ISO 15590-4:2019

Petroleum and natural gas industries - Factory bends, fittings and flanges for pipeline transportation systems - Part 4: Factory cold bends

This document specifies the technical delivery conditions for bends made by the cold bending process for bend with radii 5xOD or higher for use in pipeline transportation systems for the petroleum and natural gas industries as defined in ISO 13623. This document also specifies the requirements for the manufacture of two product specification levels (PSLs) of cold bends corresponding to product specification levels given for pipe in ISO 3183. This document is applicable to cold bends made from seamless and welded pipe of unalloyed or low-alloy steels. NOTE 1 These are typically C-Mn steels or low-alloy steels that are appropriate for the corresponding level and grade of line pipe in accordance with ISO 3183. This document is not applicable to the selection of the cold bend product specification level. It is the responsibility of the purchaser to specify the PSL, based upon the intended use and design requirements. NOTE 2 See also ISO 3183:2012, Introduction. This document is not applicable to field cold bends and pipeline bends made by other manufacturing processes.

Industries pétrolières et gazières—Coudes d'induction, raccords et brides d’usine pour systèmes de transport par conduites — Partie 4: Coudes usinés à froid

General Information

• Status: Published
• Publication Date: 23-Sep-2019
• ICS: 75.200 - Petroleum products and natural gas handling equipment
• Technical Committee: ISO/TC 67/SC 2 - Pipeline transportation systems
• Drafting Committee: ISO/TC 67/SC 2/WG 10 - Pipeline flanges, fittings and shopbends
• Current Stage: 9092 - International Standard to be revised
• Start Date: 19-Jun-2025
• Completion Date: 13-Dec-2025

Overview

ISO 15590-4:2019 specifies technical delivery conditions for factory cold bends used in pipeline transportation systems for the petroleum and natural gas industries. It applies to bends produced by the cold bending process with radii of 5×OD or greater, manufactured from seamless or welded unalloyed or low-alloy steels (typical C‑Mn or low‑alloy grades). The standard defines requirements for two product specification levels (PSLs) aligned with pipe PSLs in ISO 3183 and covers manufacturing, testing, inspection, marking and documentation for factory cold bends (not for field cold bends or bends made by other processes).

Key Topics and Requirements

• Scope and applicability: Factory cold bends for pipeline systems (r ≥ 5×OD); purchaser responsibility to specify PSL and any supplementary requirements.
• Product Specification Levels (PSL): Two PSLs corresponding to ISO 3183 pipe PSLs; selection is by the purchaser based on design and service conditions.
• Manufacturing requirements: Mother pipe selection, qualification test bend, production bending, post‑bending heat treatment, forming/sizing, welds and end preparation. Annex A provides a Manufacturing Procedure Specification (MPS) option.
• Mechanical and material testing:
  • Chemical composition verification
  • Tensile testing and Charpy V‑notch impact testing
  • Hardness testing (through‑thickness and surface)
  • Metallographic examination, guided bend/flattening tests where applicable
• Non‑destructive testing (NDT): Visual inspection, magnetic particle or liquid‑penetrant testing, ultrasonic testing of the bend body, seam testing, NDT personnel qualifications (ISO 9712 referenced).
• Inspection, documentation and marking: Inspection documents per ISO 10474, hydrostatic testing, gauging, dimensional checks and traceability requirements.
• Special considerations: Annex B covers PSL 2S bends ordered for sour service; these annexes apply only when specified by the purchaser.

Practical Applications and Users

ISO 15590-4 is intended for:

• Bend and fitting manufacturers producing factory cold bends for pipelines.
• Pipeline designers and engineers specifying bend geometry, pressure ratings and material PSLs.
• Procurement/specification engineers who must designate PSL and supplementary requirements on purchase orders.
• Quality, inspection and NDT personnel responsible for testing, documentation and acceptance of factory bends.
• Operators and contractors in the petroleum and natural gas sectors rely on this standard to ensure bend integrity, traceability and conformance to pipeline system requirements.

Related Standards

Key referenced and related standards include:

• ISO 3183 (steel pipe for pipeline transportation systems)
• ISO 13623 (pipeline system definitions)
• ISO 6892, ISO 148‑1 (tensile and Charpy testing)
• ISO 9712 (NDT personnel qualification)
• ISO 10474 (inspection documents) These related standards are referenced directly within ISO 15590-4 for test methods, inspection and conformity requirements.

Keywords: ISO 15590-4:2019, factory cold bends, pipeline cold bending, petroleum and natural gas, PSL, ISO 3183, NDT, hydrostatic testing, manufacturing procedure specification.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15590-4
First edition
2019-09
Petroleum and natural gas
industries — Factory bends,
fittings and flanges for pipeline
transportation systems —
Part 4:
Factory cold bends
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 3
4 Symbols and abbreviated terms . 5
4.1 Symbols . 5
4.2 Abbreviated terms . 5
5 Conformance . 6
5.1 Units of measurement . . 6
5.2 Rounding . 6
5.3 Conformity to this document . 6
6 Designation of cold bends . 7
7 Pressure rating and design . 7
8 Information provided by the purchaser . 7
8.1 General information . 7
8.2 Additional information . 8
8.3 Information on the mother pipe . 9
9 Manufacturing . 9
9.1 Mother pipe . 9
9.2 Qualification test bend .10
9.3 Production cold bending .10
9.4 Post-bending heat treatment .10
9.5 Forming and sizing after bending .10
9.6 Strip/plate end welds . .11
9.7 Jointers and girth welds .11
9.8 End preparation .11
10 Testing and inspection .11
10.1 General requirements .11
10.2 Extent of testing and inspection .12
10.2.1 Qualification test bend .12
10.2.2 Production bends .12
10.2.3 Production test bends .12
10.3 Chemical composition .12
10.4 Physical testing .12
10.4.1 General.12
10.4.2 Tensile testing .12
10.4.3 Charpy V-notch impact testing .16
10.4.4 Through-thickness hardness testing .17
10.4.5 Surface hardness testing .17
10.4.6 Metallographic examination .18
10.4.7 Guided bend testing .18
10.4.8 Flattening tests .18
10.5 Non-destructive testing .18
10.5.1 Visual inspection .18
10.5.2 Weld seam testing .19
10.5.3 Inspection of bend ends . .19
10.5.4 Magnetic particle testing or liquid-penetrant testing on the bend body .20
10.5.5 Ultrasonic testing on the bend body .20
10.5.6 Level of residual magnetism .20
10.5.7 Repairs .20
10.5.8 NDT personnel .20
10.6 Dimensions .20
10.7 Gauging .22
10.8 Hydrostatic testing .22
11 Inspection document .23
12 Marking .23
Annex A (normative) Manufacturing procedure specification .25
Annex B (normative) PSL 2S cold bends ordered for sour service .27
Bibliography .31
iv © ISO 2019 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 2, Pipeline
transportation systems.
A list of all parts in the ISO 15590 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
Introduction
This document makes reference to line pipe and bends with delivery conditions based on ISO 3183.
This document contains additional requirements for special applications as follows:
— Manufacturing procedure specification (Annex A);
— PSL 2S cold bends ordered for sour service (Annex B).
The requirements of the annexes apply only where they are specified on the purchase order. This
document does not provide guidance on when it is necessary to specify the above supplementary
requirements defined in the annexes. It is the responsibility of the purchaser to specify, based upon the
intended use and design requirements, the supplementary requirements that will apply for a particular
purchase order.
Further or differing requirements can be needed for individual applications. This document is not
intended to inhibit a manufacturer from offering, or the purchaser from accepting, alternative equipment
or engineering solutions for the individual application. This can be particularly applicable where there
is innovative or developing technology. Where an alternative is offered, it is the responsibility of the
manufacturer to identify and provide details of any variations from this document.
vi © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 15590-4:2019(E)
Petroleum and natural gas industries — Factory bends,
fittings and flanges for pipeline transportation systems —
Part 4:
Factory cold bends
1 Scope
This document specifies the technical delivery conditions for bends made by the cold bending process
for bend with radii 5xOD or higher for use in pipeline transportation systems for the petroleum and
natural gas industries as defined in ISO 13623.
This document also specifies the requirements for the manufacture of two product specification levels
(PSLs) of cold bends corresponding to product specification levels given for pipe in ISO 3183. This
document is applicable to cold bends made from seamless and welded pipe of unalloyed or low-alloy steels.
NOTE 1 These are typically C-Mn steels or low-alloy steels that are appropriate for the corresponding level
and grade of line pipe in accordance with ISO 3183.
This document is not applicable to the selection of the cold bend product specification level. It is the
responsibility of the purchaser to specify the PSL, based upon the intended use and design requirements.
NOTE 2 See also ISO 3183:2012, Introduction.
This document is not applicable to field cold bends and pipeline bends made by other manufacturing
processes.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 80000-1:2009, Quantities and units — Part 1: General
ISO 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method
ISO 3183:2012, Petroleum and natural gas industries — Steel pipe for pipeline transportation systems
ISO 6507 (all parts), Metallic materials — Vickers hardness test
ISO 6508 (all parts), Metallic materials — Rockwell hardness test
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 6892-2, Metallic materials — Tensile testing — Part 2: Method of test at elevated temperature
ISO 7438, Metallic materials — Bend test
ISO 7539-2, Corrosion of metals and alloys — Stress corrosion testing — Part 2: Preparation and use of
bent-beam specimens
ISO 8501-1, Preparation of steel substrates before application of paints and related products — Visual
assessment of surface cleanliness — Part 1: Rust grades and preparation grades of uncoated steel substrates
and of steel substrates after overall removal of previous coatings
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
ISO 10474, Steel and steel products — Inspection documents
ISO 10893-4, Non-destructive testing of steel tubes — Part 4: Liquid penetrant inspection of seamless and
welded steel tubes for the detection of surface imperfections
ISO 10893-5, Non-destructive testing of steel tubes — Part 5: Magnetic particle inspection of seamless and
welded ferromagnetic steel tubes for the detection of surface imperfections
ISO 10893-8, Non-destructive testing of steel tubes — Part 8: Automated ultrasonic testing of seamless and
welded steel tubes for the detection of laminar imperfections
ISO 10893-9, Non-destructive testing of steel tubes — Part 9: Automated ultrasonic testing for the detection
of laminar imperfections in strip/plate used for the manufacture of welded steel tubes
ISO 10893-10:2011, Non-destructive testing of steel tubes — Part 10: Automated full peripheral ultrasonic
testing of seamless and welded (except submerged arc-welded) steel tubes for the detection of longitudinal
and/or transverse imperfections
ISO 10893-11:2011, Non-destructive testing of steel tubes — Part 11: Automated ultrasonic testing of the
weld seam of welded steel tubes for the detection of longitudinal and/or transverse imperfections
ISO 13623, Petroleum and natural gas industries — Pipeline transportation systems
ASNT SNT-TC-1A, Recommended Practice No. SNT-TC-1A: Personnel Qualification and Certification in
Nondestructive Testing
ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products
ASTM A435, Standard Specification for Straight-Beam Ultrasonic Examination of Steel Plates
ASTM A578/ A578M, Standard Specification for Straight-Beam Ultrasonic Examination of Rolled Steel
Plates for Special Applications
ASTM E18, Standard Test Methods for Rockwell Hardness of Metallic Materials
ASTM E92, Standard Test Method for Vickers Hardness of Metallic Materials
ASTM E112, Standard Test Methods for Determining Average Grain Size
ASTM E165, Standard Test Method for Liquid Penetrant Examination
ASTM E213, Standard Practice for Ultrasonic Testing of Metal Pipe and Tubing
ASTM E214, Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing
ASTM E340, Standard Test Method for Macroetching Metals and Alloys
ASTM E709, Standard Guide for Magnetic Particle Testing
ASTM E797, Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method
ASTM G39, Standard Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test Specimens
NACE/TM 0177:2016, Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking in Hydrogen
Sulfide (H S) Environments
NACE/TM 0284:2016, Standard Test Method — Evaluation of Pipeline and Pressure Vessel Steels for
Resistance to Hydrogen-Induced Cracking
2 © ISO 2019 – All rights reserved

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
arc
curved portion of a bend
3.2
agreed
agreed upon by the manufacturer (3.17) and purchaser (3.21), and specified in the purchase order
3.3
bend angle
amount of directional change through the cold bend
3.4
bend qualification test
qualification test that produces a cold bend in accordance with the MPS (3.18) and demonstrates that
bends that meet the specified requirements of this document can be produced
3.5
bend radius
distance from the centre of curvature to the centreline axis of the bent pipe
3.6
chord
line segment connecting start and stop points of the bend zone measured at the centreline axis
3.7
defect
imperfection (3.11) of a size and/or population density greater than specific acceptance criteria
Note 1 to entry: The specific acceptance criteria are specified in ISO 3183.
3.8
extrados
outer curved section of the arc (3.1)
3.9
heat
batch of steel prepared in one steel-making operation
3.10
if agreed
required to be as prescribed, or more stringent than is prescribed, if agreed upon by the manufacturer
(3.17) and the purchaser (3.21) and specified in the purchase order
3.11
imperfection
discontinuity or irregularity in the product wall or on the product surface that is detectable through
inspection methods
3.12
indication
evidence obtained by non-destructive inspection (3.20)
3.13
cold bending
controlled bending process using presses at room temperature
3.14
inspection
activities, such as measuring, examining, testing, weighing or gauging one or more characteristics
of a product and comparing the results of such activities with the specified requirements in order to
determine conformity
3.15
intrados
inner curved section of the arc (3.1)
3.16
lamination
internal metal separation that creates layers, generally parallel to the pipe/bend surface
3.17
manufacturer
firm, company, or corporation responsible for making and marking the product
3.18
manufacturing procedure specification
MPS
document that specifies the properties and description of the mother pipe (3.19), the cold bending
procedure, the post- bending heat treatment equipment and cycle, if applicable, the qualification bend
testing results, the non-destructive testing procedures and the weld end bevel details used for the
manufacture of the cold bends
3.19
mother pipe
straight section of pipe from which a cold bend is made
3.20
non-destructive inspection
inspection (3.14) to reveal imperfections (3.11), using radiographic, ultrasonic or other methods that do
not involve disturbance, stressing or breaking of the materials
3.21
purchaser
party responsible for both the definition of the requirements for a product order and the payment of
that order
3.22
submerged-arc welding
SAW
welding process that produces melting and coalescence of metals by heating them with an arc(s)
between a bare metal consumable electrode(s) and the workpiece, wherein the arc (3.1) and molten
metal are shielded by a blanket of granular flux
3.23
service condition
condition of use that is specified by the purchaser (3.21) in the purchase order
Note 1 to entry: In this document, “sour service” and “offshore service” are service conditions.
3.24
strip end weld
weld that joins strip ends together
4 © ISO 2019 – All rights reserved

3.25
plate end weld
weld that joins plate ends together
3.26
tangent
straight section at the ends of a cold bend
3.27
wall thinning
amount of reduction from the actual wall thickness of the pipe to the wall thickness in the extrados
(3.8) after cold bending (3.13)
4 Symbols and abbreviated terms
4.1 Symbols
A elongation of tensile test specimen after fracture, expressed as a percentage
L crest to valley depth
CVD
D and D outside diameters of two adjacent crests
2 4
D outside diameter of the intervening valley
D specified diameter, outside or inside
D maximum measured diameter, outside or inside
max
D minimum measured diameter, outside or inside
min
Dn nominal pipe diameter
L distance between adjacent crests for waving
O out-of-roundness
R bend centreline radius
b
R nominal mid-thickness radius of the mother pipe
p
R ultimate tensile strength
m
R yield strength for 0,5 % total elongation
t,0,5
t minimum wall thickness at the bend intrados
i
t minimum wall thickness required in accordance with ISO 13623, or other applicable de-
min
sign code, for the straight pipe adjacent to the bend, including any corrosion allowance
4.2 Abbreviated terms
BQT cold bend qualification test
CB cold bending
CTOD crack tip opening displacement testing
CVD crest to valley depth
HAZ heat-affected zone
HIC hydrogen-induced cracking
HFW high-frequency electric welding process for pipe during manufacturing
MT magnetic particle testing
NDT non-destructive testing
OD outside diameter
PSL product specification level
PT liquid-penetrant testing
RT radiographic testing
SAW submerged arc welding process for pipe during manufacture
SAWH submerged arc helical welding process for pipe during manufacture
SAWL submerged arc longitudinal welding process for pipe during manufacture
SSC sulfide stress-cracking
SWC step-wise cracking
UT ultrasonic testing
5D 5 xOD
10D 10 xOD
5 Conformance
5.1 Units of measurement
In this document, data are expressed in both SI units and USC units. For a specific order item, unless
otherwise stated, only one system of units shall be used, without combining data expressed in the
other system.
For data expressed in SI units, a comma is used as the decimal separator and a space is used as the
thousands separator. For data expressed in USC units, a dot (on the line) is used as the decimal separator
and a space is used as the thousands separator.
5.2 Rounding
Unless otherwise stated in this document, to determine conformance with the specified requirements,
observed or calculated values shall be rounded to the nearest unit in the last right-hand place of figures
used in expressing the limiting value, in accordance with ISO 80000-1:2009, Annex B, Rule A.
[3]
NOTE For the purposes of this provision, the rounding method of ASTM E29-04 is equivalent to
ISO 80000-1:2009, Annex B, Rule A.
5.3 Conformity to this document
A contract may specify that the manufacturer shall be responsible for conforming with all the applicable
requirements of this document. It shall be permissible for the purchaser to make any investigation
6 © ISO 2019 – All rights reserved

necessary to be assured of conformity by the manufacturer and to reject any material that does not
conform.
6 Designation of cold bends
Designation of cold bends according to this document, i.e. ISO 15590-4, shall take one of the
following forms:
ISO 15590-4-CB xxx-PSL 1;
ISO 15590-4-CB xxx-PSL 2;
ISO 15590-4-CB xxx-PSL 2S;
ISO 15590-4-CB xxx-PSL 2O;
ISO 15590-4-CB xxx-PSL 2SO
In this designation, the elements have the following meaning:
xxx: specified minimum yield strength, expressed in mega pascals (MPa);
PSL 1 or PSL 2: identifier for the technical delivery conditions class for cold bends in non-sour
service;
PSL 2S: identifier for PSL 2 bends for use in sour service conditions;
PSL 2O: identifier for PSL 2 bends for use in offshore service conditions;
PSL 2SO: Identifier for PSL 2 bends for use in both offshore and sour service conditions.
7 Pressure rating and design
The hoop stress in the cold bend due to internal fluid pressure shall not exceed the hoop stress
permitted in ISO 13623, or other applicable design code, for straight pipe in the location of the bend.
NOTE The purchaser normally performs the pressure design and specifies the minimum wall thickness, t .
min
The wall thickness of the bend extrados shall be at least t .
min
The wall thickness at the bend intrados shall be at least as given in Formula (1):
2rr−
bp
tt=× (1)
i min
2 rr−
()
bp
For pipelines not designed in accordance with ISO 13623, the minimum required wall thickness of the
bend extrados can be less than t .
min
The requirements in this clause address the design of a bend against internal pressure. It is necessary
that the purchaser or designer also consider other loads, both static and dynamic, and pipeline test
conditions to demonstrate conformity with the strength requirements of ISO 13623.
8 Information provided by the purchaser
8.1 General information
The purchaser shall provide the following information:
a) number of this document and year of publication (i.e. ISO 15590-4:2019);
b) bend designation of each bend;
c) quantity of bends;
d) supply of mother pipe by the purchaser or the manufacturer;
e) required bend dimensions, including:
— diameter (inside or outside),
— minimum intrados and extrados wall thickness after cold bending,
— bend radius,
— bend angle and
— tangent lengths.
f) end preparation, if different from square ends;
g) equipment and method used for cold bend.
8.2 Additional information
The purchaser should specify the following additional information:
a) minimum design temperature;
b) maximum design temperature (and any requirement for high-temperature tensile testing);
c) maximum wall thickness;
d) special dimensional requirements;
e) requirements for supplementary inspection and testing;
f) requirements for gauging and other measurements of dimensions, if different from this document,
i.e. 15590-4;
g) pipeline design standard or design factors, if different from ISO 13623;
h) pipeline operating conditions;
i) mechanical-property requirements at the maximum design temperature;
j) Charpy impact test temperature;
k) requirements for proof, burst or hydrostatic testing;
l) hold-points for witness and approval by purchaser;
m) surface condition;
n) coating or painting requirements;
o) marking requirements, if different from this document, i.e. 15590-4;
p) requirements for ends or bevel protection (e.g. end caps or bevel protectors);
q) packaging and shipping instructions;
r) third-party inspection organization;
s) inspection document required in accordance with ISO 10474;
8 © ISO 2019 – All rights reserved

t) requirements for format and additional content of the inspection document;
u) additional requirements for hardness testing;
v) other special requirements.
8.3 Information on the mother pipe
The following information on the mother pipe shall be provided to the manufacturer:
a) purchasing specification;
b) pipe diameter, inside or outside;
c) pipe wall thickness, nominal or minimum;
d) pipe lengths;
e) pipe manufacturer;
f) pipe material specification and pipe material certificates, including chemical composition, heat
treatment, mechanical properties, dimensions and results of NDT;
g) welding procedure specification for SAWL and SAWH pipe;
h) weld-seam-repair welding-procedure specification for SAWL and SAWH pipe;
i) applicability of Annex B for sour service.
Information f), g) and h) is necessary for the design of the bending procedure by the manufacturer.
9 Manufacturing
9.1 Mother pipe
Mother pipe shall be manufactured in accordance with ISO 3183.
Mother pipe for the manufacture of PSL 2 bends shall be in accordance with ISO 3183 PSL 2.
Mother pipe for the manufacture of PSL 2S bends shall be made in accordance with ISO 3183:2012,
Annex H, with the additional requirements specified in Annex B of this document.
Mother pipe for the manufacture of PSL 2O bends shall be made in accordance with ISO 3183:2012,
Annex J.
Mother pipe for the manufacture of PSL 2SO bends shall be made in accordance with ISO 3183:2012,
Annex H; ISO 3183:2012, Annex J; and the additional requirements specified in Annex B of this
document.
The mother pipe may be supplied by either the purchaser or the manufacturer.
If the mother pipe is supplied by the purchaser, the manufacturer should be consulted on the required
properties and dimensions of the mother pipe (including seam weld and seam repair weld) regarding
its suitability for cold bending.
The body of the mother pipe shall have no weld repairs.
The wall thickness of the mother pipe shall have adequate allowance for wall thinning at the extrados
due to cold bending.
9.2 Qualification test bend
The manufacture of all PSL-level test bends shall be carried out in accordance with an MPS that shall
conform to Clause 9 before commencement of production, or at the beginning of production, if agreed.
NOTE Annex A gives details on MPS.
A test bend with at least sufficient arc length to conform to Table 1 shall be manufactured in accordance
with each preliminary MPS. The inspection and testing of the test bend shall include sufficient tangents,
if included in the produced bends.
The test bend shall be tested and inspected in accordance with Clause 10. The MPS used for production
shall, for each of the essential variables in Table 1, specify
— the values recorded during the manufacturing of the test bend, and
— the permissible range during production bending.
The variation in essential variables shall not exceed the permissible limits given in Table 1.
9.3 Production cold bending
Cold bending shall be carried out in accordance with an MPS as specified in Annex A.
9.4 Post-bending heat treatment
Post-bending heat treatment may be performed to achieve the required material properties, improve
corrosion resistance or to relieve residual stresses due to cold bending process.
The temperature of each furnace-load of bends shall be monitored by thermocouples connected
directly to selected bends and shall be recorded. The type and location of the thermocouples shall be as
specified in the MPS or in the dedicated drawings issued for heat treatment loading.
Heat treatment of stress relieving after cold bending is required for up to a 10D radius, irrespectively of
the service.
Heat treatment of stress relieving after cold bending is required for any radius for sour or offshore
service.
The heat treatment of stress relieving will be carried out between 480 °C and 675 °C, with holding time
30 minutes for 25,4 mm (1 in); but never less than 30 minutes and cooling in the furnace or in still air.
The maximum cooling rate shall be 200 °C/h.
Due to the inherent characteristics of the TMCP method, plates manufactured to this specification
cannot be formed or post-weld heat treated at a temperature above 595 °C, without some risk of
sustaining irreversible and significant losses in strength and toughness.
9.5 Forming and sizing after bending
Sizing without subsequent heat treatment is permitted for ovality and diameter corrections in the
tangents provided the induced permanent strain does not exceed 1,5 %.
Table 1 — Essential variables and maximum permissible variations
a
Essential variable Maximum permissible variations
Pipe grade None
Pipe manufacturer None
a
The permissible variations apply to the values obtained in the approved to BQT.
b
The pipe long seam shall be placed on the neutral axis during bending. It does not apply to SAWH pipes.
10 © ISO 2019 – All rights reserved

Table 1 (continued)
a
Essential variable Maximum permissible variations
Mother pipe seam weld WPS and welding consumables None
Cold bending machine tools None
Mother pipe process of manufacture None
Cold bending machine None
Nominal mother pipe diameter None
Nominal mother pipe wall thickness ±3 mm (0.118 in) or ±10 % whichever is the smallest
Bend radius An approved MPS qualifies all larger radii (but not
smaller) in the following ranges:
a) 5D up to and including 7D
b) >7D up
b
Longitudinal weld seam location ±15° from the location in the test bend
Post-bending heat treatment Method: no change
Soaking time: +15
min
Soaking temperature: ±15 °C (±27 °F)
Heating and cooling rates by agreement
a
The permissible variations apply to the values obtained in the approved to BQT.
b
The pipe long seam shall be placed on the neutral axis during bending. It does not apply to SAWH pipes.
9.6 Strip/plate end welds
Cold bends shall not contain coil-strip end welds or plate end welds.
9.7 Jointers and girth welds
Whenever possible, the girth weld should be at least 1 m far from the bend section. When girth welds are
within 1 m from the bend area or in the bend section, it shall be subjected to radiography examination
after bending.
9.8 End preparation
Cold bends shall be supplied with square ends unless otherwise specified by the purchaser.
10 Testing and inspection
10.1 General requirements
An MPS shall be approved or production bends accepted only after all testing and inspection required
in Clause 10 have been performed and all results meet the specified requirements.
Except where otherwise stated in Clause 10, the testing and inspection methods and acceptance criteria
for cold bend shall be as required by ISO 3183 for pipe of the same steel grade and type.
The upper limit of yield stress for offshore service pipe (PSL 2) may be increased by agreement.
Testing and inspection shall be carried out on cold bends after final heat treatment of stress relieving,
when applicable.
Test results already available for the mother pipe may be used in place of testing and inspections where
indicated in Table 2.
If the pipeline installation techniques require post-weld heat treatment of the bend, the purchaser may
require additional testing to demonstrate that the mechanical properties of the bend are also achieved
after post-weld heat treatment. The purchaser shall specify the details of the post-weld heat treatment
cycle that shall be used during the pipeline installation. The test requirements and acceptance criteria
shall be by agreement.
10.2 Extent of testing and inspection
10.2.1 Qualification test bend
The extent of testing and inspection that shall be performed on each test bend is as specified in Table 2
for each bend product specification level.
The location and type of tests shall be as specified in Table 3, with the locations for the extraction of
samples as shown in Figure 1.
For SAWH pipe, the inspection and testing requirements shall be by agreement.
If a mechanical test specimen of a qualification test bend fails to conform to the requirements in this
document and provided that R and R are not less than 95 % of the specified minimum values,
t0,5 m
then two additional specimens from the same test bend may be tested, if agreed. The specimen shall
be taken in the same manner as the failed specimen and from the area adjacent to the area from the
failed specimens. The test requirements shall be considered to be met only if both retested specimens
conform to the specified requirements.
10.2.2 Production bends
The extent of testing and inspection that shall be performed during production is as specified in Table 2
for each bend product specification level.
10.2.3 Production test bends
For large bend quantities, the production-test bend frequency, extent of destructive testing and
retesting shall be by agreement.
10.3 Chemical composition
The chemical composition of each bend shall conform with the requirements for pipe of the same grade
and type as specified in ISO 3183.
10.4 Physical testing
10.4.1 General
Test pieces shall be prepared in accordance with ISO 3183.
If thermal cutting has been used to remove samples, the full extent of the heat-affected region shall be
removed during the preparation of the test pieces.
10.4.2 Tensile testing
10.4.2.1 Test pieces
Test specimens shall be taken from cold bend in final condition, after heat treatment of stress relieving
(if any) and NDT testing. Test specimens shall be in accordance with ASTM A370 or ISO 6892-1, using
rectangular full-size specimens or the largest sub-size specimens allowed. Flattening of test pieces
shall be carried out according to ISO 3183:2012, 10.2.3.2.
12 © ISO 2019 – All rights reserved

Table 2 — Summary of testing and inspection requirements
Test PSL 1 PSL 2 Acceptance
c c
Physical tests Tensile T T In accordance with
ISO 3183
and with 10.4.2.1 and
10.4.2.2
Impact N T In accordance with
ISO 3183
Through-thickness hardness O T In accordance with 10.4.4.2
Surface hardness T and P T and P In accordance with 10.4.5.2
Metallography T T In accordance with 10.4.6.2
a
HIC N T In accordance with B.4.2
ab
SSC N T In accordance with B.4.3
CTOD N O By agreement
e e
Guided bend (weld seam) In accordance with
ISO 3183
e e
Flattening In accordance with
ISO 3183
NDT Visual inspection T and P T and P In accordance with
ISO 3183 and 10.5.1
d e
Weld seam (UT or RT) T and P In accordance with 10.5.2
or B.7.3
d
Bend ends (laminations) P P In accordance with 10.5.3
or B.7.1
d
Bend body (MT or PT) T and P T and P In accordance with 10.5.4
Bend body (UT) transverse N T and P In accordance with 10.5.5
d
defects or B.7.2
e e
Bend body (UT) laminations N In accordance with 10.5.5
or B.7.2
Residual magnetism ends P P In accordance with 10.5.6
Repairs P P In accordance with
ISO 3183 and 10.5.7
Dimensions Wall thickness T and P T and P In accordance with 10.6
D bend body P P In accordance with 10.6
D at ends P P In accordance with 10.6
Out-of-roundness ends T and P T and P In accordance with 10.6
Out-of-roundness body T and P T and P In accordance with 10.6
Linear dimensions P P In accordance with 10.6
Angle P P In accordance with 10.6
Radius T and P T and P In accordance with 10.6
End squareness P P In accordance with 10.6
Out of plane P P In accordance with 10.6
End preparation By agreement By agreement
Gauging By agreement In accordance with 10.7
Hydrostatic test By agreement I
...