GS118-1 Fabrication of Fixed Offshore Steel Structures To Eemua 158

GS 118-1
FABRICATION OF FIXED OFFSHORE

STEEL STRUCTURES TO EEMUA 158
June 1992
Copyright © The British Petroleum Company p.l.c.

Copyright © The British Petroleum Company p.l.c.
All rights reserved. The information contained in this document is
subject to the terms and conditions of the agreement or contract under
which the 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 without the prior written
permission of Manager, Standards, BP International Limited, unless
the terms of such agreement or contract expressly allow.
BP GROUP RECOMMENDED PRACTICES AND SPECIFICATIONS FOR ENGINEERING
Issue Date June 1992

Doc. No. GS 118-1 Latest Amendment Date
Document Title
(Replaces BP Engineering Standard 111)
APPLICABILITY - Does not preclude adaptation for other applications

Regional Applicability: United Kingdom
Business Applicability: BP Exploration
SCOPE AND PURPOSE
This specification supplements EEMUA 158 which has been prepared as a Joint Industry
Users document for use primarily within the UK Continental Shelf.
BP Group GS 118-1 modifies and relaxes on some of the requirements of EEMUA 158
and gives advice on interpretation and on the selections of options
AMENDMENTS
Amd Date Page(s) Description
CUSTODIAN
Welding Technology
Issued by:-
Engineering Practices Group, BP International Limited, Research & Engineering Centre
Chertsey Road, Sunbury-on-Thames, Middlesex, TW16 7LN, UNITED KINGDOM
Tel: +44 1932 76 4067 Fax: +44 1932 76 4077 Telex: 296041
CONTENTS
Section Page
FOREWORD .................................................................................................................. iii
1. INTRODUCTION..................................................................................................... 1
1.1 Scope .......................................................................................................................... 1
*2. QUALITY ASSURANCE ......................................................................................... 1
2.1 Documentation............................................................................................................ 1
* 2.1.1 General ............................................................................................................ 1
3. MATERIALS ............................................................................................................ 4
3.1 Weldable Structural Materials...................................................................................... 4
3.2 Welding Consumables ................................................................................................. 4
3.3 Miscellaneous Materials............................................................................................... 4
3.3.1 Bolts, Nuts and Washers........................................................................................ 4
3.5 Material Handling........................................................................................................ 5
3.5.2 Maintenance of Identity ......................................................................................... 5
3.5.4 Storage Conditions ................................................................................................ 5
4. QUALIFICATION OF WELDING PROCEDURES AND PERSONNEL............. 5
4.2 Approval Process for Welding Procedures ................................................................... 5
4.2.1(d) Initial Submission............................................................................................. 5
4.3 Restrictions on Welding Practices................................................................................ 5
4.4 Welding Procedure Qualification Tests ........................................................................ 7
4.4.1 General Requirements............................................................................................ 7
4.4.2 Types of Test Weld................................................................................................ 8
4.4.2.3 Single Tests and Demonstrations ........................................................................... 8
4.4.3 Inspection and NDT Requirements and Acceptance Criteria................................... 9
4.4.3(b) Non-destructive Testing................................................................................... 9
4.4.4 Mechanical Test Requirements and Acceptance Criteria......................................... 9
4.4.4(d) Hardness Survey .............................................................................................. 9
4.4.4(e) Charpy Tests.................................................................................................... 9
4.4.5 Failed Procedures .................................................................................................. 10
4.5 Essential Variables....................................................................................................... 10
4.5.1 Materials Related Variables.................................................................................... 10
4.5.2 Weld Geometry Related Variables ......................................................................... 10
4.5.4 Procedural Variables.............................................................................................. 11
4.5.5 Welding Parameter Variables ................................................................................. 11
5. CONSTRUCTION .................................................................................................... 12
5.2 Preparation and Assembly............................................................................................ 12
5.2.3 Spacing of Seams and Splices. ............................................................................... 12
* 5.2.7 Alignment and Fit Up of Welding Joints.................................................................. 12
5.3 Control of Production Welding.................................................................................... 12
5.3.2 Welding Consumables and Equipment.................................................................... 12
5.3.5 Weld Execution ..................................................................................................... 13
5.3.7 Weld Repairs ......................................................................................................... 13
5.3.9 Weld Profile and Surface Finish ............................................................................. 13
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PAGE i
5.3.11 Production Controls............................................................................................... 13
5.4 Post-Weld Heat Treatment .......................................................................................... 13
* 5.4.1 Welds Requiring PWHT................................................................................... 13
5.4.2 PWHT Procedures................................................................................................. 13
* 5.5 Bolted Connections ............................................................................................... 14
7. INSPECTION AND NON-DESTRUCTIVE TESTING.......................................... 14
7.3 Qualification of Inspection and NDT Procedures and Personnel................................... 14
7.3.1 Non-Destructive Testing Procedures...................................................................... 14
7.3.2 Qualification of Inspection and NDT Personnel...................................................... 15
7.4 Non Destructive Testing Techniques ........................................................................... 15
7.4.1 Visual Inspection ................................................................................................... 15
7.4.2 Ultrasonic Testing.................................................................................................. 15
7.4.3 Radiography .......................................................................................................... 15
7.4.4 Magnetic Particle Inspection .................................................................................. 15
TABLE 2 ......................................................................................................................... 16
TABLE 3 ......................................................................................................................... 16
TABLE 5 ......................................................................................................................... 16
TABLE 6 ......................................................................................................................... 16
ATTACHMENT 1 .......................................................................................................... 18
QUESTIONNAIRE ON PROPOSALS FOR WELDING PRACTICES ............................ 18
APPENDIX A.................................................................................................................. 21
DEFINITIONS ................................................................................................................. 21
APPENDIX B.................................................................................................................. 22
LIST OF REFERENCED DOCUMENTS......................................................................... 22
APPENDIX C.................................................................................................................. 23
SUPPLEMENTARY COMMENTARY............................................................................ 23
GS 118-1
PAGE ii
FOREWORD
Introduction to BP Group Recommended Practices and Specifications for Engineering
The Introductory volume contains a series of documents that provide an introduction to the
BP Group Recommended Practices and Specifications for Engineering (RPSEs). In
particular, the 'General Foreword' sets out the philosophy of the RPSEs. Other documents in
the Introductory volume provide general guidance on using the RPSEs and background
information to Engineering Standards in BP. There are also recommendations for specific
definitions and requirements.
Value of this Guidance for Specification
This Guidance for Specification clarifies certain of the EEMUA Publication 158 requirements
and lists those additional BP requirements, i.e. not fully detailed in EEMUA Publication 158.
Application
This Guidance for Specification is intended to guide the purchaser in the use or creation of a
fit-for-purpose specification for enquiry or purchasing activity.
Text in italics is Commentary. Commentary provides background information which supports

the requirements of the Specification, and may discuss alternative options. 'Specification' or
'Approval' actions are indicated by an asterisk (*) preceding a paragraph number.
This Guidance for Specification is based upon an industry specification and may refer to
certain local, national or international regulations but the responsibility to ensure compliance
with legislation and any other statutory requirements lies with the user. The application of this
Guidance for Specification to other sea areas or for other structures may also be appropriate,
depending on the design philosophy selected and the sea areas. BP will specify when this
specification is to be used for these other sea areas or other structures.The user should adapt
or supplement this document to ensure compliance for the specific application.
Specification Ready for Application
A Specification (BP Spec 118-1) is available which may be suitable for enquiry or purchasing
without modification. It is derived from this BP Group Guidance for Specification by
retaining the technical body unaltered but omitting all commentary, omitting the data page
and inserting a modified Foreword.
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PAGE iii
Principal Changes from Previous Edition
BP Engineering Standard 111, originally issued in December 1985, has been completely
revised and re-issued as this BP Group Guidance for Specification following the issue of
EEMUA Publication 158 in 1989.
Feedback and Further Information
Users are invited to feed back any comments and to detail experiences in the application of
BP RPSE's, to assist in the process of their continuous improvement.
For feedback and further information, please contact Standards Group, BP Engineering or the
Custodian. See Quarterly Status List for contacts.
GS 118-1
PAGE iv
1. INTRODUCTION
1.1 Scope
This BP Specification specifies general requirements supplementary to

EEMUA Publication No. 158:1989, for the construction of fixed
offshore steel structures in the North Sea and is for use with a
supplementary specification to adapt it for each specific application.
Pipeline risers and any other pipework supplied integrally with the
structure are not covered by this Specification.
The titles and numbering of the text of this BP Specification follow

those of EEMUA Publication No. 158. As a result of this, gaps in
numbering may occur. All text is cross referenced to EEMUA
Publication No. 158, and qualifies, substitutes, modifies or adds to its
requirements.
Where additional text is to be read as an extension of the text of

EEMUA Publication No. 158, the text numbering of EEMUA
Publication No. 158 has been extended accordingly.
(Addition to EEMUA 158 1.1)
*2. QUALITY ASSURANCE
The Contractor shall supply a quality manual which shall be submitted to BP with the
tender documents.
Following an order the contractor shall submit a quality plan which shall be subject to
approval by BP.
The Contractor shall ensure that the quality requirements are applied to the materials,
equipment and services provided by sub-contractors.
(Addition to EEMUA 158 2)
2.1 Documentation
* 2.1.1 General
The contractor's quality assurance system shall ensure that all

documentation specified in 2.1.2 of this specification is presented to
BP, and any regulatory authority.
The method of indexing and collating all documentation shall be agreed

between BP and the contractor within an agreed period after contract
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award, and shall be subject to final approval by BP before the
commencement of fabrication. BP will specify those documents that
are required prior to and during the progress of the work only, and
those that are required for permanent record.
(Additional to EEMUA 158 2)
2.1.2 Project Documentation
The documents required for any particular project shall include, but not
necessarily be limited to those covered by 2.1.2 and 2.1.3 of this
specification.
Prior to the commencement of each part of the fabrication, the

following documentation may be subject to approval by BP:-
(a) Fabrication sequences, welding procedures, forming procedures

and erection sequence.
(b) Fabrication drawings including identification of material grades,

weld details and NDT requirements; plate seam arragements
drawings; plate cutting drawings.
(c) Drawings and calculations of temporary works, inclusive of

support points, jacking points and sling points, approved by a
professionally qualified engineer in the contractor's employ.
(d) List of proposed welding procedures and their areas of

application.
(e) Qualified welding procedures and weld-repair procedures in

accordance with this Specification for both permanent work and
temporary attachments.
(f) Certificates of welders, welding operators, arc/ air gougers and

tackers, qualified in accordance with this Specification.
Additionally, documents detailing qualifications and experience

of engineers and all QA and QC personnel.
(g) Material identification and control procedures.
Additionally, certificates for material supplied by the contractor.
(h) Key plans showing an unambiguous member identification and

weld marking scheme.
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(i) Detailed procedures for non-destructive testing and inspection,
and the format of the NDT certificates.
(j) Contractor's in-house procedures for the control of fabrication

drawings and their revisions.
(k) Procedures for control of tolerances during fabrication.
(l) PWHT procedures.
(m) Leak test procedures.
(n) Coating and coating repair procedures.
* 2.1.3 Following completion of any part of the work the contractor shall
submit copies of the following documentation for approval by BP:
(a) Tolerance-drawing records which shall be updated continually

and issued at least every month.
(b) Plans marked to relate certificate references for all materials to

their final position in the structure.
(c) Weld plans showing unique weld-seam references and a list of

weld procedure numbers used for each individual weld.
(d) PWHT reports.
(e) NDT test reports and key plans showing final identification
numbering, test report numbers and the results.
(f) Production mechanical test records if required and leak test

reports for all items tested.
(g) As-built drawings and specifications showing in detail the

manner in which the work was performed and all changes,
additions, corrections or revisions made during the course of
fabrication. These drawings shall also indicate the number of
the welding procedure specification used for each weld.
(h) On final completion, a line drawing shall be produced detailing

and numbering the layout of all node joints. The numbering
system used shall be indexed against all inspection/NDT
reports. This is to facilitate ease of node identification and
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correlated NDT during in-service sub-sea and topside
inspections.
3. MATERIALS
3.1 Weldable Structural Materials
Steel plate, tubulars and sections shall be in accordance with BP Group

GS 136-2.
(Substitution for EEMUA 158 3.1)
3.2 Welding Consumables
BP may require supplementary batch testing of welding consumables.

Evidence is also required to confirm that the consumables will produce
satisfactory CTOD results after PWHT.
Batch definition which limit a batch number to a single dry blend of flux and/or a
single heat of filler are normally considered acceptable and no additional batch
testing is required. The exception being when BP are still not convinced that all
batches of the consumables would pass the welding procedure qualification tests.
Additional batch testing could be waived, however, if the contractor also achieves
the required weld metal charpy energy in additional tests from each procedure
plate at a temperature 10 below the specified temperature. In cases where BP is
not satisfied with the batch definition the contractor shall propose a batch testing
programme for BP approval.
3.3 Miscellaneous Materials
3.3.1 Bolts, Nuts and Washers
Mild steel bolts and nuts shall be to BS 4190 Grade 4.6 and washers to
BS 4320. Mild steel stud bolts and washers shall be to BS 4882. All
threaded connections shall have a suitable locking device so that they
are incapable of becoming undone. However, locking welds shall not
be used on nuts and bolts to BS 4882 and free machining nuts and bolts
to BS 4190 Grade 4.6. In a torqued connection, the tensioned length
of the bolt shall be at least 5 diameters long and the torque requirement
shall be specified on the drawing.
For subsea applications high strength bolts, nuts and washers shall be to
BS 3692 Grade 8.8 with Chemical Composition as per BS 4882 Grade
L7. These Bolts shall be heat-treated and charpy toughness following
thread rolling to achieve an hardness of not more than 300Hv or shall
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have machined threads. All bolts, nuts and washers shall be Cadmium
plated and dehydrogenated to BS 3382: Part 7: 1966.
Bolting materials for the splash zone shall be manufactured from

MARINEL cupro-nickel alloy.
(Modification to EEMUA 158 3.3.1)
3.5 Material Handling
3.5.2 Maintenance of Identity
Dot matrix stamps are an acceptable alternative to round nosed stamps.
(Addition to EEMUA 158 3.5.2)
3.5.4 Storage Conditions
Damage to any part of the steelwork either before, during or after

erection shall immediately be brought to the notice of BP.
4. QUALIFICATION OF WELDING PROCEDURES AND PERSONNEL
4.2 Approval Process for Welding Procedures
4.2.1(d) Initial Submission
To comply with the essential variables, some extra SWIS information

will be necessary.
For SMAW : the stub length assumed for the run-out
lengths quoted.
For SAW : the number and orientation of wires.
For SSFCAW : the polarity.
4.3 Restrictions on Welding Practices
A questionnaire (Attachment 1) has been prepared which addresses

each of the points listed in EEMUA 158 Clause 4.3. This should be
returned with the tender.
EEMUA 158 Clause 4.3 does not prohibit the practices listed, it merely warns the
contractor of some which concern BP. If a contractor has background data which
convinces BP that is is sensible to permit one or other of these practices, then
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PAGE 5
approval may be given. To ensure that any such proposals are made clearly in the
tender, and that appropriate background data are submitted with the tender, a
questionnaire (Attachment 1) has been prepared which addresses each of the points
listed in this clause. This should be returned with the tender.
4.3(b) SMAW bead widths exceeding the lesser of 16 mm or four times the core wire
diameter.
(Modification to EEMUA 158 4.3(b))
The BP supplementary requirements are simply to correct errors in EEMUA 158
4.3(h) SSFCAW for heat inputs exceeding 1.5 KJ/M for all welding passes other than the
root pass.
(Modification to EEMUA 158 4.3(h))
4.3(k) SSFCAW followed by any other process, including the mixing of weld metal at weld
intersections.
(Modification to EEMUA 158 4.3(k))
Past experience has shown that there can be a substantial reduction in weld metal
toughness when SSFCAW is followed by other welding processes. This is equally
true for individual butt welds and at the intersection of welds, where the first joint
involves SSFCAW and the second any other welding process. BP will require
detailed, assurance testing before this 'mixing' of weld metal is allowed to proceed.
4.3(l) Heat inputs exceeding 3KJ/mm for grade 450 material and 3.5 KJ/mm for grade 355
material.
(Modification to EEMUA 158 4.3(l))
4.3(n) Butt welds where both edges are square and are greater than 8 mm thick and T butt
welds without a bevel where the thickness of the incoming member is greater than 8
mm.
(Modification to EEMUA 158 4.3(n))
4.3(o) Included angles of bevelled welds below 45 degrees (except as covered by 4.5.2(g)).
(Modification to EEMUA 158 4.3(o))
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4.3(r) Use of any welding technique in which the welder is not permitted to put the final
capping pass adjacent to the plate.
(Modification to EEMUA 158 (4.3(r))
'Temper bead' means any welding technique in which the welder is not permitted to
put the final capping pass adjacent to the plate, regardless of the stated objective
for this restriction. The acceptability of such a technique will depend on the
tenderer's ability to show that the technique has no effect on hardness.
Alternatively, if there is a hardness effect, the tenderer will need to control bead
placement so as to guarantee compliance with the specified hardness limit.
4.3(t) Single-pass fillet welds (other than by submerged arc) with a design leg length greater
than 6 mm.
(Modification to EEMUA 158 4.3(t))
4.3(w) SSFCAW without a split second layer.
Problems have been experienced on past projects with poor toughness in the root
area of SSFCAW Welds. The problem was solved by ensuring a small bead size and
adequate interrun tempering. Splitting the second layer of weld metal was found to
be particularly effective.
4.3(x) Use of single bevel or K weld preparations for in-plane butt welds.
It is very difficult to detect defects on the sidewall of square edge preparations.

Special ultrasonic techniques e.g. tandem probe are effective but they are time
consuming and expensive.
4.4 Welding Procedure Qualification Tests
4.4.1 General Requirements
When rolled steel sections have been purchased with transverse Charpy
properties, testing in the HAZ shall also be transverse.
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For fillet weld tests, the root gap shall be set at 2 mm with the two
plates fully restrained. The fillet weld leg length qualified by this test is
the actual leg length minus the 2 mm gap. Only consumables which
have been qualified on butt welds may be used.
It is assumed that all fabricators will take advantage of the opportunity to qualify
T-butt welds using plate butt (with single bevel or K preparations). For stub to
barrel welds however, the test 4.4.2.3(b) is required in addition.
The PWHT soak time of 4 hours minimum may not qualify the procedure for the
possibility of a repeat PWHT. The Contractor may wish to cover this eventually by
testing at longer soak times.
Although 30 mm plates are required for fillet weld procedure qualification, and the
preheat in the test will therefore be the one appropriate to the 90 mm combined
thickness, this is not the minimum preheat permitted for fillet welds. The ruling
clause is 4.5.4(b), which will permit the same reduction for lesser combined
thickness as BS 5135 will permit.
4.4.2 Types of Test Weld
4.4.2.3 Single Tests and Demonstrations
4.4.2.3(a) Mechanical tests shall be taken to evaluate both sides of the repair. The
requirement for PWHT or CTOD test depends on the plate thickness not on the repair
weld depth.
(Addition to EEMUA 158 4.4.2.3(a))
4.4.2.3(b) The internal weld shall not be undertaken until the single-sided weld root has
been fully visually inspected.
(Addition to EEMUA 158 4.4.2.3(b))
4.4.2.3(c) The maximum root gap which will be permitted in this test is the 12 mm limit
from section 5.2.7.
(Addition to EEMUA 158 4.4.2.3(c))
4.4.2.3(d) Visual examination shall also include a measurement of bead width.
(Addition to EEMUA 158 4.4.2.3(d))
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4.4.3 Inspection and NDT Requirements and Acceptance Criteria
4.4.3(b) Non-destructive Testing
Welding procedure qualification tests shall be inspected against the

Table 3 requirements of Category I for butt welds and Category V for
fillet welds.
(Addition to EEMUA 158 4.4.3(b))
Reference here, and in 4.4.1 and 7.2.3 of EEMUA 158 to the 'third day after the
completion of welding' result from the practice of certain fabricators of recording
only the day on which welding or NDT took place. Where the Contractor's system
includes a record of the time at which welding was completed, or PWHT or NDT
was started, then this delay time may be taken to mean 48 hours, since this is the
minimum period guaranteed by the 'third day' wording.
4.4.4 Mechanical Test Requirements and Acceptance Criteria
Where dissimilar material welds involve a thickness transition to

compensate for a difference in strengths, the requirements for the
stronger material shall apply.
4.4.4(d) Hardness Survey
Individual hardness figures in the weld, or in the HAZ of the quench

and tempered grade 450 steel, shall not exceed 325 HV10.
(Addition to EEMUA 158 4.4.4(d))
It is recognised that existing procedure qualifications are unlikely to comply

precisely with the hardness survey defined here. Qualifications using a similar
approach (i.e. using surveys down the HAZ rather than parallel to the plate
surface) will normally be acceptable, but the old-fashioned 'parallel' surveys may
have conditions attached to their acceptance since they are less searching - e.g. the
acceptance level for such surveys may be set 25 HV lower than for the 'correct'
survey.
4.4.4(e) Charpy Tests
Charpy test on single bevel or K weld preparations shall be taken from

the bevelled edge. Tests from the square edge are not required.
The root weld centreline charpy notch for the punch- through technique
shall be at the intersection of the columnar grains of the punch-through
bead.
(Addition to EEMUA 158 4.4.4(e))
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PAGE 9
* 4.4.4(f) Unless approved otherwise by BP the weld metal CTOD requirement
is 0.25 mm at a test temperature of 0°C for piles and -10°C in all other
cases.
The consumable that is proposed for use on node stub to can welds
shall require CTOD testing in the weld metal where the stub (brace) is
over 40 mm thickness. This is intended as a mandatory consumable
verification test and shall be conducted after PWHT unless specified
otherwise by BP.
HAZ CTOD tests are not required unless specified otherwise by BP.
(Addition to EEMUA 158 4.4.4(f))
4.4.5 Failed Procedures
Additional retests may be permitted when the cause of failure was a

machining or testing error, rather than any fault with the weld.
4.5 Essential Variables
4.5.1 Materials Related Variables
4.5.1(a) Procedures for castings shall require qualification using cast steel base material.
(Addition to EEMUA 158 4.5.1(a))
4.5.1(h) If the thickness of the protective finish applied to the weld bevel is greater than
that used for the procedure qualification tests.
(Modification to EEMUA 158 4.5.1(h))
4.5.2 Weld Geometry Related Variables
4.5.2(i)The qualified root gap for double sided welds is limited to a maximum of 6 mm.
(Modification to EEMUA 158 4.5.2(i))
4.5.2(e) In certain circumstances BP may be able to offer a relaxation on the requirement for qualification in
all of the 4 positions. As a minimum, however, the highest and lowest heat input positions will be
qualified for the range of thickness using the same fundamental procedure. In addition a single
additional test will be required, on the thickest material, in each of the remaining two positions.
(Additional commentary, to EEMUA clause only)
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PAGE 10
4.5.4 Procedural Variables
4.5.4(c) The simplest way of complying with this clause is to allow the test plate to cool to the minimum
specified preheat before starting each pass of the cap. If this has not been done with existing
qualifications, then the measured interpass temperature in the cap becomes the minimum 'preheat'
for capping.
4.5.4(e) Where existing procedure qualifications are being offered, the depth of gouging
may not have been measured during all relevant test welds. In such a case, the
contractor may provide a single 3G demonstration plate - or 1G for any SAW
procedure involved - of the greatest thickness covered by the appropriate
procedure. In this demonstration, the backgouging should taper from nil to 10 mm
over a distance not less than 500 mm. Charpy tests should then be taken from the
bottom of the first side welded; at locations representing 1 mm steps of
backgouging depth. The minimum permissible backgouging depth will then be set 2
mm deeper than the depth beyond which all of the Charpy tests meet the normal
root Charpy test requirements.
4.5.4(f) Backgouging beyond the 10 mm limit will be permitted where the ligament
after gouging still exceeds either 10 mm or the ligament which remained after
backgouging the appropriate procedure qualification test.
(Modification to EEMUA 158 4.5.4(f))
4.5.5 Welding Parameter Variables
4.5.5(b) Where existing procedure qualifications are being offered, it is unlikely that all runs with a
particular size of electrode will have been controlled within this tolerance on the mean value
although this would be mandatory for procedures run especially for EEMUA fabrication. If
examination of the 'as run' sheet shows that the standard deviation of the actual run lengths for fill
and cap passes exceeds 10% of the mean for that electrode diameter, then that existing qualification
is unlikely to be accepted.
4.5.5(f) The maximum heat input during production welding is limited to the lesser of
10% or 0.2 KJ/mm greater than that used during procedure qualification.
(Modification to EEMUA 158 4.5.5(f))
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4.5.5(g) If the equipment used for SAW SSFCAW or GSFCAW does not indicate wire
feed speed but does indicate current, then the 5% tolerance will apply to the current.
(Modification to EEMUA 158 4.5.5.(g))
4.5.5(i, k, l) If existing procedure qualifications are being offered and these parameters have not been
measured during procedure qualification BP may still be able to accept these procedures subject to
the acceptance of additional verification tests.
5. CONSTRUCTION
5.2 Preparation and Assembly
5.2.3 Spacing of Seams and Splices.
5.2.3(b) This restriction is not mandatory for castings.
(Clarification to EEMUA 158 5.2.3 (b))
* 5.2.7 Alignment and Fit Up of Welding Joints
The contractor must seek BP approval in writing before attempting to

weld single sided closure butt welds with a root gap exceeding that
permitted by 4.5.2(h). A single qualification test (4.4.2.3 c) is required
at 12 mm gap.
(Addition to EEMUA 158 4.5.2(h))
Effort should be made to ensure that the number of wide gap closure welds within
the structure are kept to a minimum. Wide gaps require a higher degree of welder
skill and they are more prone to weld root defects, poor toughness and cracking.
5.3 Control of Production Welding
5.3.2 Welding Consumables and Equipment
The Storage and control of welding consumables shall comply with BP

Group GS 118-4.
Before the start of production BP may require the Contractor to have

the SAW flux control system audited by the consumable manufacturer
and an audit report shall be made available to BP.
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5.3.5 Weld Execution
Ultrasonic inspectors for single-sided closure welds shall perform a pre-

weld survey of the joint fit-up. Scribed lines shall be drawn 100 mm
away from the root face on either side of the weld to assist ultrasonic
examination of the completed weld.
5.3.7 Weld Repairs
The minimum toe-to-toe separation of weld repairs shall be 75 mm.
5.3.9 Weld Profile and Surface Finish
Toe grinding shall not be less than 0.5 mm or more than 1.5 mm
penetration into the base metal and shall extend 0.5 mm below visible
undercut. Profile requirements for TKY joints within jackets are shown
in Fig. 5 of EEMUA 158. BP may specify additional requirements for
certain joints and this will be shown on the design drawings.

5.3.11 Production Controls
The Contractors production monitoring system should incorporate the

use of portable arc monitoring equipment.
5.4 Post-Weld Heat Treatment
* 5.4.1 Welds Requiring PWHT
PWHT shall only be repeated with BP approval.
Even where the Drawing defines an as welded joint thicker than these
rules, a CTOD tested procedure is still required.
5.4.2 PWHT Procedures
Based on the steel makers recommendations BP may define different

soaking temperature for grade 450 material and castings.
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PAGE 13
* 5.5 Bolted Connections
Bolting procedures shall be submitted to BP for approval.
Bolted connections shall comply with the following unless otherwise

specified on the Drawings:
When not specifically indicated on the Drawings, holes for bolted

connections shall have a diameter 1.5 mm larger than the bolt size.
Holes shall be made only by drilling, or subdrilling and reaming.
Where close tolerance bolts are required the hole shall be made to
within +0.5 mm and -0 mm of the specified bolt diameter.
Bolt heads and nuts shall be drawn tight against the work by a method
acceptable to BP. Bolt heads shall be tapped with a hammer while the
nut is being tightened. Having been finally tightened, the nuts shall be
locked. All high strength bolts shall be pretensioned to the proper
proof stress or shall have the torque level specified. All such bolting
details shall be subject to prior review by BP.
Where surfaces joined by bolting have a slope greater than 1:20 with
respect to the plane normal to the bolt axis, suitable tapered washers
shall be used.
All bolts shall be provided with either a lock nut, a locking washer, or
an alternative locking device. All bolt locking devices shall be subject
to prior review by BP.
Bolts shall be threaded to such a length that not more than one thread
will be within the grip of the structural members.
Bolts shall be of a length that will extend entirely through the nut, but
not more than 10 mm beyond.
(Addition to EEMUA 158)
7. INSPECTION AND NON-DESTRUCTIVE TESTING
7.3 Qualification of Inspection and NDT Procedures and Personnel
7.3.1 Non-Destructive Testing Procedures
Procedures shall be prepared and qualified in accordance with BP

Group GS 132-2.
GS 118-1
PAGE 14
7.3.2 Qualification of Inspection and NDT Personnel
The qualification and reporting relationships of Inspection and NDT

personnel are specified in BP Group GS 132-2.
7.4 Non Destructive Testing Techniques
7.4.1 Visual Inspection
The requirement of BP Group GS 132-2 shall also apply. Internal visual

examination of single-sided closure welds roots shall be carried out
using a high intensity light source.
7.4.2 Ultrasonic Testing
The requirements of BP Group GS 132-2 shall also apply.
7.4.3 Radiography
7.4.4 Magnetic Particle Inspection
GS 118-1
PAGE 15
TABLE 2
(b) The requirements for Castings are the same as for grade 355 steel)
(Modification to EEMUA Table 2 (b))
TABLE 3
(d) Alternative inspection requirements may also be specified for critical partial
penetration welds.
(Addition to EEMUA Table 3 (d))
(f) For nodes where scanning from internal surfaces is not possible, examination shall be
to the Purchaser's approval (BS 3923 Level 4).
(Addition to EEMUA 158 Table 3)
(g) The option given in Table 5 of BS 3923 to delete inspection from the lower surfaces
for plate and pipe butt welds below 35 mm shall not apply.
(h) A chevron cracking check is required for Inspection Categories I to IV on submerged-

arc welds 25 mm thick or above.

TABLE 5
This should read table 6.
The acceptance levels for lack of fusion defects do not apply. Lack of fusion defects are not
acceptable.
(Modification to EEMUA 158 Table 5)
TABLE 6
This should read table 5.
Undercut shall not exceed 0.25 mm for all welds in jacket structures and piles.
(Modification to EEMUA 158 Table 6)
GS 118-1
PAGE 16
TABLES 5 & 6
EEMUA 158 was published with these tables incorrectly numbered and wrongly positioned. Table 5 on page
119 should be table 6 on page 120 and table 6 on page 120 should be table 5 on page 119.
GS 118-1
PAGE 17
ATTACHMENT 1
QUESTIONNAIRE ON PROPOSALS FOR WELDING PRACTICES
Clause 4.3 of EEMUA 158 defines restrictions on a variety of welding practices, making their
use subject to the specific approval of the purchaser. Any decision on approval would be
based on an assessment of the background data submitted by the tenderer.
To ensure an equitable assessment of tenders, BP requires tenderers to nominate their

intentions in these areas at the time of tender.
Tenderers are required to answer YES or NO to the questions on the list which follows
covering all of the relevant topics. This requirement has been made to encourage tenderers to
be open about their intentions prior to contract.
A 'Yes' response must be supported by data submitted with the tender that demonstrates to
the satisfaction of BP's Professional Engineer that use of the practice will provide the required
welding quality.
A 'No' response means that the practice is not proposed. BP reserve the right to hold the
Contractor to this response, and to reject any subsequent request for approval, without
explanation.
Tenderers shall also include details of the definition of a batch or lot used by the chosen
welding consumables manufacturers, and of the testing carried out by the manufacturer on
each batch or lot, as required by Clause 3.2 of EEMUA 158.
GS 118-1
PAGE 18
Are any of the following practices proposed for this enquiry? Answer
(YES/NO)
(1) SMAW for heat inputs exceeding 3 kJ/mm __________
(2) SMAW bead widths exceeding either of 16 mm or

four times the core wire diameter __________
(3) SMAW vertical down __________
(4) GMAW (except for the root pass in double-sided SAW welds) __________
(5) SSFCAW without the voltage and wire-feed speed set

and locked __________
(6) SSFCAW for heat inputs exceeding 1.5 kJ/mm (except

for root passes) __________
(7) SSFCAW with weave beads __________
(8) SSFCAW vertical up (except for root run) __________
(9) SSFCAW in combination with another process __________
(10) Heat input exceeding 3 kJ/mm for grade 450 or

3.5 kJ/mm for grade 355 material __________
(11) Welding on materials less than 30 mm thick with a

heat input exceeding 3.5 kJ/mm __________
(12) Square edge butt and T butt welds greater than

8 mm thick __________
(13) Included angles of bevelled welds below 45 degrees

(except for tubular intersections) __________
(14) Included angles below 60 degrees for closing welds

in tubulars above 40 mm thick __________
(15) Welding on the second side of a joint without back

gouging, except for SAW procedures using the 'punch-
through' technique __________
(16) Use of a 'temper bead' technique __________
(17) Maximum interpass temperature exceeding 250oC __________
GS 118-1
PAGE 19
(18) Single-pass fillet welds (other than by SAW) with
a design leg length greater than 6 mm __________
(19) Use of backing strips __________
(20) Use of ceramic inserts __________
(21) Use of single bevel or K weld preparation for in plane butt welds __________
GS 118-1
PAGE 20
APPENDIX A
DEFINITIONS
Definitions
Standardised definitions may be found in the BP Group RPSEs Introductory volume.
certifying authority: an independent agency which, for UK waters, certifies the

design and/or fabrication of an offshore structure for statutory
purposes.
third party inspectorate: an impartial body, independent of, but appointed by, BP.
Note: Any specific application of the terms and the responsibilities of the parties
defined above is a matter for the relevant Conditions of Contract.
single sided weld: applies to joints welded from one side only.
double sided weld: applies to joints welded from both sides regardless of weld
preparation.
GS 118-1
PAGE 21
APPENDIX B
LIST OF REFERENCED DOCUMENTS
A reference invokes the latest published issue or amendment unless stated otherwise.
Referenced standards may be replaced by equivalent standards that are internationally or

otherwise recognised provided that it can be shown to the satisfaction of the purchaser's
professional engineer that they meet or exceed the requirements of the referenced standards.
Documents already referenced in EEMUA 158 are not included here.
EEMUA Publ. No 158 Construction specification for fixed offshore structures in the North
Sea
Available from:-
The Engineering Equipment and Materials Users Association

14-15 Belgrave Square
LONDON SW1W 8PS
BS 3382 Specification for electroplated coatings on threaded components:-

Part 7:1966 Thicker platings for threaded components
BS 3692 Specification for ISO metric precision hexagon bolts, screws and
nuts. Metric units
BS 3923 Methods for ultrasonic examination of welds
BS 4190 Specification for ISO metric black hexagon bolts, screws and nuts
BS 4320 Specification for metal washers for general engineering purposes.

Metric series
BS 4882 Specification for bolting for flanges and pressure containing

purposes
BP Group GS 118-4 Storage and control of welding consumables

(was BP Std 165)
BP Group GS 132-2 Non-destructive testing of welds for offshore application

(was BP Std 188)
BP Group GS 136-2 Structural steel materials for use in the fabrication of fixed offshore
steel structures
(was BP Std 109)
GS 118-1
PAGE 22
APPENDIX C
SUPPLEMENTARY COMMENTARY
DESIGN DRAWINGS - POINTS FOR CONSIDERATION BY THE DESIGN

CONTRACTOR
EEMUA Publication 158 clarifies a number of points for consideration by the design
contractor(s). In particular the following should be reflected on the design drawings by the
design contractor:-
Node Stub Geometry

Clause 5.2.3(e) of EEMUA 158 defined a minimum perpendicular clearance between node
barrels and the brace/stub weld. This should be reflected on the drawings.
Welding from One Side Only (single-sided welding)

Clause 5.2.4 of EEMUA 158 suggests that this should be any tubular weld where the internal
diameter is less than 600 mm. Any restrictions on the locations of closure welds in larger
members should be defined on the drawings.
Closure Weld Radiography

Clause 5.3.5 of EEMUA 158 identifies the possibility that some critical closure welds
(normally those with uncomfortably low fatigue lives) will receive early radiography in
addition to the final ultrasonic and magnetic particle examination. These welds should be
identified on the drawings.
Welds Requiring/Not Requiring PWHT

Clause 5.4.1 of EEMUA 158 provides a general definition, then leaves the designer free to
indicate exceptions. It may be preferable to indicate on the drawings all nodes (and other
welds) which require PWHT.
Dimensional Tolerances
Clause 6.1 of EEMUA 158 states that the 158 tolerances only apply if the drawings do not
specify alternatives, and clause 6.2.2.3 of EEMUA 158 specifically requires the drawings to
define skid beam tolerances.
Extent of Inspection and NDT

Clause 7.2.2.4 of EEMUA 158 requires that each weld be allocated a category from Table 3.
This should be designated on the design drawings.
Leak Testing
Clause 7.4.5 offers the option for components other than buoyancy tubes and jacket leg
sections to be leak tested; these should be designated on the drawings.
GS 118-1
PAGE 23
Weld Profiles
Although Figure 5 of EEMUA 158 defines the requirements for tubular intersections, clause
7.5.2 of EEMUA 158 implies that the requirements for other welds will be stated on the
drawings.
Joint Details
Joint details for welds between materials of different strengths (e.g. between Grade 450 and
Grade 355 or castings) should be shown on the drawings.
Primary Structure
EEMUA 158 defines the requirements for fabrication work on primary structures of offshore
installations. It is important that there is a clear definition of primary structure. This should
be in the form of a single list or alternatively the design drawings should indicate the
boundaries between primary and non-primary structure.
A separate specification would be issued to cover fabrication of non-primary structure.
Risers
Risers are excluded from 158; a further revision of BP Group GS 118-10 'Welding of
Transmission Pipelines; will deal with riser fabrication and installations. Until this is
available additional requirements for risers e.g. a specification for bolting and hydrostatic
testing should be indicated on the drawings.
GS 118-1
PAGE 24

GS118-1 Fabrication of Fixed Offshore Steel Structures To Eemua 158

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GS 118-1

FABRICATION OF FIXED OFFSHORE

Copyright © The British Petroleum Company p.l.c.

Issue Date June 1992

APPLICABILITY - Does not preclude adaptation for other applications

SCOPE AND PURPOSE

Introduction to BP Group Recommended Practices and Specifications for Engineering

Value of this Guidance for Specification

Text in italics is Commentary. Commentary provides background information which supports

Specification Ready for Application

Feedback and Further Information

This BP Specification specifies general requirements supplementary to

The titles and numbering of the text of this BP Specification follow

Where additional text is to be read as an extension of the text of

(Addition to EEMUA 158 1.1)

*2. QUALITY ASSURANCE

(Addition to EEMUA 158 2)

The contractor's quality assurance system shall ensure that all

The method of indexing and collating all documentation shall be agreed

(Additional to EEMUA 158 2)

2.1.2 Project Documentation

Prior to the commencement of each part of the fabrication, the

(a) Fabrication sequences, welding procedures, forming procedures

(b) Fabrication drawings including identification of material grades,

(c) Drawings and calculations of temporary works, inclusive of

(d) List of proposed welding procedures and their areas of

(e) Qualified welding procedures and weld-repair procedures in

(f) Certificates of welders, welding operators, arc/ air gougers and

Additionally, documents detailing qualifications and experience

(g) Material identification and control procedures.

Additionally, certificates for material supplied by the contractor.

(h) Key plans showing an unambiguous member identification and

(j) Contractor's in-house procedures for the control of fabrication

(k) Procedures for control of tolerances during fabrication.

(l) PWHT procedures.

(m) Leak test procedures.

(n) Coating and coating repair procedures.

(Addition to EEMUA 158 2)

(a) Tolerance-drawing records which shall be updated continually

(b) Plans marked to relate certificate references for all materials to

(c) Weld plans showing unique weld-seam references and a list of

(d) PWHT reports.

(f) Production mechanical test records if required and leak test

(g) As-built drawings and specifications showing in detail the

(h) On final completion, a line drawing shall be produced detailing

(Addition to EEMUA 158 2)

3.1 Weldable Structural Materials

Steel plate, tubulars and sections shall be in accordance with BP Group

3.2 Welding Consumables

BP may require supplementary batch testing of welding consumables.

(Addition to EEMUA 158 3.2)

3.3 Miscellaneous Materials

3.3.1 Bolts, Nuts and Washers

Bolting materials for the splash zone shall be manufactured from

(Modification to EEMUA 158 3.3.1)

3.5 Material Handling

3.5.2 Maintenance of Identity

Dot matrix stamps are an acceptable alternative to round nosed stamps.

(Addition to EEMUA 158 3.5.2)