div.1 and Div.2. For vessels installed in Canada, the requirements of CSA B51 shall also be met. The scope of this Standard supplement/clarify the requirements for mechanical design, fabrication process, nondestructive examination, inspection and testing of pressure vessels.
1.2.
The scope of this Standard is also applicable for category ‘H’ fittings as defined by CSA B51 for fittings installed in Canada such as pulsation suppression devices, drain pots, instrument seal pots, filters, strainers.
1.3.
Where there are different requirements within this standard due to specific requirements for service and/or materials being utilized, the more stringent criteria shall be applied.
1.4.
Paragraphs that have interpretations associated with them are denoted by the letter INT in the left hand margin next to the paragraph number. The interpretations may be found in Appendix F and this is additional information to further explain the requirements of the relevant paragraph.
2. RESPONSIBILITIES 2.1.
Director Of Engineering 2.1.1.
2.2.
Subject Matter Expert 2.2.1.
2.3.
Responsible to revise and update this Standard.
Project Engineering Manager 2.3.1.
2.4.
Responsible for approving and implementing this standard.
Responsible to ensure this standard is properly implemented when adopted for a project.
Project Discipline Engineer 2.4.1.
Responsible to ensure the requirements of this standard are incorporated in the course of a project design.
3. REFERENCED STANDARDS 3.1.
Suncor Standards and Drawings 3.1.1.
The following Suncor Energy Inc. Standards are being used as references; STD 0213
Positive Material Identification (PMI)
STD 0214
Painting
STD 0300
Structural Engineering Criteria
STD 0301
Design of Steel Structures
STD 0302
Furnishing of Steel Structures
STD 0603
Alloy Cladding
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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STD 0903
Welding Requirements
STD 1003
Fireproofing of Structures and Equipment
PQA-GS-0019
Use of Advanced UT In Lieu of RT For Examination of ASME Code Section I and Section VIII Vessel Welds
Industry Standards 3.2.1.
ASME Boiler and Pressure Vessel Codes
3.2.1.1.
Section I
Power Boilers
3.2.1.2.
Section II
Material Specifications (Parts A, B, C, D)
3.2.1.3.
Section V
Non-Destructive Evaluation
3.2.1.4.
Section VIII
Pressure Vessels (Division 1 and 2)
3.2.1.5.
ASME B16.5
Pipe Flanges and Flanged Fittings NPS ½ Through NPS 24
3.2.1.6.
ASME B16.11
Forged Steel Fittings, Socket-Welding and Threaded
3.2.1.7.
ASME B16.20
Metallic Gaskets for Pipe Flanges - Ring-Joint, Spiral Wound & Jacketed
3.2.1.8.
ASME B16.47
Large Diameter Steel Flanges NPS 26 Through NPS 60
3.2.1.9.
ASME SA-388
Standard Practice for Ultrasonic Examination of Heavy Steel Forgings
3.2.1.10. ASME SA-435
Standard Specification for Straight-Beam Ultrasonic Examination of Steel Plates
3.2.1.11. ASME SA-578
Standard Specification for Straight-Beam Ultrasonic Examination of Plain and Clad Steel Plates for Special Applications
3.2.1.12. ASME CC 2235
Use of Ultrasonic Examination in Lieu of Radiography Section I and Section VIII, Divisions 1 and 2
3.2.2.
CSA Standards
3.2.2.1. 3.2.3.
CSA B51
Boiler, Pressure Vessel, and Pressure Piping Code
ASTM Standards
3.2.3.1.
ASTM E-112
Standard Test Methods for Determining Average Grain Size
3.2.3.2.
ASTM E-165
Standard Test Method for Liquid Penetrant Examination
3.2.3.3.
ASTM E-21
Elevated Temperature Tension Tests of Metallic Materials
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Pressure Vessels ASME Section VIII, Div. 1 and Div. 2 3.2.4.
Revision:
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WRC Bulletins
3.2.4.1.
WRC 107-79
Local Stress in Spherical and Cylindrical Shells Due to External Loadings
3.2.4.2.
WRC 297-84
Local Stresses in Cylindrical Shells Due to External Loadings on Nozzles
3.2.4.3.
WRC 305
Hydrogen Attack Limit of 2¼ Cr-1 Mo Steel
3.2.4.4.
WRC 275-82
The use of 2¼ Cr-1 Mo Steel for Thick Wall Reactor Vessels in Petroleum Refinery Processes – An Interpretative View of 25 Years of Research and Application
3.2.5.
NACE Publications
3.2.5.1.
NACE 8X194
Material and Fabrication Practices for New Pressure Vessels Used in Wet H2S Refinery Service
3.2.5.2.
NACE MR0103
Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments
3.2.5.3.
NACE MR0175
Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment
3.2.5.4.
NACE RP0472
Methods and Controls to Prevent In Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments
3.2.5.5.
NACE RP0403
Avoiding Caustic Stress Corrosion Cracking of Carbon Steel Refinery Equipment and Piping
3.2.6.
API Publications
3.2.6.1.
API 934A
Materials and Fabrication of 2 1/4Cr-1Mo, 2 1/4Cr-1Mo-1/4V, 3Cr1Mo, and 3Cr-1Mo-1/4V Steel Heavy Wall Pressure Vessels for Hightemperature,High-pressure Hydrogen Service
3.2.6.2.
API 934C
Materials and Fabrication of 1 1/4Cr-1/2Mo Steel Heavy Wall Pressure Vessels for High-pressure Hydrogen Service Operating at or Below 825 °F (441 °C)
3.2.6.3.
API 938
An Experimental Study of Causes and Repair of Cracking of 1¼ Cr-½ Mo Steel Equipment
3.2.6.4.
API 941
Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants
3.2.6.5.
API 945
Avoiding Environmental Cracking in Amine Units
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Pressure Vessels ASME Section VIII, Div. 1 and Div. 2 3.2.7.
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Reference Books
3.2.7.1.
T. Sakai, S. Nose
Effect of Hydrogen on MPT and Dehydrogenation During Shutdown in Hydroprocessing Reactors, ASME International, 1997
3.2.7.2.
J.R. Foulds
Graphitization of Steels in Elevated Temperature Service - Journal of Materials Engineering and Performance Volume 10, No.4, Aug. 2001
3.2.7.3.
R.A White
Materials Selection for Petroleum Refineries and Gathering Facilities, NACE International, Ed.1998
3.2.7.4.
Henry Bednar
Pressure Vessel Design Handbook, Krieger Publishing Co., 2nd Edition
3.2.7.5.
Dennis Moss
Pressure Vessel Design Manual, Gulf Publishing Co., 3rd Edition
3.2.7.6.
G.R. Prescott
Hydrogen Induced Cracking in 2¼ Cr-1 Mo Welds
3.2.7.7.
T. Iwadate
Prevention of Fracture in High Temperature / High Pressure Reactors Made of Cr-Mo Steels, JSW research studies
3.2.7.8.
E. Upitis, F. Shadid, T. Kaups
“Pressure Vessel Breakdown Prevention, Examination and Restoration” – Chicago Bridge and Iron Technical Services Company
3.2.7.9.
L. Brownell, E. Young
Equipment Design, John Whiley & Sons, Ed.1959
3.2.7.10. R. W. Straiton
A Report on Residual Stress Effects Observed on Train “C” Regenerator C1C-5, Bechtel Co.
3.2.7.11. L.P. Zick
Stresses in Large Horizontal Cylindrical Pressure Vessels on Two Saddle Supports. Original paper published in September 1951 "THE WELDING JOURNAL RESEARCH SUPPLEMENT."
4. DEFINITIONS AND ACRONYMS 4.1.
The “Owner” - means Suncor Energy Inc.
4.2.
The “Buyer” - means Suncor or its representative designated for that project.
4.3.
“Owner’s Engineer” - means a registered, professional engineer employed directly by Suncor responsible for the technical integrity of the project.
4.4.
“Owner’s Inspector” - means the company and/or person authorized for inspection.
4.5.
The “Supplier” - means the entity, manufacturer, fabricator, vendor, or contractor that supplies the material or services.
4.6.
“Code” means the rules presented in ASME Code Section VIII Division 1 and Division 2. ASME Code Section VIII Division 3 is not referred in the scope of this standard.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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4.7.
“Local Authorities” means the governmental regulatory authority controlling laws, codes, rules, or regulations for the design, fabrication and testing of Pressure Vessels.
4.8.
“Sour Service” –This service is defined in Standard 0903.
4.9.
“Amine Service” – Services containing amines such as MEA, DEA, MDEA or DGA used for H2S removal.
4.10. “Hydrogen Service” – This service is defined in Standard 0903 4.11. “Caustic Service” – Services containing sodium hydroxide (NaOH) or caustic potash (KOH). 4.12. “Hydrofluoric (HF) Acid Service” – streams containing hydrofluoric acid. 4.13. “Cyclic Service” – Services in which the following conditions may occur; • • •
Operating pressure and/or temperature variations Forced vibrations Variations in external loads
4.14. “General Service” – Any service that is different than the ones presented in paragraphs 4.8 to 4.13. 5. STANDARD 5.1.
General 5.1.1.
All pressure vessels shall be designed, fabricated, examined, inspected, tested, and stamped in accordance with the latest edition of the ASME Code (see definition in paragraph 4.6), any mandatory national, state, and local laws and the supplementary requirements provided in this Standard.
5.1.2.
Any alterations made on existing registered equipment shall be made in accordance with the requirements specified in the edition of the Code which was originally used for design and fabrication of the equipment.
5.1.3.
Maintenance of pressure vessels may be permitted to other codes such as API 510 or National Board Inspection Code, NB-23 as allowed by regulations in a particular jurisdiction.
5.1.4.
All pressure vessels designated to operate in Canada and fabricated outside Canada shall be approved by the National Board of Boiler and Pressure Vessel Inspectors. All conditions of approval provided by Canadian Local Authorities shall be confirmed in the Manufacturer’s Data Report (MDR). The MDR shall refer to the latest revision of approved design.
5.1.5.
Where the Owner's Engineer is required to provide information and or decisions within this standard, this information shall be noted on the mechanical data sheets, vessel drawings and/or technical specifications as applicable.
5.1.6.
The requirements within this Standard represent Suncor's minimum technical requirements. Modifications to these requirements shall require an approved deviation. The requirements resulting from approved deviations shall be noted on the mechanical data sheets, vessel drawings and/or technical specifications as applicable.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Design Requirements 5.2.1.
Design Pressure
5.2.1.1.
“Design Pressure” (Pd) – shall be considered as the Process Design Pressure and is the maximum pressure measured at the highest point of the vessel. The Design Pressure shall be provided in the vessel data sheet and in the fabricator documents.
5.2.1.2.
Unless otherwise specified, Pd of a vessel shall be selected as the maximum between; Pd = 1.10 x MOP or Pd = MOP + 25 [psig] where; MOP = Maximum Operating Pressure at the top of vertical vessels (or the top of the shell on horizontal vessels), as required by process conditions for normal operation, start-up, shutdown, or any other transitory fluctuations.
5.2.1.3.
Vessel maximum allowable working pressure (MAWP) shall be determined by using the following restrictions; a. MAWP shall meet or exceed the vessel Design Pressure (Pd). For vessels installed in Alberta, MAWP shall not exceed Pd.
INT
b. Nozzle reinforcement required to withstand external pipe loads shall be considered as a potential limitation for MAWP. 5.2.1.4.
The following supplementary requirements shall be considered when establishing the design static head; a. Horizontal vessels and vertical vessels designated to store liquid (such as surge/charge or storage vertical vessels), shall be designed for the flooded condition. b. All other vertical vessels (such as fractionation towers) shall be designed to satisfy all of the following cases; i. Vessel subject to design pressure and temperature and filled with liquid up to the highest operating level. ii. Vessel subject to normal operating pressure and temperature and completely or partially flooded with liquid. The degree of flooding to be approved by Owner’s Engineer.
5.2.1.5.
Vessels exposed to vacuum during normal operation, shall be designed to withstand an external pressure of 15 psi (103 kPag) [full vacuum].
5.2.1.6.
Vessels exposed to steam-out, shall be designed to withstand an external pressure of 7 psig (48 kPag) [half vacuum] at @ 100°F (38°C).
5.2.1.7.
Components of vessel envelope exposed to different operating pressures on both surfaces (such as intermediate heads or internal shells and heads of jacketed vessels) shall be designed to withstand the following two cases;
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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a. Internal design pressure (applied on concave side) plus vacuum design pressure (if applicable) applied on convex side. b. External design pressure (applied on convex side) plus vacuum design pressure (if applicable) applied on concave side.
INT
5.2.1.8.
All pressure vessels (including their supports) shall also be designed for field hydrotest in erected position.
5.2.1.9.
Both the shop and field hydrotest pressures shall be determined based on vessel MAWP assuming that vessel is being corroded.
5.2.1.10.
The maximum membrane stress generated in the vessel envelope during the hydrotest, shell not exceed 90% of the specified minimum yield strength for ferritic steels, or 100% of the specified minimum yield strength for austenitic steels or non-ferrous materials.
5.2.2.
Design Temperature
5.2.2.1.
The design temperature shall be considered uniform across the entire vessel and shall be the maximum value of the following options; a. For vessels operating up to 750°F (399°C) use maximum operating temperature plus 50°F (28°C). b. For vessels operating over 750°F (399°C) use maximum operating temperature plus 25°F (14°C). c. Maximum foreseen upset temperature.
INT
INT
5.2.2.2.
The minimum design metal temperature (MDMT) shall be considered to be the minimum temperature at which the vessel can be subjected at combination of stresses greater than 30% of allowable stress Sa (or 20% if designed in accordance with Division 2) any time during the operating lifetime.
5.2.2.3.
On vessels where in-service metallurgical or hydrogen embrittlement is not expected, MDMT is determined based on the lowest expected temperature in service taking into account the normal operation, shock chilling or auto refrigeration, lowest ambient temperature, startup, shutdown and other known or anticipated upset conditions.
5.2.2.4.
For vessels where in-service metallurgical or hydrogen embrittlement is expected the MDMT shall be considered equal with the Minimum Pressurization Temperature (MPT) where MPT is considered the minimum temperature at which toughness of embrittled material meets the required design value. Adherance to the MPT is not necessary for activities such as shop hydrotesting of new equipment where in-service embrittlement is irrelevant. The MPT shall be established after determining the following information and the MPT shall be noted on the vessel datasheet and drawings. a. Determine the minimum ambient temperature in the location where the equipment will operate. b. Determine if the equipment is located outdoor. c. Determine the minimum process operating temperature.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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d. Determine if the equipment will be exposed to auto refrigeration (Joule Thompson effect) in the case of pressure fluctuations. Determine the temperature drop induced by auto refrigeration. e. Determine if the mechanical properties of vessel pressure envelope will be affected by; f. For Cr-Mo alloys described in Appendix B (where embrittlement by precipitates may occur), calculate “X” factor = (10 x P + 5 x Sb + 4 x Sn + As) / 100 for base and weld metal. Determine the toughness shift induced by the longest PWHT for the base or weld metal with the highest “X” factor as described in Appendix B. MPT shall not be less than 100°F (38°C). g. For Cr-Mo alloys described in Appendix C (where embrittlement due to temper embrittlement from tramp elements P, As, Sn, Sb may occur), calculate “J” factor = (Si + Mn) x (P + Sn) x 10,000 for base metals and “X” factor for weld metal. For the base metal with the highest “J” factor, obtain step cooling test results as described in Appendix C. For weld metal with the highest “X” factor, determine the toughness shift induced by the longest PWHT. MPT shall not be less than 100°F (38 °C). h. Determine the degree of embrittlement induced by atomic (nascent) hydrogen charged into vessels as a result of aqueous corrosion or Hydrogen Service. i. Determine the degree of embrittlement caused by carbon segregation (graphitization) in vessels operating at temperatures higher than 750°F (399°C). j. Determine the contribution of stress concentrations (including flaws) that are expected over the life of the vessel. k. Determine the impact exemption temperature of material, using curves presented in ASME Code Section VIII, Div 1, Fig.UCS-66 and UCS-66.1 or Section VIII, Div 2, paragraph 3.11.8. 5.2.2.5.
The start up procedure shall protect the vessel from; a. Excessive stress induced in the pressure envelope at temperatures below the Minimum Pressuring Temperature (MPT). b. Rapid modifications of pressure and temperature, which will induce crack propagation as a result of non-uniform stress distribution across vessel wall.
5.2.2.6.
Design temperature may be increased up to the lower of the following two values; a. Temperature limit of the flange rating b. Maximum temperature at which the allowable stress Sa of material used for pressure envelope, remains unchanged.
5.2.2.7.
For guidance in determining the vessel MDMT, refer to Figure 1 below.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2 Carbon Steel
MDMT=MPT
Use Fig UCS 66 to establish MDMT
No
Is temperature ≤750°F Yes
Adjust MDMT to reflect effects embrittlement due to Temperature Embrittlement
H2 Service
≤ 1¼ Cr.
MDMT=MPT1
Non H2 Service
Determine temper embrittlement shift using step cooling test per API-934A to calculate MPT1
≥ 2¼ Cr.
Yes
Use Fig UCS 66 to establish MDMT
No
Equipment located outdoor?
No
Can autorefrigeration occur?
MDMT = lowest ambient metal temperature
No
Warm-up required before pressurization?
Yes
MDMT = autorefrigeration temperture
Yes
Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
MDMT=MPT
MPT2 = 100°F
MPT ≥ 100°F
MPT = Max (MPT1, MPT2)
≥ 2¼ Cr.
≤ 1¼ Cr.
Material Grade
Material Grade
PROJECT SERVICES
Adjust MDMT to reflect effects embrittlement due to Atomic Hydrogen
Carbon Steel
Temperature Embrittlement
Exposure to Atomic Hydrogen
Subject:
Yes
No
Department:
Can material embrittlement occur?
MDMT Determination
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Figure 1
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Pressure Vessels ASME Section VIII, Div. 1 and Div. 2 5.2.2.8.
5.2.3.
Number:
0601 Revision:
9
All vessels provided with internal refractory for cold wall design, shall be externally painted with temperature indicating paint or alternative means of ensuring the equipment is not overheated as a result of internal refractory failure.
DESIGN LOADS The following loads shall be determined considering input from the Owner’s Engineer and/or process licensor as applicable.
5.2.3.1.
Vessel Weight a. The weights (dead loads) are impacting the design of the vessel pressure envelope, the supports, the lifting lugs as well as the foundation. The combination of the weights shall be determined for the following cases and noted on the vessel general arrangement drawing; i. “Fabricated Weight” - Consists of fabricated weight of the vessel pressure envelope, vessel supports, all internal and external welded attachments such as nozzles, internal support clips and rings, external vacuum rings, insulation rings and pipe support clips. ii. “Erection Weight” – Consists of vessel “Fabricated Weight” plus the weight of all demountable (bolted) internal and external attachments that will be installed before vessel erection (internals, ladders and platforms, insulation, pipe supports, portion of piping, instruments and bolted lifting devices). The selection of the attachments to be installed prior to erection shall be defined on case by case basis and shall be incorporated in the Construction Plan. iii. “Empty Weight” – Consists of vessel “Erection Weight” and fully dressed with all internals including packing beds and grid supports (if applicable), all platforms and ladders, all insulation, the fireproofing, all pipe supports and the weight of the attached piping supported by vessel, all valves and instruments supported by vessel. The “Empty Weight” represents the weigh of the vessel ready for operation without any liquid level. iv. “Operating Weight” – Consists of vessel “Empty Weight” plus the weight of operating product up to High Liquid Level and if applicable the weight of catalyst beds. v. “Test Weight” – Consists of fully dressed vessel (except any catalyst or packing beds) plus weight of water flooding the vessel. This weight is determined for the case of the field hydrotest. b. In establishing the “Operating Weight”, the trays shall be considered as flooded with liquid with an approximate depth of 2” (50 mm) for valve and bubble cap trays and 24” (610 mm) to 48” (1220 mm) for chimney trays. c. For the purpose of estimating vessel weights, platforms shall be in accordance with drawings DD00-M-108-1; DD00-M-109-1; DD00-M-111-1. Horizontal vessels shall be provided with one top rectangular platform with the length equal with vessel tangent to tangent and the width not smaller than 4 ft (1.2 m).
5.2.3.2.
Loads Induced By Wind And Earthquake a. Wind or seismic loads as well as the design methods are presented in the governing national codes such as National Building Code (NBC), International Building Code (IBC)
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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and ANSI/ASCE Standard 7-98. Further to this, jurisdictional requirements shall also be considered. b. The external attachments (platforms, ladders, piping and insulation) have to be considered as a part of surface exposed to wind as well as an element in establishing of shape factors. If the design of the platforms is not fully defined at the time when the Purchase Order is issued, the effect of external attachments shall be approximated by considering an increase of the vessel size as follows; Effective diameter = K x Vessel O.D. + 2 x IT + OHP Where ‘K’ shall be considered as follows;
IT = OHP =
K
Vessel diameter [ft]
1.5
9
Insulation thickness [ft] Outside diameter of the insulated overhead pipe [ft]
c. On towers with height-to-diameter ratio (H/D) exceeding 10, the vortex shedding effect shall be taken in consideration. d. The towers with H/D ratio exceeding 15 shall also be verified for buckling due to axial compression in accordance with Code Case 2286. e. Maximum tower H/D ratio shall not exceed 33. 5.2.3.3.
Loads Induced By Piping a. The piping loads given in Appendix E shall be used in the design of nozzles. These pipe loads consist of a combination between pipe gravity (including the weight of fluid and insulation) as well as forces and moments induced by thermal expansion/ contraction of the piping system or by spring type supports. The pipe loads shall be considered acting simultaneously with the internal pressure/vacuum, the gravity loads and the loads induced by wind or earthquake. b. Stress analysis in accordance with the method presented in WRC 107 and WRC 297 for junction between the nozzle and vessel envelope (shell and heads). This stress analysis shall be provided on all nozzles connected with piping (process connections). As acceptable alternate provide FEA. c. The stress levels in the pressure envelope shall be limited to values not exceeding the requirements presented in Figure 5.1 of ASME Code Section VIII, Div.2, with the following additional interpretations; i. For vessels designed in accordance with ASME Section VIII, Div.1 the value of ‘S’ shall be considered as maximum allowable stress for Div.1. ii. Once actual piping loads have been established, nozzle designs shall be reassessed to ensure allowable stress levels are not exceeded.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Loads Induced By Other Attachments
5.2.4.1.
The loads induced by lifting devices are impacting the design of the vessel pressure envelope and skirt supports. Unless otherwise specified, both vessel envelope and skirt support (where applicable) shall be designed to withstand the erection loads. As a minimum, the evaluation shall include the following requirements; a. If attached on shell or head, local stress analysis shall be performed around the attachment point. Depending of design configuration this analysis can be performed by using the method presented in WRC 107 and WRC 297 or FE analysis. b. Evaluate the capacity of overall vessel envelope and skirt support (where applicable) to withstand the collapse induced by bending moments during erection.
5.2.4.2.
The loads induced by special internal and external attachments such as chimney/accumulator trays or “stab-in” reboilers shall be considered as concentrated gravity loads present during the operation case. If applicable, the eccentricity of these loads shall be specified.
5.2.4.3.
Stress analysis in accordance with the requirements presented in WRC 107 and WRC 297 for junction between the clips required for pipe supports and vessel envelope (shell and heads). As acceptable alternate provide FEA.
5.2.4.4.
Stress evaluation in the junction between vessel envelope and supports. Depending of design configuration this analysis can be performed by using the method presented in WRC 107 and WRC 297, FEA or any other specialized method such as Zick’s analysis (reference 3.2.7.11) for saddle supports.
5.2.5.
Cyclic Loads
5.2.5.1.
The effect of cyclic loads shall be evaluated for vessels in cyclic service.
5.2.5.2.
The design data shall include the range of load variance as well as the number of cycles estimated to occur during vessel operating lifetime.
5.2.5.3.
All vessels designed in accordance with ASME Code Section VIII, Div. 1 and Div. 2 exposed to cyclic loads shall be assessed for fatigue evaluation in accordance with paragraph 5.5.2 (Screening Criteria for Fatigue Analysis) from ASME Code Section VIII, Div.2. For ASME VIII Div. 1 vessels, the assessment shall be per paragraph 5.5.2.3 (Fatigue Analysis Screening, Method A) except that a limit of 1000 cycles maximum shall be used for all situations.
5.2.5.4.
The stress levels in the pressure envelope shall be limited to values not exceeding the requirements presented in figure 5.1 of ASME Code Section VIII, Div. 2 except that for vessels designed in accordance with ASME Section VIII, Div. 1 the maximum stress ‘S’ shall be limited to maximum allowable stress in accordance with Div. 1.
5.2.5.5.
FE analysis shall be provided to determine the local stress induced by the cycle. The analysis shall be performed in any restrained portion or gross discontinuities of the pressure envelope. Examples of this include junctions between nozzles and shells/heads, transitions between shells and heads, internal ring supports attached on shell or transitions between vessel envelope and supports.
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5.2.6.
Revision:
9
Vessels designed in accordance with ASME Code Section VIII, Div. 1 and Div. 2 exposed to progressive distortion as a result of cyclic loads (such as coker drums) shall be evaluated in accordance with paragraph 5.5.6 of ASME Code Section VIII, Div. 2.
Transportation Loads
5.2.6.1.
The typical accelerations factors to be considered during the vessel transportation are per Table 1 below;
Type of transportation Ocean Rail Road 5.2.6.2.
Table 1 Amplification factors (Impact factors) Axial direction Vertical direction Radial direction Ka Kv Kr 1.5 1.5 1.0 1.5 2.0 1.0 1.0 1.5 0.5
The calculated forces shall be considered as acting in vessel center of gravity (CG). The forces shall be determined as; a. Fa = Ka x W; b. Fv = Kv x W; c. Fr = Kr x W where W is the shipping weight
5.2.6.3.
Vertical force Fv shall be considered as acting in addition to the shipping weight.
5.2.6.4.
All vessels supported by saddles or shipping saddles or other type of shipping supports shall be investigated for buckling, local circumferential bending, and shear stresses. Unless otherwise specified by client or process licensor, the L. P. Zick analysis (reference 3.2.7.11) or alternate FE analysis may be used for this investigation.
5.2.7.
Erection Loads
5.2.7.1.
The design of both lifting and tailing lugs shall consider the weight of fully dressed vessel including all welded internals, insulation, bolted internals, platforms, ladders as well as parts of external piping system. The rigging impact factor shall be considered as follows; a. Impact factor value equal with 1.8 for all total lifting weight of 200,000 lb and lower. b. Impact factor value equal with 1.5 for all total lifting weight over 200,000 lb. c. Maximum local stress induced in shells, heads or skirt supports during erection shall be limited as follows; i. The maximum local membrane stress intensity shall not exceed 66% of the material yield strength. ii. The loads due to erection shall not be considered as self limiting. iii. The combination of primary membrane and bending stresses shall not exceed 90% of material yield strength.
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Temporary bracing may be considered to address stresses during erection of vessels.
Requirements For Design Of Cylindrical Shells
5.2.8.1.
Minimum thickness of corroded cylindrical shell and dished heads shall be the greater of;
D + 100 Kor K3/16" (5 mm) 1000 Where D = Vessel diameter (either external or internal) [in] 5.2.8.2.
Minimum thickness of corroded spherical heads shall be the greater of;
D + 200 Kor K3/16" (5 mm) 2000 Where D = Vessel diameter (either external or internal) [in] 5.2.8.3.
The following additional criteria shall be considered in calculating the required thickness of vessels and supports; a. All horizontal vessels supported by saddles shall be investigated for buckling, local circumferential bending, and shear stresses. Unless otherwise specified, the L. P. Zick analysis may be used for this investigation. b. Maximum deflection of general vertical vessels shall not exceed H/100 when exposed to any combination of loads except of seismic loads. c. For columns provided with trays the maximum deflection shall be limited to H/200. NOTE: Dimension ‘H’ shall be considered to be the height from the base of the support ring to the top of the vessel.
5.2.8.4.
All vertical vessels with a diameter of 36” (914 mm) and smaller equipped with trays, packing or catalyst beds, shall be provided with a top bolted cover. Additionally, internals shall be designed in accordance with the following options; a. The whole internals shall be designed as a removable cartridge from the top of the tower. This option can be applied only if the vessel is equipped with trays but not with packing or catalyst beds. b. The whole tower shall be designed in bolted subsections separated by girth flanges. The girth flanges shall be designed to withstand the combination of the internal pressure/vacuum and the bending moment induced by wind, earthquake and piping loads.
5.2.9.
Requirements For Design Of Heads And Conical Transitions
5.2.9.1.
All heads, which are part of pressure envelope, shall be formed in elliptical, spherical, or dished shape. The 2:1 ellipsoidal heads are preferred.
5.2.9.2.
All heads shall be provided with an integral cylindrical transition with a length not smaller than 2” (5 mm) or 1.5 x plate thickness.
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5.2.9.3.
When applicable, the stress analysis shall also include an evaluation of pressure envelope buckling induced by lugs, legs, or ring type supports.
5.2.9.4.
Conical elements complete with torical transition on the large end (knuckle type) shall be used on vessels if one of the following conditions occur; a. Operates at temperatures over 750°F (399°C) b. Thickness exceeds 2” (51 mm)
5.2.9.5.
Intermediate heads required to separate two vessels may be used under the following restrictions; a. Only on vessels designed in accordance with ASME Code, Section VIII, Division 1. Design to be in accordance with Figure UW13.1(f). b. Only on vessels that operates in General service. c. Only on vessels without cladding on convex side of the head (head external surface). d. Only on vessels where PWHT is not required.
5.2.9.6.
Heads shall have the same inside diameter as the adjoining shell course when cladding or applied lining is specified.
5.2.9.7.
Code Case 2260 shall not be used without written approval from Suncor.
5.2.9.8.
Code Case 2261 shall not be used.
5.2.10. Requirements For Design Of Nozzles, Manways And Flanges 5.2.10.1.
The following nozzle sizes shall be avoided; a. Nozzles with a size equal with NPS 1¼”, 2½”, 3½” and 5” b. Nozzles provided with ASME flanges Class 400.
5.2.10.2.
“Set-on” type nozzles may be accepted with the following restrictions; a. The attachment weld shall be full penetration. b. The surface of vessel envelope surrounding nozzle location shall be ultrasonically examined and found free of cracks and laminations. The width of examined area shall be the larger of two plate thickness or two inches. c. Nozzle size is smaller than NPS 2½”. d. The attachment weld shall be inspected by PT or MT after the root and final cover pass.
5.2.10.3.
For situations where nozzles are required to be flush with the inside vessel surface, such as for drains, or for process reasons, this shall be noted on the vessel data sheet.
5.2.10.4.
Flange bolt holes shall straddle the north/south centerline in the plan and the vertical centerline in the elevation.
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5.2.10.5.
Connections NPS 1½” and larger shall be flanged.
5.2.10.6.
Typically nozzles NPS 4" and smaller shall be provided as long weld neck (LWN). Where LWN is not practical these nozzles shall be fabricated of pipe Sch. XH (XS) or thicker.
5.2.10.7.
Connections smaller than NPS 1½” may be provided subject to Owner’s Engineer approval only. Where approved, the connections shall be fabricated using Class 3000 or higher, integrally reinforced fittings, these include weldolets (WOL), sockolets (SOL) or threadolets (TOL). The attachment weld between the o-let and vessel surface shall be full penetration type. These fittings shall be considered only under the following restrictions; a. Vessels where ASME Class 600 flanges or lower are suitable. b. Minimum nozzle size is NPS ¾”. c. Vessels that are not internally coated, cladded or protected by weld overlay. d. Nipples shall be made of minimum Sch. 160 pipe.
5.2.10.8.
Where required, threaded plugs can be fabricated from bar stock that conform to ASME B16.11. The plugs shall be a mimimum of 3” (75 mm) long or ¼” (6 mm) longer than the insulation thickness.
5.2.10.9.
Flanges for nozzles NPS 24 and smaller shall be provided in accordance with ASME B16.5.
5.2.10.10. Flanges for nozzles NPS 26 through NPS 60 shall be provided in accordance with ASME B16.47. Unless otherwise specified by client or process licensor, flange dimensions shall be selected in accordance with series “A”. 5.2.10.11. Flanges with sizes exceeding the scope of ASME B16.5 and B16.47, shall be designed in accordance with ASME Code Section VIII, Div.1, Appendix 2 or Section VIII, Div.2, paragraph 4.16 and supplementary requirements provided in Appendix C, paragraph C.1.8 5.2.10.12. The “slip-on” (SO) type flanges can be used under the following restrictions; a. Design pressure limited by Class 150. b. Design temperature between -20°F (-29°C) and 500°F (260°C). c. Vessel service is General Service. d. Vessel is not cladded. e. Flange shall be welded inside and out with minimum two passes per each side. NOTE: Slip-on flanges shall be positioned so that the distance from the face of the flange to the pipe end is equal to the nominal pipe wall thickness, plus approximately ⅛” (3 mm). The welds shall be applied in a manner that will not damage the flange face. 5.2.10.13. Lap joint (LJ) flanges as well as threaded flanges shall not be used on any vessel external connection that is part of pressure envelope. 5.2.10.14. The facing of all flanges designed for pressures up to and including equivalent of ASME Class 1500 shall be raised face (RF) type. All raised face flanges shall be provided with a Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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facing having a surface finish between 125 µin and 250 µin (3.2 µm - 6.3 µm) arithmetical average roughness height (AARH). For services with hydrogen partial pressure greater than 75 psia, the flange face shall be between 125 µin -150 µin (3.2 µm - 3.8 µm). 5.2.10.15. Gaskets shall be spiral wound type with an external ring in accordance with ASME B16.20. Gaskets required for ASME flanges Class 900 and higher, as well as for all flanges larger than NPS 24” shall also be provided with an inner retention ring of the same material as the windings. 5.2.10.16. Internally coated vessels shall be provided with flat non-asbestos (Grafoil preferred) type gaskets. For vessels with flange rating exceeding Class 300, the decision of using flat nonasbestos gaskets shall be approved by Owner’s Engineer. 5.2.10.17. The facing of all flanges designed for pressures exceeding ASME Class 1500 shall be ring joint (RTJ) type or self energized seal type. 5.2.10.18. All nozzles and manways shall be located in such a way as to avoid the interference with the other butt welds of vessel pressure envelope. The minimum clearance between the edges of any two welds and between the attachment weld and any longitudinal seam or circumferential seam shall be at least two vessel thicknesses. Where this requirement cannot be maintained, the acceptable interference shall meet the following criteria; a. The vessel seam shall be fully RT examined for a length of minimum 6” (150 mm) on both sides of the interference. b. Minimum distance between the vessel seam and the tangent to the adjacent nozzle OD shall be no less than two vessel thickness. In such a case the minimum acceptable size of a nozzle is NPS 6”. 5.2.10.19. Similar criteria shall be used in the case of interferences with nozzles complete with repads with the following supplementary requirements; a. All criteria presented in paragraph 5.2.10.18 shall be applied also to the repad. b. In the case that vessel seam will not interfere with the nozzle but only with the repad then the space between the nozzle and the vessel seam shall also meet the requirements presented in paragraph 5.2.10.18. 5.2.10.20. Pad reinforced nozzles shall not be used on vessels where at least one of the following conditions is applicable; a. Normal operating temperatures of 750°F (399°C) and higher b. Design pressures of 1000 psig (6890 kPag) and higher NOTE: In all cases presented above the nozzles and manways shall be of the integrally self-reinforced type. 5.2.10.21. The reinforcing pads shall be provided with one ¼” NPT threaded hole (minimum of one per each segment if the repad is fabricated from multiple segments). On insulated vessels in hydrocarbon service with normal operating temperatures of 500°F (260°C) and higher, the Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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holes shall be fitted with a ¼” NPT nipple ending a minimum of ½” (12 mm) beyond the outside surface of the insulation cladding. 5.2.10.22. Where segmented reinforcing pads are used, the butt weld between the segments shall be full penetration and oriented in the vessel’s circumferential direction. 5.2.10.23. The typical nozzle external projection measured from the outside vessel surface to the flange face shall be a minimum of; a. 8" (200 mm) for NPS 4" and smaller b. 10" (250 mm) for NPS 6" to NPS 12” c. 12” (300 mm) for NPS 14” and larger NOTE: In the case of insulated vessels the nozzle projections presented above shall be from insulation surface to the flange face. 5.2.10.24. Nozzle projection through the top platforms shall be not less than 6” (150 mm) above the edge of toe plate attached on grating. 5.2.10.25. All connections required for thermowells shall be flanged and having an internal diameter (ID) not smaller than 1¾” (45 mm). In the case of cladded vessels, the nozzle ID shall be considered at the internal surface of weld overlay. 5.2.10.26. Access manways shall be provided on all vessels with diameter exceeding 36”. Vessels with a smaller diameter shall be provided with handholes or bolted heads or flat covers, as specified. 5.2.10.27. Access manways shall have a minimum 23" (585 mm) I.D. Manways NPS 24” and larger are required where; a. Installation and removal of trays and other bolted internals is required. b. The manway is to be used as air supply / ventilation. c. The manway is to be used as an emergency access during the vessel maintenance. 5.2.10.28. All manways shall be provided with hinged covers or covers supported by davits. 5.2.10.29. All vessels provided with side manways shall also be provided with a minimum NPS 2” ventilation nozzle located at or near the highest point. On horizontal vessels, the ventilation nozzle and the access manway shall be located close to the opposite ends of the vessel. The required ventilation nozzle may be used for other purposes as well. For example, where applicable, the top manways can also be used as ventilation. The minimum size of ventilation nozzles shall be selected as follows; Nozzle ID = 2 x (V / 110)
0.5
where V is vessel volume in ft³
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5.2.10.30. Towers equipped with trays or packing shall be provided with manways as follows; a. One manway located in the tower bottom section below the lowest tray or below the lowest packing bed. b. One above the top tray or above the top packing bed c. One at each liquid distributor d. One at the feed zone e. One above each chimney tray f. Within continuous train of trays, one manway per each set of 10 (ten) trays g. One between each packing section. NOTE: Owner’s Engineer shall provide the fabricator of internals with the information referring the internal diameter of manways. 5.2.10.31. On vertical vessels without internals, the access manways shall be located near the base of the shell. 5.2.10.32. Horizontal vessels longer than 75 ft (23 m) shall also be provided with the second manway (egress access). 5.2.10.33. Manways shall be oriented in such a way as to ensure self-draining back into the vessel (manway centerline shall not be inclined below horizontal in this case). 5.2.10.34. All access manways shall be provided with a grab rung (minimum 1” diameter) located above the manway and welded on vessel internal surface. Where there is not practical because the space limitation, the manway may be provided with two grab rungs located at 45° on each side of manway (such as 10 and 2 o’clock) and welded on vessel internal surface. 5.2.10.35. If the depth of internal free space below any manway exceeds 36” (900 mm), an appropriate number of internal ladder rungs welded on vessel internal surface shall also be provided. 5.2.10.36. All internal separation plates (baffles) and trays shall be provided with bolted manways to permit access to all internal surfaces of the vessel envelope. The minimum size of rectangular access (minimum hole size) shall not be smaller than 18” (460 mm) x 16” (410 mm) if the access is oriented horizontally (such as trays) and not smaller than 20” (510 mm) x 20” (510 mm) if the access is oriented vertically (such as vertical baffles). An acceptable alternative is to provide additional manways in the vessel wall. 5.2.10.37. On vertical vessels provided with skirt support, there shall be not any removable connections (such as flanged or threaded connections) inside of vessel skirt due to the potential fire hazard created by leaks. 5.2.10.38. Nozzle corrosion allowance shall be at least equal with vessel corrosion allowance.
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5.2.11. Requirements For Design Of Supports And External Attachments 5.2.11.1.
The skirt support shall be attached to the bottom head by full penetration welding. The surface of transition weld between the support and bottom head shall be provided with a minimum 3 to 1 transition in order to minimize the stress concentration. The lap joint technique used to attach skirt supports shall be avoided.
5.2.11.2.
The thickness of skirt support shall not be less than ¼” (6 mm).
5.2.11.3.
The attachment between the bottom head and skirt support shall be provided as a weld build-up or as a forged ring in any of the following cases; a. On vessels exposed to fatigue as a consequence of pressure and thermal cycles. b. On vessels on which the transition between skirt support and head requires UT examination. c. On vessels with head thickness exceeding 2” (50 mm).
5.2.11.4.
The design of skirt support base plate shall be provided in accordance with the following requirements; a. Minimum anchor bolt size shall be 1” (25 mm). The maximum size of anchor bolts shall be 2½” (64 mm). b. Bolt allowable stress shall be considered 18,000 psi for ASTM A307B, 22,000 psi for ASTM A193 B7, and 25,000 psi for ASTM A325. c. The calculated bolt diameter of anchor bolts shall be increased by ⅛” (3 mm) for corrosion allowance. d. The size of anchor bolt-holes shall exceed the size of the bolts by ½” (12 mm). e. Minimum space between two anchor bolts shall not be less than 6 (six) bolt diameters.
5.2.11.5.
To safeguard against fatigue in anchor bolts, the anchor bolts shall be pretensioned at approximately 10% of bolt allowable stress. This shall be applicable in situations where the following condition applies; 0.5 x W x D < 0.5 x F x H where;
W = Tower operating weight [lb] D = Tower diameter [ft] F = Maximum force induced by wind or earthquake [lb] H = Tower height including the skirt support [ft]
For further guidance on pretensioning requirements for anchor bolts, refer to reference 3.2.7.4
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5.2.11.6.
The top 2 ft (600 mm) portion of skirt supports attached on vessels operating at temperatures exceeding 750°F (399°C) or lower than -20°F (-29°C), shall be fabricated from the same material type (same P number) as the base material of vessel bottom head.
5.2.11.7.
All skirt support openings required for access, nozzles and ventilation shall be provided with adequate reinforcements (sleeves) to compensate for the size of the openings.
5.2.11.8.
All skirt support openings required for nozzle passage shall be provided with a pipe sleeve with a length not smaller than 4” (100 mm). The pipe sleeve ID shall accommodate; a. Nozzle OD + 2 x Insulation thickness + 1” (25 mm) gap b. Nozzle OD + 2 x Height of guiding gussets + ¼” (6 mm) gap
5.2.11.9.
The height of skirt support shall be designed to allow; a. Minimum 36” (915 mm) clearance below the bottom head to base plate. b. Minimum 6” (150 mm) clearance between the bottom of access opening and the top of the anchor bolts. c. Minimum 12” (300 mm) clearance between the top of access opening and tangent line of bottom head. d. When the skirt is fabricated from two different materials, minimum 36” (915 mm) clearance between the top of access opening and tangent line of bottom head.
5.2.11.10. Support skirts for vessels shall be provided with a hot box if at least one of the following requirements are met; a. Vessel design temperature is 700°F (371°C) and higher. b. Vessel operating temperature is higher than 600°F (316°C). c. Normal operating temperature varies in cycles over a range of minimum 400°F (222°C). 5.2.11.11. The height of the hot box shall be the maximum between
R x t and those in Table 2
below; Table 2 Height of Hot Box
Vessel Internal Diameter
6” (150 mm)
Up to 72” (1830 mm)
8” (200 mm) 10” (250 mm) 12” (300 mm)
Over 72” (1830 mm) to 120” (3050 mm) Over 120” (3050 mm) to 168” (4270 mm) Over 168” (4270 mm)
where ‘R’ = vessel radius [in] and ‘t’ = head thickness [in] Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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5.2.11.12. The size of skirt access openings shall not be smaller than 23" (510 mm) ID. 5.2.11.13. All skirt supports shall have at least four (4) NPS 2” ventilation holes, located near the top of the skirt, equally spaced. For vessels where the operating temperature is at or above the process fluid auto ignition temperature in air, ventilation holes shall not be used. This is to mitigate the risk of fire damage in the event of a process leak occurring within the skirt. 5.2.11.14. Skirts supported by elevated beam structures or rings (that allows free air circulation beneath the skirt) do not need ventilation holes. 5.2.11.15. Leg or lug type supports may be used if all following restrictions are met; a. Vessel diameter is 8 ft (2.44 m) or smaller. b. Vessels H/D ratio is 3 or smaller. c. Hot box is not required per paragraph 5.2.11.10. 5.2.11.16. Vessel supports as well as the surrounding portion of vessel pressure envelope attached to the supports shall be designed to withstand the combined effect of fully dressed vessel weight, piping loads, wind or seismic loads. 5.2.11.17. Where saddle wear plates are required to reduce the stress in the horizontal vessels envelope, shall be seal welded all around and provided with a ¼” NPT diameter vent hole at the lowest point. 5.2.11.18. External reinforcing pads designated to support clips for pipe supports, ladders and platforms shall be seal welded all around except at the lowest point. The weld leg shall be designed to withstand the operating loads as well as the dynamic cyclic loads during the vessel transportation to erection point. The reinforcing pads shall be provided with rounded corners with a radius of minimum 1” (25 mm) or larger. 5.2.11.19. Reinforcing pads shall not be used in the following cases; a. On all vessel surfaces with normal operating temperatures of 750°F (399°C) and higher. 5.2.11.20. Internal rings supporting the catalyst beds shall be fabricated in accordance with one of the following alternatives; a. Forged rings welded with full penetration weld to vessel base metal. b. Rings fabricated by weld build up and machined to the final dimensions. The material used for weld build-up shall be similar to that used for the base metal of vessel pressure envelope. c. On heavy wall vessels the entire ring supports (or part of them) may be integrally forged with cylindrical shells. d. After welding, the transition between the base metal of the rings and shell shall be ground smooth with a minimum radius of ¼” (6 mm). The fabrication method used shall be reviewed and approved by the Owner’s Engineer before award of the contract.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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5.2.11.21. Where fire protection is required the external surface of vessel supports shall be provided with fire proofing clips in accordance with the requirements presented in Suncor standards 0060 and 1003. 5.2.11.22. If not otherwise specified, standard drawing GD00A-N-0007/0001 shall be used as reference for the skirt supports requiring fireproofing. In addition all access openings shall be provided with bolted covers. Where installation of bolted covers is impractical or for the critical vertical vessels operating at temperatures in excess of 600°F (316°C) (such as reactors, coke drums, vacuum towers, coker fractionators) the skirt support internal surface shall also be fireproofed. 5.2.12. Corrosion Allowance 5.2.12.1.
Corrosion allowance shall be determined in accordance with ASME Section VIII, Div. 1, paragraph UG-25. The corrosion allowance shall be added to all pressure containing parts exposed to process as well as on all surfaces of non-removable internals. Unless otherwise specified, the minimum corrosion allowances shall be as follows; a. Carbon and low alloy steels ⅛” (3 mm). 1 b. Nonferrous and high alloy steels /32” (0.8 mm).
NOTE: Corrosion allowance applied on all surfaces of removable internals shall be considered half of the corrosion allowance for pressure envelope.
5.3.
5.2.12.2.
Any cladding and/or weld overlay shall be considered the equivalent of corrosion allowance. Consequently cladding and weld overlay shall not be considered as part of calculated minimum vessel thickness.
5.2.12.3.
Internal coatings may not be used where temperatures exceed 200°F (93 °C) in normal operation (or expected upset conditions such as steam-out) without Owner’s Engineer approval.
Materials 5.3.1.
General
5.3.1.1.
Cast steels shall not be used in the fabrication of pressure vessels.
5.3.1.2.
Materials used in fabrication of vessel pressure envelope shall be selected from the list presented in Appendix A. Different materials will require Owner review and special approval before award of the contract or PO.
5.3.1.3.
The use of ASME materials categories P3, P5B, P6 and P7 shall be avoided in the fabrication of pressure vessel envelope.
5.3.1.4.
Solid high alloy steels used for fabrication of the pressure boundary, shall be selected based on the following restrictions; a. Ferritic type stainless steels (such as type 400 series) shall not be used.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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b. Austenitic type stainless steels (such as type 300 series) shall have low carbon content (0.03%) and/or stabilized in order to avoid sensitization of weld metal and heat affected zone. 5.3.1.5.
All carbon steel components used in fabrication of pressure envelope shall be fully killed.
5.3.1.6.
All low alloy ASME P4 materials (1 Cr-½ Mo and 1¼ Cr-½ Mo) shall meet the specific requirements presented in Appendix B.
5.3.1.7.
All low alloy ASME P5A and P5C materials (2¼ Cr-1 Mo, 2¼ Cr-1 Mo-¼ V, 3 Cr-1 Mo and 3 Cr-1 Mo-¼ V) shall meet the specific requirements presented in Appendix C.
5.3.1.8.
In accordance with reference in paragraph 3.2.7.2, design of carbon steel pressure vessels, shall be restricted as follows; a. Normal operating temperature shall be limited to not more than 750°F (399°C), for vessels designed to operate at pressures over 100 psig (689 kPag) and/or with a wall thickness of 2” (50 mm) and over. Maximum graphitization degree of the steel structure shall not exceed 5% after 30 years of continuous operation. b. Subject to Owner’s Engineer approval, and only for vessels designed in accordance with ASME Code Section VIII, Division 1, maximum operating temperature can be increased to 800°F (427°C), if design pressure is limited up to 100 psig (680 kPag) and vessel wall thickness does not exceed 2” (50 mm). This is to ensure the maximum degree of graphitization does not exceed 10% after 30 years of continuous operation. c. Subject to Owner’s Engineer approval, and only for vessels designed in accordance with ASME Code Section VIII, Div.1, temperature excursions up to 825°F (440°C) can be accepted only on vessels with MAWP not exceeding 100 psig (689 kPag) and with a wall thickness not exceeding 2” (50 mm). The design shall also require a temperature monitoring program to ensure excursion time up to 825 °F does not result in graphitization levels that would impact vessel life. In no case shall the total accumulated excursion time exceed 25,000 hours through the vessel lifetime. For these applications, the fabricator shall provide supplementary material coupons installed inside of the vessel envelope that will be used to monitor the degree of graphitization.
5.3.1.9.
The limits in Table 3 below shall be considered for selection of materials used for pressure envelope; Table 3 Design Temp. °F (°C)
ASME P no.
Operating Temp. °F (°C)
Design Limitations
P4
900 (482)
1000 (538)
Div.1 only
P4
800 (427)
850 (454)
Div.2 only
P5A
800 (427)
850 (454)
Div.1 and Div.2
P5C
850 (454)
900 (482)
Div.1 and Div.2
For materials not listed, the limitation shall be in accordance with ASME Section II. Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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5.3.1.10.
Carbon Steel materials used for vessel supports and exposed to temperatures between -20°F (-29°C) and 500°F (260°C) may be fabricated from SA283 Gr.C, or Gr.D, SA516 Gr.60 or Gr.70.
5.3.1.11.
Vessel supports, exposed at temperatures lower than -20°F(-29°C), shall be fabricated of materials and use weld procedures suitable for the lowest ambient temperature. Material toughness shall be provided in MTR or shall be confirmed by additional Charpy “V” impact tests (minimum 3 tests per heat). Minimum absorbed energy shall be not lower than 15 ft-lb (20 J).
5.3.1.12.
All welding procedures used for external attachment welds to the vessel shall be qualified to the vessel MDMT.
5.3.1.13.
External welded attachments required for vessels operating at temperatures over 750°F (400°C), shall be fabricated from similar materials (same P number) as that used for the vessel pressure envelope.
5.3.1.14.
For vessels operating at temperatures below 750°F (399°C), lifting lug materials shall be based on the required single use or permanent design.
5.3.1.15.
Materials required for pressure envelope of vessels subjected to PWHT shall meet the required mechanical properties after being exposed to two PWHT cycles. In such a case the required mechanical properties shall be clearly specified in vessel data sheet.
5.3.2.
Plates
5.3.2.1.
All carbon steel plates used for fabrication of pressure envelope shall be normalized. Plates ½” (12 mm) thick and thinner may be accepted as rolled (not normalized) in services other than the ones presented in paragraphs 4.8 to 4.9. Special heat treatments required to improve mechanical properties (such quench-tempering or normalizing and tempering) shall be clearly specified in vessel data sheet.
5.3.2.2.
Formed ferritic plates (such as heads) made of carbon steel or low alloy steel shall be supplied with the following supplementary requirements; °
a. On all plates designed to operate in low temperature service [below -20 F (-29°C)] or made of materials with improved toughness properties, the grain size shall be determined in accordance with ASTM E-112. The grain size shall be ASTM #5 or finer. The results shall be reported on the mill test certificate. Presence of Widmanstatten structure is not acceptable. 5.3.3.
Bolts And Nuts
5.3.3.1.
Bolts and nuts used as parts of pressure envelope and their temperature limitations shall be as per Table 4 below;
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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Material SA 193-B7 / SA 194-2H
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Table 4 Min. Temp. °F (°C) Div.1 UCS 66 or Div.2 Table 3.4
Max. Temp. °F (°C) 800 (427)
-20 (-29°C)
1000 (538) [Div.1] 800 (427) [Div.2]
-55 (-48)
800 (427)
SA 193-B8M / SA 194-8M
-325 (-198)
1200 (649) [Div.1] 800 (427) [Div.2]
SA 320-L7M / SA 194-4
-150 (-101)
650 (343)
SA 193-B16 / SA 194-4 SA 193-B7M / SA 194-2HM
5.3.3.2. 5.4.
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Internal, non-pressure retaining bolting shall be of the same material as the vessel internals (solid, cladding or weld overlay).
Fabrication 5.4.1.
Welding shall comply with Suncor Standard 0903 requirements.
5.4.2.
All pressure retaining welds (part of vessel pressure envelope) shall be full penetration, using registered welding procedures (WPS) supported by proper procedure qualification records (PQR).
5.4.3.
The preferred type of weld geometry shall be completed from both sides (weld with backing). In cases of closing seams or in the cases where the access for welding is limited to one side, the root pass shall be welded using a WPS that will assures the required mechanical (particularly toughness) properties.
5.4.4.
Vessels subjected to PWHT shall have all the internal and external non-removable attachments welded prior to the stress relieve heat treatment.
5.4.5.
Where due to design, construction or transportation constraints some external attachments cannot be welded prior to PWHT, a buttering layer of weld or fillet welded pad shall be attached on the vessel surface (in the location where the attachment will be welded) prior to the heat treatment. The buttering layer option shall be a minimum of ⅜” (9 mm) thick completed with at least two passes.
5.4.6.
Small attachment welds can be provided after final PWHT under the following restrictions;
5.4.6.1.
Total length of fillet weld shall not exceed 16” (400 mm).
5.4.6.2.
The total thickness of weld deposit shall not exceed ⅜” (9 mm) and shall be provided in multiple passes.
5.4.6.3.
The weld will not be used as pressure retaining component.
5.4.6.4.
The weld shall not intersect any other pressure retaining welds.
5.4.6.5.
Vessel pressure envelope is made of carbon steel.
5.4.6.6.
The attachment weld is provided on vessel external surface.
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5.4.6.7.
The local thickness of pressure envelope shall not exceed 1¼” (32 mm).
5.4.6.8.
During the welding process, the preheat temperature shall be maintained at 250°F (121°C) or higher.
5.4.6.9.
The WPS and PQR shall be qualified to provide an as welded deposit with hardness not exceeding 200 HB.
5.4.6.10.
Minimum thickness of pressure envelope measured at the location of attachment weld is ¾” (19 mm).
5.4.7.
PWHT equipment shall have the following stencilled on two locations 180° apart in clearly visible letters, “STRESS RELIEVED – DO NOT WELD”. The same note shall also be marked on the insulation jacketing at two locations 180° apart by either stencil or weatherproof label.
5.4.8.
The PWHT temperature shall not be lower than;
5.4.8.1.
1125°F (607°C) for ASME P1 materials (Carbon Steel).
5.4.8.2.
1250°F (677°C) for ASME P4 materials (1 Cr-½ Mo and 1¼ Cr-½ Mo)
5.4.8.3.
1275°F (691°C) for ASME P5A and P5B Gr.1 materials (2¼ Cr-1 Mo)
5.4.9.
Minimum PWHT temperature of carbon steel materials (P1) containing traces of vanadium exceeding 0.004% shall be determined as follows; PWHT temperature = 1100 + 3260 x (V% - 0.004) where; V% = Vanadium content [%] NOTE: Alternate PWHT procedures at lower temperatures for extended period of time shall not be used.
5.4.10. All machined faces, flange faces and threaded connections shall be protected against oxidation due to PWHT. 5.4.11. Vessel circumferential welds shall be located to facilitate visual inspection with all internals installed in place. 5.4.12. All attachment welds subjected to external loads that may induce a stress in pressure envelope exceeding 30% of allowable limit, shall be welded with full penetration on the pressure envelope (complete fusion) for the full length of the weld and shall be free from defects including undercut, overlap, or abrupt ridges or valleys. 5.4.13. On vessels operating at temperatures exceeding 800°F (427°C), all welds shall be ground smooth to eliminate sharp corners and edges. A gradual transition from weld surface to the base metal is required to eliminate stress concentration points. 5.4.14. All skirt support butt welds shall be full penetration type. 5.4.15. For all vertical vessels provided with skirt supports and minimum 8 anchor bolts, an anchor bolt template shall be fabricated and supplied for construction of foundation. The bolt holes in the template shall be perforated simultaneously with the ones provided in the support base plate. The Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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template shall be provided either with anchor bolts guiding sleeves or shall be double plate type. Total height of the template shall not be smaller than the height of anchor bolt chairs or the distance between top of compression ring and bottom of support base plate. 5.4.16. The internal surface on vessels provided with internals organized as removable cartridge shall be checked with a template to ensure that the assemblies can be inserted and withdrawn without interference or binding. The diameter of the template shall be no smaller than the specified ID of the vessel minus 1/16” (2 mm). 5.4.17. A jig set shall be used to fix the flange alignment and the distance between the instrument connections required for level gauges or for level controllers with bridles. 5.4.18. All arc strikes and/or temporary attachment welds present on fabricated pressure envelope shall be removed. The base metal surface shall be properly conditioned by grinding in order to eliminate the defects and surface stress risers. After surface conditioning the area shall be MT or PT examined. Any defects found shall be repaired and re-examined. 5.5.
Inspection And Testing 5.5.1.
Supplementary specific requirements for vessels fabricated of P4 and P5 steels are provided in Appendix B and Appendix C.
5.5.2.
Except otherwise specified, all carbon steel plates thicker than ½” (12 mm), shall have the bevelled edges MT or PT examined. If open laminations are present, then all adjacent surfaces shall be UT examined in order to determine the extent of the defect. The defect may be repaired with the following restrictions;
5.5.2.1.
The plate material is carbon steel P1.
5.5.2.2.
The total extent of defect before repair is within the limits defined in ASME SA-20.
5.5.3.
RT examination shall be provided on the butt welds for;
5.5.3.1.
Vessels that meet ALL the following requirements shall be “SPOT” examined and stamped “RT-3”; a. Vessels designed in accordance with ASME Code Section VIII, Div.1 b. Vessels that will operate in General Service or, if designed to operate in Sour Service, will have internal surfaces protected by cladding or weld overlay. c. Vessels are not subjected to cyclic service. d. Vessels are not subjected to sustained vibrations (other than induced by wind or earthquake). e. Vessels have a maximum wall thickness of 1¼” (32 mm). f. Vessels not subjected to PWHT.
5.5.3.2.
Vessels that meet ALL the following requirements shall be “FULL” examined in accordance with the definition provided in ASME Code Section VIII, Div.1 paragraph UG-116 (e)(2) and UW-11(a)(5) and stamped “RT-2”;
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a. Vessels designed in accordance with all requirements presented in paragraph 5.5.3.1. b. Vessels on which for economic reasons the weld efficiency “E” needs to be considered equal to 1.0. 5.5.3.3.
Vessels that meet ANY of the following requirements shall be “FULL” examined in accordance with the definition provided in ASME Code Section VIII, Div.1 paragraphs UG116 (e)(1) and UW-11(a)(2) to UW-11(a)(4) and stamped “RT-1”; a. Vessels designed in accordance with ASME Code Section VIII, Div.2. b. Vessels subjected to cyclic service. c. Vessels subjected to sustained vibrations (other than induced by wind or earthquake). d. Vessels subjected to PWHT. NOTE: Due to restrictions imposed by fabrication schedule, availability or due to limitations of equipment used for RT examination and/or for economic reasons, the RT examination may be partially or totally replaced with automated UT in accordance with ASME Code Case 2235 and standard PQA-GS-0019.
INT
5.5.4.
Manual UT examination in accordance with ASME Code Section VIII, Div.1, Appendix 12 or ASME Code Section VIII, Div.2, paragraph 7.5.4 shall be applied on the following welds.
5.5.4.1.
Corner welds (“D” category) of pressure envelope on vessels that meet ANY of the following requirements; a. All vessels designed in accordance with ASME Code Section VIII, Div.2. b. Vessels subjected to cyclic service. c. Vessels subjected to sustained vibrations (other than induced by wind or earthquake). d. Vessels subjected to PWHT.
5.5.4.2.
Butt welds of vessel pressure envelope that meet ANY of the following requirements; a. On vessels subjected to PWHT, to be used as an alternate to RT examination required after PWHT. b. On closing seams and other butt welds with access restricted from one side.
INT
5.5.4.3.
All weld build-ups applied inside or outside of vessel pressure envelope.
5.5.4.4.
All welds between “Set-on” nozzles and vessel pressure envelope.
5.5.5.
MT examination in accordance with ASME Code Section VIII, Div.1, Appendix 6 or ASME Code Section VIII, Div.2, paragraph 7.5.6 shall be applied on the following welds on materials with ferritic structure;
5.5.5.1.
Internal and external surfaces of pressure envelope welds on vessels that meet ANY of the following requirements;
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a. Vessels subjected to cyclic service. b. Vessels subjected to sustained vibrations (other than induced by wind or earthquake). c. Vessels subjected to PWHT. 5.5.5.2.
The surface of internal attachment welds that meet ANY of the following requirements; a. Attached on vessels designed in accordance with ASME Code Section VIII, Div.2. b. Attached on vessels subjected to cyclic service. c. Attached on vessels subjected to sustained vibrations (other than induced by wind or earthquake). d. Subjected to high loads (stress induced in vessel envelope exceed 20% of allowable limit. e. Attached on vessels subjected to PWHT.
5.5.5.3.
The surface of external attachment welds that meet ANY of the following requirements; a. Attached on vessels subjected to cyclic service. b. Attached on vessels subjected to sustained vibrations (other than induced by wind or earthquake). c. Attached on vessels subjected to PWHT. d. Subjected to high loads (stress induced in vessel envelope exceed 20% of allowable limit). e. Attachment welds between vessel pressure envelope and pipe supports
5.5.5.4. INT
5.5.6.
The surface of the weld between skirt support and base plate as well as between the skirt support and compression ring.
PT examination in accordance with ASME Code Sec.VIII, Div.1, Appendix 8 or Section VIII Div.2, paragraph 7.5.7 can be used in lieu of MT examination in the following situations;
5.5.6.1.
All cases presented in paragraphs 5.5.5.1 to 5.5.5.4 when vessel pressure envelope is fabricated from austenitic stainless steels (steels without ferromagnetic properties) or on the internal surfaces protected by austenitic stainless steel used as cladding and/or weld overlay.
5.5.6.2.
On all external attachment welds subjected to light loads (stress induced in vessel envelope is lower than 20% of allowable limit).
5.5.6.3.
On all internal attachment welds subjected to light loads (stress induced in vessel envelope is lower than 20% of allowable limit) on vessels designed to operate in General service.
5.5.7.
MP or PT examination shall be carried out on all formed surfaces (knuckles and flares) such as formed heads and conical transitions designed to operate at temperatures below –20°F (-29°C).
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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After forming process, the following supplementary NDE shall be performed on all formed heads fabricated from welded segments that will operate in services at temperatures below –20°F (-29°C), or when due to the forming process the extreme fiber is elongated more than 5% and welding is performed prior to forming;
5.5.8.1.
All welds between the segments shall be 100% radiographed in accordance with ASME Code, Section VIII, Div.1 or Div.2.
5.5.8.2.
All welds between the segments shall be MT or PT examined in accordance with ASME Code, Section VIII, Div.1 or Div.2.
5.5.9.
Weld overlay shall be PT examined in accordance with ASME Code Sec.VIII, Div.1, Appendix 8 or Section VIII Div.2, paragraph 7.5.7. Where weld overlay surface will be machined, the examination shall be performed after machining. If heat treatment is required, the examination shall be provided after heat treatment. Unless otherwise specified by client or process licensor, the extent of PT examination shall cover;
5.5.9.1.
All weld overlay restoration (applied over the pressure retaining welds)
5.5.9.2.
Minimum 50% of weld overlay applied over internal surface of nozzles.
5.5.9.3.
Minimum 10% of weld overlay applied over internal surface of shells and heads.
5.5.10. Hardness examination shall be performed on weld deposits and adjacent heat affected zones (HAZ) as follows; 5.5.10.1.
Brinell hardness on external or internal surfaces of pressure retaining welds subjected to PWHT - Minimum one reading per weld.
5.5.11. The shop hydrotest of new vessels shall be performed in accordance with the following requirements; 5.5.11.1.
The test pressure shall be calculated based on vessel MAWP (corroded). For vertical vessels the test pressure shall also have included the equivalent static head of flooded vessel on operating position.
5.5.11.2.
Any required internal coating and/or external priming/painting shall be applied after the hydrotest.
5.5.11.3.
The test temperature shall not be lower than the greater of the two following calculated values; a. MDMT +30°F (+17°C) b. NDT +60°F (+24°C), where NDT is determined in accordance with ASTM E208.
5.5.11.4.
For vessels clad with (or fabricated from) austenitic stainless steel the chloride content in the water used for hydrotest shall be lower than 50 ppm.
5.5.11.5.
Vertical vessels shall be properly supported to prevent any plastic deformation, buckling or denting of pressure envelope.
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5.5.12. The field hydrotest of new or existing vessels shall be performed in accordance with the following requirements; 5.5.12.1.
The top test pressure shall be calculated based on vessel MAWP (corroded).
5.5.12.2.
Any new required internal coating and/or external priming/painting shall be applied after the hydrotest.
5.5.12.3.
The test temperature shall not be lower than the greater of the two following calculated values; a. MDMT + 50°F (MDMT + 28°C) b. FTP, where FTP is determined in accordance with ASTM E208.
5.6.
5.5.12.4.
For vessels clad with or fabricated with austenitic stainless steel, the chloride content in the water used for the hydrotest shall be lower than 50 ppm.
5.5.12.5.
If water with chloride content less than 50 ppm is not available, then water containing more than 50 ppm chloride but no more than 250 ppm may be used only if the duration of the test procedure is 72 hours or less and includes rinsing the vessel with water containing less than 50 ppm chloride immediately upon completion of the hydrotest. The test and rinsing procedure shall be subject to review and approval by the Owner’s Engineer.
Documentation and Approval Requirements 5.6.1.
The Supplier shall furnish the following documents for each fabricated equipment;
5.6.1.1.
Manufacturer's Data Report (Code form).
5.6.1.2.
Detailed drawings showing the "as built" dimensions of the completed vessel. Copies of the Vendor's certified shop drawing showing dimensional changes, if any. Fabrication drawings shall include the following information; a. All applicable Codes and Standards. b. The following vessel weights; Fabricated weight; Empty weight; Operating Weight. See paragraph 5.2.3 for details. c. Nozzle size, rating, facing, location, projection, diameter and thickness of reinforcement pad, and attachment weld sizes. d. Support mounting dimensions and location. e. Location and details for all appurtenances such as platform clips, pipe support clips, davits, insulation support rings, fireproofing supports, stiffening rings, etc f. Overall vessel dimensions. g. Thickness of pressure containing components (base metal and cladding thickness shall be shown separately). h. Nameplate with data included.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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5.6.1.3.
Material test reports on all components requiring documentation by the Code, including certificates for bolting materials.
5.6.1.4.
Test reports provided on weld deposits and HAZ (where applicable)
5.6.1.5.
Copy of the hydrostatic test pressure chart.
5.6.1.6.
Copy or rubbing of the nameplate, including Code stamping.
5.6.1.7.
Records of all weld NDE, including map of all weld seams, weld identification, extent of examination performed, and full report of all results.
5.6.1.8.
All design calculations.
5.6.1.9.
Vacuum or external pressure rating of vessel.
5.6.1.10.
Heat treatment records, impact test results, and ultrasonic test results shall also be included when applicable. Heat treatment records shall include a copy of the temperature recording chart obtained during postweld heat treatment as well as hardness testing results. (The cycle of heating, soaking, and cooling shall be shown).
5.6.2. 5.7.
Number:
0601
It is the sole responsibility of the fabricator to apply and obtain all necessary approvals and registration from the local Regulatory Authorities.
Special Service Requirements 5.7.1.
This section provides additional requirements for vessels designed to operate in special services. The designer is cautioned to ensure the appropriate requirements for each applicable service environment are addressed and that more than one service requirement may be applicable.
5.7.2.
Material and Fabrication Requirements for Equipment in Sour, Amine, Caustic, Hydrogen, Hydrofluoric Acid or Cyclic service as described in paragraphs 4.8 thru 4.13
5.7.2.1.
Stamping or indentation marking shall not be allowed on a vessel internal surface for clad equipment.
5.7.2.2.
For new construction, no welding, hammering or cutting shall be performed after PWHT. Any grinding performed after PWHT shall ensure metal temperatures are kept below 500°F (260°C).
5.7.2.3.
Connections smaller than NPS 1½” shall not be used.
5.7.2.4.
All internal attachment welds shall be full penetration type.
5.7.3.
Material and Fabrication Requirements for Equipment in Sour Service or Hydrofluoric (HF) Acid Service
5.7.3.1.
Base materials shall conform with requirements of NACE MR0103 or MR0175/ISO 15156 as applicable.
5.7.3.2.
Carbon Steel plates shall have the following requirements; a. Vacuum degassed and normalized.
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b. Material chemistry shall be restricted as follows; INT
i. S ≤ 0.003% ii. P ≤ 0.012% iii. V ≤ 0.015% iv. Cb ≤ 0.015% v. V + Cb ≤ 0.02% Chemical analysis reported on Certified Material Test Reports shall include Cb, V, Ti, S, P, Ni, Mo, Cr, Cu 5.7.3.3.
Plates shall be 100% UT examined, in accordance with ASME SA 578 Scanning S1, acceptability Level C. Repair of defects requires Owner’s Engineer approval.
5.7.3.4.
For carbon steels, the maximum permissible Carbon Equivalent (C.E.) for plate materials shall be 0.43 for materials less than 1” thick and 0.45 for thicknesses 1 inch and greater where; C.E. = C + Mn/6 + (Ni + Cu)/15 + (Cr + Mo + V)/5 where all values are in weight percent. Deliberate additions of Boron or Titanium are not permitted.
5.7.3.5.
All cold formed heads of carbon or low alloy steels shall be stress relieved or normalized after forming. If the hot forming temperature is equal to or greater than the normalizing temperature then additional normalizing heat treatment after completion of forming will not be required. In the case that normalizing is provided then the mechanical properties of material shall be reconfirmed.
5.7.3.6.
MP or PT examination shall be carried out on all formed surfaces (knuckles and flares) such as formed heads and conical transitions.
5.7.3.7.
After forming process, the following supplementary NDE shall be performed on all formed heads fabricated from welded segments. a. All welds between the segments shall be 100% RT examined in accordance with ASME Code, Section VIII, Div.1 or Div.2. b. All welds between the segments shall be MT or PT examined in accordance with ASME Code, Section VIII, Div.1 or Div.2.
5.7.3.8.
Carbon steel forgings except the standard components such as flanges fabricated in accordance with ASME B16.5 or B16.47 shall be; a. 100% UT examined (after machining) in accordance with ASME SA 388 and ASME Code Section V Article 5. Any defect which does not meet the requirements presented in ASME Code Section VIII Div.1 Appendix 12 or Section VIII Div.2 paragraph 3.3.4, shall be rejected. b. Vacuum degassed and normalized or quenched and tempered.
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c. Provided with material chemistry restricted as follows; INT
i. S + P ≤ 0.015% ii. C.E. ≤ 0.45%. 5.7.3.9.
Bolting material which is part of a vessel pressure envelope shall be ASME SA 193, Gr. B7M (bolts) and ASME SA 194, Gr. 2HM (nuts).
5.7.3.10.
For carbon and low alloy steels, PWHT shall be required after fabrication is complete.
5.7.3.11.
All internal attachment welds shall be full penetration type and designed to permit access for inspection.
5.7.3.12.
Welds on vessels shall be examined as follows; a. “FULL” RT of butt welds in accordance with the definition provided in ASME Code Section VIII, Div.1 paragraphs UG-116 (e)(1) and UW-11(a)(2) to UW-11(a)(4) and stamped “RT-1”. b. Manual UT examination in accordance with ASME Code Section VIII, Div.1, Appendix 12 or ASME Code Section VIII, Div.2, paragraph 7.5.4 shall be applied on category D (Corner welds) of pressure envelope.
INT
c. For carbon and low alloy steels, WFMT examination is required according to ASME Code Section VIII, Div.1, Appendix 6 or ASME Code Section VIII, Div.2, paragraph 7.5.6 on all accessible internal welds. 5.7.3.13.
5.7.4.
Material and Fabrication Requirements for Carbon Steel Equipment in Amine Service
5.7.4.1. 5.7.5.
For severe sour services, the designer may consider the use of corrosion resistant weld overlay, cladding or solid alloy construction in lieu of carbon steel construction to address corrosion and cracking risks. This decision will be subject to Owner’s Engineer approval.
All equipment shall be PWHT after fabrication is complete to avoid Amine Stress Corrosion Cracking (ASCC).
Material and Fabrication Requirements for Hydrogen Service
5.7.5.1.
Carbon steel shall not be used in fabrication of vessels exposed to Hydrogen Service (paragraph 4.10).
5.7.5.2.
On vessels in hydrogen service, the weld detail between the nozzle and vessel envelope shall be in accordance with ASME Sec.VIII, Div.1, figure UW-16 (f-2) and (f-4) or Sec.VIII, Div.2, table 4.2.13 so that they can be RT examined.
5.7.5.3.
All external attachments on vessels operating in Hydrogen Service, shall be welded with full penetration on the pressure envelope.
5.7.5.4.
All nozzles shall be integrally self reinforced type.
5.7.5.5.
The attachment between the bottom head and skirt support shall be provided as a weld build-up or as a forged ring.
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5.7.5.6.
Leg or lug type supports may not be used.
5.7.5.7.
Reinforcing pads shall not be used.
5.7.5.8.
All welds shall be ground smooth to eliminate sharp corners and edges. A gradual transition from weld surface to the base metal is required to eliminate stress concentration points.
5.7.5.9.
MP or PT examination shall be carried out on all formed surfaces (knuckles and flares) such as formed heads and conical transitions.
5.7.5.10.
After forming process, the following supplementary NDE shall be performed on all formed heads fabricated from welded segments; a. All welds between the segments shall be 100% RT examined in accordance with ASME Code, Section VIII, Div.1 or Div.2. b. All welds between the segments shall be MT or PT examined in accordance with ASME Code, Section VIII, Div.1 or Div.2.
5.7.5.11.
5.7.6.
Material and Fabrication Requirements for Caustic Service
5.7.6.1.
5.7.7.
All cold formed heads made of low alloy steel shall be stress relieved or normalized after forming. If the hot forming temperature is equal to or greater than the normalizing temperature then additional normalizing heat treatment after completion of forming will not be required. In the case that normalizing is provided then the mechanical properties of material shall be reconfirmed.
Equipment in caustic service shall be designed in accordance with requirements in Figure 1, Caustic Soda Service Chart, of NACE RP0403-2003. The requirements for PWHT shall also be applicable to cold formed heads.
Material and Fabrication Requirements for Cyclic Service
5.7.7.1.
The following requirements are in addition to those given in paragraph 5.2.5 for cyclic loads.
5.7.7.2.
Where conical elements are used they shall be complete with torical transitions on the large end (knuckle type).
5.7.7.3.
“Set-on” type nozzles shall not be used.
5.7.7.4.
The mean diameter of the heads shall match the mean diameter of the skirt support.
5.7.7.5.
Leg or lug type supports may not be used.
5.7.7.6.
Reinforcing pads shall not be used.
5.7.7.7.
All welds shall be ground smooth to eliminate sharp corners and edges. A gradual transition from weld surface to the base metal is required to eliminate stress concentration points.
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APPENDIX A – TYPICAL FABRICATION MATERIALS A.1. PLATES Material Carbon Steels - P1 Low alloy Steels - (1 Cr – ½ Mo) Low alloy Steels - (1¼ Cr – ½ Mo – Si) Low alloy Steels - (2¼ Cr – 1 Mo) Low alloy Steels - (2¼ Cr – 1 Mo – ¼ V) Low alloy Steels - (3 Cr – 1 Mo) Low alloy Steels - (3 Cr – 1 Mo – ¼ V) High alloy Steels - P8 (e.g.: 304L, 316L, 317L)
ASME P no. P1 P4 P4 P5A P5C P5A P5C P8
ASME Standard SA 516 Gr.70 & 65 & 60 SA 387.12 Cl.1 & 2 SA 387.11 Cl.2 SA 387.22 Cl.1 & 2 SA 832.22V; SA 542.D Cl.4a SA 387.21 Cl.1 & 2 SA 832.21V; SA 542.C Cl.4a SA 240
ASME P no. P1 P4 P4 P5A P5C P5A P5C P8
ASME Standard SA 105; SA 350.LF2 SA 182.F12 Cl.1 & 2 SA 182.F11 Cl.1 & 2 SA 182.F22 Cl.1 & 3 SA 182.F22V SA 182.F21 SA 182.F3V SA 182
ASME P no. P1 P4 P4 P5A P5C P5A P5C P8
ASME Standard SA 266.2; SA 266.4 SA 336.F12 SA 336.F11 Cl.1 & 2 & 3 SA 336.F22 Cl.1 & 3 SA 336.F22V SA 336.F21 Cl.1 & 3 SA 336.F3V SA 336
ASME P no. P1 P4 P4 P5A P5C P5A P5C P8
ASME Standard SA 106.B; SA 333.6 SA 335.P12 SA 335.P11 SA 335.P22; SA 369.FP22 N/A SA 369.FP21 N/A SA 312
A.2. SMALL FORGINGS Material Carbon Steels - P1 Low alloy Steels - (1 Cr – ½ Mo) Low alloy Steels - (1¼ Cr – ½ Mo – Si) Low alloy Steels - (2¼ Cr – 1 Mo) Low alloy Steels - (2¼ Cr – 1 Mo – ¼ V) Low alloy Steels - (3 Cr – 1 Mo) Low alloy Steels - (3 Cr – 1 Mo – ¼ V) High alloy Steels - P8 (e.g.: 304L, 316L, 317L) A.3. LARGE FORGINGS Material Carbon Steels - P1 Low alloy Steels - (1 Cr – ½ Mo) Low alloy Steels - (1¼ Cr – ½ Mo – Si) Low alloy Steels - (2¼ Cr – 1 Mo) Low alloy Steels - (2¼ Cr – 1 Mo – ¼ V) Low alloy Steels - (3 Cr – 1 Mo) Low alloy Steels - (3 Cr – 1 Mo – ¼ V) High alloy Steels - P8 (e.g.: 304L, 316L, 317L) A.4. PIPES Material Carbon Steels - P1 Low alloy Steels - (1 Cr – ½ Mo) Low alloy Steels - (1¼ Cr – ½ Mo – Si) Low alloy Steels - (2¼ Cr – 1 Mo) Low alloy Steels - (2¼ Cr – 1 Mo – ¼ V) Low alloy Steels - (3 Cr – 1 Mo) Low alloy Steels - (3 Cr – 1 Mo – ¼ V) High alloy Steels - P8 (e.g.: 304L, 316L, 317L)
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A.5. FITTINGS Material Carbon Steels - P1 Low alloy Steels - (1 Cr – ½ Mo) Low alloy Steels - (1¼ Cr – ½ Mo – Si) Low alloy Steels - (2¼ Cr – 1 Mo) Low alloy Steels - (2¼ Cr – 1 Mo – ¼ V) Low alloy Steels - (3 Cr – 1 Mo) Low alloy Steels - (3 Cr – 1 Mo – ¼ V) High alloy Steels - P8 (e.g.: 304L, 316L, 317L)
ASME P no. P1 P4 P4 P5A P5C P5A P5C P8
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
ASME Standard A 234.WPB; SA 420.WPL6 SA 234.WP12.Cl.1, SA 369.FP12 SA 234.WP11.Cl.1, SA 369.FP11 SA 234.WP22.Cl.1, SA 369.FP22 N/A N/A N/A SA 403
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APPENDIX B – SUPPLEMENTARY REQUIREMENTS FOR VESSELS FABRICATED OF 1 CR-½ MO AND 1¼ CR-½ MO STEELS Unless otherwise specified, all materials type 1 Cr-½ Mo and 1¼ Cr-½ Mo shall meet the following supplementary requirements; B.1. MATERIALS B.1.1.
B.1.1.1.
Roll bonded cladding shall be avoided due to the possibility of disbonding caused by hydrogen. Where cladding is required, explosion bonded cladding or weld overlay shall be used to protect the vessel internal surface.
B.1.1.2.
The materials used for fabrication of the pressure envelope shall be Quenched and Tempered (Q&T).
B.1.2.
INT
At design temperatures of 750°F (399°C) and higher, in hydrogen service;
Chemical analysis for each material heat. As a minimum the analysis shall present the concentration (%) of the following elements; C, Si, Mn, Cr, Mo, V, Nb, Ti, Cu, Ni, P, S, Sn, Sb, As. The materials shall have the following restricted chemistry;
B.1.2.1.
C < 0.15%
B.1.2.2.
Cu < 0.20%
B.1.2.3.
Ni < 0.30%
B.1.2.4.
P < 0.007%
B.1.2.5.
S < 0.007%
B.1.2.6.
PSR = Cr + Cu + 2 x Mo + 10 x V + 7 x Nb + 5 x Ti – 2 < 0 reference [3.2.6.3]
B.1.2.7.
X bar = (10 x P + 5 x Sb + 4 x Sn + As) / 100 < 15
B.1.2.8.
The chemistry shall be tested with a frequency of one per each melt, heat or batch.The chemistry shall be tested with a frequency of one per each melt, heat or batch.
or (S+P < 0.014%)
reference [3.2.6.3]
B.1.3.
On quench and tempered materials, tensile tests at room and design temperature shall be performed. The tested material shall have been subjected to an equivalent of 3 PWHT. The yield strength shall not be lower than the tabulated values presented in ASME Sec. II D, table “Y-1”.
B.1.4.
Charpy V impact tests shall be performed according to the methodology presented in API 934A to determine the temperature at which the absorbed energy is 40 ft-lb (T40 temperature). A minimum of 18 specimens (3 specimens at 6 different temperatures) shall be used to generate the transition temperature curve. The tested material shall have been exposed to an equivalent of 3 PWHT cycles. The T40 temperature shall be used as reference value to determine vessel MDMT. The test shall be applied on each heat and/or batch of material (plates, pipes, fitting, forgings).
B.1.5.
Hardness shall not exceed 225 BHN. Test frequency to be 3 tests per each heat or batch.
B.1.6.
100% UT examination shall be provided on all custom forgings (after machining) and plates (heads after forming) used for pressure envelope. As a minimum, the test shall be done as follows;
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B.1.6.1.
All forgings - Surface scan in accordance with SA 388 and ASME Sec. V, Article 5. For vessels designed to operate in Hydrogen Service, in addition to ASME acceptance criteria, any defect which cannot be encompassed within ¼” (6 mm) diameter sphere, shall be rejected.
B.1.6.2.
All plates - Full surface scan in accordance with SA 578 scanning S1. The acceptance level is Level C. For vessels designed to operate in Hydrogen Service, in addition to ASME acceptance criteria, any defect which cannot be encompassed within ¼” (6 mm) diameter circle, shall be rejected.
B.1.7.
All welding consumables to be used shall have the “X” factor limited to 15. The Cu and Ni content shall be limited to 0.20% and respectively 0.30%. Minimum test frequency shall be one per each heat.
B.2. FABRICATION
INT
B.2.1.
All nozzles shall be self reinforced type.
B.2.2.
The nominal chemistry of welding consumables shall match the nominal chemistry of the base materials.
B.2.3.
All welding consumables shall be low hydrogen (max. of 8 ml hydrogen per 100 g of weld metal) H8 as per AWS 4.3. The coated consumables as well as the flux shall be baked and stored in accordance with manufacturer’s specifications.
B.2.4.
The qualification of each WPS shall include Charpy V impact test provided to determine the temperature at which the absorbed energy is 40 ft-lb (T40). This temperature shall be used as reference value to determine the vessel MDMT. Minimum 18 (eighteen) specimens extracted from a weld deposit coupon shall be used to determine T40.
B.2.5.
All welds performed on pressure envelope (including the attachment welds) shall be preheated at a minimum temperature of 300°F (149°C) through all base metal thickness. The preheating shall be maintained during the welding process. For welds 3” and thicker the preheat shall be maintained without interruption until its completions when a DHT or ISR will be provided.
B.2.6.
Any attachment weld to the pressure envelope shall be full penetration type. The transition between the attachment and vessel envelope shall be ground smooth and flush to the vessel surface with a transition radius not smaller than ¼” (6 mm).
B.2.7.
External clips attached to the pressure envelope shall be;
B.2.7.1.
Fabricated from materials with similar chemistry as the vessel base metal and shall be attached, by a full penetration weld, directly to the vessel surface.
B.2.7.2.
The clips may be fabricated from different type of steel welded on top of a buttering layer applied on the vessel surface. The clip shall be welded on top of this layer with full penetration.
B.2.8.
On vessels with a wall thickness exceeding 3” (75 mm), after completion of welding an Intermediate Stress Relief (ISR) heat treatment shall be performed on all restrained welds (such as welds around the nozzles). The ISR shall be provided at minimum 1100°F (593°C) for a period of time not shorter than 2 hours.
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On vessels with a wall thickness exceeding 3” (75 mm), all circumferential and longitudinal butt welds shall receive a Dehydrogenation Heat Treatment (DHT). The DHT shall be provided at minimum 600°F (316°C) for a period of time not shorter than 2 hours.
B.2.10. The final PWHT shall be performed at a minimum temperature of 1275°F (691°C). The PWHT temperature shall be maintained constant for a period of time equal to; Total minimum time [hours] = Shell thickness [in] x 1 hour B.3. NON DESTRUCTIVE EXAMINATION (NDE) B.3.1.
The following NDE sequence shall be provided during the fabrication process;
B.3.1.1.
The following NDE shall be performed prior to final PWHT;
B.3.1.1.1. MT examination on all edges prepared for welding (plates and forgings). B.3.1.1.2. MT examination of formed plates required on pressure envelope (on heads after forming). B.3.1.1.3. MT examination of any temporary external attachment welds, after they have been removed and the surface ground smooth. B.3.1.1.4. RT examination of all pressure retaining butt welds. RT examination can be replaced by computerized UT examination in accordance with Code Case 2235 and standard PQA-GS-0019. B.3.1.1.5. Where applicable, RT examination on all butt welds of the Cr-Mo portion of the skirt support. B.3.1.1.6. Where internal ring supports (fabricated as weld build-up or full penetration welded on vessel surface) are provided, manual UT examination of the junction between vessel surface and internal support rings (provided from outside of pressure envelope). B.3.1.1.7. Where applicable, 10% UT examination of weld overlay bonding (provided from outside of pressure envelope). B.3.1.1.8. Where applicable, PT examination on entire surface of the first layer of weld overlay (applicable only if a second layer of weld overlay will be applied after final PWHT). B.3.1.1.9. Where 300 series stainless steel weld overlay is applied on vessel internal surface, Ferrite number readings of the weld overlay are required before final PWHT. The limitation of ferrite content shall be in accordance with Standard 0903. Readings are required on each element covered with weld overlay as well as on each weld overlay restoration applied over the circular seams. Test frequency is one reading per each weld overlay restoration and each surface covered with weld overlay. B.3.1.2.
The following NDE shall be performed after final PWHT but prior to the hydrotest;
B.3.1.2.1. RT examination of all pressure retaining butt welds. RT examination can be replaced by computerized UT examination in accordance with Code Case 2235 and standard PQA-GS-0019. For vessel designed in accordance with ASME Section VIII Div.2 the
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computerized UT examination shall follow the requirements provided in paragraph 7.2.2 of the Code. B.3.1.2.2. All the other pressure retaining welds shall be manual UT examined. B.3.1.2.3. Where applicable, manual UT examination of the junction between vessel surface and internal support rings (from outside). B.3.1.2.4. Where applicable, manual UT examination of the junction between pressure envelope and skirt support. B.3.1.2.5. Where applicable, manual UT examination of the weld overlay deposit, from outside, as follows; a. All surfaces covered with weld overlay applied on nozzles. b. All weld overlay applied over the base metal seams. B.3.1.2.6. Where applicable, manual UT examination of the weld overlay surface within 2” on both sides of support rings as well as on the machined surfaces of weld overlay (from inside). The examined surface shall be free of any disbondment. B.3.1.2.7. Where applicable, PT examination of all finished weld overlay surfaces. B.3.1.2.8. Hardness tests of the weld deposit after final PWHT. Test frequency shall be two (2) locations per weld. The maximum hardness shall not exceed the limit provided in Standard 0903. The tests shall be performed on external surface. B.3.1.2.9. Hardness tests on the weld deposit of all butt welds located on the Cr-Mo portion of skirt support. The test frequency shall not be less than two (2) locations per weld. The maximum hardness shall not exceed 225 BHN. B.3.1.3.
The following NDE shall be performed after hydrotest;
B.3.1.3.1. MT examination of all external attachment welds. B.3.1.3.2. Where applicable, MT examination of the junction between the skirt and vessel envelope. B.3.1.3.3. MT examination of all butt welds on pressure envelope (from outside) and from inside if there is no internal cladding/weld overlay. B.3.1.3.4. If internal cladding and/or weld overlay is applied on vessel internal surface, PT examination of all internal attachment welds. B.3.1.4.
Chemical analysis tests of 300 series stainless steel weld overlay. As a minimum, the concentration of the following elements shall be provided in the inspection report; C, Cr, Ni, Cb, Mo and V. The acceptable limits shall be in accordance with the requirements provided in Standard 0903.
B.3.1.5.
Production Charpy V impact tests on the weld metal and HAZ at the temperature determined in accordance with the requirements presented in paragraph B.2.4. One set of 3 specimens shall be provided for each WPS and for each batch of welding
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consumables. The specimens shall be heat treated to an equivalent of 3 PWHT cycles. The absorbed energy shall not be lower than 40 ft-lb. Run-off tabs shall be used wherever possible.
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APPENDIX C – SUPPLEMENTARY REQUIREMENTS FOR VESSELS FABRICATED OF 2¼ CR-1 MO, 2¼ CR-1 MO-¼ V, 3 CR-1 MO AND 3 CR-1 MO-¼ V STEELS The requirements presented in this appendix are supplementing the requirements for design and fabrication of vessels designated to operate in Hydrogen Service at high pressure and high temperature (reference 3.2.6.4). C.1. DESIGN C.1.1. At design temperatures of 750°F(399°C) and higher, in hydrogen service, roll bonded cladding shall be avoided due to the possibility of disbonding caused by hydrogen. Where cladding is required, explosion bonded cladding or weld overlay shall be used to protect the vessel internal surface. C.1.2. The shell components shall be fabricated as follows; INT
C.1.2.1.
Integrally forged cylinders for wall thickness exceeding 6” (150 mm).
C.1.2.2.
Rolled plates for wall thickness 6” (150 mm) or smaller.
C.1.3. For thicknesses exceeding 2” (50 mm), the formed or forged heads shall be hemispherical type. C.1.4. On vertical vessels, the junction between the bottom head and the skirt support shall be designed as follows; C.1.4.1.1. Integral forged ring (“Y” ring), fully machined, in accordance with ASME Sec.VIII, Div.2 table 4.2.5, detail 7. C.1.4.1.2. Machined weld build-up. All corners and transitions of the weld build-up shall be rounded in order to reduce stress concentrations. Minimum radius shall not be less than ½” (12 mm). C.1.4.1.3. Within the limitations imposed by shell thickness, the end of the shell may be fully machined to accommodate the transition required to bottom head and skirt support. C.1.5. Dissimilar welding techniques between parts of the pressure envelope shall be avoided. All pressure boundary components shall have the same nominal material chemistry. C.1.6. Internal rings designated to support catalyst beds or any other trays, shall be fabricated in accordance with one of the following alternatives; C.1.6.1.
Integrally forged with the vessel body.
C.1.6.2.
Partially forged with the vessel shell with the remainder of the ring fabricated from weld build-up. The minimum height of the forged portion of these rings shall be ½” (12 mm).
C.1.7. All nozzles shall be forged self-reinforced type designed for butt-welding in accordance with ASME Sec.VIII, Div.1 fig. UW 16.1 (details f1 to f4) or in accordance with ASME Code Section VIII, Div. 2 table 4.2.13. INT
C.1.8. For vessels designed in accordance with ASME Code Section VIII, Div.2, all custom made flanges that will be bolted on piping system shall be designed in accordance with ASME Code Section VIII, Div.2 paragraph 4.16 and using the allowable stresses defined for ASME Section VIII, Div.1. Flange geometry shall allow the possibility of using hydraulic bolting tensioners.
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C.1.9. External welded attachments on the pressure envelope shall be reduced to minimum. C.1.10. The insulation supports shall not be welded directly to the vessel surface. Insulation supports shall be strapped around the vessel surface. C.1.11. On the vertical vessels provided with skirt support, the space between the external surface of the bottom head and the top of skirt internal surface shall be provided with a minimum 10” (250 mm) deep hot box. See the additional requirements presented in paragraph 3.6.11. C.2. MATERIALS INT
C.2.1. The materials used for fabrication of shells, heads and large nozzles as well as for transition between bottom head and skirt support shall be Quenched and Tempered (Q&T). C.2.2. Unless otherwise specified, all gaskets shall be spiral wound type 321 stainless steel windings and graphite filler. All gaskets shall be provided with external rings. The manway gasket shall also be provided with 321 type stainless steel inner retention ring.
INT
INT
C.2.3. All internal welded attachments subjected to negligible mechanical loads (maximum 10 ksi stress in the welds), can be attached by full penetration welding directly on the vessel internal surface before the final PWHT or, where applicable, on the weld overlay surface after the final PWHT. The weld shall have a smooth transition to the vessel surface with a radius of minimum ¼“ (6 mm). C.2.4. Where required, the weld overlay can be completed in one layer welding technique (such as 309 LNb or 309 LMo stainless steel) or multi-layer welding technique using a combination of type 309L as a first layer and type 309 LNb or 309 LMo stainless steels as second layer. C.2.5. The materials used for pressure envelope components shall meet the following requirements; C.2.5.1.
The chemistry of pressure envelope base metal shall be restricted as follows;
C.2.5.1.1. C = max 0.13% C.2.5.1.2. Cu = max 0.20% C.2.5.1.3. Ni = max 0.25% C.2.5.1.4. Si = max 0.5% C.2.5.1.5. Mn = max 0.35% C.2.5.1.6. “J” factor = (Si + Mn) x (P + Sn) x 10,000 < 100 C.2.5.2.
For material less than 4“ (100 mm) thick;
C.2.5.2.1. S = max. 0.007% C.2.5.2.2. P = max. 0.007% C.2.5.3.
or S + P < = 0.014%
For material with thickness 4” (100 mm) and greater;
C.2.5.3.1. S = max. 0.005% C.2.5.3.2. P = max. 0.010%
or S + P = max. 0.014%
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C.2.5.4.
Records of chemical analysis for each material heat or batch shall present the concentration (%) of the following elements; C, Cr, Mo, V, Cu, Ni, P, S, Sn, Sb, As, Si, Mn.
C.2.5.5.
Cooling from the austenitizing temperature shall result in a minimum 90% bainite. Fabricator shall provide records of austenitizing and tempering temperatures as well as photographic records including metallography for each material heat or batch. The photographic records shall be provided on specimens located at half thickness.
C.2.5.6.
Materials shall be selected such that their mechanical properties are acceptable as specified on the equipment data sheet after the equivalent of three (3) full PWHT cycles and the required ISR.
INT
C.2.5.7.
Fabricator shall provide test data indicating the mechanical properties (Tensile strength, Yield strength and Toughness) on heat-treated (Q&T) materials exposed to simulated minimum (one cycle) and maximum (3 cycles) PWHT. In all cases the Yield strength values shall not be lower than the tabulated values presented in ASME Code Section II D, Table Y-1. The Tensile strength values shall not be lower than 90% of the tabulated values presented in ASME Code Section II D, Table U. The tests shall be performed at room temperature.
INT
C.2.5.8.
Fabricator shall perform Step Cooling Tests using the step temperatures, holding times and cooling rates in accordance with API 934A paragraph 5.5.3.2, applied on two (2) sets of specimens with minimum eighteen (18) specimens per set. The specimens shall be subjected to the following heat treatments;
C.2.5.8.1. Set 1 - Exposed to an equivalent of minimum PWHT cycle to determine the transition temperature curve before step cooling heat treatment. C.2.5.8.2. Set 2 – Exposed to an equivalent of maximum PWHT cycle plus the step cooling heat treatment. C.2.5.8.3. After heat treatment, the specimens shall be Charpy V-notch impact tested at a minimum six (6) different temperatures (3 specimens at each temperature) in accordance with paragraph 6.2.3.1 of API 934A in order to develop two (2) transition curves. C.2.5.8.4. If not otherwise specified the acceptance criteria for the 40 ft-lb (55J) absorbed energy shall be in accordance with the following formulas; For base metals; For weld deposit;
CV (TT 40) + 3 × ΔCV (TT 40) ≤ 32° F CV (TT 40) + 3 × ΔCV (TT 40) ≤ 50° F
where: CV (TT 40) = Temperature corresponding to 40 ft-lb (55J) energy obtained on specimens exposed to minimum PWHT cycle. ΔCV (TT 40) = Shift of Temperature (temperature difference) corresponding to 40 ft-lb (55J) energy obtained on specimens exposed to maximum PWHT cycle and step cooling heat treatment. The test specimens shall also satisfy the requirements presented in ASME Code Section VIII, Div.2 paragraph 3.11.3 or ASME Code Section VIII, Div.1 paragraph UG84. They have to be extracted form half thickness of material. Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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As a minimum, the number of step cooling tests required on materials shall be established as follows;
C.2.5.9.1. Custom made forgings used for shells and nozzles - The test shall be applied on each material heat. C.2.5.9.2. Plates – The test shall be applied on the heat with the highest “J” factor. C.2.5.9.3. Welding consumables – The test shall be applied on weld deposits made of each batch or lot. In situations where flux has been changed for a given batch, each batch and flux combination shall require testing. C.2.5.10. Material hardness (3 tests per each material heat) shall not exceed 225 BH for conventional Cr- Mo steels and 235 BH for Cr-Mo-V steels. C.2.5.11. 100% UT examination shall be provided on all custom forgings (after machining) and plates (heads after forming) used for pressure envelope. As a minimum, the test shall be done as follows; C.2.5.11.1. All forgings - Surface scan in accordance with SA 388 and ASME Sec. V, Article 5. For vessels designed to operate in Hydrogen Service, in addition to ASME acceptance criteria, any defect which cannot be encompassed within ¼” (6 mm) diameter sphere, shall be rejected. C.2.5.11.2. All plates - Full surface scan in accordance with SA 578 scanning S1. The acceptance level is Level C. For vessels designed to operate in Hydrogen Service, in addition to ASME acceptance criteria, any defect which cannot be encompassed within ¼” (6 mm) diameter circle, shall be rejected. C.2.5.12. All surfaces of forgings as well as the formed plates shall be MT examined in accordance with API 934A paragraph 8.2.2. All bevels shall also be examined. C.2.6. The nominal chemistry of all welding consumables shall match the nominal chemistry of the base materials. C.2.7. All welding consumables including fluxes shall be low hydrogen (max. of 8 ml hydrogen per 100 g of weld metal) H8 per AWS A4.3. C.2.8. Coated welding consumables as well as the flux shall be baked and stored per manufacturers recommended practice. Fabricator shall provide for review and approval of the standard procedure used to handle the flux, electrodes and other welding consumables which may absorb humidity from ambient. C.2.9. For welding consumables, the Bruscato “X” factor shall not exceed 15 ppm. C.3. FABRICATION C.3.1. All welds required on pressure envelope shall be full penetration type. Any butt weld shall be ground smooth to the vessel surface. Any external or internal projection of the weld deposit shall be limited to maximum ⅛” (3 mm).
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C.3.2. Any attachment weld to the pressure envelope shall be full penetration type. Transition between the attachment and vessel envelope shall be ground smooth and flush to the vessel surface with a transition radius not smaller than ¼“ (6 mm). C.3.3. External clips attached to the pressure envelope shall be; C.3.3.1.
Fabricated from materials with similar chemistry as the vessel base metal and shall be attached, by a full penetration weld, directly to the vessel surface.
C.3.3.2.
The clips may be fabricated from different type of steel welded on top of a buttering layer applied on the vessel surface. The clip shall be welded on top of this layer with full penetration.
C.3.4. All joints between the nozzles and vessel body shall be fabricated with the bevels designed for butt-welding. C.3.5. All consumables used throughout all the fabrication process shall be similar (same brand name, type and source of fabrication) to that used for the PQR associated with the qualified and approved WPS. No equivalent substitute shall be allowed. C.3.6. When welding the basemetal of pressure envelope, the thickness of weldmetal deposited per pass shall typically be ¼” (6 mm). Welds having thicker weldmetal deposition per pass are not acceptable due to their low toughness. C.3.7. As a minimum, each welding procedure specification (WPS) used on the pressure envelope shall be qualified in accordance with API 934A, paragraph 7.2. The Step Cooling Test required for WPS qualification, shall be developed in accordance with the requirements presented in API 934A paragraph 6.2.3. C.3.8. The FCAW welding process shall not be used for any weld required for the vessel pressure envelope or for the low alloy portion of skirt support. FCAW may be used only for weld overlay application. C.3.9. All welds performed on the pressure envelope (including the attachment welds) shall be preheated in accordance with the requirements presented in API 934A paragraph 7.3.1. The preheat temperature shall be maintained without interruption until the weld is finished and an Intermediate Stress Relief (ISR) or Dehydrogenation Heat Treatment (DHT) is performed. C.3.10. All restrained welds and any unrestrained weld with a thickness 7” (178 mm) and greater shall be subjected to ISR heat treatment in accordance with the requirements presented in API 934A paragraph 7.3.2.2. The ISR temperature shall not be lower than 1250°F (677°C) and shall be maintained for minimum 2 hours for weld thicknesses up to 7” (178 mm) and minimum 4 hours for weld thicker than 7” (178 mm). INT
INT
C.3.11. For unrestrained welds with thickness less than 7” (178 mm), the application of DHT in accordance with API 934A paragraph 7.3.2.3 may replace the ISR. The minimum DHT temperature shall not be lower than 690°F (366°C) and shall be maintained for minimum 4 hours. C.3.12. The ESW process may be utilized with Owner’s Engineer approval with the following restrictions; C.3.12.1. Maximum permissible strip width is 5“ (125 mm).
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C.3.12.2. The flux used for production welding shall be identical to that used for procedural qualification. C.3.13. Multiple pass weld overlay (first layer of type 309L followed by a minimum one layer of 309LCb or 309LMo) is required on the following surfaces; C.3.13.1. All nozzle internal surfaces. C.3.13.2. Each flange face. The minimum thickness of the last pass weld overlay shall be 3/16” (5 mm). After weld overlay application, the seal face of the flange shall be machined. Minimum thickness of last finished layer of weld overlay shall be ⅛” (3 mm). C.3.13.3. The overlay restoration applied over the butt welds around each nozzle. C.3.13.4. All surfaces of each support ring including the transition zone between the ring and the shell surface. After weld overlay application, the upper surface of each ring support shall be machined. The minimum thickness of last layer of weld overlay shall be ⅛” (3 mm). C.3.13.5. When weld overlay is applied by manual or semi-automatic welding process. C.3.14. The entire weld overlay shall be applied before the final PWHT with the exception that the second pass of weld overlay, provided in accordance with the requirements presented in the previous paragraph shall be applied after the final PWHT. C.3.15. All WPS to be used for weld overlay application shall be supported by PQR’s containing disbonding test results and acceptance criteria. The test coupon shall be 100% UT examined 10 days after cool down and shall have zero percent disbondment. As an alternative, previously qualified disbonding test results can be submitted for review and approval by Owner’s Engineer where representative of the proposed WPS and operating conditions. As a minimum, the disbonding test procedure shall meet the requirements presented in API 934A, paragraphs 7.5.2.3 and 7.5.2.5. C.4. NON DESTRUCTIVE EXAMINATION C.4.1. The following NDE shall be performed prior to final PWHT; C.4.1.1.
UT examination of the heads after forming and prior to weld overlay application. Test shall be performed in accordance with SA 578 Scanning S1. Maximum acceptable size of defect shall not exceed ¼“ (6 mm). Any crack type defects shall be rejected.
C.4.1.2.
MT examination on all edges prepared for welding.
C.4.1.3.
MT examination on all external attachment welds.
C.4.1.4.
MT examination of any temporary attachment welds, after they have been removed and the surface ground smooth.
C.4.1.5.
MT examination of the welds between the vessel envelope and supports.
C.4.1.6.
Where applicable, MT examination on all butt welds on the skirt support as well as on the weld between skirt and base ring.
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C.4.1.7.
RT examination, or UT examination in accordance with Code Case 2235 and standard PQA-GS-0019 of all circumferential and longitudinal butt welds between cylindrical shells and heads (after ISR or DHT). The fabricator shall prove that computerized UT examination will be able to detect defects not larger than 1/16” oriented in any direction across the weld and HAZ.
C.4.1.8.
RT examination, or manual UT examination on all circumferential butt welds around the nozzles or other restrained butt welds not specified above (after ISR).
C.4.1.9.
Manual UT examination of the weld build-up applied on internal rings after finishing (machining) of weld overlay surface (from machined weld overlay surface).
C.4.1.10. PT examination on first layer of weld overlay. The examination is required only where the second layer of weld overlay will be applied after final PWHT. C.4.1.11. Determination of ferrite number (FN) on weld overlay surface. C.4.1.12. PMI examination. C.4.2. The following NDE shall be performed after final PWHT but prior to the hydrotest; C.4.2.1.
UT examinations in accordance with Code Case 2235 to the maximum possible extent of all butt welds. The fabricator shall prove that computerized UT examination will be able 1 to detect defects not larger than /16” (1.6 mm) oriented in any direction across the weld and HAZ.
C.4.2.2.
Manual UT examination of all remaining butt welds.
C.4.2.3.
Manual UT examination of all junctions between the shell and internal ring supports (from outside of the vessel envelope).
C.4.2.4.
Manual UT examination of the junction between the bottom head and the skirt support.
C.4.2.5.
Manual UT examination (from outside of the vessel envelope) of the weld overlay applied on the following surfaces;
C.4.2.6.
All nozzles.
C.4.2.7.
All shells and heads.
C.4.2.8.
Manual UT examination of the weld overlay surface within 2” (50 mm) on both sides of support rings as well as on the machined surfaces of weld overlay (from inside). NOTE: Unless otherwise specified by client or process licensor, maximum acceptable defect size of any disbondment shall not exceed ¼“ (6 mm) diameter. The location of all defects shall be mapped and presented to the Client for review and approval. The maximum density of acceptable defects shall not exceed the ratio of one defect per 10 ft² ( 1 m²). No defects are acceptable within the weld overlay applied on nozzle surfaces, on weld overlay restoration over the pressure welds as well as on the weld overlay applied on the ring supports.
C.4.2.9.
PT examination of all finished weld overlay surfaces.
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C.4.2.10. Hardness tests of the welds of vessel pressure envelope. Test frequency shall be in accordance with API 934A, paragraph 7.4.2 but not less than two (2) locations per weld. The hardness (minimum one test per weld) shall not exceed 225 BH for conventional CrMo steels and 235 BH for Cr-Mo-V steels. C.4.2.11. Hardness tests on the weld deposit of all butt welds located on the low alloy portion of skirt support. The test frequency shall not be less than two (2) locations per weld. The hardness (minimum one test per weld) shall not exceed 225 BH for conventional Cr- Mo steels and 235 BH for Cr-Mo-V steels. C.4.3. The following NDE shall be performed after vessel hydrotest; C.4.3.1.
PT examination of all internal attachment welds.
C.4.3.2.
Spot PT examination of the weld overlay.
C.4.3.3.
Manual UT examination of all locations where defects were detected prior to the hydrotest.
C.4.3.4.
Chemical examination of the weld overlay. Chemical analysis tests of type 347 or type 316L weld overlay deposit shall be within the standard limits for a depth of minimum 0.1” measured from process surface. The concentration of the following elements shall be determined; C, Cr, Ni, Cb, Mo and V. As a minimum, the test frequency shall be of two (2) samples per each independent surface covered with weld overlay. This request is in addition to the qualification of the WPS/PQR.
C.4.4. Defect acceptance criteria for RT technique shall be in accordance with ASME Code SEC.VIII, Div.1, Appendix 4 or Section VIII Div.2, paragraph 7.5.3 with the supplementary restriction that maximum acceptable defect size shall be limited to ¼“ (6 mm) regardless of thickness. No cracks, undercuts, lack of fusion, concave root, incomplete penetration, or sharp corners and transitions will be accepted. C.4.5. Defect acceptance criteria for UT technique shall be in accordance with ASME Code Sec.VIII, Div.1, Appendix 12 or Section VIII Div.2, paragraphs 7.5.4 and 7.5.5 with the supplementary restriction that maximum acceptable defect size shall be limited to ¼“ (6 mm) regardless of thickness. C.4.6. The junctions between the vessel body and all internal support rings as well as between the bottom head and the skirt support shall be free of cracks, undercuts, lack of fusion, incomplete penetration, or sharp corners and transitions. C.4.7. Defect acceptance criteria for MT technique shall be in accordance with ASME Code Sec.VIII, Div.1 Appendix 6 or Section VIII Div.2, paragraph 7.5.6. C.4.8. Defect acceptance criteria for PT technique shall be in accordance with ASME Code Sec.VIII, Div.1, Appendix 8 or Section VIII Div.2, paragraph 7.5.7. C.4.9. Ferrite number readings of the weld overlay shall be performed before final PWHT. The acceptable range shall be restricted between 4 and 10. Readings are required on each element covered with weld overlay as well as on each weld overlay restoration applied over the circular seams one reading per seam. The test frequency shall be as follows;
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C.4.9.1.
Minimum six (6) ferrite readings on the surface surrounding each location selected on the shell, heads and ring supports.
C.4.9.2.
Minimum two (2) ferrite readings on the surface surrounding each location selected on weld overlay restoration applied over strength welds and nozzles.
C.5. POST WELD HEAT TREATMENT C.5.1. If furnace is used, the chemistry of the flue gas shall be controlled so that the concentration of excess oxygen will be kept to a minimum. C.5.2. If local PWHT will be required, the length of heated zone shall not be shorter than (R x t)0.5 on each side of the weld where “R” is the vessel external radius in inches (mm) and “t” is the wall thickness in inches (mm). C.5.3. During the local PWHT cycle, any portion of the wall within a length of (R x t)0.5 adjacent to the furnace shall be maintained at a temperature not lower than 400°F (204°C). C.5.4. Due to the possibility of overlay embrittlement and cracking induced by the formation of sigma phase during PWHT cycle, the weld overlay shall receive minimum exposure to the PWHT. The fabricator shall sequence the weld overlay application considering both the ISR and PWHT cycles.
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APPENDIX D – SUPPLEMENTARY REQUIREMENTS FOR HEAVY WALL VESSELS D.1. GENERAL D.1.1. Heavy wall vessels represent all vessels with a wall thickness exceeding 2” (50 mm) regardless of the type of material used for pressure envelope. D.2. MATERIALS D.2.1. The yield strength (Sy) of the materials, shall not be lower than the tabulated values presented in ASME Section IID table Y-1. The actual tensile strength value shall be provided for information only. D.2.2. All plates shall be UT examined in accordance with SA 578 and the following requirements; D.2.2.1.
Materials for vessels designed to operate in General Service shall be scanned in accordance with SA 578, paragraph 5.6.1. The largest defect shall not exceed the limits provided in acceptance Level B.
D.2.3. All custom made forgings shall be UT examined in accordance with SA 388 and ASME Sec.V. Any defect, which cannot be encompassed within ½” (12 mm) dia. circle or does not meet ASME Code acceptance criteria, shall be rejected. D.2.4. All materials shall be Charpy “V” impact tested at MDMT temperature. D.2.5. All MTR’s for plates and forgings shall have a photomicrograph. The MTR’s shall document the ferrite structure and grain size, in accordance with ASTM E112. Presence of Widmanstatten structures or ferrite grain size coarser than #5 shall not be accepted. D.3. NOZZLES D.3.1. All nozzles shall be integrally self reinforced type. D.3.2. On vessels operating at temperatures over 750°F (399°C), as well as on vessels with pressure envelope of 3” (75 mm) and thicker, the weld detail between nozzle and vessel envelope shall be in accordance with ASME Sec.VIII, Div.1, figure UW-16 (f-2) and (f-4) or Sec.VIII, Div.2, table 4.2.13 so that they can be RT examined. D.3.3. Except where internal nozzle projection is specified, all nozzles shall be ground smooth and flush with the internal vessel surface. D.3.4. If not otherwise specified, all forgings required for nozzles shall be supplied in the Normalized and Tempered (N&T) or Quench and Tempered (Q&T) condition. The heat treatment shall be selected as such to ensure the uniformity of steel microstructure across thickness. D.4. FABRICATION D.4.1. All butt welded joints on pressure envelope shall be welded with full penetration from both sides. D.4.2. All internal attachments shall be welded with full penetration. D.4.3. All external attachments on vessels operating at temperatures over 750°F (399°C) shall be welded with full penetration on the pressure envelope. Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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D.4.4. All attachment welds on vessels operating over 750°F (399°C) shall be flush smooth to the vessel surface with a radius of ¼” (6 mm) or larger. D.5. NON DESTRUCTIVE EXAMINATION (NDE) D.5.1. All butt-welded joints on the pressure envelope shall be RT examined after final PWHT. D.5.2. RT examination may be replaced by computerized UT in accordance with ASME Code Case 2355 and standard PQA-GS-0019. The examination procedure shall be reviewed and approved by Owner’s representative prior to being used. D.5.3. All category “D” welds on the pressure envelope shall be UT examined after final PWHT. D.5.4. All edges prepared for welding shall be MT examined. D.5.5. All attachment welds (both internal and external) shall be MT examined after final PWHT. If vessel internal surface in covered with cladding or with weld overlay, the MT examination shall be replaced by PT examination.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
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APPENDIX E – NOZZLE LOADS FOR VESSELS FABRICATED FROM STEEL E.1. GENERAL E.1.1.
For sizes NPS 1½ thru NPS 24, refer to Table 6 below to establish nozzle load requirements.
E.1.2.
Nozzles NPS 30 and larger, the following formulas shall be used to determine forces and moments to be ued for nozzle design;
E.1.2.1.
Imperial units:
• Nozzles located on cylindrical shells: Radial Force FR = b x 449.6 x D Longitudinal Bending Moment ML = b x 95.9 x D² Circumferential Bending Moment MC =b x 73.8 x D² Resultant Bending Moment MR = (ML2 + ML2)1/2 = b x 121 x D2 • Nozzles located on heads: Radial Force Resultant Bending Moment E.1.2.2.
(lb) (ft-lb) (ft-lb) (ft-lb)
FR = b x 449.6 x D MR = b x 121 x D2
(lb) (ft-lb)
Metric units:
• Nozzles located on cylindrical shells: Radial Force FR = b x 2000 x D Longitudinal Bending Moment ML = b x 130 x D² Circumferential Bending Moment MC=b x 100 x D² Resultant Bending Moment MR = (ML2 + MC2)1/2 = b x 164 x D2 • Nozzles located on heads: Radial Force Resultant Bending Moment
(N) (N-m) (N-m) (N-m)
FR = b x 2000 x D MR = b x 164 x D2
(N) (N-m)
Where: D = Nozzle nominal diameter (in, for imperial and metric formulas) FR = Radial Force ML = Longitudinal bending moment MR = Circumferential bending moment b = factor based on flange class rating per Table 5 below; Flange Class Rating
150
Table 5 300 600
900
1500
2500
‘b’ factor
0.6
0.7
1.8
3.0
3.3
0.8
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E.1.2.3.
The loadings computed from these equations shall be considered as being caused by 67% thermal and 33% dead weight load.
E.1.2.4.
The pipe loads are considered acting at the junction between nozzle and vessel envelope per the orientations shown in Figure 2 below. Figure 2 FR
MC
ML
Table 6 Nozzle NPS
1½”
2”
3”
Class 150 300 600 900 1500 2500 150 300 600 900 1500 2500 150 300 600 900 1500 2500
FR (lb) 375 445 505 570 630 695 605 710 810 910 1010 1110 810 945 1,080 1,215 1,350 1,485
MC and ML (lb-ft) 103 125 125 125 148 148 184 184 243 243 273 273 428 428 553 723 856 856
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
FR (N) 1,668 1,979 2,246 2,535 2,802 3,092 2,691 3,158 3,603 4,048 4,493 4,938 3,603 4,204 4,804 5,405 6,005 6,606
MC and ML (N-m) 140 170 170 170 200 200 250 250 330 330 370 370 580 580 750 980 1,160 1,160 Page 61 of 66
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Table 6 Nozzle NPS
4”
6”
8”
10”
12”
14”
Class 150 300 600 900 1500 2500 150 300 600 900 1500 2500 150 300 600 900 1500 2500 150 300 600 900 1500 2500 150 300 600 900 1500 2500 150 300 600 900 1500 2500
FR (lb) 1,080 1,260 1,440 1,620 1,800 1,980 1,620 1,890 2,160 2,430 2,700 2,970 2,160 2,520 2,880 3,240 3,600 4,015 2,700 3,150 3,600 4,045 5,155 6,106 3,240 3,780 4,315 5,620 7,405 8,460 3,780 4,405 5,825 6,756 9,406 13,756
MC and ML (lb-ft) 804 804 1,070 1,298 1,696 1,696 2,124 2,537 3,054 3,747 5,008 5,060 3,968 4,212 4,868 7,708 9,604 10,408 6,653 8,777 10,149 13,432 16,463 18,669 9,139 9,817 15,563 20,992 26,163 28,892 10,363 11,949 19,104 25,875 33,620 43,474
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
FR (N) 4,804 5,605 6,405 7,206 8,007 8,807 7,206 8,407 9,608 10,809 12,010 13,211 9,608 11,210 12,811 14,412 16,014 17,860 12,010 14,012 16,014 17,993 22,930 27,160 14,412 16,814 19,194 25,000 32,940 37,630 16,814 19,594 21,150 30,050 41,840 61,190
MC and ML (N-m) 1,090 1,090 1,450 1,760 2,300 2,300 2,880 3,440 4,140 5,080 6,790 6,860 5,380 5,710 6,600 10,450 13,020 14,110 9,020 11,900 13,760 18,210 22,320 25,310 12,390 13,310 21,100 28,460 35,470 39,170 14,050 16,200 25,900 35,080 45,580 58,940
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Table 6 Nozzle NPS
16”
18”
20”
22”
24”
Class 150 300 600 900 1500 2500 150 300 600 900 1500 2500 150 300 600 900 1500 2500 150 300 600 900 1500 2500 150 300 600 900 1500 2500
FR (lb) 4,315 5,035 6,119 8,619 11,710 16,670 4,855 5,665 7,655 10,935 14,806 20,950 5,395 6,295 8,320 11,805 15,100 22,285 5,935 6,925 8,736 12,320 16,836 24,091 6,475 7,555 8,860 12,825 17,144 24,484
MC and ML (lb-ft) 12,701 16,530 18,765 35,154 44,949 57,584 14,951 21,708 34,011 46,299 59,030 75,346 17,024 26,089 42,375 57,400 70,131 92,871 18,824 30,315 50,931 68,641 88,453 113,908 20,247 35,715 59,170 81,571 103,094 132,761
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
FR (N) 19,194 22,397 27,220 38,340 52,090 74,150 21,596 25,199 34,050 48,640 65,860 93,190 23,998 28,002 37,010 52,510 67,170 99,130 26,400 30,804 38,860 54,800 74,890 107,160 28,802 33,606 39,410 57,050 76,260 108,910
MC and ML (N-m) 17,220 22,410 25,440 47,660 60,940 78,070 20,270 29,430 46,110 62,770 80,030 102,150 23,080 35,370 57,450 77,820 95,080 125,910 25,520 41,100 69,050 93,060 119,920 154,430 27,450 48,420 80,220 110,590 139,770 179,990
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APPENDIX F – INTERPRETATIONS The paragraph numbers referenced in this Appendix refer to the relevant paragraph in the main body of this Standard or within the preceeding Appendices and provide interpretations where the letter INT are denoted in the left hand margin. 5.2.1.3
ABSA (the Registration Boiler Branch in Alberta) interpret the term “Design Pressure” as the local pressure in any point of the equipment that is equal with the sum between the MAWP and design static head to that point. In accordance with this interpretation the “Design Pressure” can be equal with the MAWP or higher than it.
5.2.1.9
It is recommended that shop hydrotest pressure shall be calculated using vessel MAWP as a reference. That gives the possibility to repeat the hydrotest using the same pressure as indicated on the nameplate any time during the vessel operating lifetime.
5.2.2.2
In accordance with ASME Code paragraph UCS (from Div.1) or paragraph 3.11 (from Div.2), at temperatures lower than MDMT, it is possible to expose the material at a stress level that will not exceed approximately 16% of Yield Strength (approx. 30% of allowable stress per Div.1 or approx. 25% of design stress intensity per Div.2). At a stress level below this limit any crack tip will not propagate. See ASTM E208 for more information.
5.2.2.4
The “temper embrittlement” and “hydrogen embrittlement” deteriorate the mechanical properties of brand new materials (particularly the toughness gets reduced). Generally the temper embrittlement occurs when the high strength low alloy steels are exposed at temperatures between 950°F (510°C) and 1300°F (704°C) (within PWHT temperature range). Temper embrittlement is generated by separation of low melting temperature elements (such as Sn, Sb, As, P) at the boundary of the grain structure. The temper embrittlement is also time related. On 1 Cr and 1¼ Cr steels the effect is shadowed by carbide formation. Additional information about this phenomenon is provided in WRC275, and API 938. The hydrogen embrittlement occurs during the operation when the steel is exposed to Hydrogen Service. During operation the atomic hydrogen is absorbed in the metal structure. At shut-down, when the temperatures get reduced below 400°F (204°C), the absorbed hydrogen will recombine in molecular form and will generate a very high stress (>80,000 psi) that will lead to local plastic deformations, micro -cracks and formation of micro voids in the steel structure. Additional information is provided in WRC-275, WRC-305 and in reference 3.2.7.9. Another embrittlement that affects carbon steels is due to graphitization of steel structure. The graphitization occurs when the steel is exposed long time at temperatures exceeding 800°F (427°C). See reference 3.2.7.2 for more information.
5.4.9
This is an empirical formula resulted from a series of tests described in reference 3.2.7.11. As acceptable alternate, the PWHT temperature may be established experimentally for given purchased steel by using hardness test results provided on welded specimens exposed to different PWHT temperatures. The relation between hardness values and PWHT temperature shall indicate the limit over which the stress relaxation occurs.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
Page 64 of 66
MAJOR PROJECTS
Corporate Technical Standard Department: Subject:
PROJECT SERVICES Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
Number:
0601 Revision:
9
5.5.4, 5.7.3.12.b Manual UT examination provides the capability to detect three-dimensional and two-dimensional defects in the full penetration butt welds and “D” category welds but cannot properly be used to detect defects in fillet welds (attachment welds). 5.5.5
MT examination can be performed to detect superficial defects within 3/16” depth measured from weld surface. The type of detectable defects can be three-dimensional or two-dimensional oriented perpendicular to magnetic field.
5.5.6
PT examination shall be performed to detect only superficial open defects included within weld deposits or heat affected zone (HAZ).
5.7.3.2.b
5.7.3.8.c
The requirement applies only for the plates used for pressure envelope. The intent is; •
To limit the amount of S and P in order to avoid the defective steel structures generated by the presence of these two elements. Due to fabrication process steels with higher content of S and P will present a lamellar distributed structure (such as onion layers) cause by uneven segregation of perlite. The phenomenon is more relevant in thicker plates. Perlite is a brittle structure and will facilitate crack propagation as SOHIC, HIC, SCC sometime associated with blistering.
•
Limit the Vanadium and Columbium content. Sometime they are used as micro alloying elements in order to condition mechanical properties. As a side effect, their presence will also prevent the relaxation of residual stress at lower PWHT temperatures. Consequently when these two elements are present the PWHT temperature shall be substantially increased.
•
Limit the Carbon Equivalent (C.E.). Higher CE will increase the amount of brittle structures and the thickness of HAZ that will lead to a lower toughness.
To limit the amount of S and P in order to avoid the defective steel structures generated by the presence of these two elements. Due to fabrication process heavy forgings with higher content of S and P will have and uneven segregation of perlite. Perlite is a brittle structure and will facilitate crack propagation.
APPENDIX B B.1.4
The 18 specimens shall be divided in six groups of three specimens. Each group of specimens shall be impact tested at a specific temperature different from the other groups. The result shall be used to establish a toughness transition curve. This curve shall be used to determine the temperature at which the toughness is 40 ft-lb (T40). This temperature will be used as MDMT as long as the equipment will not be exposed to Hydrogen Service. In the case of Hydrogen Service, the MDMT will be represented by the sum between T40 and the additional temperature excursion induced by hydrogen embrittlement. See references 3.2.6.3, 3.2.7.1 for more information.
B.2.4
The 18 specimens shall be divided in six groups of three specimens. Each group of specimens shall be impact tested at a specific temperature different from the other groups. The result shall be used to establish a toughness transition curve. This curve shall be used to determine the temperature at which the toughness is 40 ft-lb (T40). This temperature will be used as MDMT as long as the equipment will not be exposed to Hydrogen Service. In the case of Hydrogen Service, the MDMT will be represented by the sum between T40 and the additional temperature excursion induced by hydrogen embrittlement. See references 3.2.6.3, 3.2.7.1 for more information.
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
Page 65 of 66
MAJOR PROJECTS
Corporate Technical Standard Department: Subject:
PROJECT SERVICES Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
Number:
0601 Revision:
9
APPENDIX C C.1.2.1
Even if the fabrication has the capacity of rolling thicker plates the concern is related with the quality (the frequency and size of defects) of longitudinal seams. Suncor does not accept using thicker plates due to increased probability of obtaining defects and the problems associated with the time required to repair these defects. In addition laboratory tests indicate that weld metal quality and structure is always lower that the one of base metal. Consequently this potential problem shall be avoided on thicker elements (associated with a higher design temperature and/or pressure).
C.1.8
The flanges belonging to the piping system connecting these nozzles are not designed for allowable stress that is equal with the one specified for Div.2.
C.2.1
In Hydroprocessing equipment (such as reactors) the required toughness of new material shall as high as possible. That is because this original toughness will get reduced during PWHT and in operation. Consequently the steel structure shall be bainite. The N&T heat treatment can not ensure a minimum 90% conversion of normalized structure into a bainitic one due to the improper cooling process during the Normalizing phase.
C.2.3
Negligible loads are considered the ones that generate a local stress not exceeding 10% of the allowable limit.
C.2.4
The weld overlay applied in a single layer technique can be accepted provided the weld overlay surface will not be embrittled as a result of PWHT.
C.2.5.7
The requirement asses the potential degradation of mechanical properties of original bainitic steel structure. It is requested for one PWHT cycle which is typically provided in fabrication process and also for 3 PWHT cycles that consider any shop and field repairs. These tests are mandatory because for this types of steels, the PWHT temperature is always higher than Tempering temperature and consequently the microstructure is modified by PWHT cycle.
C.2.5.8
The requirement asses the potential degradation of mechanical properties induced by embrittlement of steel structure. The PWHT temperature and the operating temperature induce a significant reduction of steel toughness. The requirement addresses the maximum range of toughness reduction that has to be used as reference when the Minimum Pressurization Temperature (MPT) is established.
C.3.11 The DHT shall be accepted only on not restrained welds such as longitudinal and circumferential butt welds on cylindrical shells and spherical heads. The DTH shall not be accepted on restrained welds such as the welds around the nozzles, the weld build-ups and the welds between mechanically loaded attachments and pressure envelope (i.e. internal ring supports). C.3.12 The ESW technique may be used only if the fabricator proves that he got long experience in using it on similar equipments. The acceptance of using ESW technique may be provided only after reviewing the welding procedure that has to incorporate the results of disbanding tests. This process shall not be accepted on combination of operating parameters exceeding 800°F (427°C) and 1500 psig (10,335 kPag). Also it is recommended to restrict the width of welding consumable (strip) to maximum 5” (125 mm).
Standard 0601, Rev 9, Pressure Vessels ASME Section VIII, Div. 1 and Div. 2
Page 66 of 66
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