30 December 2012 Engineering Technical Practice Engineering Group Instruction for Supply GIS 46-010 Pressure Vessels This “Revision for Review” has all tracked changes removed because of the extensive changes from the published version. The file with all changes tracked is available by request to: Michael Faulkner (BP Houston) [email protected] +1 281-366-0086
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30 December 2012
Engineering Technical Practice
Engineering
Group Instruction for Supply
GIS 46-010
Pressure Vessels
This “Revision for Review” has all tracked changes
removed because of the extensive changes from the
published version. The file with all changes tracked is
available by request to:
Michael Faulkner (BP Houston)
+1 281-366-0086
Pressure Vessels
Page 2 of 74 GIS 46-010
30 December 2012
Table of Contents
Page
Foreword ........................................................................................................................................ 6
1 Scope .................................................................................................................................... 7
2 Normative references ............................................................................................................. 7
3 Terms and definitions ............................................................................................................. 7
4 Symbols and abbreviations .................................................................................................... 9
5 General ................................................................................................................................ 10
5.1 Overall responsibilities .............................................................................................. 10
5.2 Manufacturer’s responsibilities .................................................................................. 11
5.3 Quality assurance ..................................................................................................... 11
6 Materials requirements ........................................................................................................ 12
6.1 General ..................................................................................................................... 12
6.2 Certificates of compliance ......................................................................................... 12
6.3 Certified material test reports .................................................................................... 12
7 Design requirements ............................................................................................................ 13
7.1 General ..................................................................................................................... 13
7.2 Load conditions ......................................................................................................... 13
7.3 Wind loading ............................................................................................................. 14
7.4 Seismic loading ......................................................................................................... 15
7.5 Snow loading ............................................................................................................ 15
7.6 Motion induced loads ................................................................................................ 15
7.7 Cyclic loading ............................................................................................................ 15
7.8 Local loading ............................................................................................................. 15
7.9 Wind-induced vibration of vertical vessels ................................................................. 15
7.10 Transportation loads ................................................................................................. 16
7.11 Lifting loads ............................................................................................................... 17
7.12 Design calculations ................................................................................................... 17
8 Vessel components.............................................................................................................. 18
Copyright © 2011 BP International Ltd. All rights reserved.
This document and any data or information generated from its use are classified, as a
minimum, BP Internal. Distribution is intended for BP authorised recipients only. The information contained in this document is subject to the terms and conditions of the
agreement or contract under which this document was supplied to the recipient's
organisation. None of the information contained in this document shall be disclosed outside the recipient's own organisation, unless the terms of such agreement or contract
expressly allow, or unless disclosure is required by law.
In the event of a conflict between this document and a relevant law or regulation, the
relevant law or regulation shall be followed. If the document creates a higher obligation, it
shall be followed as long as this also achieves full compliance with the law or regulation.
Pressure Vessels
Page 3 of 74 GIS 46-010
30 December 2012
8.1 Vessel shells and transitions ..................................................................................... 18
8.2 Formed heads ........................................................................................................... 18
8.3 Connections, nozzles, and manways ........................................................................ 19
8.4 Flanges ..................................................................................................................... 22
8.5 Blind flanges and bolted flat heads ........................................................................... 25
8.6 Quick-opening closures............................................................................................. 25
8.7 Quick-actuating closures ........................................................................................... 25
8.8 Supports ................................................................................................................... 25
8.9 Anchor bolts .............................................................................................................. 27
8.10 Internal attachments ................................................................................................. 27
8.11 External attachments ................................................................................................ 28
8.12 Removable internals ................................................................................................. 31
8.13 External jackets ........................................................................................................ 31
8.14 Nameplates ............................................................................................................... 32
9 Spares ................................................................................................................................. 32
10 Fabrication requirements ..................................................................................................... 32
10.1 General ..................................................................................................................... 32
10.2 Tolerances ................................................................................................................ 33
10.3 Joints ........................................................................................................................ 34
10.4 Welding ..................................................................................................................... 35
10.5 Temporary welded attachments ................................................................................ 38
11 Examination requirements ................................................................................................... 38
11.1 General ..................................................................................................................... 38
11.2 Preparation ............................................................................................................... 39
11.3 Examination of materials ........................................................................................... 40
11.4 Surface examination of welds ................................................................................... 40
11.5 Volumetric examination of welds ............................................................................... 41
11.6 Hardness testing ....................................................................................................... 42
11.7 Repair of welding defects .......................................................................................... 42
11.8 Positive materials identification (PMI) ........................................................................ 42
12 Inspection requirements ....................................................................................................... 42
13 Post weld heat treatment ..................................................................................................... 43
14 Pressure test........................................................................................................................ 43
14.1 General ..................................................................................................................... 43
14.2 Hydrostatic test ......................................................................................................... 45
14.3 Pneumatic test .......................................................................................................... 45
15 Cleaning, surface preparation, painting, and marking .......................................................... 46
15.1 Cleaning ................................................................................................................... 46
15.2 Surface preparation and painting .............................................................................. 46
15.3 Marking ..................................................................................................................... 47
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16 Preparation for shipment ...................................................................................................... 48
16.1 General ..................................................................................................................... 48
16.2 Preparations for the vessel ....................................................................................... 48
16.3 Preparations for spares and crated parts .................................................................. 49
16.4 Securing and padding ............................................................................................... 49
16.5 Material safety data sheets ....................................................................................... 50
17 Documentation ..................................................................................................................... 50
17.1 Proposal documentation ........................................................................................... 50
17.2 During design and fabrication ................................................................................... 51
17.3 Final documentation .................................................................................................. 53
Annex A (Normative) Supplementary requirements for special services ....................................... 55
A.1 General ................................................................................................................................ 55
A.2 Anhydrous ammonia service ................................................................................................ 55
A.3 Butane storage .................................................................................................................... 55
A.4 Amine service ...................................................................................................................... 55
A.5 Caustic service .................................................................................................................... 55
A.6 Cyanides service ................................................................................................................. 56
A.7 Cyclic service ....................................................................................................................... 56
A.8 Hydrofluoric acid .................................................................................................................. 56
A.9 Hydrogen service ................................................................................................................. 56
A.10 Low temperature service ...................................................................................................... 57
A.11 Propane storage .................................................................................................................. 57
A.12 Sour water, wet H2S, or wet sour service ............................................................................. 57
Annex B (Normative) Supplementary requirements for chrome-moly vessels ............................... 61
B.1 General ................................................................................................................................ 61
B.2 Fabrication ........................................................................................................................... 62
B.3 Examination requirements ................................................................................................... 62
B.4 1,25Cr-0,5Mo vessels (including Vanadium enhanced) ....................................................... 62
B.5 2.25Cr-1Mo vessels (including Vanadium enhanced) .......................................................... 62
Annex C (Normative) Supplementary requirements for stainless steel vessels ............................. 64
C.1 Fabrication ........................................................................................................................... 64
C.2 Welding ................................................................................................................................ 64
C.3 Examination requirements ................................................................................................... 64
Annex D (Normative) Supplementary requirements for clad plate or weld-overlay construction .... 66
D.1 Design ................................................................................................................................. 66
D.2 Clad plate material ............................................................................................................... 68
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D.3 Cladding re-instatement ....................................................................................................... 68
D.4 Weld overlay ........................................................................................................................ 69
D.6 Welding procedures ............................................................................................................. 70
D.7 Internal attachments ............................................................................................................ 71
D.8 Examination of weld overlay and clad re-instatement ........................................................... 71
D.8.1 UT examination ......................................................................................................... 71
D.8.2 PT examination ......................................................................................................... 72
D.8.3 Chemical analysis ..................................................................................................... 72
Annex E (Normative) Supplementary requirements DHT and IPWHT ........................................... 73
E.1 Dehydrogenation heat treatment .......................................................................................... 73
E.2 Intermediate post weld heat treatment ................................................................................. 73
List of Tables
Table 1 - Minimum transportation acceleration loadings ................................................................ 17
Table 2 - Minimum thickness of nozzles ........................................................................................ 20
Table 3 - Quality levels for straight beam examinations from flat surfaces .................................... 23
Table 4 - Flatness tolerances of gasket contact surface ................................................................ 34
List of Figures
Figure 1 - Skirts on vertical vessels of moderate pressure and temperature ................................. 26
Figure 2 - Skirts on high pressure, or high temperature, or cyclic service vessels ......................... 26
Figure 3 - Typical arrangement to prevent hold up of water at insulation rings .............................. 29
Figure 4 - Typical clad nozzle attachment to shell ......................................................................... 66
Figure 5 - Attachment of lightly loaded attachment to a clad vessel .............................................. 66
Figure 6 - Attachment of a moderately loaded attachment to a clad vessel ................................... 67
Figure 7 - Method for cladding a raised face flange ....................................................................... 67
Figure 8 - Unacceptable method for cladding a ring type joint flange ............................................ 67
Figure 9 - Cladding re-instatement at a vessel seam .................................................................... 69
Pressure Vessels
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Foreword
This is a revised issue of Engineering Technical Practice (ETP) GIS 46-010.
Due to extensive changes, revisions are not identified by a bar in the left margin, as is normal practice.
Significant content from the March 2012 edition of PIP VESV1002 has been
incorporated into this GIS as deemed appropriate.
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1 Scope
This GIS describes the design, fabrication, examination, inspection, testing, and documentation
requirements for pressure vessels designed, fabricated, and certified in accordance with one of the
following standards:
a. ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.
b. ASME Boiler and Pressure Vessel Code, Section VIII, Division 2.
c. BSI PD 5500.
d. European Standard EN 13445.
2 Normative references
The following referenced documents may, to the extent specified in subsequent clauses and normative
annexes, be required for full conformance to this GIS:
• For dated references, only the edition cited applies.
• For undated references, the latest edition (including any amendments) applies.
BP
GIS 18-013 Weld Overlay, Integral Cladding, and Limited Loose Lining of Pressure
Vessels and Other Components
GIS 36-102 Hardness Testing, Post Weld Heat Treatment, Stress Relief, and Pickling for
Pressure Vessels, Piping, and Other Components
GIS 36-103 Positive Materials Identification (PMI) for Pressure Vessels, Piping, and
other Components
3 Terms and definitions
For the purpose of this GIS, the following terms and definitions apply:
ASME Code
ASME Boiler and Pressure Vessel Code.
ASME VIII-1
ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.
ASME VIII-2
ASME Boiler and Pressure Vessel Code, Section VIII, Division 2.
BP
The BP p.l.c., an associate or subsidiary, or other organization as defined in the Conditions of Contract for
the project.
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Certificates of compliance
A document by which the material manufacturer (or seller to the extent that the Code allows) certifies that
the material represented has been produced and tested in accordance with the requirements of the basic
material specification shown on the certificate
Certified material test report
A document, or documents, on which are recorded the results of tests, examinations, repairs, or treatments
required by the material specification.
Cladding re-instatement (clad restoration)
The process in which small areas at nozzles and attachments, where the cladding has been removed for
welding of the base material, are re-clad by welding.
Fabrication plan
A detailed description of the processes and sequence of the processes to be used to fabricate the
equipment.
Inspection and test plan
A detailed matrix of quality assurance and inspection activities to be performed by the fabricator. The
format of the document includes provisions to indicate monitoring and witness points.
Quality assurance
Planned and systematic actions necessary to provide adequate confidence that a product or service
satisfies given requirements for quality.
Quality control plan
The manufacturer's job specific documented plan for ensuring that all specified technical requirements
will be followed. The quality control plan includes the following minimum elements; fabrication schedule
including all heat treatment requirements, forming and rolling procedures, and an inspection and test plan
with a schedule identifying all inspection points required by BP.
Quality control system
The manufacturer's documented system for ensuring that all applicable code requirements for the
manufacturing process including material handling and identification, design, fabrication, inspection and
testing are followed.
Quality plan
A document setting out the specific quality practices, resources and sequence of activities relevant to a
particular product, service, contract or order.
Reinforcing plate
Reinforcing element as used in ASME Code, compensation plate as used in BSI PD 5500, or reinforcing
plate as used in BS EN 13445.
Weldment
Weld, HAZ, and adjacent parent metal.
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4 Symbols and abbreviations
ASS Austenitic stainless steel.
CMTR Certified material test report.
CUI Corrosion under insulation.
DHT Dehydrogenation heat treatment.
DN Nominal pipe diameter.
DSS Duplex stainless steel.
EDS Equipment data sheet.
FCAW Flux cored arc welding.
FEA Finite element analysis.
FN Ferrite number (per Welding Research Council Bulletin Number 342).
GMAW Gas metal arc welding.
GTAW Tungsten inert gas welding.
HAZ Heat affected zone.
HIC Hydrogen-induced cracking.
HRB Rockwell hardness number, B scale, tested with a steel ball.
HBW Brinell hardness measured by tungsten carbide ball (also referred to as HB).
Hv10 Vickers hardness measured with a 10 kgf indenter (also referred to as HV).
IPWHT Intermediate post-weld heat treatment (also known as ISR Intermediate stress relief).
LWN Long welding neck.
MSDS Material safety data sheet.
MDMT Minimum design metal temperature.
MT Magnetic particle testing.
NDE Non-destructive examination.
NPS Nominal pipe size.
PCN Personnel Certification in Non-Destructive Testing.
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PMI Positive material identification.
PQR Procedure qualification record.
PT Liquid or dye penetrant testing.
QA Quality assurance.
Q+T Quenched and tempered.
RT Radiographic testing.
PWHT Post-weld heat treatment.
PWHTmin Shortest time for which the vessel may be heat treated to meet code requirements.
PWHTmax Longest time for which the vessel may be heat treated.
SMAW Shielded metal arc welding.
SAW Submerged arc welding.
TMCP Thermo-mechanical control process.
UT Ultrasonic testing.
WFMT Wet fluorescent magnetic particle testing.
WPQ Welder/welding operator performance qualification.
WPS Welding procedure specification.
5 General
5.1 Overall responsibilities
a. Vessels shall be provided in accordance with this GIS and the following:
1. Local jurisdictional requirements.
2. The design code specified on the EDS.
3. Other codes and standards referenced in this GIS.
4. Additional requirements listed on the EDS.
b. Vessels shall be in compliance with the specified design code, which includes the application
of the code stamp or certificate of conformity.
c. Vessels that are designed in accordance with the ASME Code shall also be registered with the
National Board.
d. Deviations from this GIS shall be submitted in writing for approval by the BP Technical
Authority. The rational for the requested deviation shall be clearly stated with the request.
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e. If a conflict is identified between this GIS, the design drawings, EDS, referenced codes and
standards, or any supplementary specification, then written clarification shall be obtained from
BP before proceeding with any work.
f. BP’s review of manufacturer’s documentation (i.e., fabrication drawings, design calculations,
weld procedures, etc.) shall not relieve the manufacturer of their responsibility to conform to
the requirements of this GIS and the other contract documents.
g. If the design of the vessel or a vessel component is furnished by BP, the manufacturer shall not
be relieved of their responsibility to conform to the requirements of this GIS and the other
contract documents.
h. Release for shipment by the BP inspector shall not relieve the manufacturer of their
responsibility to conform to the requirements of this GIS and the contract documents.
5.2 Manufacturer’s responsibilities
a. The manufacturer shall be responsible for mechanical design, provision of materials,
fabrication, inspection, testing, and quality of workmanship.
b. The manufacturer shall be responsible for the detailed design for all lifting and tailing lugs,
trunions, and devices.
c. Approval of the manufacturer’s drawings by BP does not relieve the manufacturer of any of
these responsibilities.
d. BP shall at all times be allowed access to the shop of any manufacturer or sub-contractor
engaged in supplying material or in fabricating the vessel for the purpose of inspecting, and if
necessary, rejecting such material and work that does not meet with the requirements of this
GIS.
e. Data sheets, drawings, quality control records, and any other items that may be of assistance to
BP for purpose of determining the acceptability of the vessel shall be made available to BP for
inspection.
f. No portion of the vessel construction (such as plate forming, welding, heat treatment, non-
destructive examination, painting, etc.) shall be subcontracted to others without prior written
approval from BP. The names and addresses of any companies to which work is subcontracted
shall be indicated in the quotation. The manufacturer shall be responsible for assuring that
subcontracted fabrication work is in accordance with this GIS and the contract documents.
5.3 Quality assurance
a. The manufacturer shall operate a quality control system to ensure that the technical
requirements of the specified pressure vessel code are achieved.
b. The manufacturer shall submit a fabrication plan, an inspection and test plan, and a quality
plan for approval by BP prior to the start of any fabrication.
c. The inspection and test plan shall contain the following elements as a minimum:
1. Activities and associated control procedure and specification reference governing the
activity.
2. Acceptance criteria.
3. Responsible party for activity execution.
4. Objective evidence of activity execution or verifying document.
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5. Quality documents including inspection and test records to be compiled into the pressure
vessel record book.
6. Manufacturer participation at the inspection and test stages.
7. BP participation (to be completed by BP) at the inspection and test stages.
8. Regulatory agency or third party/authorized inspector participation at the inspection and
test stages.
d. The quality plan shall state all quality related activities, reference standards, acceptance
criteria, and the names of the responsible persons in the manufacturer’s organization. Spaces
for signatures and dates relating to inspections shall be provided.
e. The manufacturer shall ensure that technical and quality assurance requirements specified in
the purchase order are applied to all materials, equipment, and services provided by sub-
contractors.
6 Materials requirements
6.1 General
a. All materials shall be new and unused.
b. Materials salvaged from existing equipment shall not be used.
c. Material substitutions shall not be made without approval.
d. Steel plates shall be made in an open-hearth, basic-oxygen, or electric-arc furnace.
e. The records of Charpy V-notch impact tests for steel plates shall record the percent shear
fracture and the lateral expansion for each specimen.
f. All impact test values shall be reported in the material’s certified test reports.
g. Any stamping of the materials shall be done with low stress (round bottom) stamps.
6.2 Certificates of compliance
a. Objective evidence of compliance with the requirements of the material specification shall be
maintained in the records of the material manufacturer.
b. Certificates of compliance shall include reports or results of tests required by the material
specification or the purchase order.
6.3 Certified material test reports
a. Supplementary or special requirements, in addition to the requirements of the material
specification, as required by the purchase order shall be included on the CMTR.
b. The specification of the material being represented (including the year of issue) and the
material heat number shall be included on the CMTR.
c. All such documents shall identify the applicable material specification and shall be identified
to the material represented.
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7 Design requirements
7.1 General
a. The vessel design shall be in accordance with the applicable requirements of the specified
design code, this GIS, and all contract documents.
b. Any assumptions made in calculations shall be clearly stated. If computer calculations are
submitted, the name of the program and the version number shall be supplied. Input and output
data shall be included.
c. The maximum design temperature rating shall be increased to the highest temperature possible
without affecting the minimum required thickness of the shell or heads and without changing
the pressure class of the flanges.
d. A vessel may be designed and stamped for more than one condition of pressure and coincident
metal temperature.
e. Unless otherwise specified on the EDS, vessels shall be assumed to operate completely filled
with operating fluid having a minimum specific gravity of 1,0.
f. MAWP shall be calculated (not set equal to the design pressure) unless otherwise specified by
BP on the EDS.
g. For vessels constructed to ASME VIII-1, the coincident ratio used when calculating the
MDMT of the vessel shall not be less than 1,0.
7.2 Load conditions
7.2.1 Load condition definitions
The following definitions apply for the load case combinations specified in Clause 7.2.2.
a. Dead load (L1) is the installed weight of the vessel, including internals, catalyst or packing,
refractory lining, platforms, insulation fireproofing, piping, and other permanent attachments.
This does not include the weight of any liquid or catalyst contents.
b. Operating live load (L2) is the weight catalyst plus the weight of the liquid at the design liquid
level, including that on trays.
c. Pressure load (L3) is the MAWP (internal or external at the coincident temperature)
considering the pressure variations through the vessel, if any.
d. Thermal load (L4) is the load caused by the restraint of thermal expansion/interaction of the
vessel and/or its supports.
e. Test load (L5) is the weight of the test medium, usually water.
f. Wind load (L6) shall be determined in accordance with Clause 7.3.
g. Seismic load (L7) shall be determined in accordance with Clause 7.4.
h. Piping and superimposed equipment loads (L8) are loads caused by piping (other than the dead
load), and loads caused by superimposed equipment.
7.2.2 Load condition requirements
Vessels and their supports shall be designed to satisfy all of the following load conditions:
a. Erected condition with full wind load (L1 + L6).
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b. Design condition with wind load (L1 + L2 + L3 + L4 + L6 + L8 + snow load).
1. Both full and zero pressure loads (L3) shall be included for check of maximum
longitudinal tensile and compressive stress.
c. Design condition with seismic load (L1 + L2 + L3 + L4 + L7 + L8 + snow load).
1. Both full and zero pressure loads (L3) shall be included for check of maximum
longitudinal tensile and compressive stress.
d. Future (corroded) pressure test (L1+ test pressure + L5 + 0,25*L6).
1. Vessels shall be designed to permit application of a full hydraulic test to the vessel in its
operating position in the fully corroded condition. It may be assumed that the wind
loading during full hydraulic test does not exceed 25% of the design wind load.
2. The general primary membrane tensile stress under this load condition in the corroded
condition shall not be greater than either of the following:
a) For hydrostatic testing, 90% of the specified minimum yield strength at 38°C
(100°F), in both circumferential and longitudinal directions.
b) For pneumatic testing, 80% of the specified minimum yield strength at 38°C
(100°F), in both circumferential and longitudinal directions.
e. Lift condition
1. See the EDS and Clause 7.9.
2. Erection load: 1,5 times total weight of vessel during erection.
7.3 Wind loading
a. Unless otherwise specified on the EDS:
1. For US sites, wind load shall conform to ASCE-7 and governing local jurisdictional
requirements; importance factor shall be for Category III; velocity pressure exposure
coefficient and gust response factors shall be Exposure C for inland and coastal and
Exposure D for offshore installation.
2. In UK, BS 6399: Part 2 shall be used for wind loading and Enquiry Case 5500/127 in
BSI PD 5500 provides the method for calculating the load.
3. For other locations, see the EDS and governing local jurisdictional requirements.
b. The maximum allowable deflection at any location on a vertical vessel in the corroded
condition shall not be greater than 150 mm per 30 m (6 inches per 100 feet) of vessel height.
c. The projected area of vessel accessories such as platforms, ladders, piping, and other
equipment attached to the vessel shall be considered in the wind load calculation.
d. If spoilers are to be added to a vessel:
1. The column projected area shall be calculated using the projected diameter taken at the
outside edge of the spoilers multiplied by the height of the section under consideration.
2. The column projected area normal to wind, and the corresponding force coefficient, for
the column height where spoilers have been added, shall be used in the design of the
vessel and supporting structure to calculate the overturning load.
e. The wind induced moment and shear forces at the base of the vessel shall be determined and
indicated on the manufacturer’s fabrication drawings.
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7.4 Seismic loading
a. Unless specified otherwise on the EDS, the seismic loads shall be determined in accordance
with ASCE 7 and governing local jurisdictional requirements.
b. The allowable stress design method shall be used. When the pressure vessel is designed using
the allowable stress method and the supporting structure or foundation bolts are designed using
the strength design method a check shall be made that there is no inconsistency between the
two design methods.
c. Vertical columns may be considered as “cantilevered column systems” provided they are
anchored to a foundation at grade.
Flexibility of the supporting structure may alter the response of a heavy vessel.
d. The seismic induced moment and shear forces at the base of the vessel shall be determined and
indicated on the manufacturer’s fabrication drawings.
7.5 Snow loading
Unless specified otherwise on the EDS, the snow load shall be determined in accordance with
ASCE 7 and governing local jurisdictional requirements.
7.6 Motion induced loads
The motion induced loads listed on the EDS shall be applied to all load cases listed Clause 7.2.
7.7 Cyclic loading
a. If the EDS specifies that the vessel is in cyclic service, the rules in Code Section VIII,
Division 2, Paragraph 4.1.1.4, shall be used as a basis for establishing further action.
b. A fatigue analysis shall always be performed for agitator mounting nozzles and their
attachment to the vessel.
7.8 Local loading
a. If external loads for nozzles or attachments are furnished on the EDS, the local membrane and
surface stresses caused by local loads (e.g., piping loads, platform loads, etc.) shall be
determined using the WRC Bulletin 107 and 297 procedures, or other local stress analysis
procedures approved by BP.
b. For local loads and pressure, the allowable stresses are 1,5S for local primary membrane stress
and 3S for primary membrane plus secondary bending stress at nozzles, platform lugs, etc.,
where S is the Code-allowable stress at the design temperature.
7.9 Wind-induced vibration of vertical vessels
a. Vessels with a height to diameter ratio of either the entire vessel or the top third of the vessel is
greater than or equal of 15 shall be evaluated for dynamic behaviour from wind excitation as
described in Dynamic Response of Tall Flexible Structures to Wind Loading or by other
similar proven evaluation methodology.
b. Critical wind velocities shall be determined for every change in vessel outer diameter.
c. Acceptable vessel critical wind velocities (first and second modes) shall be less than 7 m/s
(15 mph) or greater than 27 m/s (60 mph).
d. For a vessel with critical wind velocities between 7 m/s (15 mph) and 27 m/s (60 mph):
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1. A means of either preventing vortex formation (e.g., by spoilers, piping, ladders, or
platforms) or vibration dampening shall be provided.
2. If it is determined that a vessel can vibrate and the attributes of the vessel (e.g., normal
attachments) cannot be changed to put the vessel in a range where vibration cannot occur,
wind spoilers shall be added to the vessel in accordance with one of the following
methods. The method used to deter wind-induced vibration shall be approved by BP.
a) Helical spoilers
1) A three-start system of spoilers in a helical pattern shall be provided on the top
third of the vessel.
2) The exposed width of the spoilers beyond insulation should be 0,09D and a
pitch of 5D, where D is the diameter of the top third of the vessel.
3) The spoiler system may be interrupted to provide clearance at vessel
appendages.
b) Short vertical spoilers
1) A three-start system of short vertical spoilers arranged in a helical pattern shall
be provided on the top-third of the vessel.
2) The exposed width beyond insulation of the spoilers should be 0,09D and the
pitch (i.e., height of one helical wrap) between 5D and 11D.
3) A minimum of eight spoilers should be provided over the pitch distance (i.e.,
each complete helical wrap) and a minimum of 1,5 helical wraps over the top-
third of the vessel.
4) The spoiler system may be interrupted to provide clearance at vessel
appendages.
7.10 Transportation loads
a. Vessels subject to transportation loadings shall be analysed for the following conditions:
1. Bending between supports.
2. General primary membrane tensile stress.
3. Compressive stress at supports and fixture attachment points.
b. Calculated general primary membrane tensile stress shall not exceed that listed in
Clause 7.11e.
c. Vessels shall be analysed for actual vertical, lateral, and longitudinal loadings as applicable.
d. Minimum acceleration loadings are shown in Table 1 for the various modes of transportation.
e. If erection loadings are greater than the transportation loadings, the vessel shall be designed
for the most severe vertical, lateral, and longitudinal loading condition.
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Table 1 - Minimum transportation acceleration loadings
Transportation Mode Vertical acceleration Lateral acceleration
Longitudinal acceleration Downward Upward
Truck (highway speeds) 1,7∙g 0,5∙g 0,3∙g 1,8∙g
Truck (<25 MPH or multi-wheel transporter)
1,3∙g 0,2∙g 0,2∙g 0,2∙g
Rail 2∙g 2∙g 2∙g 3∙g
Inland barge 1∙g 0,2∙g 0,75∙g 0,4∙g
Oceangoing ship or barge 2∙g 2∙g 0,75∙g 0,4∙g
Notes:
1. If multiple modes of transportation are used, the most severe condition shall be used for
evaluation.
2. 1,0∙g is a load equal to the shipping weight of the vessel.
7.11 Lifting loads
a. The lift weight shall include all components to be included in the lift (e.g., trays,
ladders/platforms, insulation, additional piping with insulation, etc.).
b. A minimum impact factor of 2,0 shall be applied to the lift weight for the design of lifting
devices.
c. Local stresses in the vessel shell/head/skirt/base rings from lifting attachments (e.g., lugs,
trunnions, etc.) shall be determined for the imposed loadings using WRC Bulletins 107 or 297
procedures, or other accepted local stress analysis procedures (e.g., finite element analysis),
and the allowable stress values shall be as specified in Clause 7.8b.
d. Shear stresses for fillet welds on the lifting attachments to the vessel shell or head shall not be
greater than 0,55 times the Code-allowable stress at 38ºC (100ºF) for the material selected.
e. For vertical vessels having height-to-diameter ratios greater than 8 and lifting weighing more
than 11 300 kgf (25 000 pounds), the following lifting stress calculations shall be performed:
1. Bending stresses in the vessel shell and skirt from the loadings imposed during the lift
from the horizontal to vertical position shall be checked.
2. Calculated general primary membrane tensile stress shall not be greater than 80% of the
material’s specified minimum yield strength at 38ºC (100ºF).
3. Calculated compressive stress shall not be greater than 1,2 times the allowable
compressive stress (B factor specified by ASME VIII-1 or ASME VIII-2
Paragraph 4.4.12).
7.12 Design calculations
a. Calculations to satisfy the pressure vessel code of construction requirements shall be
performed using COMPRESS, PVElite, or Finglow software packages.
b. All design calculation reports shall be submitted for review and approval.
c. The following vessel components shall be subject to analysis and the results submitted for
review and approval:
1. Thermal and stress analysis of vessel and skirt attachment region.
2. Localized stress analysis of internal and external attachments to the shell.
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3. Localized stress analysis of nozzles subject to piping loads.
4. Thermal analysis of nozzles, skirt, and appurtenances where thermal gradients may be
induced into the shell.
a) Information from this analysis shall be used to determine the need for a fatigue
evaluation.
b) If the vessel is exempt from fatigue evaluation the results of the thermal analysis
shall be included as part of the user’s design specification.
d. For ASME VIII-1 pressure vessels, the vessel or vessel component shall be evaluated by the
rules of VIII-2 under the provision of VIII-1 Paragraph U-2(g) when a rule exists for the
design of a vessel or vessel component in VIII-2 but not in VIII-1.
e. The allowable stress value used under Clause 7.12d shall be the allowable stress value from
ASME VIII-1.
f. When a finite element analysis is performed, a report shall be generated and submitted for
review and approval by BP.
g. When calculations to EN 13445-3 Annex B are performed, they shall be submitted for review
and approval by BP.
8 Vessel components
The following clauses contain design, fabrication, and examination requirements for various components
of pressure vessels as called for on the EDS.
8.1 Vessel shells and transitions
a. ASME torispherical heads (knuckle radius not less than 6% of crown radius and L/t ratio not
more than 500) are acceptable for vessels with a design pressure of 5 barg (75 psig) or less,
where vessel head is not providing support to vessel or auxiliary equipment. Heads providing
support to vessel, agitators, pumps, or other equipment shall be 2:1 ellipsoidal or
hemispherical.
b. Transitions shall be made with knuckle and flare when any of the following conditions apply:
1. Vessel is in cyclic or hydrogen service.
2. Section is subject to a major support reaction (for example, skirt-to-cone attachment).
3. The transition thickness or attached shell thickness is over 30 mm (1,25 inches).
4. All loadings per ASME VIII-1 Appendix 1-5 or 1-8, whichever is applicable, are not
available.
c. The minimum thickness of shells and transitions, exclusive of forming and corrosion
allowances, shall be as follows:
1. 5 mm (3/16 inch) for carbon steel and low-alloy steels.
2. 6 mm (1/4 inch) for stainless and high-alloy steels.
8.2 Formed heads
8.2.1 General
a. Heads shall be supplied as one of the following as specified on the EDS:
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1. Hemispherical.
2. 2:1 Elliptical.
3. ASME F&D.
4. Toriconical.
b. Intermediate heads shall:
1. Be designed with a corrosion allowance applied to both sides.
2. Be fitted so that the internal head OD equals the shell ID.
3. Have a continuous fillet weld from the end of the head plate to shell.
4. Have the attachment welds magnetic particle or liquid penetrant examined.
c. The minimum thickness of heads, exclusive of forming and corrosion allowances, shall be as
follows:
1. 5 mm (3/16 inch) for carbon steel and low-alloy steels.
2. 6 mm (1/4 inch) for stainless and high-alloy steels.
d. If an agitator is to be mounted on a nozzle or studding outlet in a formed head, the head design
shall be sufficient to provide the rigidity and stress levels appropriate for the associated
dynamic loadings. The head design shall be agreed with the agitator supplier and BP before the
head is ordered.
e. For carbon steel and C-Mn steels, cold-formed heads shall be normalized or stress-relieved
prior to welding to the shell.
8.2.2 Joints in formed heads
a. All joints in formed heads shall be full penetration.
b. All joints in formed head shall be fully radiographed before forming.
c. All joints in formed head shall be ground flush with the plate surfaces before forming.
d. After forming, if the spin hole remains in the final construction, it shall be repaired with a
metal plate butt-welded in place and given full volumetric examination.
e. After forming, all joints in formed head shall receive 100% surface examination on both sides.
8.3 Connections, nozzles, and manways
8.3.1 General
a. Connections may be any of the following types:
1. Flanged forging.
2. Pipe or rolled plate nozzle with a flange.
3. Pipe or rolled plate nozzle with a welded hub and clamp.
4. Pipe or rolled plate nozzle with a square cut or bevelled end for welding to external
piping.
5. Studding outlets.
b. Connections shall not be made with:
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1. Threaded coupling.
2. Socket weld fitting.
3. Single filet welds.
c. Nozzles shall be flanged unless otherwise stated on the EDS.
8.3.2 Design
a. The MAWP shall not be limited by nozzle reinforcement.
b. The MAP shall not be limited by nozzle reinforcement.
c. Internal projections shall not be used for nozzle reinforcement calculations.
d. Nozzles in dished heads shall be positioned such that the nozzle, reinforcing pads, and
attachment welds are not within the knuckle region of the dished head.
8.3.3 Construction details
a. Set-on nozzles (surface mounted) shall not be used.
b. The nozzle to parent component weld shall be full penetration.
c. Nozzles DN 300 (NPS 12) and larger shall be made from forgings, rolled plate, or seamless
pipe.
d. Nozzles smaller than DN 300 (NPS 12) shall be constructed using forgings or seamless pipe.
e. Nozzles DN 50 (NPS 2) and smaller shall be constructed using either:
1. LWN or heavier forgings when the forging length is 450 mm (18 in) or less.
2. Welding stub welded to seamless pipe if the nozzle length is greater than 450 mm (18 in).
An example would be a DN 50 (NPS 2) bottom outlet nozzle of a vertical vessel that
routes through the skirt.
f. Rolled plate used as nozzle necks shall have:
1. Full volumetric examination prior to attachment to other components.
2. Acceptance criteria in accordance with the relevant design code for full NDE.
g. The minimum pipe schedule used for nozzles shall be as shown in Table 2.
h. Nozzles not directly connected to internals shall be flush with the inside surface of the vessel
wall.
i. Nozzle with an internal projection shall have a fillet weld at the inside corner.
j. All inside nozzle neck edges shall be rounded to 3 mm (1/8 inch) minimum radius.
Table 2 - Minimum thickness of nozzles
Material Size (DN (NPS)) Minimum pipe schedule1
Carbon steel and low alloy, clad steels
50 (2) or smaller Schedule 160
Larger than 50 (2) Schedule XS
High alloy and non-ferrous materials
50 (2) or smaller Schedule 80S
Larger than 50 (2) Schedule STD
Notes: (1) Pipe wall thickness designations per ASME B36.10M.
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8.3.4 Reinforcing pads
a. Reinforcing pads shall be external to the vessel.
b. Reinforcing pads shall not be used on internal heads.
c. Reinforcing pads shall not be used if any of the following conditions apply:
1. Operating temperature is warmer than 300°C (572°F).
2. Operating partial pressure of hydrogen exceeds 7 bar(a) (100 psia) and operating
temperature exceeds 230°C (450°F).
3. Design is for non-intrusive inspection.
4. Parent wall thickness exceeds 50 mm (2 in).
5. Ferritic vessels where operating temperature is colder than -50°C (-58°F).
6. Cyclic service.
d. Reinforcing pad thickness shall not exceed the parent wall thickness the nozzle is attached to.
e. Reinforcing pads shall be full penetration welded to the nozzle.
f. If multi-segmental reinforcing pad elements are used, the design shall follow the requirements
of ASME VIII-1 Paragraph UG-37(h).
g. Each pad segment shall have one American Standard Taper Pipe Thread (NPT) 1/4 inch
(6 mm) telltale hole for testing purposes. See Clause 14.1f for testing of reinforcing pads. Each
hole shall be located near the lowest point of a pad with the vessel in its operating position to
permit drainage.
h. Reinforcing pads that are not circular shall have rounded corners of 75 mm (3 inches)
minimum radius.
8.3.5 Nozzle external projection
a. Minimum projection from the outside of the vessel wall to the nozzle face shall be:
1. For nozzles less than or equal to DN 200 (NPS 8): 200 mm (8 inches).
2. For nozzles larger than DN 200 (NPS 8): 250 mm (10 inches).
b. The dimension from the face of the nozzle to the vessel centreline or reference line shall be
rounded up to the next greater 10 mm (1/2-inch) increment.
c. Projection of flanged nozzles with external piping attached shall permit removal of bolting
from either side without removal of insulation.
d. Nozzles in hydrogen service or service above 345°C (650°F) shall be extended such that
flanges and bolting are outside vessel insulation.
e. Nozzles shall be extended sufficiently such that flanges and bolting are outside vessel
insulation.
f. When establishing nozzle and manway projections, the following shall apply:
1. Clearance shall be provided for removing flange stud bolts from between the flange and
vessel and for accessing flange stud nuts.
2. Clearance shall be provided for flange studs and nuts if nozzles penetrate insulation or
platforms.
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8.3.6 Nozzle loading
a. Nozzles supporting agitators, pumps, or other mechanical equipment shall be suitably
reinforced to withstand the mechanical loadings specified by the equipment manufacturer and
approved by BP.
b. Dynamic loading shall be evaluated for an infinite number of stress reversals using the
applicable stress concentration factor as follows:
1. 5 for as welded attachment welds.
2. 3,5 for contoured and blend ground nozzle attachment welds.
Use of heavier nozzle necks, conventional reinforcing pads with properly contoured
fillet welds, and formed heads of appropriate stiffness may result in a design suitable for
an infinite number of cycles.
c. Nozzle reinforcement for pressure relief devices shall be designed and reinforced for thrust
reaction.
d. Gussets shall not be used to strengthen, stiffen, or reinforce nozzles, unless demonstrated by
calculations to be suitable for the specified cyclic life and thermal condition, and the
dimensional requirements (e.g., tolerances) of the device as furnished by the device
manufacturer are considered.
8.4 Flanges
8.4.1 General
a. Flanges welded on a nozzle shall be weld neck flanges unless otherwise specified on the EDS.
b. The dimensions and pressure-temperature ratings of standard flanges for nozzles and manways
DN 600 (NPS 24) and smaller shall be in accordance with ASME B16.5.
c. The dimensions and pressure-temperature ratings of standard flanges for nozzles and manways
larger than DN 600 (NPS 24) shall be in accordance with ASME B16.47 to the series specified
on the EDS.
d. Custom weld neck flanges may be used in accordance with the design code.
e. Slip-on flanges shall not be used in any of the following conditions:
1. Cyclic service.
2. Design temperature above 260°C (500°F).
3. When the vessel contents are flammable or toxic, toxic, or in steam service.
f. If studded connections are used, the following shall apply:
1. The holes in a studded connection and the studs shall be machined in accordance with
PIP VEFV1129.
2. Indicator type studs for studded connections, if used, shall be in accordance with
ASME PCC-1 Figures 1 and 2.
3. A spacer ring of the same material as the nozzle flange may be provided behind the
flange to increase the effective stud length. See note on PIP VEFV1129.
4. If a spacer ring is used, the thickness of the ring shall be equal to or greater than the
mating flange thickness.
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5. Studs and spacer ring, if required, shall be provided for each studded connection on the
vessel.
6. Studded connections shall be checked to assure the remaining thickness of the drilled
holes is in accordance with the specified design code.
g. Bolt holes in all fixed flanges and studding outlets shall straddle the natural centrelines.
h. For a vessel supported by a skirt, flanges of nozzles in the bottom head shall be located outside
the skirt.
i. For lap joint flanges DN 100 (NPS 4) and larger that face upward (i.e., the nozzle inclines
from the horizontal at an angle of 30 degrees or greater), safety retainer clips shall be provided
as follows:
1. A minimum of three clips shall be welded to the nozzle neck at the back of the flanges.
2. The spacing of the clips between the back of the lap and the face of the flange shall be
one length-through-hub dimension (i.e., dimension Y in ASME B16.5).
j. Except for standard flanges in accordance with ASME B16.5 and B16.47, all carbon, low-
alloy, and high-alloy steel forgings greater than 75 mm (3 inches) in thickness shall be
examined ultrasonically in accordance with ASME SA-745 with the following requirements:
1. Quality levels for straight beam examinations from flat surfaces shall be in accordance
with Table 3.
2. Quality level for straight beam examinations from curved surfaces shall be QL-5.
3. Quality level for all angle beam examinations shall be QA-1. Notch depth shall be in
accordance with QA-1 or 6 mm (0,25 inch), whichever is less.
Table 3 - Quality levels for straight beam examinations from flat surfaces
Forging thickness (t) mm (inches)
Quality level
75 (3) < t ≤ 200 (8) QL-2
200 (8) < t ≤ 300 (12) QL-3
t > 300 (12) QL-4
8.4.2 Flange facing and surface finish
a. A splice welds on gasket contact surfaces of a lap ring or flange shall not be used.
b. Except for lapped flanges, flanges shall have one of the following configurations:
1. Raised face.
2. Ring type joint.
3. A construction that provides outer confinement to the gasket if required in accordance
with Clause 8.4.2e,
c. The height of a raised face shall be per one of the following:
1. In accordance with ASME B16.5.
2. In accordance with ASME B16.47.
3. As specified on the EDS.
4. 1,5 mm (1/16 inch).
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d. For all flanges (except ASME B16.5 and ASME B16.47 flanges) and shop-fabricated lap
rings, the gasket contact surface flatness tolerance shall be in accordance with the following:
1. 0,150 mm (0,006 inch) total indicator reading in both the radial and circumferential
directions.
2. The total circumferential tolerance shall not occur in less than 20 degrees arc.
3. Measurement shall be made using a dial indicator after all other operations (i.e.,
fabrication and heat treatment of the flange or lap ring, and attachment to the shell or
nozzle neck) that can affect flatness tolerance have been completed.
e. Gasketed flange joint designs (i.e., body flange and nozzle joints) larger than DN 600
(NPS 24) shall provide outer confinement of the gasket for any of the following conditions
when the gasket is not a robust metal reinforced gasket (e.g., spiral-wound with outer gauge
ring, double-jacketed corrugated metal gaskets with a corrugated metal filler, etc.):
1. Design pressure is equal to or greater than 2 MPa (300 psi).
2. Design temperature is warmer than 260°C (500°F).
3. MDMT is colder than -29°C (20°F).
4. Cyclic service.
5. Joint requires metallic gasket.
f. For flat gaskets, flange faces shall be machined to a surface roughness between 3,2 and
12,5 μm (125 and 500 μin) Ra, except where the manufacturer of a selected proprietary gasket
advises otherwise.
g. Flange facings used with spiral wound gaskets shall be machined a surface roughness between
3,2 and 6,3 μm (125 and 250 μin).
8.4.3 Flange bolting
a. Flanged joints shall be designed such that hydraulic bolt tensioners can be used on the
following:
1. Joints with nominal bolt diameter 50 mm (2 in) and over.
2. Duties where the nominal bolt diameter is 40 mm (1,5 in) and over, and the flanges are
either on hydrogen service or are PN 110 (Class 600) or over.
3. If specified on the EDS for nominal bolt diameter 25 mm (1 in) and over.
b. Bolts for bolt tensioning shall be extended by the length of one nut and provided with a cap for
protection during service.
c. Nozzles adjacent to shell girth flanges or horizontal vessel saddles shall be located with
clearance such that bolt tightening equipment can be used on the girth flange bolts.
d. For marine applications (offshore environments), the coating for bolting shall be hot dip spun
galvanising [with approximately 50 microns (2 mils) zinc].
e. For non-marine applications, the bolting shall be uncoated unless otherwise specified on the
EDS.
8.4.4 Gaskets
a. Gaskets specified on the EDS shall be provided by the vessel manufacturer.
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b. Pressure and leak test gaskets shall comply with Clause 14.1k.
c. Spare gaskets shall comply with Clause 16.1c.
8.5 Blind flanges and bolted flat heads
a. Except for blind flanges in accordance with ASME B16.5 and B16.47, rolled plate for flat
covers and blind flanges greater than 75 mm (3 inches) thick shall be examined in accordance
with ASME SA-578 acceptance standard - Level B after cutting to final size.
b. Nozzles shall not be placed in ASME B16.5 or ASME B16.47 blind flanges unless the
applicable ASME blind flange standard specifically allows such an opening while keeping the
pressure and temperature rating.
Weld-neck reducing flanges are preferred over nozzles in a blind flange.
c. The vessel manufacturer shall provide all necessary bolting and gaskets for all nozzles or
manways where they provide the blind flange or bolted flat head.
8.6 Quick-opening closures
a. Swing bolts (i.e., eye bolts) shall be of one-piece construction without welding. Hinge pins
shall be solid and of the same material as the swing bolts.
b. The design, operation, and maintenance of quick opening closures shall be subject to separate
review by BP.
8.7 Quick-actuating closures
a. Quick-actuating closures shall be designed per ASME VIII-1 Paragraph UG-35.2 or
ASME VIII-2 Paragraph 4.8 and Annex 4.B.
b. Requirements on the operation or maintenance of the quick-actuating closure shall be
submitted for review by BP.
8.8 Supports
8.8.1 Skirts
a. Vertical vessels shall be designed to be self-supporting without guys or braces.
b. Support skirts shall be in accordance with Figure 1 or Figure 2.
c. For vessels with a design temperature of 345°C (650°F) and above, a hot box shall be provided
at the junction between the skirt and shell.
d. For vertical vessels constructed from materials other than carbon steel, the material of the top
of the skirt shall be of the same material specification and grade as the vessel plate to which it
is attached for a length at least equal to the greater of the following:
1. 2,5 * √(skirt radius * skirt thickness).
2. 600 mm (24 in).
e. Skirts on vessels 2 m (6 ft) or less in diameter shall have at least one access opening. On
vessels with diameters over 2 m (10 ft) and skirt heights over 2,5 m (8 ft), two access openings
may be provided in the skirt.
f. The minimum skirt access opening shall be 600 mm (24 in) diameter, or 450 mm (18 in) x
900 mm (36 in) obround.
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Figure 1 - Skirts on vertical vessels of moderate pressure and temperature
Figure 2 - Skirts on high pressure, or high temperature, or cyclic service vessels
8.8.2 Legs or column supports
a. Leg supports or columns shall not bear on the knuckle or crown of formed heads.
b. The stress analysis of the legs on spheres shall be submitted for review and approval by BP.
8.8.3 Saddles
a. Horizontal vessels shall be investigated for buckling and local stresses. The method of L.P.
Zick may be used for this investigation.
b. Horizontal vessels shall be supported on two saddles only.
c. Slots shall be provided for the anchor bolts in one saddle to allow for thermal expansion.
d. The saddle support that is “fixed” and the support that is “sliding” (slotted) shall be indicated
on the fabrication drawings.
e. Saddles shall be continuously welded to the shell.
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8.9 Anchor bolts
8.9.1 General
a. The quantity and size of anchor bolt shall be determined by the vessel manufacturer and
indicated on the design calculations and manufacturer’s fabrication drawings.
b. Anchor bolts shall be furnished and installed by others (not the vessel manufacturer).
c. Anchor bolts shall not be less than 19 mm (3/4 inch) diameter.
d. The number of anchor bolts shall be a multiple of four (4).
e. When high-strength anchor bolts are not specified on the EDS:
1. Anchor bolts (such as carbon steel, ASTM F1554-36, etc.) shall have an allowable stress
of 138 MPa (20 000 psi) based on the tensile stress area of the preaded portion.
2. Anchor bolts shall have a maximum anchor bolt diameter is 50 mm (2 inch).
f. The design loadings for anchor bolts embedded in concrete shall be determined by either the
simplified method (i.e., neutral axis of bolt pattern at centreline of vessel) or the shifted neutral
axis method in accordance with Process Equipment Design.
g. For vessels on concrete foundations, the design concrete bearing stress used shall be 11,4 MPa
(1 658 psi), unless otherwise specified on the EDS.
8.9.2 High-strength anchor bolts
1. The use of high strength anchor bolts is only permitted when specified on the EDS.
2. Unless otherwise indicated on the EDS, high-strength anchor bolts (such as
ASTM F1554-105) shall have an allowable stress of 207 MPa (50 000 psi).
8.9.3 Vertical vessel anchor bolts
a. Anchor bolts shall straddle normal centrelines.
b. The anchor bolt configuration shall provide radial clearance for a bolt tensioning device.
c. All parts of the base ring support system (base ring, chairs, compression ring, gussets, skirt,
etc.) shall be designed to accommodate a pretension force on the anchor bolts equal to 75% of
the allowable anchor bolt stress.
d. If the number of anchor bolts is not specified on the EDS, then the number of anchor bolts
shall be maximized but not spaced closer than 457 mm (18 inch).
8.10 Internal attachments
8.10.1 General
a. Internal attachments to the pressure boundary shall not be designed to leave an enclosed area
that cannot be visually inspected.
b. The welding of internal attachments to the pressure boundary shall be continuous on all
surfaces to eliminate corrosion pockets.
c. Internal attachments shall be fabricated from the same material specification and grade of
material as the shell or lining to which they are attached.
d. Internal attachments shall be designed to be naturally draining.
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e. If a vessel corrosion allowance is specified, the size of the welds shall include allowance for
corrosion.
f. The minimum thickness of welded internal attachments shall be 5 mm (3/16 inch) plus the
corrosion allowance for each wetted side.
g. The minimum fillet weld size shall be 5 mm (3/16 inch) in the corroded condition.
h. All seams and corner joints shall be sealed.
i. Internal attachments shall be designed and installed to satisfy one of the following
requirements:
1. The distance between the weld-toe of the attachment is not within 50 mm (2 inch) of a
pressure boundary weld toe.
2. The portion of the pressure boundary weld that is covered by the attachment shall be
ground flush and given 100% volumetric examination before the internal attachment is
made.
3. The attachment shall be coped or notched to clear all weld area and each weld-toe by at
least 25 mm (1 inch).
j. The stresses in the attachment and attachment weld shall be checked to ensure they are within
the allowable limits of the code of construction.
8.10.2 Manway grab rungs
When other internal fixtures do not afford suitable safe footing and handholds for persons entering
or leaving the vessel, manways in vessels shall be supplemented with rungs attached to the inside of
the vessel shell.
8.11 External attachments
8.11.1 General
a. External attachments to the pressure boundary shall not be designed to leave an enclosed area
that cannot be visually inspected.
b. Pipe segments shall not be directly attached to a pressure boundary and used as supports for
any ladders, platforms, piping, etc.
c. The welding of external attachments to the pressure boundary shall be continuous on all
surfaces to eliminate corrosion pockets.
d. External attachments shall be fabricated from the same material specification and grade of
material as the shell to which they are attached.
e. External attachments shall be designed and constructed to prevent the channelling and hold up
of rainwater.
f. The minimum thickness of welded external attachments shall be 5 mm (3/16 inch).
g. The minimum fillet weld size shall be 5 mm (3/16 inch).
h. All seams and corner joints shall be sealed.
i. External attachments shall be designed and installed to satisfy one of the following
requirements:
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1. The distance between the weld-toe of the attachment is not within 50 mm (2 inch) of a
pressure boundary weld toe.
2. The portion of the pressure boundary weld that is covered by the attachment shall be
ground flush and given 100% volumetric examination for the length of the overlap plus at
least 50 mm (2 inch) on each side before the attachment is made.
3. The attachment shall be coped or notched to clear all weld area and each weld-toe by at
least 25 mm (1 inch).
j. The stresses in the attachment and attachment weld shall be checked to ensure they are within
the allowable limits of the code of construction.
k. Galvanized clips or attachments shall not be welded to a vessel.
8.11.2 Insulation supports
a. The distance between insulation support rings shall be approximately 3 000 mm (120 in), but
not more than 3 700 mm (145 in).
b. Support ring design shall be included on the manufacturer’s drawings and submitted for
review and approval by BP.
c. On vertical vessels, there shall be a continuous gap of not less than 10 mm (3/8 in) between the
vessel and the inside edge of the insulation support ring, see Figure 3.
d. Insulation support rings shall not be welded directly to the shell, see Figure 3.
Figure 3 - Typical arrangement to prevent hold up of water at insulation rings
VESSEL
FLAT BAR
WELDED CLIP
MIN GAP 10mm (3/8 in)
8.11.3 Fireproofing supports
a. Fireproofing supports shall be provided and installed by the vessel manufacturer on skirts and
saddles when concrete fireproofing is specified on the EDS.
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b. Fireproofing supports for concrete fireproofing shall be Nelson R6P Rectangular Slotted Stud
or equivalent.
c. If the vessel manufacturer is also responsible for supplying the fireproofing material, the vessel
manufacturer shall ensure the fireproofing material and painting system are compatible.
8.11.4 Nameplates brackets
a. A nameplate bracket shall be provided on all pressure vessels by the vessel manufacturer.
b. Nameplate brackets shall be located near a manway and shall not be obstructed when the
manway is open.
c. The nameplate bracket may be designed in compliance with PIP VEFV1101.
d. For insulated vessels:
1. At least two nameplate brackets shall be provided by the vessel manufacturer.
2. The design code required nameplate shall be installed on a bracket designed to be totally
encased under the vessel insulation.
3. An additional nameplate bracket and duplicate nameplate shall be attached to the vessel
support (not the pressure vessel shell) and project beyond the insulation.
8.11.5 Manway davits and hinges
a. All manways shall be provided with either a davit or a hinge.
b. The selection of davits or hinges shall be as stated on the EDS.
c. Manways that are orientated at an angle other than 0° or 90° from the horizontal plane shall be
designed with a hinge such that the hinge opens in the horizontal plane only.
d. Stops shall be provided to prevent damage to vessel shell or insulation from the over-rotation
of the manway hinge or davit.
e. Manway hinges may be designed in compliance with PIP VEFV1116
f. Manway davits may be designed in compliance with PIP VEFV1117 or PIP VEFV1118.
g. Eyebolts used in manway davit designs shall be one-piece forgings.
8.11.6 Vacuum stiffening rings
a. Vacuum stiffening rings shall be designed as a flat bar type and made from plate matching the
plate material specification and grade of the vessel.
b. Vacuum stiffening rings shall be continuous fillet welded on the top and bottom of the ring.
c. Vessels subject to thermal cycling, such as coke drums, shall not use vacuum stiffening rings.
8.11.7 Lifting attachments
8.11.7.1 Vertical vessels
a. Lifting lugs or trunnions shall be provided as indicated on the EDS.
b. Lifting trunions shall only be used when the vessel shell would be overstressed in bending
during the lift or erection with the lifting lugs were located at the top of the vessel.
c. The load factor for design shall be 1,5 unless otherwise specified.
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d. Attachment of lifting lugs shall be such that water cannot be trapped between the vessel and
the lifting lug.
e. The length of the lifting lug shall be such that the vessel may be fully insulated prior to the lift.
f. For thick-walled vessels with a formed head and a top, centre nozzle, the lifting lug may be
attached to a lifting flange when specified on the EDS.
1. Calculations of the stresses in the nozzle neck and head shall be submitted for review and
approval.
2. The lifting flange shall be provided with full bolting.
3. The lifting lug shall be inserted through the lifting flange and fillet welded on both sides
of the lifting flange.
g. Calculations for the stresses in the vessel shall be submitted for review and approval.
h. The stress analysis shall identify the angle at which results in the maximum stress at each
lifting point during the lift from horizontal to vertical.
8.11.7.2 Horizontal vessels
a. Horizontal vessels shall be provided with lifting lugs welded to the shell when specified on the
EDS
b. Calculations of the local stresses in the shell shall be submitted for review and approval.
8.11.8 Earthling bosses
Vessel shall be supplied with two earthing bosses (grounding lugs) attached to the support steel.
8.12 Removable internals
a. All portions of the vessel, including removable internals, shall be designed to be completely
self-draining.
b. Removable internals shall be designed or sectioned to pass through vessel manways.
c. Agitator baffles shall be designed to pass through the agitator mounting flange.
d. The weight of the individual parts of components that are normally disassembled such as tray
decks, downcomers, distributor piping, baffles, minor beams, etc. shall not exceed 29 kg
(65 lbs) including attached vapour-liquid contacting devices.
e. The weight of tray manways shall not exceed 22 kg (50 lbs).
f. Flanges for internal non-pressure piping may be slip-on or fabricated from plate to the
dimensions of ASME B16.5 Class 150 unless otherwise specified on the EDS.
g. Trays and other column internals shall be in accordance with GIS 46-040.
8.13 External jackets
Half-pipe or pipe section jackets shall be designed in accordance with one of the following
a. ASME VIII-1 Appendix EE.
b. ASME VIII-2 Paragraph 4.11.6.
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c. For half-pipe jackets or pipe sections welded to shells and/or heads, jacket to shell welds shall
be full penetration and full strength welds, and 100% liquid penetrant examination shall be
performed.
8.14 Nameplates
a. Nameplates shall be of stainless steel with the required data stamped or, preferably, engraved.
Lettering shall be a minimum of 4 mm (3/16 in) high.
b. The nameplate shall show at least the following information:
1. Order number.
2. Item number.
3. Date of manufacture.
4. Order placed by.
5. Manufacturer’s name.
6. Manufacturer’s serial number.
7. Design code and its date.
8. Maximum pressure rating and at coincident temperature.
9. Minimum design temperature and coincident pressure.
10. Extent of volumetric weld NDE, inspection category or equivalent descriptor.
11. PWHT.
12. Test pressure new.
13. Test pressure corroded.
14. Total weight empty.
15. Any code or statutory markings required.
16. BP equipment tag number or a Works Identification Number (of nine digits).
9 Spares
a. Spares shall be provided as specified on the EDS.
b. Minimum spares shall be provided as follows:
1. Two (2) sets of spare service gaskets shall be furnished for vessel girth, manway, and
blinded flanges.
2. An additional 10% of studs, bolts, and nuts shall be provided.
10 Fabrication requirements
10.1 General
a. Machining shall be performed after welding or heat treatment if such operations change
machined surface characteristics or geometry (e.g., flange face flatness).
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b. Only stainless steel brushes, stainless steel grit, glass beads, or other high quality abrasive that
does not result in contamination of the surface shall be used to mechanically clean stainless
steel, high nickel alloy, titanium, or zirconium surfaces.
c. Special care shall be taken to prevent stress raisers which can cause low impact strength
because of notch effect or abrupt change in section.
d. Welder’s and welding operator’s symbols and reference lines may be stamped on the material
in accordance with the provisions of the design code, provided that a round-nose stamp is
employed and the symbol is located a minimum of 25 mm (1 inch) from the edge of the weld.
e. The following materials shall not be used to mark on or coat the vessel:
1. Marking inks that contain halogens.
2. Lubricants.
3. Crayons.
4. Adhesives.
5. Tapes (e.g. duct tape).
6. Coatings to prevent adhesion of weld spatter.
7. Paints containing sulphur.
8. Chlorine compounds that decompose to hydrogen chloride.
9. Carbon.
10. Harmful metal or metal salts (e.g., zinc, lead, or copper).
10.2 Tolerances
a. Tolerances on the vessel shall comply with PIP VEFV1102 after pressure testing unless
otherwise specified on the EDS.
b. Tolerance shall be stated on the fabrication drawings in either the main dimensions or as an
additional tolerance drawing.
c. The allowable flatness tolerances of gasket contact surfaces of flanged shell girth joints, after
PWHT if required, shall be as shown in Table 4 for the designated service condition.
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Table 4 - Flatness tolerances of gasket contact surface
Vessel diameter (mm (in)) Allowable tolerance (mm (in) (1)
Normal service Special service (2)
< 380 (15) 0,8 (0,03) 0,08 (0,003)
> 380 (15) to 760 (30) 0,8 (0,03) 0,150 (0,006)
> 760 (30) to 1 140 (45) 0,8 (0,03) 0,225 (0,009)
> 1 140 (45) 0,8 (0,03) 0,300 (0,012)
Notes:
(1) Total tolerance on peripheral gasket contact surface shall not occur on less than a 0,35 radian (20 degree) arc.
(2) Design temperatures greater than 454°C (850°F), or a flange rating greater than ISO PN 110 (ASME Class 600).
10.3 Joints
10.3.1 General
a. The location of all longitudinal and circumferential joints shall be shown on the fabrication
drawings.
b. If two sections of unequal thickness are butt welded together, the inside (process face) shall be
flush.
c. Weld joints shall be prepared by machining, grinding, or thermal cutting.
1. If thermal cutting is performed, the joint surfaces shall be ground to sound metal prior to
welding.
2. Preheat requirements for thermal cutting shall be the same as those specified in the WPS.
d. Except as permitted in Clause 10.3.1e, longitudinal joints shall be located to clear nozzle
openings, nozzle attachment welds, and reinforcing pad attachment welds by at least 50 mm
(2 inch) when measured from weld toe to weld toe.
e. When a nozzle opening, nozzle attachment weld, reinforcing plate, or reinforcement plate weld
cannot be located to not cross a longitudinal or circumferential joint, then the following shall
apply.
1. The vessel manufacturer shall demonstrate to BP that the plates cannot be re-orientated or
shifted around such that the item is not able to provide the necessary weld toe clearance.
2. Alignment of the butted plates under the reinforcement plate shall be flush.
3. The longitudinal and/or circumferential weld shall be ground flush and given 100%
volumetric and surface examination for a length equal to three times the diameter of the
opening before attachment of the pad.
4. The location of the nozzle and weld seam shall be approved by BP.
f. Any weld subject to severe forming (i.e., in which the ratio of thickness to local radius is
greater than 5 present) shall have full volumetric examination before forming and full surface
examination after forming.
10.3.2 Longitudinal joints
a. Longitudinal seams shall not fall within the tray-downcomer area of trays or behind any other
large obstruction that prevents inspection of the welds.
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b. Longitudinal joints shall be offset between courses by at least five times the plate thickness, or
150 mm (6 inches), whichever is greater.
c. Longitudinal joints shall be so located to give as much access as possible for internal visual
inspection, consistent with the presence of the internals.
d. Longitudinal joints in horizontal vessels shall not be located:
1. Under the saddle or saddle wear plate.
2. Within 50 mm (2 inches) of the saddle or saddle wear plate attachment welds.
3. Within 15 degrees of the horn of the saddle or saddle wear plate.
10.3.3 Circumferential joints
a. Circumferential joints shall be located at least 50 mm (2 inches) above or below the tray ring
attachment welds.
b. Circumferential joints shall be located at least 50 mm (2 inches) away from horizontal vessel
saddle or saddle wear plate attachment welds.
10.4 Welding
10.4.1 General
a. All butt joints shall be full penetrations if access is available from both sides of the joint.
b. For joints inaccessible from the inside, an alternative method for obtaining a full penetration
and full fusion weld from one side shall be submitted to BP for review and approval.
c. Butt joints shall not use permanent backing strips.
d. All welds, including those for non-pressure parts and attachments, including temporary
attachments and shipping attachments, shall be made by welders, welding operators, and
welding procedures qualified under the provisions of Code Section IX and approved by BP.
e. Welds shall be in accordance with the supplementary provisions of the Code, and with
recognized and generally accepted good welding practices including, but not limited to, the use
of clean and dry materials, good techniques, and the proper chemistry.
f. The following documents shall be provided to BP for review and approval before the start of
fabrication:
1. Welding procedure specification.
2. Procedure qualification record.
3. Welder performance qualification.
4. Detailed weld map.
5. Welding procedures.
6. Fabrication drawings.
g. The detailed weld map shall include, as a minimum, a sketch of all weld joints, welding
symbols used in accordance with AWS A2.4, and associated weld procedure numbers.
h. Arc strikes on the pressure shell shall be minimized.
i. Arc strikes on shall be conditioned to eliminate surface stress concentrations.
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j. Defects found from arc strikes shall be removed and the surface shall be repaired and re-
examined.
k. Significant weld repairs shall be subject to approval by BP.
l. Removable start-up and run-off tabs may be used for longitudinal welds; the tab materials shall
be of the same material specification and grade as the base metal.
m. Unless specifically approved by BP, use of weld materials with strengths higher than that of
low-hydrogen weld materials for any welding processes is not permitted.
n. Welding consumables shall:
1. Be the same nominal composition as the parent metal.
2. Not contain addition of alloys via the flux, other than that required to make up for losses
(e.g., in the arc).
3. Filler wire shall be homogeneous and not of a self-shielding type.
4. Have material properties (e.g., tensile strength, yield strength, etc.) equal to or greater
than the minimum requirements for the base metal at both ambient and design
temperature.
o. A local DHT shall be performed for all carbon steel butt-welds and corner joint welds (i.e.,
ASME weld category A, B, and C) that are 50 mm (2 inch) and greater in thickness (See
Annex E).
p. An IPWHT shall be performed for all carbon steel nozzle attachment welds (i.e., ASME weld
category D) that are 50 mm (2 inch) and greater in thickness (See Annex E).
10.4.2 Welding processes
a. The following welding processes shall not be used:
1. Self-shielded flux-cored arc (FCAW).
2. Any welding process approved by BP for a different purchase order, but not submitted or
approved for the subject purchase order and item.
b. Manual shielded metal arc with covered electrode (SMAW) of carbon and low alloy steels
shall be made using low hydrogen electrodes.
c. Semi-automatically Submerged arc (SAW) may be used.
d. Gas metal arc using solid wire (GMAW) may be used.
1. The type of metal transfer (short-circuiting arc, globular or spray transfer) shall be stated
on the WPS under electrical characteristics.
2. The process is applicable to carbon steel and weld overlay where a satisfactory level of
dilution is demonstrated.
3. GMAW using a short-circuiting arc shall only be used for depositing metal that is
subsequently removed (e.g., tack welds, double welded joints).
4. Field welding is subject to approval to BP.
e. Gas tungsten arc, manual or automatic (GTAW) may be used.
f. Gas shielded flux-cored arc (FCAW) may be used.
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1. The type of metal transfer shall be stated on the WPS; globular or spray is acceptable but
using a short-circuiting arc is prohibited.
2. Rutile wire may be used for welding carbon and low alloy steels and stainless steel.
FCAW shall not be used for other alloys.
3. Basic cored wires may only be used for the deposition of fill passes in butt welds in the
1G and 1GR position.
4. For welds subject to PWHT and requiring impact testing, the FCAW brand name for
rutile wires shall be an essential variable.
5. Fillet welding procedures in 1F and 2F positions shall be separately qualified for leg
length greater than 6 mm (1/4 inch).
g. The use of metal cored wires is subject to specific approval by BP.
10.4.3 Weld procedure and welder qualification
a. Changes to the approved WPS or PQR shall also be submitted for review and approval by BP.
b. The WPQ shall be made available for review upon request.
c. Repair procedures shall be submitted for review and approval if the repairs could be
detrimental to the material or delivery of the vessel.
d. Unless otherwise agreed, the position of the impact test specimens for tests of weld metal and
HAZ shall be:
1. Weld metal centreline.
2. Fusion line.
3. Fusion line plus 2 mm (1/16 in).
4. Fusion line plus 5 mm (1/4 in).
10.4.4 Dissimilar welds between austenitic stainless steels and ferritic steels
a. Welds joining austenitic stainless steels to ferritic steels shall be made with filler metal as
follows:
1. For services not exceeding 340°C (650°F), one of the following shall be used:
a) ASME SFA-5.4 classification E309L.
b) SFA-5.9 classification ER309L.
c) The filler metals given in 10.4.4a.2 below.
2. For services exceeding 340°C (650°F), one of the following shall be used:
a) ASME SFA-5.14 classification ER NiCr-3 (comparable to INCO 82).
b) ASME SFA-5.11 classification E NiCrFe-3 (comparable to INCO 182) or
E NiCrFe-2 (comparable to INCO A).
c) Another filler metal as specified on the EDS.
d) Approval is required for dissimilar welds in services exceeding 340°C (650°F).
b. The preheat shall be based on the ferritic material.
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c. The first layer of weld overlay deposits shall be made using the preheat required for the base
plate.
d. Subsequent weld layers may use the preheat required for the alloy deposits.
10.5 Temporary welded attachments
a. Attachment point of spiders, braces, or other temporary attachments shall be of the same
material alloy as the point on the vessel to which it is attached.
b. All temporary attachments shall be removed before hydrostatic testing.
c. Temporary attachments shall be removed flush with the vessel shell and non-destructively
examined [i.e., magnetic particle examination (MT) or dye penetrant examination (PT)], in
addition to visual examination, to ensure no cracks have been generated.
d. Temporary welds shall be in accordance with Clause 10.4.1b.
e. Fabrication aids (e.g., clips and brackets) shall not be hammered off but shall be removed
without damage to base metals.
1. Gouges from cutting tools shall be welded with an approved procedure and ground flush
and smooth.
2. Areas where attachments have been removed shall be subjected to examination by
DP/MT.
3. Temporary attachment removal and repairs shall be performed prior to PWHT and
hydrotest.
4. Peening shall not be used.
11 Examination requirements
11.1 General
a. The extent of examination and special documentation, in addition to the minimum
requirements of the design code, shall be as specified in the contract documents.
b. All specified NDE, including that for non-pressure parts and attachments, shall be performed
in accordance with the design code.
c. For specific welded pressure joint examination requirements, see the EDS.
d. The minimum degree of examination of welded butt joints shall be spot radiography.
e. See BP’s contract documents for requirements for examining the accessible surfaces of
completed corner joint welds by magnetic particle, liquid penetrant, ultrasonic, or other non-
destructive methods.
f. Welded joints that are inaccessible after assembly shall be examined by PT or MT in
accordance with the following instructions, and repaired as required before painting, assembly,
and testing:
1. After back-chipping to sound metal, the root pass and its opposite side shall be examined.
2. After any required machining or grinding, the finished surfaces of the weld shall be
examined, and all indications on the finished weld surfaces shall be repaired by grinding
or welding before the pressure testing.
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g. If an examination reveals an unacceptable imperfection, the imperfection shall be repaired and,
as a minimum, the repair shall be examined by the same method, to the same extent, and by
the same acceptance criteria that revealed the condition.
h. The following items shall be examined by magnetic particle or liquid penetrant examination:
1. The following surfaces of butt-type joints greater than 50 mm (2 inches) thick:
a) After back-chipping or gouging root pass to sound metal, the back-chipped or
gouged surface.
b) All accessible surfaces of completed weld.
2. The following surfaces of non-butt type joints, including those in nozzles and
communicating chambers, if the vessel section and/or head is designed using a joint
efficiency of 1.00:
a) After back-chipping or gouging root pass to sound metal, the back-chipped or
gouged surface.
b) All accessible surfaces of completed weld.
3. The cut edge of openings in vessel walls greater than 13 mm (1/2-inch) thick into which
nozzles and communicating chambers are attached with a full penetration weld through
the nozzle or communicating chamber wall.
a) The examination shall be performed before nozzle attachment, and a re-examination
performed after attachment if accessible.
4. All accessible surfaces of completed welds for the following:
a) Welds (i.e., internal and external) if the thickness of the pressure part is greater than
50 mm (2 inches).
b) Welds attaching vertical vessel supports (e.g., skirts, lugs, legs, etc.).
c) Welds attaching vessel lifting (i.e., erection) lugs.
d) Welds attaching manway davits.
i. Fracture mechanics assessment of weld flaws shall not be used to justify weld defects not
acceptable to the design code.
11.2 Preparation
a. The NDE schedule and NDE procedures shall be submitted to BP for review and approval.
b. Personnel concerned with inspection, interpretation, and NDE shall be qualified to at least
PCN Level 2 or ASNT Level 2 if the qualification has been obtained through examination by
an independent organisation. Evidence of the qualification shall be available to BP for
verification.
c. BP reserves the right to test and monitor the performance of any NDE operator employed by
the manufacturer or their sub-contractor and to exclude any that are deemed unsatisfactory.
d. Calibration certificates for NDE equipment shall be available for inspection at all times.
e. Before fabrication, materials shall be visually inspected for defects on accessible surfaces.
f. Heads and shell sections that are annealed or normalized shall be free of mill scale (by sand
blasting, grit blasting, or pickling) prior to inspection.
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g. Materials for marking, painting, or inspection on stainless or nickel based alloys shall not
contain chlorine, bromine, or other halogens, sulphur, zinc, or any low melting point metals.
11.3 Examination of materials
a. Plates of thickness 50 mm (2 in) and above shall be subject to UT check for laminations.
b. Forgings of thickness 50 mm (2 in) and above shall be subject to a 100% UT check for
subsurface defects.
11.4 Surface examination of welds
a. Any surface examination required in this specification shall be performed in a manner
equivalent to the design code methodology in terms of examination extent, location selection,
acceptance criteria, repair method, and re-examination.
b. Welds shall be free from surface breaking defects.
c. Pressure welds in ferritic materials, not subject to RT or UT, shall be examined by MT at
back-chipped surface and at finished weld surface. Skirt attachment welds of ferritic materials
shall be examined by MT.
d. On ferritic vessels subject to PWHT, the shell to nozzle welds on nozzles greater than DN 200
(NPS 8) shall be subject to MT after PWHT.
e. Magnetic particle inspection techniques liable to damage the vessel by arcing are not
permitted.
f. After hydrotest, the following surface examinations shall be made:
1. MT shall be made after hydrotest on external welds and the location of any temporary
welds.
2. Internal welded surfaces and HAZs, including pressure boundary welds, internal
attachment welds, and the location of any temporary welds may be inspected by WFMT
after PWHT and hydrostatic test when specified on the EDS. Any indication revealed by
WFMT shall be removed.
3. If a repair is required, repair area shall be given PWHT after welding, equipment shall be
hydrostatically re-tested ,and repaired area shall be re-inspected by WFMT.
4. Surface preparation for WFMT inspection shall be accomplished by:
a) Blasting to SSPC SP 5/NACE No. 1 (white metal) with fresh (not reused)
aluminium oxide or coal slag grit.
Coal slag is known by several trade names such as Black Beauty, Black Blast, or Black
Diamond.
b) If approved, power wire brushing or grinding to a clean metal surface for limited
areas not accessible for sand-blasting.
Power wire brushing might mask flaws.
5. For small pressure vessels where internal inspection after hydrostatic testing is
impractical, the following shall apply:
a) Welds identified for WFMT shall be inspected by WFMT prior to making final
closure seam.
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b) Inaccessible welds shall be inspected by UT from outside surface after hydrostatic
testing.
11.5 Volumetric examination of welds
a. Any volumetric examination required in this specification shall be performed in a manner
equivalent to the design code methodology in terms of examination extent, location selection,
acceptance criteria, repair method, and re-examination.
b. Volumetric examination of welds shall be done using any of the following recordable NDT
methods.
1. X-ray source.
2. Radio isotope gamma ray source (with restrictions listed in Clause 11.5c).
3. Digital RT.
4. TOFD UT equipped with creeping wave probe(s).
5. Phased array UT.
c. Gamma ray shall be subject to the following restrictions. Isotopes not listed below shall not be
used.
1. Iridium-192 shall only be used for thicknesses of 5 mm up to and including 38 mm
(1,5 in).
2. Cobalt-60 shall only be used for thicknesses greater than 38 mm (1,5 in) up to and
including 50 mm (2 in).
3. Selenium-75 shall only be used for thickness of 5 mm up to and including 30 mm
(1,125 in). The source design shall be thermally stable and non-activating.
4. Elemental selenium shall not be used.
5. The RT film density shall be between 2,5 and 3,5 inclusive.
6. The RT film shall be high definition film.
7. A suitable radiation survey meter in good working condition and calibrated for the types
and energies of gamma radiation being used shall be available at the work location.
d. For thickness greater than 50 mm (2 in), recordable UT methods such as TOFD UT equipped
with creeping wave probe(s) or phase array UT shall be used.
e. If PWHT is performed for any reason, all volumetric examinations for record shall be done
after any PWHT.
f. For vessels constructed to ASME Section VIII:
1. For ferritic plates of thickness below 50 mm (2 inch), UT inspection, when required or
specified, shall be in accordance with SA-578/578M, including Supplementary
Requirements S1, S2, S3, and S4. Acceptance Level C shall be used.
2. For ferritic plates of thickness 50 mm (2 in) and above, UT inspection, when required or
specified, shall be per SA-435/435M.
3. For ferritic forgings, UT inspection, when required or specified, shall be per
SA-541/541M including Supplementary Requirement S2.
g. For vessels constructed to BSI PD 5500:
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1. UT inspection of plate shall be in accordance with BS EN 10160. The required quality
classes shall be S1 for the through thickness check (on 100 mm grid) and E1 for the edge
check, unless otherwise specified by BP.
2. Forgings shall be MT tested to BS EN 10228-1 and the required quality class shall be
class 3 unless otherwise specified by BP.
3. Forgings and pipe shall be UT tested per BS EN 10228-3. The required quality class shall
be class 3 unless otherwise specified by BP.
11.6 Hardness testing
a. Hardness testing shall be in accordance with GIS 36-102.
b. Hardness of weld metal shall be measured on the vessel shall not exceed 200 HBW after any
PWHT.
11.7 Repair of welding defects
a. Repairs of weld defects shall be considered major when one of the following exists:
1. The defect size exceeds 9 mm (3/8 inch) in depth.
2. The defect size exceeds one-half the wall thickness of the component.
3. The defect resulted in leakage during a pressure test.
b. All weld repairs shall receive surface examination.
c. Major weld repairs shall receive full volumetric examination.
11.8 Positive materials identification (PMI)
a. PMI shall be in accordance with GIS 36-103.
b. PMI shall be performed to the extent specified on the EDS.
c. The PMI procedure shall be submitted for review and approval.
12 Inspection requirements
a. BP’s inspection requirements (i.e., review, witness, inspection, hold points, and inspection
documentation) are furnished on BP’s inspection and testing requirements sheet.
b. If major components or services are obtained from sub-contractors, BP’s inspector shall be
notified and given the option of inspecting those items at their point of manufacture.
c. BP’s quality surveillance and notification requirements shall be included in all suborders.
d. The manufacturer shall arrange for certified drawings to be available for use by BP’s inspector
at the sub-contractor’s location.
e. The manufacturer shall ensure, either directly or through sub-contractors, that the inspections
necessary for conformance to BP’s contract documents are performed.
f. The performance of quality surveillance by BP’s inspector shall not relieve the manufacturer
or their sub-contractors of responsibility for meeting the requirements of the contract
documents.
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13 Post weld heat treatment
a. PWHT shall be in accordance with GIS 36-102.
b. Unless otherwise approved by BP, alternative PWHT requirements of ASME VIII-1
Table UCS 56.1 or ASME VIII-2 Table 6.16 shall not be used.
c. Unless otherwise specified on the EDS, PWHT of test specimens shall include one extra
PWHT cycle for potential future field repair.
d. PWHT shall be performed after all welding, weld repairs, and nondestructive examination is
completed, but before any pressure testing.
e. Furnaces used for PWHT shall be constructed to prevent flame impingement on the vessel.
f. Except as specified in Clause 13g, pressure parts made of austenitic stainless steel, if hot
formed, shall be solution annealed between 1 010°C (1 850°F) and 1 120°C (2 050°F)
followed by rapid cooling through the sensitization range.
g. Solution annealing of stabilized grades or “L” grades of austenitic stainless steel with 0,035%
carbon max is not required.
h. Vessels shall not come into contact with galvanized components during PWHT.
i. On ferritic vessels subject to PWHT, the shell to nozzle welds on nozzles greater than DN 200
(NPS 8) shall be subject to MT after PWHT.
j. Any local PWHT shall be subject to approval.
k. Field PWHT procedures shall detail the type of heating, type and effectiveness of insulation,
and means of determining metal temperature.
14 Pressure test
14.1 General
a. Unless otherwise specified on the EDS, the test pressure shall be based on the MAP (new and
cold).
See ASME VIII-1 Paragraph UG-99(c).
b. Prior to the pressure test, the inside and outside of the vessel shall be thoroughly cleaned and
shall be free from slag, scale, dirt, grit, weld splatter, and pieces of metal, paint, oil, etc. Welds
shall be free of slag, oil, grease, paint, and other foreign substances that might prevent
interpretation of the required tests.
c. Vessels shall not be painted or controlled shot-peened before the pressure test, with the
following exceptions:
1. Surfaces that are to be painted, but are inaccessible after assembly (e.g., mating surfaces
of lap-joint stub ends, flanges and nozzle necks, flange bolt holes, welded joints, etc.)
shall be painted before assembly and pressure testing.
2. Welded joints that are inaccessible after assembly (e.g., joints covered by lap-type
flanges) shall be examined by PT or MT and repaired as required before painting,
assembly, and pressure testing. See Clause 11.1f for specific examination requirements.
d. The test pressure shall be measured at the high point of the vessel in the test position.
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e. All welds shall be sufficiently cleaned and free of scale or paint before pressure testing to
permit proper examination for defects.
f. Reinforcing pad attachment welds and accessible surfaces of inside nozzle to vessel wall welds
shall be tested for the absence of leaks with a gauge pressure of 15 psig (100 kPa) dry air or
nitrogen and bubble forming solution. This test shall be performed before the final hydrostatic
or pneumatic test as applicable.
g. All facilities and materials (e.g., blinds, bolting, and gaskets) required for testing shall be
provided.
h. The service gasket shall be used for the pressure test.
i. The service bolts shall be used for the pressure test.
j. The temperature of the pressure-retaining components during the pressure test, regardless of
test media, shall be:
1. At least 60°F (15°C), but not warmer than 120ºF (50ºC) and
2. At least 30ºF (17ºC) warmer than the minimum design metal temperature of the vessel.
k. Gaskets shall be used for test purposes in accordance with the following:
1. If a flanged joint is not to be disassembled after testing, the specified service gasket shall
be used. Service gaskets used for testing shall be left installed for shipment for all blind
flanged connections.
2. If a joint is to be disassembled after testing and has flanges in accordance with
ASME B16.5 or ASME B16.47, the test gasket may be selected by manufacturer.
3. If the joint is to be disassembled after testing, employs nonstandard flanges (i.e., other
than ASME B16.5 or ASME B16.47), and the service gasket is not specified, the test
gasket description shall be submitted to BP for approval.
l. Unless specified for the service condition, joint sealing compound or gasket lubricant shall not
be used.
m. All bolting and washers, if used for testing, shall be properly lubricated for assembly before
the initial hydrostatic test.
n. Except for leakage that can occur at temporary closures for those openings intended for welded
connections, leakage shall not be permitted at the time of the required inspection.
o. Leakage from temporary seals shall be directed away to avoid masking leaks from other joints.
p. Sensitive leak tests, if specified, shall be performed before hydrostatic testing.
q. Flanged joint assemblies specified to be provided with service gaskets (e.g., main body flange
joints, manways, blind flange nozzles) and which are disassembled following tests shall be
reassembled using new service gaskets. If the joints are shipped unassembled, new service
gaskets for field installation shall be suitably packaged, marked, and shipped with the vessel.
See Clause 16.1c.
r. Welding, burning, or grinding, including cosmetic grinding of pressure retaining welds, shall
not be performed on vessels that have been pressure tested unless approved by BP. This
includes but shall not be limited to welds for shipping attachments, refractory or insulation
clips, stiffeners, spiders, or grinding for surface preparation.
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s. If field assembly and erection is specified in the contract documents, the final pressure test
shall be performed at the installation site. A detailed test procedure shall be provided to BP for
review before testing.
t. If hydrostatic testing at the installation site is specified in the contract documents, BP shall
furnish a fill line and a drain line for the test water at a location adjacent to the test site.
u. A detailed test procedure shall be submitted to BP for approval.
14.2 Hydrostatic test
a. If specified on the EDS, liquids other than water may be used for hydrostatic testing in
accordance with the design code.
b. Horizontal vessels designed to support a full weight load of water shall be tested resting on its
support saddles, without additional supports or cribbing.
c. Vertical vessels being tested in the erected position, whether shop or field, shall have design
consideration given to the additional pressure and weight from the fluid head.
d. Vessels shall be adequately supported during the pressure test to prevent damage.
e. Testing of vessels shall be performed with test water that is clean and free of debris.
f. Water shall not contain more than 10 PPM suspended solids.
g. Brackish or untreated water shall not be used.
h. Except as permitted in Clause 14.2i, testing of vessels or components made of austenitic
stainless steel materials shall be performed with water containing a maximum of 50 ppm
chloride.
i. If the duration of the test procedure is 72 hours or less and the procedure includes rinsing with
water containing less than 50 ppm chloride, testing of vessels or components made of
austenitic stainless steel materials may be performed with water containing greater than
50 ppm chloride but less than 250 ppm chloride.
j. Test water shall not be in contact with austenitic stainless steel for greater than 72 hours unless
treated with an appropriate biocide.
k. Before application of the test pressure, the test water and the vessel material shall be permitted
to equalize to approximately the same temperature.
l. The test pressure shall be held for a minimum of one hour, or as specified on the EDS.
m. After completion of the hydrostatic test:
1. The vessel shall be immediately drained.
2. Standing water (including on internals) shall be wiped dry and shall not be allowed to
evaporate to dryness.
3. Vessel shall be closed as quickly as practicable.
14.3 Pneumatic test
a. Detailed, written procedures for pneumatic testing shall be submitted for review and approval
by BP.
b. If acoustic emission monitoring of the pneumatic test is specified on the EDS, procedures for
the monitoring shall be submitted to BP for review and approval.
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c. The pneumatic test medium shall be one of the following:
1. Inert gas.
Inert gas cannot support combustion.
2. Clean, dry, oil-free air in accordance with ISO 8573-1 Class 1, 2, or 3 air, with a dew
point ranging from -20°C to -70°C (+4°F to -94°F).
d. Pneumatic testing shall not be permitted unless:
1. Hydrostatic testing is not practical as determined by BP.
2. All butt-welds have received full volumetric examination.
3. All attachment welds, including weld attaching non-pressure parts to pressure parts have
received full surface examination.
4. Non-essential personnel have evacuated the testing area for a safe distance specified in
ASME PCC-2 Article 5.1.
5. The vessel manufacturer demonstrates that all materials used ensure fracture toughness
during the test at the test temperature.
15 Cleaning, surface preparation, painting, and marking
15.1 Cleaning
a. The vessel shall be thoroughly cleaned inside and outside.
b. Grit, scale, oil, grease, weld rod stub ends, sand, water, free moisture, and all other foreign
material shall be removed from the vessel.
c. High alloy vessels shall be blown dry with ambient temperature air, only after all standing
water has been removed.
d. If specified on the EDS, all or part of the following vessel cleaning procedure shall be
performed before shipping:
1. Perform solvent or detergent wash.
2. Rinse.
3. Perform wet-dry test in accordance with ASTM A380.
4. If rust stains appear in wet-dry test, acid clean with passivation solution.
The appropriate application method of hand wipe, spray, or circulating should be
chosen based on the extent of rusting.
5. Repeat wet-dry test.
6. If rusting reappears, consider pickling solution.
7. Rinse.
8. Dry.
15.2 Surface preparation and painting
a. External surface preparation, priming, and painting shall only be carried out after pressure tests
have been satisfactorily completed.
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b. Austenitic alloy steel and nickel-iron-chromium alloy material parts with design metal
temperatures above 400°C (750°F) shall not be painted.
c. External coating shall be as specified in the EDS.
d. Removable lifting flanges, removable tailing lugs shall be painted yellow.
e. Lifting devices that are intended to be cut off after erection shall receive full surface
preparation, priming, and painting as the component it is attached to, except the final colour
shall be yellow for the areas that are to be cut off.
f. The BP inspector shall have absolute and immediate authority to reject any stage of surface
preparation, priming, or painting.
g. Any rejected surface preparation, priming, or painting shall be remediated as instructed by the
BP inspector to include possibly re-surface preparation on the entire vessel.
15.3 Marking
a. All markings shall be in the English language.
b. All markings shall also be in an additional language if so specified on the EDS.
c. Markings shall be at least 150 mm (6 in) high letters in contrasting paint.
d. All PWHT vessels shall have the following notice painted on two sides of the shell and
insulation covering, if present, in three-inch high letters visible in the shipping position from
grade (See Clause 10.1e):
POSTWELD HEAT TREATED - DO NOT BURN OR WELD
e. All vessels with non-metallic linings shall have the following notice painted on two sides of
the shell and insulation covering, if present, in three-inch high letters visible in the shipping
position from grade (See Clause 10.1e):
LINED VESSEL - DO NOT BURN OR WELD
f. On vertical vessels, the marking shall be located on two opposite sides near the bottom tangent
line and repeated at approximately each 3 m (10 ft) of height, but rotated π/2 radians
(90 degrees).
g. On horizontal vessels, the markings shall be located on both sides near the horizontal
centreline.
h. The North and East orientations shall be center-punched on the outside of each vertical vessel
approximately 150 mm (6 inches) above the bottom tangent line and 150 mm (6 inches) below
the top tangent line. The punch marks shall be circled with white paint.
i. The purchase order number and the vessel identification number shall also be painted with
contrasting paint on non-pressure attachments such as saddles, skirt, or support brackets.
j. All temporary support components required for maintaining vessel roundness or shipping shall
be painted yellow and marked: “SHIPPING/FABRICATION DEVICE. REMOVE BEFORE
UNIT STARTUP”.
k. The center of gravity of the vessel shall be marked in contrasting paint.
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16 Preparation for shipment
16.1 General
a. The manufacturer shall be responsible for suitably packaging each vessel or component and
adequately supporting and securing all vessel internals to protect them from damage or loss
during handling and shipment.
b. When specified on the EDS, a certified weight shall be obtained for the vessel prior to
shipment preparations.
c. The manufacturer shall include a packing list in each shipment.
d. All spares shall be suitably packaged, marked, and shipped with the vessel.
e. All bolting and other loose parts shall be suitably packaged and identified with the purchase
order number and vessel tag number.
f. Uncoated bolts and nuts shall be coated with a suitable thread lubricant to prevent corrosion
during transportation and storage. The lubricant shall be easily removable with mineral spirits
or a solvent.
g. Internals which cannot be safely shipped in place shall be identified, tagged, and shipped
separately.
h. For internals which have specified clearances or tolerances, a minimum of one of each type
(e.g., tray type or distributor type) shall be trial assembled into the vessel to ensure proper fit
before shipment.
i. Design and construction details for shipping saddles shall be submitted to BP for review and
approval.
j. Austenitic stainless steel vessels shall be protected from exposure to salt water, salt spray, and
chlorides during ocean or over the road shipment.
k. Vessels that will undergo ocean shipment shall have a preparation and shipping plan submitted
for approval.
1. Vessels shall not be transported to the jobsite as above-deck cargo without prior written
approval of BP.
2. If nitrogen is used, the vessel shall be clearly marked identifying that nitrogen is present.
The method and location of such marking shall be agreed upon between vessel
manufacturer and BP.
l. All packaging and protection shall be suitable for outdoor storage for a minimum period of
6 months.
16.2 Preparations for the vessel
a. Flanged openings shall be protected and made waterproof with one of the following:
1. Plastic flange protectors.
2. Metal flange protectors with rubber gaskets.
b. Covers for flanged opening shall be secured with at least 25% complement of total flange
bolting (minimum of 4 bolts).
c. Welding stub ends shall be protected with plastic caps.
d. Threaded couplings shall be protected with bull plugs and sealed with joint compound.
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e. Socket weld fittings shall be protected with plastic caps.
f. Weld bevels shall be closed with plastic caps.
g. Nozzles, including attached piping, within or passing through vessel support skirts shall be
adequately supported for shipping and handling.
h. Machined surfaces (except weld bevels), flange faces, threaded surfaces, and other finished or
delicate parts shall be well-greased and protected against rusting and damage during shipment.
i. Weld bevels shall be free of dirt, oil, grease, scale, rust, and other foreign materials.
j. Weld bevels of carbon steel and ferritic alloy steel materials shall be coated, after cleaning, on
the inside and outside for a distance of approximately 75 mm (3 in) from the end of the weld
bevel with a weldable rust preventive approved by BP.
k. Holes in reinforcing pads and saddle wear plates shall be plugged with room temperature
vulcanizing (RTV) silicone sealer or rust preventative grease that is compatible with the base
material.
l. Blind flanged connections, including manways, shall have the blinds attached with a full
complement of new service bolts and service gasket.
m. Hardened washers shall be provided under nuts for all bolts having diameters of 32 mm
(1-1/4 inches) or larger to prevent damaging the back side of the flange. The washers shall be a
minimum of 6 mm (1/4 inch) thick.
n. Joints shall be assembled in accordance with ASME PCC-1.
o. If the permanent saddles of horizontal vessels are used for support during shipment, saddle
extensions constructed of timber or other suitable materials shall be secured to the saddles to
provide adequate ground clearance for boot or nozzle projections, if any, that extend below the
permanent saddle base plate.
16.3 Preparations for spares and crated parts
a. All items shipped not attached to the main vessel shall be packaged and crated for secure
shipment.
b. All parts with nozzles, flanges, or connections (such as piping spools) shall be protected as
listed in Clause 16.2.
c. Crates shall be durably marked with:
1. The receiving address.
2. The vessel item number.
3. The purchase order number.
d. Markings shall be in a minimum of two (2) locations and a minimum lettering size of 25 mm
(1 inch).
e. All markings shall be in the English language.
f. All markings shall also be in an additional language if so specified on the EDS.
16.4 Securing and padding
a. Ropes, chains, and straps may be used to secure the vessel and associated equipment to the
transporter deck.
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b. Padding shall be placed between cables or chains and stainless steel or high alloy equipment to
prevent discoloration of the vessel shell and/or contamination of the metal.
c. Nozzles and manways shall not be used as tie-down points.
d. External attachments other than lifting lugs and tailing lugs shall not be used as tie down
points unless the external attachment has specifically been designed as such.
e. If carbon steel shipping saddles are used for stainless steel or high alloy vessels, the saddles
shall be padded.
16.5 Material safety data sheets
a. Vessels or materials that contain or are coated with any of the following shall be prominently
tagged at openings to indicate nature of contents and precautions for shipping, storage, and
handling:
1. Insulating oils.
2. Corrosion inhibitors.
3. Antifreeze solutions.
4. Desiccants.
5. Chemical substances.
6. Hydrocarbon substances.
b. Regulated substances shall have a material safety data sheet (MSDS).
c. MSDS shall fully conform to regulations for MSDS preparation specified by entity that has
jurisdiction and shall include a statement that the substance is considered hazardous by
regulation.
d. If any products are exempt from regulation, a statement to that effect shall be included.
e. All MSDSs shall be forwarded to the receiving facility before shipment.
f. All MSDSs shall be placed in a protective envelope(s) and shall be affixed to the outside of the
shipment.
17 Documentation
The following documentation shall be required.
17.1 Proposal documentation
a. The manufacturer shall supply all relevant information necessary for appraisal of the
mechanical design by BP, which includes but is not limited to the following:
1. Confirmation of compliance with the code of construction and all documents that are part
of the enquiry or provide requests for clarification or deviations.
2. A typical quality control plan.
3. The proposed manufacturing plan.
4. A listing of any proposed suppliers and sub-contractors, including names and addresses.
5. A definition of the welding processes and techniques to be used, including that for
overlay applications.
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6. A list of any requested exceptions or deviations to the contract documents including this
GIS.
7. Details of previous fabrication experience on vessels of similar size and of the same
materials and construction.
b. The base proposal for the construction of the vessel shall be provided in full compliance with
BP’s request for quotation.
c. An alternative design proposal may be submitted if considered less costly and/or an
improvement in the delivery schedule.
1. The improvements in cost and schedule shall be realized without any of the following:
a) Loss of capability.
b) Shortening the anticipated life of the vessel.
c) Increase in the total lifecycle cost of the vessel.
d. Alternative design proposals shall be in accordance with the following:
1. Shall be accompanied by the base proposal and be clearly identified as an alternate
proposal.
2. Shall clearly state the intended use of ASME Code Cases.
3. Shall be fully and clearly described and substantiated by sketches or drawings.
4. Shall include a list of specific exceptions to BP’s request for quotation, the EDS, and the
contract documents including this GIS.
17.2 During design and fabrication
a. Work shall not begin unless the plans and procedures applicable to that work have been
approved by BP.
b. The following shall be submitted for review and approval by BP:
1. Quality plan.
2. Inspection and test plan.
3. Fabrication plan.
4. Names and addresses of all suppliers and sub-contractors.
5. Full set of fabrication drawings.
6. Complete calculations.
7. Welding procedure specifications (WPS).
8. Procedure qualification record (PQR).
9. Weld map.
10. Heat treatment procedures.
11. Pressure test procedure.
12. PWHT procedure.
13. NDE procedures.
14. Drawings of trays, packing, and internals, if applicable.
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15. Centre of gravity and foundation loading diagram.
16. Draft ASME forms.
17. Draft final pressure vessel record book (see Clause 17.3b).
c. The fabrication drawings shall include, but shall not be limited to, the following:
1. Applicable information on the pressure vessel data sheet.
2. Dimensions of vessel components.
3. General vessel details including nozzle details.
4. Gasket and flange details including flange face finishes.
5. Internal construction details including shell attachments and location.
6. Full scale drawing of the vessel nameplate.
7. Support and other appurtenance details including an anchor bolt template.
8. Weld joint details in cross-section, weld map, and applicable welding procedures.
9. Clad and weld overlay details.
10. Heat treatment requirements.
11. Weld hardness requirements.
12. Non-destructive testing requirements.
13. Identification of pressure limiting components.
14. Tolerances to which the vessel will be built.
d. Fabrication drawings shall use the system of units specified by BP.
e. Revisions of drawings, plans, procedures, and other previously submitted documents shall be
submitted for further approval by BP.
f. No modifications shall be made to the approved drawings, plans, procedures, and other
approved documents without the approval of BP.
g. Documents shall reference both the purchase order number and the vessel item number.
h. As a minimum, the following documents shall be available for review during manufacture:
1. Purchase orders and specifications for plates and forgings, CMTRs, chemical analysis,
and mechanical properties of pressure containing materials including weld filler
materials, except weld filler materials in carbon steel vessels.
2. Copies of actual heat treatment charts indicating complete temperature cycles, holding
times, cooling and heating rates.
3. Radiographs.
4. WPSs, PQRs, and welder qualification records.
5. NDE examination reports.
i. For components and aspects of the design that fall beyond the scope of the code, adequate
calculations shall be carried out by the manufacturer to justify and prove the integrity of the
design and shall be submitted to BP for review and approval.
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17.3 Final documentation
a. On completion of construction of each vessel, the manufacturer shall assemble and deliver the
pressure vessel record books to BP.
b. The pressure vessel record book shall contain, as a minimum, the following information:
1. Manufacturer’s Data Report (ASME forms).
2. Photocopy or photograph (not a rubbing) of the vessel nameplate.
3. Mechanical design calculations required to demonstrate compliance with the code, or to
justify and prove the integrity of the design for those components and aspects that fall
beyond the scope of the code.
4. The latest revision of the EDS marked up to reflect the as-built conditions.
5. Quality control plan including fabrication sequence, all heat treatment requirements,
forming and rolling procedure, an inspection and test plan with schedule identifying all
inspection points required by the owner, and signed inspection reports.
6. As-built fabrication drawings.
7. Welding procedure specifications (WPS), procedure qualification records (PQR), weld
map, and welder or welding operator qualification test results.
8. Personnel qualification certificates for all non-destructive examinations.
9. All reports required by the code of construction stating the results of non-destructive
inspection and testing including radiographic examination, ultrasonic testing, magnetic
particle examination, liquid dye penetrant examination, and hardness tests.
10. Pyrometer charts or other detailed records for all heat treatment performed, such as
PWHT, normalizing, and heating for forming.
11. All exceptions, deviations, and non-conformance reports (including resolution) and a
detailed description of any repairs including a sketch, photo, or drawing indicating the
location and size of the repaired area.
12. Charts or other records of required pressure tests.
13. Certified material test reports or certificates of compliance which fully identify the
specific materials they represent.
14. The PMI report for all materials subject to PMI examination.
15. A completed inspection checklist per the inspection test plan.
16. Results of all impact testing.
17. Operations and maintenance requirements/procedures as applicable.
c. Three (3) copies of the pressure vessel record book shall be delivered to BP unless a different
number of copies is specified in the contract documents.
d. The pressure vessel record book shall also be provided on a CD or DVD securely attached
within each furnished hardcopy of the book containing the following:
1. A PDF version of the pressure vessel record book.
2. The computer files of the pressure vessel calculations (i.e., COMPRESS, PVElite,
Finglow, FE/Pipe, NozzlePro files).
3. Any FEA model files with solution (i.e., ANSYS or Abacus files).
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e. Where applicable, the pressure vessel data book shall include all correspondence relating to the
approval of “state special” designs as required by the applicable jurisdictions.
f. The pressure vessel record book shall be retained by the vessel manufacturer and shall be
furnished to BP upon their request for a minimum of five (5) years.
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Annex A (Normative)
Supplementary requirements for special services
A.1 General
If the EDS indicates any of the following special services are present, the requirements contained
within that clause below shall apply.
A.2 Anhydrous ammonia service
a. All longitudinal and circumferential butt welds shall receive full volumetric NDE, after any
PWHT.
b. All welds, including external and internal non-pressure containing welds, shall be subject to
100% surface inspection by MT or PT after any PWHT.
A.3 Butane storage
a. The specified minimum tensile strength of C-Mn steels shall not exceed 550 MPa (80 ksi).
b. Weldment hardness shall not exceed Hv10 248 (Brinell 237 HBW).
A.4 Amine service
a. Carbon steel shall receive PWHT.
b. All longitudinal and circumferential butt welds shall receive full volumetric NDE, after any
PWHT.
c. All welds, including external and internal non-pressure containing welds, shall be subject to
100% surface inspection by MT or PT after any PWHT.
d. In amine service, welds and HAZ shall be blasted and examined by WFMT. If the vessel is
subject to PWHT, this examination shall be performed after PWHT.
e. Full penetration welds shall be provided on pressure boundary parts to internal attachments
such as downcomer bolting bars and segments, bed support beam seats, or any load-carrying
attachments that have the long axis parallel to the longitudinal axis of the vessel. This
requirement for full penetration welds does not extend to tray support rings, or other
circumferentially oriented attachments.
A.5 Caustic service
a. All longitudinal and circumferential butt welds shall receive full volumetric NDE after any
PWHT.
b. All welds, including external and internal non-pressure containing welds, shall be subject to
100% surface inspection by MT or PT after any PWHT.
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A.6 Cyanides service
a. All longitudinal and circumferential butt welds shall receive full volumetric NDE after any
PWHT.
b. All welds, including external and internal non-pressure containing welds, shall be subject to
100% surface inspection by MT or PT after any PWHT.
A.7 Cyclic service
a. All fillet welds shall be contoured.
b. All fillet welds shall receive toe grinding.
c. All butt weld joints shall receive full volumetric examination.
d. All welds shall receive surface examination by PT or MT.
A.8 Hydrofluoric acid
a. All longitudinal and circumferential butt welds shall receive full volumetric NDE, after any
PWHT.
b. All welds, including external and internal non-pressure containing welds, shall be subject to
100% surface inspection by MT or PT after any PWHT.
c. Material shall be to licensor and BP requirements, with restrictions on composition. Unless
otherwise agreed, it shall be ASME SA-516/SA-516M Gr. 60 normalised with:
1. Carbon equivalent 0,40%.
2. Combination of Ni + Cu + Cr 0,15%.
3. S < 0,002%.
4. Oxygen content < 0,002%.
5. P < 0,008%.
6. Nb (Cb) < 0,005%.
d. The steel shall not be calcium treated for shape control.
e. Full penetration welds shall be provided on pressure boundary parts to internal attachments
such as downcomer bolting bars and segments, bed support beam seats, or any load-carrying
attachments that have the long axis parallel to the longitudinal axis of the vessel. This
requirement for full penetration welds does not extend to tray support rings, or other
circumferentially oriented attachments.
A.9 Hydrogen service
a. All longitudinal and circumferential butt welds shall receive full volumetric NDE after any
PWHT.
b. All welds, including external and internal non-pressure containing welds, shall be subject to
100% surface inspection by MT or PT after any PWHT.
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c. Materials shall be subject to UT to ASME SA 578, including supplementary requirements S1,
S2, S3, and S4. Acceptance standard shall be Level 1.
d. All internal and external attachments welds should be full penetration welds. In instances
where a full penetration weld is not possible, the enclosed space shall be vented.
e. All longitudinal and circumferential butt welds shall receive full volumetric NDE after any
PWHT.
f. All welds, including external and internal non-pressure containing welds, shall be subject to
100% surface inspection by MT or PT after any PWHT.
A.10 Low temperature service
a. If the lowest operating temperature is below 0°C (32°F), NDE inspections shall include the
following:
1. All longitudinal and circumferential butt welds shall receive full volumetric NDE after
any PWHT.
2. All welds, including external and internal non-pressure containing welds, shall be subject
to 100% surface inspection by MT or PT after any PWHT.
b. If the lowest operating temperature is below -20°C (-4°F), all pressure containing welds shall
be subject to full volumetric examination after any PWHT.
A.11 Propane storage
a. The specified minimum tensile strength of C-Mn steels shall not exceed 550 MPa (80 ksi).
b. Weldment hardness shall not exceed Hv10 248 (Brinell 237 HBW).
A.12 Sour water, wet H2S, or wet sour service
a. All longitudinal and circumferential butt welds shall receive full volumetric NDE after any
PWHT.
b. All welds, including external and internal non-pressure containing welds, shall be subject to
100% surface inspection by MT or PT after any PWHT.
c. Materials shall be purchased and fabricated in order to be resistant to environmental cracking
in sour service and conform to the hardness and other requirements of ISO 15156 (Upstream)
or NACE MR0103 (Downstream).
d. Material shall be in the normalised condition unless approval is given for the steel to be
supplied quenched and tempered (Q+T) or made by thermo-mechanical controlled process
(TMCP).
e. The vessel shall be stress relieved.
f. Z quality plate shall be used for carbon steel. Z-quality steel plate shall be designated as one of
the following:
1. EN 10028-3 Grade P275NH + EN 10164, Z35.
2. ASME SA-516/SA-516M Grade 70 (or equivalent) + SA-770 with S3 at 35%.
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g. The plate shall meet EN 10028-3 or equivalent steel grades together with the following
supplementary requirements.
1. Steels shall be made by a low sulphur and low phosphorus refining process, for example,
in an electric furnace with double de-slagging or in the basic oxygen furnace. The steel
shall be vacuum degassed while molten.
2. The following limits by check analysis (product analysis) shall apply:
Carbon 0,200% max.
Sulphur 0,008% max.
Phosphorus 0,025% max.
Carbon equivalent (CE) 0,430 max.
The carbon equivalent value shall be calculated by the following formula:
h. Plate shall be ultrasonically examined and meet BS EN 10160 quality classes S1/E1 or
equivalent.
i. Through-thickness tensile test
1. Each plate shall conform to acceptance class Z35 of BS EN 10164 or equivalent.
2. BP may agree to a retest after consideration of information supplied. The through-
thickness test shall be made after the completion of all heat treatments.
3. In addition to the above, the tests required by the relevant material specification shall be
carried out.
j. Plate shall not be weld repaired without approval and shall be subject to an agreed repair
procedure before repair.
k. If the data sheet specifies that HIC resistant plate shall be used, the following additional
requirements shall apply.
1. Plates shall meet one of the following:
a) EN 10028-3.
b) EN 10028-6 (Q+T).
c) ASME SA-516/SA-516M (normalized).
d) ASME SA-841/SA-841M (TMCP).
2. Steels shall be made by a low sulphur and low phosphorus refining process, for example
in an electric furnace with double de-slagging or in the basic oxygen furnace. The steel
shall be vacuum degassed while molten.
3. Plates shall be in the normalized, Q+T, or TMCP condition.
4. The following limits by check analysis (product analysis) shall apply:
Carbon 0,200% max.
Sulphur 0,002% max.
Phosphorus 0,008% max.
Oxygen 0,003% max.
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Carbon equivalent (CE) 0,430 max.
The carbon equivalent value shall be calculated by the following formula:
5. Plate shall be ultrasonically examined and meet BS EN 10160 quality classes S1/E1 or
equivalent.
6. Plate shall not be weld repaired.
7. HIC/SWC test
a) Tests shall be made in accordance with NACE TM0284, in the NACE TM0284 Test
Solution A (i.e., 5 wt.% NaCl + 0,5 wt.% glacial acetic acid).
b) One set of 3 specimens shall be tested from each thickness of plate from each heat.
c) Following exposure, the test coupons shall be ultrasonically tested for evidence of
hydrogen-induced cracking/stepwise cracking before sectioning. Additional sections
for microscopic examination shall be prepared through any suspect locations, as
approved by BP.
d) The acceptance criteria shall be all of the following:
< 5,0% CLR (crack length ratio).
< 1,5% CTR (crack thickness ratio).
< 0,5% CSR (crack sensitivity ratio).
8. If a SOHIC (stress orientated hydrogen induced cracking) or soft zone cracking (SZC)
test is specified in addition to the HIC test, a NACE Standard Tensile Test shall be
carried out to TM0177 using Method A and Test Solution A. The material shall pass this
test and un-failed test samples, shall be evaluated for acceptance by one of two methods:
a) At least two metallographic sections shall be taken parallel to the sample axis. There
shall be no ladder-like cracks > 0,5 mm in length in the through-thickness direction.
b) The remaining tensile strength (after hydrogen degassing at 150°C (302°F)) shall be
≥ 80% of the original actual tensile strength of the material.
l. For downstream applications, hardness of carbon steel HAZ, as measured in the weld
procedure test, shall not exceed 248 Hv10 (Brinell 237 HBW) as per NACE RP0472.
Acceptable hardness values for other materials shall be as given in NACE MR0103. Hardness
checks on the weld deposit of the completed vessel shall conform to NACE RP0472, which
specifies a maximum hardness of Brinell 200 HBW in the weld metal.
m. For upstream applications, hardness in the weldment on cracking resistant carbon and low
alloy steels, measured in the weld procedure test, shall be in accordance with ISO 15156-2,
which specifies a maximum hardness of 250 Hv10 for the weld root area and a minimum
temperature for PWHT of 620°C (1 150°F).
The distinction is made in this GIS between refinery and upstream applications because
the environments are different. Upstream environments are more acidic and have more
chlorides than downstream. NACE MR0175 was developed for upstream applications to
avoid sulphide cracking where conditions are typically acidic (e.g., typical H2S + CO2)
environment. Later on there was recognition that the pH would not always be quite so
low, and the idea of tying requirements to anticipated pH was introduced in
BS EN ISO 15156. NACE MR0103 has been developed specifically for refineries and
this has added some other conditions to define sour service.
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n. Weldments shall be subject to blasting of the surface to an SSPC SP 5/NACE No. 1 and tested
by WFMT. This shall be made after PWHT.
o. Vessels clad with a corrosion resistant lining or fabricated from solid corrosion resistant alloys
for Upstream environments shall be in accordance with ISO 15156-3. The conditions of
acceptability for each of the material classes given in Annex A in ISO 15156-3 shall be met.
For Downstream environments, the material requirements given in NACE MR0103 shall be
met.
p. Full penetration welds shall be provided on pressure boundary parts to internal attachments
such as downcomer bolting bars and segments, bed support beam seats, or any load-carrying
attachments that have the long axis parallel to the longitudinal axis of the vessel. This
requirement for full penetration welds does not extend to tray support rings or other
circumferentially oriented attachments.
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Annex B (Normative)
Supplementary requirements for chrome-moly vessels
B.1 General
a. The plate edge preparation for welding shall be by flame cutting and grinding or by machining.
Nozzle openings shall be made by machining.
b. Material for starting and run-off plates for longitudinal automatic welding shall be of the same
chemical composition as the base material.
c. The hardness of weld crown and root surfaces, and HAZs shall not exceed:
Cr-Mo steels 225 HBW (HRB 97,6)
Cr-Mo-V steels (Vanadium modified) 235 HBW (HRB 99)
d. A fabrication sequence with IPWHT, DHT, and final PWHT, including temperature and
holding times shall be submitted with the quotation.
e. NDE inspections shall be referenced on the fabrication sequence.
f. Procedure qualification tests shall be made on plates or forgings of the same material
specification, grade, class, and thickness as the vessel using filler metal, flux, and/or inert
gases of the same type, brand, nominal chemistry, and size to be used on the actual work.
g. Two production test specimens shall be produced to test the weld metal and HAZs. One test
specimen shall simulate the weldment between two shell courses, and one test specimen shall
simulate the weldment between nozzle forging and shell.
h. The qualification test coupons shall be in the same heat treated condition as the base material
prior to welding. Test coupons shall undergo the heat treatments (IWHT/PWHT) anticipated
for the completed vessel before testing. The 0,2 per cent proof strength shall be determined.
i. The temperature and maximum amount of PWHT time is applicable to base material and
welding procedure qualification testing.
1. The maximum amount of time available for IWHT and PWHT shall be established.
2. Probable times for IWHT and final PWHT to fabricate the vessel shall be reported.
3. These times shall be subject to approval prior to the start of work.
j. Temporary shop attachments such as aids for handling and fitting shall be as follows:
1. Attachments shall be preheated (as specified for the material) with the base metal local to
the attachment.
2. If temporary attachments are of a material different from the base metal, welds shall be
alloyed to match the base metal, not the attachment. After welding, the material shall be
allowed to air cool to ambient temperature.
3. Attachment welds shall be cut above the weld during removal of the attachment.
4. The remaining stub shall be ground flush with the base material surface.
5. The surface shall be MT inspected to confirm that it is free from defects.
k. Material for starting and run-off plates for longitudinal automatic welding shall be of the same
chemical composition as the base material.
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l. One subsize production weld for chemistry and mechanical properties verification shall be
made for each heat of electrode and flux combination.
B.2 Fabrication
a. A local DHT shall be performed for all butt-welds and corner joint welds (i.e., ASME weld
category A, B, and C) that are 50 mm (2 inch) and greater in thickness (See Annex E).
b. An IPWHT shall be performed for all nozzle attachment welds (i.e., ASME weld category D)
that are 50 mm (2 inch) and greater in thickness (See Annex E).
B.3 Examination requirements
c. UT checks for laminations shall be made on all plate.
d. Forgings shall be subject to a 100% UT scan.
e. Plate edges after bevelling, but prior to welding root passes in shell, heads, and nozzles, weld
build-ups on shell and heads, background surfaces, skirt to head or shell attachment welds,
fillet welds, attachment welds and temporary welds after removal of attachments, shall be
subject to MT.
f. Welds, including external and internal non-pressure containing welds, shall be subject to 100%
surface inspection (by MT or PT) after hydrotesting.
g. Pressure containing welds and skirt attachment or support welds shall be subject to RT or UT
after hydrotesting. Radiographs shall be taken within 48 hours after weld completion.
h. Full penetration welds shall be subject to MT on the back-chipped surface and on finished
weld surfaces prior to overlay.
B.4 1,25Cr-0,5Mo vessels (including Vanadium enhanced)
a. The measured tensile strength, as recorded on the material test certificate or report, shall be
limited to 585 MPa (84,8 ksi) for plate and 655 MPa (95 ksi) for forgings.
b. The requirements included and guidance given in API 934-C and API 934-E shall apply.
c. Head or shell plate welds shall not be subjected to an austenitizing heat treatment without
specific approval.
d. Minimum preheat temperature throughout thickness shall be 150°C (300°F). The actual
interpass temperature for WPS qualification tests shall be determined and defined on PQR
documents. Welding preheats shall be maintained until IPWHT has been performed.
e. Minimum PWHT temperatures shall be based on API RP 934-C or API RP 934-E as
applicable. Note that for vessels with operating temperatures above 476°C (825°F),
API RP 934-E applies.
B.5 2.25Cr-1Mo vessels (including Vanadium enhanced)
a. The vessel shall be made by the electric furnace or basic oxygen process.
b. The requirements included and guidance given in API 934-A shall apply.
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c. A minimum and maximum PWHT shall be established. Two sets of weld procedure specimens
shall be heat treated, one for each time. The strength of the vessel shall be such that at least
two PWHT cycles remain available for BP in service, except that if the closing seam of the
vessel requires an additional PWHT, only at least one remaining PWHT cycle shall be
available for BP.
d. Materials for reactor vessels shall be vacuum degassed.
For ASME Code, see SA-20 supplementary requirement S1.
e. For plate and forgings:
1. The measured tensile strength for conventional shall not exceed 690 MPa (100 ksi).
2. Hot tensile tests at design temperature per API 934-A Paragraph 5.5.2.2 shall be required.
3. Test specimens shall be taken from the transverse ¼ t locations.
f. Plates shall be fine grain with a grain size of five (5) per ASTM E112 or finer (i.e. having a
higher number than 5).
g. Step cooling tests of all materials (plates, forgings, and weld metals) shall be performed in
accordance with paragraph 6.2.3 of API RP 934-A. Acceptance criteria shall be in accordance
with API RP 934-A paragraph 6.2.3.3.
h. Welding wire heats and electrode and flux lots shall be selected and tested to confirm that
tensile, impact, and step cooling requirements specified in B.6.3 are met in both the PWHTmin
and PWHTmax conditions.
i. Preheat temperatures for welding, manual weld overlay and thermal cutting operations shall be
in accordance with API RP 934-A. The following minimum preheat temperatures shall be
maintained during machining/welding.
1. 200°C (392°F) for all welding.
2. 120°C (250°F) for machining.
3. 150°C (300°F) for manual weld overlay.
4. 150°C (300°F) for thermal cutting operations.
j. The actual maximum interpass temperature for WPS qualification tests shall be determined
and defined on PQR documents, but shall not exceed 300°C (570°F).
k. During fabrication, intermediate PWHT shall be at temperatures lower than the final PWHT
temperature. The latter shall not exceed the tempering temperature performed at the mill for
any of the materials used.
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Annex C (Normative)
Supplementary requirements for stainless steel vessels
C.1 Fabrication
a. When forming any austenitic stainless or nonferrous materials, the forming rolls shall covered
to prevent carbon pickup or contamination of the formed material.
b. Formed heads shall be solution annealed after forming unless otherwise approved.
c. When cutting stainless steel by any thermal process (e.g., plasma arc or air arc), an allowance
shall be made for the removal of not less than 3 mm (1/8 inch) of metal by machining or
grinding to the finished dimension.
d. Grinding and cleaning of stainless steels shall be done with tools that do not leave detrimental
deposits.
Examples of acceptable tools are aluminium oxide and silicon carbide grinding wheels
and austenitic stainless steel wire brushes not previously used on other types of
materials.
e. Only stainless steel brushes and clean, iron-free sand, ceramic, or stainless steel grit shall be
used for cleaning stainless steel and non-ferrous surfaces.
f. Cleaning tools or materials shall not have been previously used on carbon steel.
C.2 Welding
g. The ferrite content of ASS weld metal, with the exception of type 904L (which is fully
austenitic), shall be in the range 3 - 10% in the as-welded and post-weld heated condition.
h. Ferrite checks shall be made on at least 5% of the welds, unless a higher percentage is
specified on the EDS.
i. Comparable low carbon austenitic filler materials shall be used when welding low carbon
grade austenitic base materials.
C.3 Examination requirements
a. Welds shall be free from cracks and fissures. The extent of PT on welds shall be as specified
on the EDS.
b. The pressure test fluid for ASS vessels shall not contain more than 50 ppm chlorides.
c. ASS vessels shall be dried within 48 hours of draining, using swabs or a flow of air at ambient
temperature. Heat shall not be applied.
d. Unless directed otherwise, ASS vessels that operate in the range of 50°C to 150°C (120°F to
300°F) shall be painted externally to the specification listed on the EDS.
e. Insulated ASS vessels operating below 50°C (120°F) shall be painted externally to the
specification listed on the EDS.
f. Equipment shall be protected such that chloride contamination cannot occur during shipment.
jan01
사각형
jan01
사각형
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g. For vessel constructed to BSI PD 5500:
1. Inspection of forgings by PT shall be to BS EN 10228-2 and the required quality class
shall be class 3 unless otherwise specified on the EDS.
2. Inspection of forgings by UT shall be to BS EN 10228-4 and the required quality class
shall be class 3 unless otherwise specified on the EDS.
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Annex D (Normative)
Supplementary requirements for clad plate or weld-overlay construction
D.1 Design
a. Linings, made by strips fillet welded to the base material, shall not be used.
b. Corrosion resistant alloy cladding or weld overlay shall not be considered in calculating
required pressure boundary thickness.
c. For all cladding materials other than titanium, nozzles shall be made either by weld overlay or
from roll clad plate as shown in Figure 4.
d. Small diameter, solid alloy nozzles may be used instead of clad nozzles provided:
1. The design temperature is less than 300°C (570°F).
2. The vessel is not in any of the special services listed in Annex A.
3. An analysis of the thermal and mechanical stresses at the interface is performed.
e. Raised faced clad flanges shall be fabricated as shown in Figure 7.
f. Ring type joint clad flanges fabricated as shown in Figure 8 shall not be used.
Figure 4 - Typical clad nozzle attachment to shell
Figure 5 - Attachment of lightly loaded attachment to a clad vessel
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Figure 6 - Attachment of a moderately loaded attachment to a clad vessel
Figure 7 - Method for cladding a raised face flange
Figure 8 - Unacceptable method for cladding a ring type joint flange
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D.2 Clad plate material
a. Clad plate shall in accordance with GIS 36-013.
b. Integrally clad plate shall be ordered per ASME SA-263, SA-264, or SA-265 with Quality
Level 1 with supplementary requirement S12.
c. Integrally clad plate shall be ordered with examination in accordance with ASME SA-578 with
Acceptance Level B and supplementary requirements S1, S3, and S4.
d. Integrally clad plate shall be ordered with shear strength tests performed in accordance with
the applicable material specification.
e. The heat treatment of integrally clad plate in accordance with ASME SA-263, ASME SA-264,
and ASME SA-265 shall be performed by the plate manufacturer.
f. All integrally clad plate, including explosion clad plate, in accordance with ASME SA-263,
ASME SA-264, and ASME SA-265 shall be cold flattened, if required, after final heat
treatment and descaling.
g. Following forming and any associated heat treatment, the knuckle region of heads pressed or
spun from clad plate shall be subject to UT and PT, and weld overlay seams shall be inspected
by UT for lack of bond at the weld to clad interface along the entire seam length.
h. Clad plate that is to receive a PWHT shall have indications that show a 50% or greater loss of
back reflection marked and recorded prior to heat treatment.
i. Subsequent to PWHT, integrally clad material shall be re-examined ultrasonically in locations
of previously recorded discontinuities and other indications that resulted in 50% or greater loss
of back reflection.
D.3 Cladding re-instatement
a. The typical detail applied in cladding re-instatement local to a seam is shown in Figure 9.
b. Chipped, gouged, or ground surface shall be cleaned of all residual alloy material.
c. The removed of the residual alloy material shall be verified with a CuSO4 etch.
d. Depth of base material removed during clad removal shall not exceed 0,8 mm (1/32 in).
e. If chip back or gouge is done from inside, as shown in Figure 9b, 5 mm (3/16 in) minimum
shall be left between edge of chipped or gouged surface and cladding.
f. Final base material weld deposit from inside shall not contact cladding and shall be ground
flush before depositing alloy weld material.
g. Weld seams that require volumetric examination shall be tested before cladding re-instatement.
h. For 11-13% chrome (405, 410S) clad vessels, each main seam shall be spot radiographed after
cladding re-instatement in addition to before it.
i. The weld overlay requirements of Clause D.4 shall also apply to cladding re-instatement
welding.
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Figure 9 - Cladding re-instatement at a vessel seam
CHIPPED OR
GOUGED SURFACE
(a) MACHINING
12mm MIN.
(1/2 in)
0.8mm MAX.
(1/32 in)
0.8mm MAX.
(1/32 in)
5mm MIN.
(3/16 in)
(b) ROOT PASS
AFTER GOUGING
CHIPPED OR
GOUGED SURFACE
12mm MIN.
(1/2 in)
COMPLETED WELD
IN BASE MATERIAL.
GRIND FLUSH BEFORE
DEPOSITING ALLOY
(c) MAIN FILL &
BACK GOUGE
2 ND PASS
ELECTRODE
1 ST PASS
ELECTRODE
(d) BACK FILL &
CLADDING
D.4 Weld overlay
a. Weld overlay shall be in accordance with GIS 18-013.
b. Weld overlay shall provide a minimum, guaranteed undiluted chemistry to a depth of 3 mm
(1/8 in) from the surface unless otherwise specified on the EDS.
c. The weld overlay shall be applied in such a manner that the weld beads run circumferentially
around the vessel.
1. The surface contour shall be relatively smooth. Adjacent weld beads shall fuse and blend
to create a flat surface without any interbead grooving.
2. Waviness is permissible but without notches and undercuts that might act as stress raisers.
3. The beads may run longitudinally for nozzles with an inside diameter of 300 mm (12 in)
and smaller and for pipe elbows if followed by blend grinding.
d. With ASS, the chemical composition of the final surface on both weld overlay and cladding re-
instatement shall conform to the corresponding AWS welding consumable classification.
e. Welding consumables used for ASS weld overlays that are subject to PWHT shall be “L”
grade, or stabilized with additions of Ti or Nb (Cb) to minimise sigma phase formation during
the heat treatment; they.
f. The ferrite content of ASS overlays, with the exception of type 904L (which is fully
austenitic), shall be in the range 3 - 10% in the as-welded and post-weld heated condition.
g. Vessels with Alloy 400 weld overlay designated for HF acid service shall have the following:
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1. Overlay shall contain a maximum of 5% iron (Fe) in the top 1,6 mm (1/16 in) of the final
deposit.
2. Overlays, deposited by manual processes, shall have a minimum of three layers.
h. ERNi-1 filler metal shall be used for the first pass when welding with the GTAW or GMAW
process.
i. The maximum diameter of SMAW electrodes shall be 3 mm (1/8 in).
j. For any low-carbon (L, LC, or ELC) grades of ASS, carbon content shall not exceed
0,03 percent.
k. For columbium (niobium) bearing grades of ASS (e.g., 347 and 309 Cb) the columbium to
carbon ratio of the deposited metal shall not exceed 16:1.
l. If a single layer overlay is offered, metallurgical and analytical evidence shall be produced to
demonstrate its acceptability.
m. The welding process shall not transfer alloying elements via the flux to achieve the specified
weld metal composition.
n. Flux shall not be re-used.
o. For ASS overlays, each batch of welding consumables, including each batch of submerged arc
or electroslag flux, shall be tested in accordance with the approved weld overlay procedure to
ensure that the resultant overlay complies with the specified microstructure and chemical
analysis.
D.6 Welding procedures
a. Welding procedures shall be qualified in accordance with the design code.
b. Qualified welding procedures for weld overlay and cladding re-instatement shall be submitted
for approval.
c. The base material for the test pieces of the welding procedure shall be of the same material
specification and grade as the vessel.
1. The same heat treatment batch of welding wire or electrode as that to be used in
production welding shall be used and the same type and brand of flux.
2. The temperature range used on the overlay qualification test plates for PWHT shall be the
same as that used in production.
3. The PWHT time at temperature for the qualification test plates shall be greater than that
used in production in order to leave at least one heat treatment available for BP.
d. The test welds shall be subject to chemical analysis throughout its depth to confirm that the
required purity of Clause D.8.3 has been achieved.
e. The test welds shall be subject to 100% UT per Clause D.8.1
f. The test welds shall be subject to 100% PT per Clause D.8.2.
g. The achievement of the required weld overlay thickness shall be demonstrated.
h. A macro section of the overlay shall be prepared and a series of hardness measurements
(Hv10) shall be made across the interface at three separate locations.
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i. The measurement of ferrite content shall be by metallographic determination and an
instrumental technique.
j. The chemical analysis results shall be used to calculate the ferrite content per the Schaeffler-
DeLong diagram.
k. The ferrite content of ASS weld metal, with the exception of type 904L (which is fully
austenitic), shall be in the range 3 - 10% in the as-welded and post-weld heated condition.
D.7 Internal attachments
a. If the design temperature is greater than 300°C (570°F), full penetration welds shall be used
for internal attachments.
b. Internal attachments shall be classified as follows:
1. Lightly loaded supports: Average shear stress across the section does not exceed 25 MPa
(3 625 psi).
2. Moderately loaded supports: Average shear stress across the section lies between 25 MPa
(3 625 psi) and 50 MPa (7 250 psi).
3. Heavily loaded supports: Average shear stress across the section exceeds 50 MPa
(7 250 psi).
c. On vessels made from clad plate, lightly and moderately loaded supports (e.g., tray support
rings) may be welded directly to the cladding without stripping back to the base material
providing:
1. The weld is essentially unidirectional (e.g., at a tray support ring) and not multi-
directional (e.g., at a bracket); and
2. The area is checked with UT for lack of bond prior to welding.
d. On vessels with weld overlay, lightly loaded supports (e.g., tray support rings) may be welded
to the overlay without stripping back to the base material.
e. Heavily loaded supports where thermal stress is present shall be integral with the shell.
D.8 Examination of weld overlay and clad re-instatement
D.8.1 UT examination
a. Weld deposited overlay shall be subject to UT in accordance with ASTM A578 primarily to
establish the presence of any lack of fusion between the weld deposit and the base material.
1. 10% of the overlay deposited during each shift shall be examined.
2. Any area of lack of fusion or other defect that cannot be contained within a 25 mm (1 in)
diameter circle shall be cause for rejection and 100% of the overlay completed during the
shift by the equipment/operator concerned shall be examined.
3. Defects shall be repaired by an approved procedure and re-examined.
b. After DHT or IPWHT (if performed), the stainless steel overlay shall be spot checked for bond
consistency by UT on strips 75 mm (3 in) wide over the vessel length at four equally-spaced
positions around the circumference.
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1. Any lack of fusion causing a loss of back reflection accompanied by an echo indication
from the plane of the interface of the overlay and base metal and having an area greater
than that of a 25 mm (1 in) diameter circle shall be repaired. This area may be of any
shape.
2. If any repair is needed, 100% of the surface shall be checked as above.
D.8.2 PT examination
a. 10% of the first layer of weld deposit overlay or clad re-instatement, plus as many “T” joints
as possible, shall receive PT surface examination.
b. If specified on the EDS, the surface of weld overlay shall be subject to 100% PT in accordance
with ASTM E165 following any PWHT, but prior to pressure testing.
D.8.3 Chemical analysis
a. The surface of weld overlay shall be subject to chemical analysis.
b. A minimum of two checks shall be made in each shell course and each head with a minimum
of one check for each 5 m (16 ft) length of butt-weld joint.
c. A minimum of one check shall also be made at each nozzle attachment weld.
d. The test locations shall be selected by BP.
e. Secondary standard Ferrite Number (FN) blocks shall be available to confirm the calibration of
the instrument.
f. The ferrite content of the final layer of 300 series austenitic stainless steel weld overlay
deposits shall be between 3 to 10FN, except for the stabilized austenitic stainless steel
types 321 and 347.
g. Stabilized 300 series austenitic stainless steel types 321 and 347 shall have a ferrite content
between 5 to 8FN in the final layer.
h. The WRC-1992 constitution diagram shall be used to predict the ferrite number.
i. Ferrite analysis shall be done with an instrument calibrated in accordance with AWS A4.2 or
ISO8249.
j. Ferrite measurements shall be made adjacent to analytical checks on the as-deposited weld
metal and these measurements repeated following any PWHT.
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Annex E (Normative)
Supplementary requirements DHT and IPWHT
E.1 Dehydrogenation heat treatment
a. Prior to commencing DHT, the weld joint shall not be allowed to cool below the minimum
preheat temperature applicable to the weld joint. The minimum preheat temperature for P4
materials shall be 150°C (300°F) minimum. Preheat temperature for P5A and P5C materials
shall be 200°C (392°F) minimum.
b. Heating for DHT shall be provided using gas ring burners or by electrical heating elements.
Ring burners shall be constructed to provide uniform heat distribution to the entire weld joint.
The weld joint and a minimum of 25,4 mm (1 in) each side of the weld joint shall be heated to
achieve an even temperature distribution through the full wall thickness of the weld joint.
c. DHT temperature shall be checked using temperature-indicating crayons, contact
thermometers, calibrated thermocouples, digital pyrometers, or laser heat measuring
instrument. Where accessible, temperature shall be measured at the side opposite from which
the heat source is applied to ensure through wall thickness heating.
d. The weld joint shall be heated and held at a DHT holding temperature of 350°C - 370°C
(662°F- 700°F). Hold time at temperature shall not be less than 2 hours.
e. After the hold time is done, the weld joint shall be wrapped in dry thermal insulation blankets
and allowed to slow cool to ambient temperature.
f. Nondestructive testing PT or MT shall be performed 48 hours after the weld joint has cooled to
ambient temperature.
g. A written report shall be prepared traceable to each weld joint receiving DHT.
E.2 Intermediate post weld heat treatment
a. IPWHT shall be carried out in a furnace and immediately after the weld joint has been
completely welded.
b. Prior to carrying out IPWHT the weld joint shall not be allowed to cool below the minimum
preheat temperature applicable to the weld joint. The minimum preheat temperature for P4
materials shall be 150°C (300°F) minimum. Preheat temperature for P5A and P5C materials
shall be 200°C (392°F) minimum. This preheat temperature shall be maintained during
handling and moving the weld joint to the furnace.
c. The furnace shall be prepared for IPWHT and heated to not less than the minimum preheat
temperature specified in the weld procedure specification applicable for the weld joint.
d. Furnace heating the weld joint above the minimum preheat temperature and the cooling the
weld joint after the IPWHT cycle shall be in accordance with the applicable ASME Boiler and
Pressure Vessel Code.
e. The weld joint shall be heated and held at a temperature indicated below.
1. For P1 materials the ISR temperature shall be between 540°C - 593°C (1 000°F 1 100°F).
2. For P5A and P5C materials the ISR temperature shall be between 650°C and 680°C
(1 202°F -1 256°F).
Pressure Vessels
Page 74 of 74 GIS 46-010
30 December 2012
f. Hold time at IPWHT temperature shall not be less than 2 hours.
g. Cooling the weld joint from the IPWHT holding temperature shall be done in a closed furnace.
Below 315°C (600°F) the weld joint shall be allowed to cool to ambient temperature inside the
furnace with the furnace doors opened.
h. IPWHT heat treatment shall be recorded and charted in a proper furnace heat treatment chart.
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