WELDING

1. Polaris
Engineering
Standard
140.10
Rev.: 0
Page: 1 of 24
Date: 07/06/09
GENERAL WELDING, FABRICATION AND INSPECTION
TABLE OF CONTENTS PAGE
I. SCOPE 2
II. REFERENCES 2
III. WELDING PROCEDURES 3
IV. WELDING PROCESSES (GENERAL) 4
V. WELDING PROCESS LIMITATIONS 5
VI. FILLER MATERIALS AND FLUXES 6
VII. WELD JOINT PREPARATION AND WELDING FABRICATION 9
VIII. PREHEAT AND INTERPASS TEMPERATURES 13
IX. POSTWELD HEAT TREATMENT 14
X. NON-DESTRUCTIVE EXAMINATION, TESTING AND INSPECTION 17
XI. REPAIRS 20
XII. SUMMARY OF WELDING VARIABLE LIMITATIONS, 21
RESTRICTIONS AND OTHER REQUIREMENTS
XIII. PROCEDURE FOR REVIEW AND ACCEPTANCE OF
VENDOR WELDING PROCEDURES 22
APPENDIX I - WELD MAP 24

2. Polaris
Engineering
Standard
140.10
Rev.: 5
Page: 2 of 24
GENERAL WELDING, FABRICATION AND INSPECTION
I. SCOPE
A. This Standard covers the minimum welding requirements, for welding of shop
and field fabrications and the weld inspection of the following:
1. Pressure containing equipment and piping, whether code stamped or not,
including but not limited to: rotating equipment, boilers, pressure vessels,
heat exchangers, air coolers, shop and field fabricated piping, fired heater
tubes, storage tanks, stacks and their attachments.
2. Equipment or piping containing toxic or corrosive materials.
3. Structural Steel
4. Other fabrications where specified.
B. This Standard modifies the requirements of applicable ASME, AWS, API and
ANSI codes and standards in effect at the revision date.
C. Conflicts between requirements of this Standard, related specifications, standards,
codes, purchase orders or drawings shall be clarified with Client or Client's
Engineer (designated Contractor) prior to proceeding with the fabrication of the
affected parts. Regarding conflicts, the Client reserves the right of final decision.
D. Where conflicts exist between this Engineering Standard and other POLARIS
Engineering Standards and/or applicable codes or regulations, the more stringent
requirement shall govern. All conflicts shall be brought to the Client’s attention
for resolution. The Client shall be the sole arbiter of any conflicts.
II. REFERENCES
This POLARIS Standard is to be used in conjunction with the latest revision of the
standards and codes listed below, unless specifically noted. The terminology "latest
revision" shall be interpreted as the revision in effect at the time of contract award. This
POLARIS Standard may reference specific sections of some of these codes and
standards. The revision of the codes and standards being referenced is noted below in
parenthesis. This information is provided to identify the subject matter being referenced.
Changes or exceptions made to the referenced code or standard shall apply to later
revisions as applicable.
A. POLARIS Engineering Standards

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Engineering
Standard
140.10
Rev.: 5
Page: 3 of 24
3. 840.1 General Requirements For Pipe Fabrication
B. National Codes and Standards
1. API American Petroleum Institute Standards
2. AWS American Welding Society Standards
3. ASME B16.5 Pipe Flanges and Fittings (1998)
4. ASME B31.1 Power Piping (2001)
5. ASME B31.3 Process Piping (2001)
6. National Board Inspection Code (NBIC)
7. ASME Boiler and Pressure Vessel Code (2001)
III. WELDING PROCEDURES
A. Welding procedure specifications (WPS) and procedure qualification test records
(PQR) for Vendor welding covered by this Standard shall be submitted to the
Client or the Client's Engineer for review and acceptance prior to the start of any
welding. No welding shall commence until welding procedure specifications and
qualification records have been accepted by Client or Client’s representative.
B. Welding performed by Subvendors is also required to go through the same review
and acceptance procedures described in III.A above. Vendors are required to
provide copies of this and all other relevant standards to their Subvendors and to
review their Subvendors welding procedures for conformance to this Standard
prior to submitting to the Client or Client's Engineer for acceptance.
C. The information contained in the welding procedure specifications and procedure
qualification test records shall include, but not be limited to the information
contained in ASME Code, Section IX and AWS D1.1. Welding procedure
specifications shall conform to ASME Section IX, Form QW-482 or equivalent.
Procedure qualification records shall conform to ASME Section IX, Form QW-
483 or equivalent. Structural steel welding procedures may conform to AWS
Prequalified or AWS Recommended Procedure formats.

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Page: 4 of 24
D. This Standard includes additional requirements and restrictions, which may not be
listed in the Vendor's submitted welding procedures. They shall be listed, when
required by this Standard, either in the welding procedure or on the weld map.
The main additional requirements are summarized in Section XII below.
E. Vendor shall prepare a “Weld Map Form" as illustrated in Appendix I of this
Standard which must be completed and submitted at the same time as welding
procedures for Client's acceptance. Vendor may submit this information in other
formats provided all information required in Appendix I is included.
F. All welders shall be qualified by means of welding performance testing. Welding
performance qualification test records shall be made available for review by the
Client or Client's Representative upon request. Welding performance tests shall
be in accordance with ASME Section IX or AWS D1.1 as applicable, under
conditions of restraint and accessibility as demanding as those to be experienced
in production by the welder. Welding performance test records shall conform to
ASME Section IX, Form QW-484 or equivalent. Welding performance testing
records for structural steel shall conform to the recommended AWS format.
G. Weld overlay or clad back-welding shall be qualified in accordance with ASME
Section IX.
H. Weld overlaying or clad restoring (back-cladding) shall be applied with a
minimum of two passes and capable of controlling dilution as evidenced by a
chemical analysis. Depth of chemical analysis shall be three-quarters of the
required overlay thickness unless specified otherwise and approved by Client.
I. When impact testing is required by the code or POLARIS Standards, impact test
results for weld and heat affected zone shall be reported with the welding
procedure qualifications.
J. When maximum Brinell hardness is specified by code, POLARIS Engineering
Standards, or Section X.D.8 of this Standard, they shall be reported with the
welding procedure qualification record and they shall not exceed the maximum
specified limits.
IV. WELDING PROCESSES (GENERAL)
A. The following welding processes are permitted, subject to the limitations set forth
in Section V below, providing that satisfactory evidence is submitted showing that
the procedures qualified are in accordance with applicable codes, standards, and
this Standard.
1. Manual shielded metal arc with covered electrode (SMAW)
2. Gas tungsten arc: manual or automatic (GTAW)

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140.10
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3. Automatic or machine submerged arc (SAW)
4. Oxy – acetylene cutting (OFC-A)
5. Gas metal arc (GMAW)
6. Flux Core Arc Welding (FCAW)
7. Plasma Arc Welding (PAW); manual, automatic or machine
B. Welding processes other than those listed above require specific approval by the
Client or Client's Engineer and shall not be assumed as acceptable by the Vendor
during bid preparation.
C. Fabricators and welders shall be capable of demonstrating satisfactory experience
with the selected acceptable welding processes listed in this standard. First time
use of a welding process requires specific written approval by Client prior to
welding.
D. Client and Client's Engineer reserve the right to disallow the use of any welding
process or welder based on excessive rates of repair.
V. WELDING PROCESS LIMITATIONS
A. GMAW and FCAW processes shall have stated in the WPS, and on the required
weld map (see Appendix I), whether the current is in the short circuiting arc or
spray transfer range. The shop and the welding personnel shall have
demonstrated production welding experience with each process to the satisfaction
of the Client and Client's Engineer.
B. GMAW is acceptable for root passes and completion of welds up to 3/8 inch
deposited weld metal thickness for groove welds and 3/8” fillet weld size. When
specific Client permission is obtained to exceed this maximum deposited
thickness; all such welds shall be 100% ultrasonically shear-wave examined
throughout their entire length.
C. FCAW, in the short circuiting arc mode, is unacceptable.
D. FCAW, spray transfer, without shielding gas, is acceptable with specific Client
approval for structural steel welding fabrication only.
E. FCAW, spray transfer, with shielding gas is acceptable for welding shop
fabricated pipe and for welding pressure retaining parts of pressure vessels
provided the following conditions are met:
1. The procedure qualification record shall include results of micro hardness
testing for both as-welded and stress relieved conditions as applicable for

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Page: 6 of 24
weld, heat affected zone, and base.
2. Production NDE shall include 100% hardness testing on all FCAW
weldments per Section X, Paragraph C.
F. GMAW and FCAW for field fabrication must have the Client's specific approval.
G. Automatic or machine type SAW is preferred. The SAW process shall have
stated on the WPS that the procedure is automatic or machine type welding in
order to be acceptable. Manual or semi-automatic SAW is prohibited.
H. Automatic or machine type SAW of P-1 materials shall be limited to 1/2 inch
maximum thickness per layer of deposit for material of 1-1/4 inch thickness or
greater and 3/8 inch maximum thickness per layer of deposit for material less than
1-1/4 inch thick. The maximum deposit for alloy and stainless steel shall be
limited to 0.4 inches per pass.
I. GTAW shall be utilized for pipe fabrication on first two layers for ferrous alloy,
and non-ferrous alloys on single welded groove joints accessible for one side only
and on other equipment as defined in the POLARIS Engineering Standards.
GTAW shall be used on all piping buttwelds on P-1 materials 2” NPS and
smaller.
VI. FILLER MATERIALS AND FLUXES
A. Filler materials and fluxes shall be as specified in ASME, Section II, Part C.,
Filler Materials and Fluxes, other than those specified in the above code and
which meet other requirements of this Standard, shall not be assumed as
acceptable by the Vendor during bid preparation.
B. All welding shall employ a filler metal unless approved by the Client in writing.
Welding employing no filler metal shall not be assumed as acceptable by the
Vendor during bid preparation. Friction welding is prohibited.
C. The specific AWS grade, ASME specifications, Manufacturer and trade name for
filler metals and fluxes to be used on the project shall be indicated on the welding
procedure specification and weld map (Appendix I).
D. Use of filler metals and fluxes for other than the Manufacturer's primary
recommended application is prohibited. For example: Filler wire intended for
OFW shall not be used for GTAW. Filler wire intended for certain welding
positions specified by the Manufacturer shall not be utilized in other welding
positions. Fluxes recommended for single pass shall not be utilized on multi-pass
welds.
E. Automatic or machine submerged arc welding fluxes are subject to the following
limitations:

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Rev.: 5
Page: 7 of 24
1. Fluxes used for welding carbon or low alloy steels shall not contribute
alloying elements to the weld.
2. The use of Lincoln 780 flux is prohibited.
3. A separate welding procedure qualification shall be required for each
brand and grade of flux and electrode combination.
4. Welding procedures employing "active" fluxes for carbon steel shall
demonstrate that hardness does not exceed 200 BHN. Hardness shall be
reported with the procedure qualification record.
5. Alloy steel shall be welded using an alloy wire and a "neutral" flux. Fluxes
shall not contribute alloying elements to the weld deposit.
F. Fluxes shall be reconditioned prior to re-use in accordance with Manufacturer's
recommendations. The use of re-crushed slag is prohibited.
G. Carbon steels of group P-1 shall be welded with A-1 analysis weld metal only.
Use of other weld metal analysis numbers requires the Client's approval.
H. For welding 70 KSI tensile strength P-1 material subject to a PWHT, filler metals
containing 1/2% Mo are permitted in order to meet the minimum tensile strength
requirement.
I. Similar base materials shall be joined with a weld metal deposit that matches the
base metal in both chemistry and mechanical properties. In cases where this
cannot be accomplished, the Vendor shall propose a choice of filler together with
the reasons for the choice for the Client's review and approval.
J. Welds joining pressure containing parts of two different ferric steels shall have a
weld metal deposit conforming to the nominal composition of the higher alloy
base materials unless otherwise approved by the Client.
K. Welds joining two different ferric steels, only one of which is a pressure retaining
part, shall have a weld metal deposit conforming to the nominal composition of
the pressure retaining part unless the engineering design specifies otherwise and
written approval is given by the Client.
L. When joining two different austenitic stainless steels, the (A-8) filler metal may
match either and must result in a ferrite number range of 3-12. Delta ferrite shall
be determined from the certified chemical analysis and the "WRC Delta Ferrite
Diagram."
M. Welds joining austenitic stainless steels to ferritic steels shall be made with filler
metal as follows:

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Engineering
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140.10
Rev.: 5
Page: 8 of 24
1. Type 309 for design temperatures not exceeding 650o
F.
2. Coated electrodes of SFA 5.11 AWS classes ENiCrFe-2 (comparable to
Huntington Alloy's INCO A) and ENiCrFe-3 (comparable to Huntington
Alloy's INCO 182) or bare electrodes of SFA 5.14 of AWS Classes
ERNiCrFe-5 (comparable to Huntington Alloy's INCO 62) and ERNiCr-3
(comparable to Huntington Alloy's INCO 82) except where process
conditions do not permit.
3. TP 310 fillers are acceptable only for welding of Type 310 base materials
to themselves.
N. For GMAW and GTAW welding of P-1 materials exceeding 65 KSI minimum
tensile strength, only AWS classification ER70-S2 or ER70-S3, filler metals of
SFA 5.18 shall be used. The use of ER70-SG & GS, ER-70C-G & GS of SFA
5.18 is prohibited without prior submittal and approval of the filler metal material
test reports (MTR’s) for each lot. Their utilization shall not be assumed as
acceptable by the Vendor during bid preparation. When use of this material is
approved by Client the material shall be marked and segregated for the job.
O. For FCAW of carbon steels exceeding 65 KSI minimum tensile strength, only
AWS Classification E7X-T1 or E7X-T5 filler metals of SFA 5.20 shall be used.
P. Use of SMAW electrode groups F-1, F-2, and F-3 as specified in ASME Section
IX, Table QW-432, are limited as follows:
1. To fillet welds or butt welds on material not exceeding 65 KSI minimum
tensile strength, in material thickness not exceeding 1/2 inch thickness.
2. F-1, F-2, and F-3 electrodes are not permitted on materials requiring
impact tests.
3. F-1 or F-2 electrodes shall not be used for pressure retaining parts or non-
pressure attachments to pressure retaining parts.
4. F-3 electrodes may be used for root passes of butt welds regardless of base
metal thickness.
Q. The receipt, use, dispersal and retrieval of welding filler materials shall be
maintained under strict control, with storage, baking and drying as recommended
by the Manufacturer to assure that completed welds conform to the approved
welding procedure specification requirements for welding materials.

9. Polaris
Engineering
Standard
140.10
Rev.: 5
Page: 9 of 24
VII. WELD JOINT PREPARATION AND WELDING FABRICATION
A. Joint designs shall be in accordance with applicable code or POLARIS
Engineering Standard requirements.
B. Weld joints shall be prepared by machining, grinding or thermal cutting. When
thermal cutting is performed, the joint surfaces shall be ground to sound metal
prior to welding. Materials shall be subjected to the same preheat requirements
for thermal cutting as required by the applicable welding procedure.
C. For austenitic material 2 inches and thicker, plate edges, including weld bevels
shall be liquid penetrated tested.
D. Welded butt joints shall meet the minimum requirements for penetration or fusion
in accordance with the applicable code or POLARIS Engineering Standard
requirements.
E. The addition of permanent backing such as rings, bars, or strips are unacceptable
and shall not be used without the Client's written approval. Their utilization shall
not be assumed as acceptable by the Vendor during bid preparation. The
additional backing referenced in this Standard is not defined by this Standard as
the weld installed on the first side of a butt weld welded from both sides.
F. Temporary (removable) backing rings, bars, or strips shall not be used without the
Client's written approval. Their utilization shall not be assumed as acceptable by
the Vendor during bid preparation.
G. If approved by the Client, the weld area exposed when backing is removed shall
be dressed and examined for cracks or defects by visual and liquid penetrated or
magnetic particle examination methods, whichever is applicable. All backing
material and unacceptable indications shall be removed completely and repaired
utilizing a weld procedure which has been accepted by the Client.
H. Materials of temporary backing rings, if approved by the Client, shall conform to
the nominal chemistry of the weld filler metal as defined in Section VI of this
Standard.
I. When Client's approval is given for use of backing rings, the Vendor welding
procedure and the weld map (Appendix I) submitted for review shall either
indicate that welding was qualified with backing ring (state on PQR) or that
backing ring will be added (stated on WPS and the weld map, Appendix I).
J. Consumable inserts require written approval by the Client. Their utilization shall
not be assumed as acceptable by the Vendor during bid preparation. If approved
by Client, they shall in all cases conform to the nominal chemistry of the weld
filler metal as defined in Section VI of this Standard. In all cases, they shall
require root shielding with inert gas.

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Page: 10 of 24
K. The materials used for pipe purging dams and methods employed in their
placement, use, and subsequent removal shall be as required to ensure that no
damage results to the piping or related components.
L. The method that is proposed by the Vendor to obtain and maintain adequate root
shielding shall be included either as part of the submitted welding procedure or as
a separate standard for review. The procedure for root shielding by inert gas shall
contain the following:
1. The composition and purity of shielding gas to be used.
2. Flow rates and time required to obtain adequate purging.
3. Pipe dam details materials to be used, type of construction, method of
placement and removal.
M. Unless otherwise specified, back-purging (root shielding), when required, shall be
maintained until completion of 2 weld layers.
N. Weld joint tolerances for root opening and alignment shall meet the requirements
of applicable codes and POLARIS Engineering Standards, and also the weld joint
sketches contained in the submitted welding procedures to ensure against lack of
penetration and lack of fusion.
O. For shop and field fabrication, when poorly fitted joints occur with excessive joint
gap or excessive offset, the Vendor shall submit a separate weld repair procedure
indicating with a sketch the method proposed to bring the joint back to original
design requirements in conformance as close as possible to the original Client
accepted welding procedure. The Vendor cannot assume that backing rings or
strips, permanent or temporary, are acceptable without the Client's review. Any
weld joints of this nature found to be slugged with supplementary filler metal are
unacceptable. The weld build up of beveled ends to close excessive gap is
unacceptable unless a Vendor welding procedure is submitted for doing so and is
accepted by the Client.
P. Grinding and cleaning of stainless steels and nonferrous material shall be done
only with tools that will not leave detrimental deposits on the base metal;
aluminum oxide or silicone carbide grinding wheels and austenitic stainless steel
wire brushes shall be used. These tools shall not have been previously used on
other than the material to be cleaned.
Q. Surfaces to be welded shall be clean and free of paint, oil, dirt, scale and other
foreign materials, which may contain lead, sulfur, and other low melting point
elements detrimental to welding. Beveled edges are to be cleaned and coated with
deoxaluminate paint prior to shipment. Preparation of the bevel just prior to
welding shall be as specified on the applicable welding procedure specification.

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R. Penning of welds to enhance mechanical properties is prohibited.
S. Tack welds which are to be incorporated into the final weld shall be subject to all
the same requirements as the applicable welding procedure, including preheat,
and are to be performed by welders qualified to perform the welding procedure
accepted for that joint. If separate tackers are used other than the welder
performing the joint weld, they shall be qualified for performance on all the same
welding variables for the portion of the weld they perform as stated in the
applicable accepted welding procedure or else the tack welds shall be completely
removed.
T. Tack welds shall be made with filler metal of the same composition as will be
used for the first pass of the weld as stated in the applicable accepted welding
procedure for the joint.
U. All slag shall be thoroughly removed from tack welds and the leading and trailing
edges shall be blend ground to a feather edge prior to welding the root pass or
covering pass.
V. Tack welds that violate any of the above requirements shall be completely
removed. Completed welds having tack welds found to violate any of the above
shall be subject to complete removal.
W. Removable start-up and run-off tabs shall be used for longitudinal welds.
Materials used for these tabs shall be of the same composition as the base weld.
X. For alloy clad plate and material, the following limitations shall apply for
preparation at the joint prior to back-cladding:
1. Cladding shall be stripped back to a minimum of 1/4 inch from the edge of
base material bevels by machining, grinding or arc gouging.
2. Removal of the cladding shall not reduce the base material thickness
below the design thickness.
3. A minimum radius of 1/16 inches shall be used at the limit of cladding
removal unless the clad material is beveled at least 30o
.
4. Preparation of local repair cavities in overlay welds that penetrate into the
base material more than 10% of its thickness, or 3/16 inch, whichever is
less, shall have the base material rewelded with the appropriate Client
accepted welding procedure consistent with the base material prior to
completing the overlay repair.
5. Copper sulfate test to ensure complete cladding removal.

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Y. Strip type lining shall be attached to the shell circumferentially and shall be
designed so that the distance between attachment welds does not exceed that
shown below. The weld between the strips shall be at least 1/4 inch and not more
than 1/2 inch in width. Strip lining shall be a multi-pass fillet-butt weld of three
(3) weld minimum design with 100% dye penetrant testing of final weld. See
Figure A below.
Figure A
Strip Welding Linings
Vessel Operating Temperature Distance Between Welds
650 ºF and Under 4 inches
Over 650 o
F Not permitted (See VII.Z)
Z. Vessels with integrally clad type linings shall be made of explosion bonded plate
or plate clad with the required lining material in the steel mill in accordance with
the mill’s standards. These standards are to be approved by Client.
AA. Weld overlays shall consist of at least two layers so that the required depth of the
top layer will have the alloy composition required for the service. The first layer
may be made with electrodes of higher alloy content to compensate for dilution
effects. The finished surface shall be 100% examined by the liquid penetrant
method of examination.
BB. All stubs, rods, flux, slag or foreign material shall be removed from the equipment
or piping after completion of welding and prior to postweld heat treatment or
hydrostatic test.
CC. The use of temporary welded attachments shall be avoided where possible. All
locations of removed temporary attachments shall be examined visually after
removal of the attachment.
1. Temporary attachments shall be removed by flame cutting, arc gouging or
grinding. Hammering off is not permitted. (This paragraph does not
apply to atmospheric storage tanks within the scope of Standard 1115.1
and API 650.)
2. Defects discovered in the base metal such as gouges, cracks or undercuts

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shall be removed and repaired and the area re-examined using the same
method of NDT that revealed the original defect.
DD. Vertical welding shall be performed vertical up. Downhill welding is not
permitted except for the GMAW root pass only.
EE. For field erection of API storage tanks, the weld seams of sketch plates for tank
bottoms and floating roofs shall contain a minimum of two weld passes. Single
pass seams are not acceptable.
FF. Branch Connections
1. Branch connections such as weldolets, threadolets, sockolets, and stub-ins
shall be joined to the header by full penetration welds. Incomplete
penetration as defined by Table 341.3.2, Note B of ASME B31.3, is not
acceptable.
2. Start and stop welds on root pass shall be feathered in.
3. Branch connections shall be prepared in accordance with Figure 328.4.4
(A), (B) or (C) of ASME B31.3. A minimum root gap of 1/16 inches shall
be maintained during welding. The root gap shall be stated in the welding
procedure specification.
VIII. PREHEAT AND INTERPASS TEMPERATURES
A. Preheat shall be at least sufficient to dry surfaces to be welded but not less than
50o
F. Higher temperatures may be required for highly restrained joints such as
closely spaced nozzles. Carbon steel plates 1.25 inch thick or more, shall be
preheated to 200o
F minimum and ferritic alloy plates to 300o
F minimum prior to
flame cutting and ground smooth prior to welding. All such prepared edges
including holes cut for nozzles or manways, shall be liquid penetrant examined or
magnetic particle inspected for cracks or laminations.
B. Minimum preheat temperatures shall not be less than that stated in ASME,
Section VIII, Division 1, Appendix R and Paragraph UCS 56; ASME B31.1,
Paragraph 131; or ASME B31.3, Table 330.1.1, as applicable. Minimum preheat
temperatures are required to be stated on the welding procedure specification.
C. Preheat maintenance shall be applied when required by the Client for the
conditions stated below. Preheat maintenance is the maintenance of the stated
minimum preheat temperature, without interruption, from start to completion of
welding. Vendor must either state on the WPS or weld map that preheat is to be
maintained when so required by Section VIII of this Standard. Loss of preheat
maintenance will require complete liquid penetrant or magnetic particle
inspection of the uncompleted seam prior to any further welding. Any defects
found must be reported to the Client's Inspector for his review.

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D. Preheat maintenance is required for the following:
1. Equipment and piping, regardless of service or wall thickness, of the P-5B,
C, and D material groups (where chrome content exceeds 4%) and of P-6
and P-7 materials.
2. Modifications to existing equipment and piping, regardless of material or
wall thickness in hydrogen service. Hydrogen service is defined as: Any
service in which the partial pressure of hydrogen in the fluid handled is 50
psia or more. This work requires a hydrogen bake-out, pre-heat
maintenance and PWHT.
3. Pressure vessel and exchanger seams, nozzle and attachment welds of P-1,
P-3, P-4 and P-5 group materials, regardless of service, if shell or head
thickness is equal to or greater than 1-1/2 inch.
4. Piping fabrication, regardless of material or service, if thickness is equal to
or greater than 3/4 inch.
E. The same preheat requirements shall be met as are required on the Client accepted
welding procedures for thermal cutting, gouging, tack welding and welding
repairs.
F. The maximum preheat and interpass temperature for P-8 materials shall be 350 o
F.
The maximum preheat and interpass temperature shall be specified on the WPS
for all materials of material group P-7 and higher.
IX. POSTWELD HEAT TREATMENT
A. Postweld heat treatment (PWHT) shall be performed in accordance with the
ASME Code and/or POLARIS Engineering Standard 840.4, as applicable. The
applicable code or Standard for PWHT shall be referenced on the weld map
(Appendix I). The maximum and minimum holding temperature and holding time
shall also be stated on the WPS. POLARIS requires a two (2) hour minimum
holding time for all equipment and piping to be heat treated.
1. For all equipment, except field fabricated tanks and piping, the post weld
heat treatment procedure outlined in the ASME Code, Section VIII,
Paragraphs UW-40, UW-49, and UCS-56, shall be followed. The
exemptions provided for in the notes to Table UCS-56 are permitted with
Client approval.
2. Complete temperature cycle of heating, soaking and cooling shall be
recorded on a chart and a copy of the continuously temperatures shall be
provided to the Client for record. Cooling rate and heating rate shall be
recorded on the WPS.

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3. Minimum and maximum PWHT temperatures and minimum holding time
shall be as specified in the appropriate code and/or POLARIS Engineering
Standard, except as specifically noted below:
a. All carbon steel vessels, exchangers, and piping requiring PWHT
are to be postweld heat treated at 1150 o
F maximum (± 25 o
F) for a
minimum of two (2) hours.
b. All 1-1/4% Cr - 1/2% Mo vessels, exchangers and piping are to be
postweld heat treated at 1325 o
F maximum (± 25 o
F) for a
minimum of two (2) hours.
c. All 5% Cr - 1/2% Mo and 9% Cr – 1% Mo vessels, exchangers and
piping are to be postweld heat treated at 1350 o
F maximum (± 25
o
F) for a minimum of two (2) hours.
d. All carbon steel and low chrome piping shall be postweld heat
treated in accordance with POLARIS Engineering Standard 840.4.
B. Postweld heat treatment may be required for carbon steel equipment and piping
for certain service conditions even when not mandatory per the applicable code or
standard. Postweld heat treatment for these services will be indicated by the
POLARIS Engineering Standards.
At a minimum the following items shall be post weld heat treated:
1. Unless otherwise specified, welds in amine equipment and piping shall be
postweld heat treated regardless of operating temperature or concentration.
This also includes piping and equipment, which may be at risk of amine
contamination as defined by the project P & ID's.
2. Unless otherwise specified, welds in caustic equipment and piping shall be
postweld heat treated regardless of the operating temperature or caustic
concentration. This also includes piping and equipment, which may be at
risk of caustic contamination as defined by the project P & ID's.
3. Postweld heat treatment is required for equipment as well as shop and
field fabricated piping of 1-1/4 Cr and higher ferritic steel weldments
regardless of thickness.
4. Postweld heat treatment is required for equipment as well as shop and
field fabricated piping of carbon steel weldments regardless of thickness
when design operating conditions are within 200 o
F of the Nelson Curve
for that material.
5. All carbon steel equipment and piping in sour service with a fluid pressure

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of 65 psia or greater and containing hydrogen sulfide (H2S) at a partial
pressure in excess of 0.05 psia (mol-fraction multiplied by total system
pressure) with, or without, water present.
6. All deaerators require post weld heat treatment.
7. All equipment in these services above shall have welds ground, smooth,
and wet fluorescent magnetic particle tested.
C. Postweld heat treatment temperatures will be in accordance with ASME B31.3,
Table 331.1.1 and POLARIS Engineering Standards 840.1 and 840.4.
D. Acceptable methods for postweld heat treatment are:
1. Furnace method
2. Local resistance method
3. Local induction method
Other methods for postweld heat treatment require Client's written approval.
E. For piping, postweld heat treatment performed by exothermic methods requires
Client's written approval and shall not be assumed as acceptable by the Vendor
during bid preparation. When approved by Client, welding procedures submitted
for review using postweld heat treatment by exothermic methods shall be
qualified as using the exothermic method proposed for heat treatment. All weld
joints postweld heat treated by exothermic methods, when approved, require
100% radiography.
F. Postweld heat treatment for stainless steels of Material Group P-8, nonferrous
materials or dissimilar materials requires approval by the Client.
G. Direct impingement by torch or furnace burner is not acceptable. Threads and
gasket surfaces shall be protected from excessive oxidation during heat treatment.
H. Equipment and piping postweld heat treated for any reason, code or process, shall
not be subjected to any further welding, hammering, pressing or forming after
postweld heat treatment without Client approval.
I. Postweld heat treatment procedures describing cleaning requirements, heating and
cooling rates, thermocouple locations, type of heating, equipment, etc., shall be
submitted to the Client for review and approval to proceed.
J. For local postweld heat treatment of thicknesses greater than 2 inches, the Vendor
shall verify that the minimum code required PWHT temperature is attained on the
unheated side of the joint. Verification may be established either by the

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attachment of thermocouples or by the submittal of test data.
K. PWHT is always required for all piping in which the wall thickness is 3/4” or
greater.
X. NON-DESTRUCTIVE EXAMINATION, TESTING AND INSPECTION
A. Non-destructive examination (NDE) shall be performed and results evaluated in
accordance with the requirements of the applicable ASME code, ANSI standard,
or API standard. Any additional NDE required above and beyond the above
mentioned codes and standards shall be as specified in this Standard and other
POLARIS Engineering Standards.
B. As a minimum, or when non-destructive examination is not specified, all welds
shall be visually examined.
C. Plate 2 inches and thicker and clad material shall be 100% ultrasonically tested at
the mill with acceptance to SA-578, Level B.
D. Brinell Hardness Tests
1. Hardness tests shall be performed when PWHT is specified, and when
required by codes, standards or POLARIS Engineering Standards.
Hardness test results shall be given in equivalent Brinell values regardless
of test method utilized. A test shall include one (1) examination in the
weld and one (1) in each heat affected zone at the toe of the weld.
2. Hardness tests on piping shall be taken as specified in POLARIS
Engineering Standards 840.1 and 840.4.
3. Hardness tests on pressure vessels, exchangers, and other equipment
where required shall be taken as follows:
a. One test for one longitudinal seam per course section, on the inside
surface where practical.
b. One test for each circumferential seam per 50 linear feet of weld,
on the inside surface where practicable.
c. One test for each major joint weld for box-type headers on air
coolers.
d. One test for each size nozzle 4 inches and over in size, if
accessible.

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e. As a minimum, one test shall be taken for each welding process
employed on pressure containing welds and also one test per
welder or welding machine operator.
f. As required in the applicable code or standard.
4. When PWHT is required, hardness tests shall be performed after PWHT.
5. Where NACE MR-0175 and/or RP-0472 are specified the hardness testing
requirements of those standards shall apply where more stringent than this
Standard.
6. Results of hardness tests shall be documented by the Vendor for review by
the Client's Inspector. The Client's Inspector shall be consulted on choice
of location for tests.
7. Hardness tests exceeding the maximum Brinell Hardness Number (BHN)
allowed shall have two more tests taken near each failed location and both
are required to be within the maximum acceptable hardness requirements.
8. Hardness test results shall be reported with the procedure qualification
record by the Vendor with submittal of welding procedure review by the
Client for the following:
a. Whenever hardness tests are required by codes or standards.
b. Whenever equipment or piping is to be postweld heat treated.
c. Whenever automatic or machine type welding processes are
employed, or whenever FCAW is to be utilized.
d. Hardness for carbon steel shall not exceed 200 BHN; hardness for
low alloy shall be in accordance with applicable codes or
standards. For other materials requiring hardness testing,
acceptance values shall be as stated in the applicable codes and
standards.
E. Production test requirements on weld overlay and back-cladding on vessels and
exchangers are as follows:
1. One chemical analysis of overlay from each girth section and component
(such as head, tubesheet, etc.) and from each back-cladded longitudinal
and circumferential seam. Also, back-cladded manway attachment and a
representative number of nozzles, at least one of each size. Production
tests shall include a minimum of one test per welding process utilized and
one test per welder or welding operator employed.

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2. For austenitic stainless steel, the overlay or back-clad for TP 347 stainless,
when specified, shall have elements Cr, Ni, Mn, Si, C and Cb reported.
3. For others, the overlay or back-clad shall meet the minimum requirements
of the specified alloy.
4. Ferrite content of austenitic stainless steel overlay and back-cladding shall
be checked by using a magnetic gage or other method approved by the
Client. Range of ferrite shall be 3-12 FN per magnetic meter.
F. Weld overlays and back-cladding for vessels and towers shall be examined by a
standard copper sulfate test prior to hydrostatic test and by liquid penetrant
examination following hydrostatic test. Overlay clad tubesheets shall be liquid
penetrant examined prior to hydro static test.
G. The Client's Inspector shall be authorized to reject work or materials and require
repair or corrections where the applicable specifications or acceptance levels have
not been met.
H. The Client's Inspector may require additional examination over and above the
minimum specified. If the weld proves to be acceptable, the cost of examination
shall be borne by the Client. If the weld proves to be unacceptable, the cost of the
examination, and all required repairs and re-examination shall be borne by the
Vendor.
I. Root and final welds in vessels, air cooler box headers, exchangers and piping
larger than 24 inches shall be magnetic particle examined when the material
thickness is equal to or greater than the following:
MATERIAL GROUP THICKNESS (INCH)
P-1 1-1/4
P-3 3/4
P-4 5/8
P-5 All
P-6 All
P-7 All
J. Welds in all non-magnetic materials, either of solid alloy or alloy clad plate shall
be examined by liquid penetrant methods.
K. Where strength welds for tube to tubesheet joints are required, Vendor shall
submit a cut-off sample before fabrication.

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L. Pressure retaining butt welds in shell or heads over 1.80 inches thick may be
manual arc process welded and shall be radiographed 100%.
M. Heads fabricated from more than one piece shall have welds radiographed 100%
prior to forming.
N. For equipment and piping requiring PWHT all required NDE of completed welds
shall be performed after the postweld heat treatment.
XI. REPAIRS
A. Welding repairs shall be performed utilizing Client approved welding procedures
under conditions and requirements as stringent as those imposed by the welding
procedure originally accepted for the particular weld.
B. The repair procedures, using welding, shall be submitted for review and shall
include the following:
1. The method of defining the type and the extent of the defect.
2. Methods used for removing the defect, and testing conducted to ensure
that the defect has been removed.
3. Welding procedures employed for re-welding and NDE methods used to
inspect weld repair area after completion of the welding.
C. Unacceptable discontinuities shall be completely removed by chipping, gouging,
grinding or other Client authorized methods (for the type of material being
repaired) to clean to sound metal and the excavated area shall be examined by
magnetic particle or liquid penetrant methods to assure complete removal of
defects.
D. Excavation for repairs by flame or arc gouging shall have the same preheat
requirements imposed as the welding procedures used to perform the weld.
E. Preheat to be used for repair welding (such as attachments, undercutting, and
other defects which do not penetrate the full weld thickness) shall be the same as
required for the original weld for the full base metal thickness.
F. Undercutting shall be repaired by blend grinding provided the required base metal
thickness by design is not reduced. Otherwise, weld metal buildup will be
required.
G. Defective work or materials that have been weld repaired shall, as a minimum, be
re-examined by the same non-destructive test method by which the defect was
originally located.

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H. Only two repair attempts shall be allowed on any one defective area. No further
attempts to repair shall be carried out without authorization of the Client.
XII. SUMMARY OF WELDING VARIABLE LIMITATIONS, RESTRICTIONS,
AND OTHER REQUIREMENTS
Limitations, restrictions and other requirements of this Standard, whether required by
ASME Section IX or not, are required to be stated in the Vendor's WPS, PQR and weld
map (Appendix I), on welding procedures submitted by the Vendor for review. The main
requirements are summarized as follows:
A. Impact test results on PQR.
B. Brinell hardness test results on PQR.
C. Mode of transfer for GMAW and FCAW to be stated on WPS and weld map of
Appendix I.
D. GMAW: Limitations and requirements.
E. FCAW: Limitations and requirements.
F. Automatic or machine type SAW to be specified in WPS.
G. Filler metals and fluxes. To have stated in the WPS and/or weld map (Appendix
I) the AWS grades ASME specifications, Manufacturers, and trade names of filler
metals and fluxes.
H. When backing is approved for use, it is required to be stated on PQR, WPS and
weld map (Appendix I).
I. Root shielding (back purge) method to be stated on WPS or separate procedure
submitted.
J. Minimum preheat temperature to be stated in WPS.
K. Preheat maintenance when required to be stated in WPS.
L. Maximum preheat and interpass temperature to be stated on WPS for P-7 group
materials and higher.
M. Postweld heat treatment holding temperature and holding time to be specified on
weld map (Appendix I) and in WPS.
N. Additional welding variables to be stated in the WPS whether essential or non-
essential per ASME Section IX are:

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1. Electrical characteristics: current and voltage ranges, and polarity, for all
welding processes.
2. AWS specification for non-consumable electrode for GTAW.
3. Travel speed and whether single or multiple arc for automatic processes of
GTAW, GMAW, SAW, FCAW/CO2 and for overlay and back-clad
welding.
4. Amount of bead overlap, extent of oscillation and wire size for overlay
and back-clad welding.
O. Block welding is prohibited. However, The Temper Bead Welding Technique per
NBIC is allowable with Client’s written approval.
P. When welding titanium, each bead and adjacent base metal shall be cleaned to
remove all surface discoloration prior to deposition of the next bead. The final
weld surface may have intermittent, iridescent straw-colored oxides.
Q. The root pass of butt welds in lube oil piping, accessible from one side only, shall
be welded with the GTAW process.
XIII. PROCEDURE FOR REVIEW AND ACCEPTANCE OF VENDOR WELDING
PROCEDURES
A. The Client requires Vendors and their Subvendors, if applicable, to submit a copy
of each welding procedure appropriate for fabrication. A copy of the weld map
(Appendix I) shall also be filled out and attached to the submittal. Procedures
cannot be reviewed unless accompanied by the weld map.
B. Submittals of welding procedures for review shall be directly to the Client and/or
Client's Engineer. No portion of this Standard shall be waived without written
approval.
C. Vendors shall review the welding procedures of their own Subvendors for
compliance to this Standard prior to submitting for review and acceptance.
D. The Client and/or Client's Engineer will review the submitted welding procedures
and weld map and make comments back to the Vendor in writing. Comments are
either (1) Acceptable without comment, (2) Acceptable with comments, (3)
Revise and resubmit per comments or (4) Unacceptable with comments. All
comments, if possible, will make reference the paragraph number of this Standard
with which the procedure must comply.

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E. Upon receiving the marked up welding procedure from the Client and/or Client's
Engineer, the Vendor must comply with the comments. The Vendor shall submit
corrected documents. The Surveillance Inspector assigned by the Client is to
verify that welding will be performed to the accepted and corrected welding
procedures, which incorporate the comments. Items in dispute shall be resolved
prior to fabrication being stated on the affected parts.

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APPENDIX I
WELD MAP
Supplier Name
Supplier Shop Order #
POLARIS PO # Pressure Vessel
Item/Tag # Heat Exchanger
Storage Tank
Design Temperature Fabricated Pipe Spools
Design Pressure Other
Min. Design Metal Temp.
Postweld Heat Treatment Yes No Required by Code Service
Time and Temperature
Impact Testing Yes No Required by Code Service
Temperature
Applicable Code or Standard
Draw a single-line sketch of the apparatus. For pipe spools, only show typical weld joints, i.e., butt, branch, and attachments, by
P-No.
Locate an example of all types of typical weld joints, dissimilar welds & attachments
Identify each different welding procedure by separate letter or number.
This form completed by This space for POLARIS Review Stamp
Email Address
Telephone
Revision
Date
This space for POLARIS Identification