ISO 15156-3:2015

Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production - Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys

ISO 15156-3:2015 gives requirements and recommendations for the selection and qualification of CRAs (corrosion-resistant alloys) and other alloys for service in equipment used in oil and natural gas production and natural gas treatment plants in H2S-containing environments whose failure can pose a risk to the health and safety of the public and personnel or to the environment. It can be applied to help avoid costly corrosion damage to the equipment itself. It supplements, but does not replace, the materials requirements of the appropriate design codes, standards, or regulations. ISO 15156-3:2015 addresses the resistance of these materials to damage that can be caused by sulfide stress-cracking (SSC), stress-corrosion cracking (SCC), and galvanically induced hydrogen stress cracking (GHSC). ISO 15156-3:2015 is concerned only with cracking. Loss of material by general (mass loss) or localized corrosion is not addressed. Table 1 provides a non-exhaustive list of equipment to which this part of ISO 15156 is applicable, including permitted exclusions. ISO 15156-3:2015 applies to the qualification and selection of materials for equipment designed and constructed using load controlled design methods. For design utilizing strain-based design methods, see ISO 15156‑1:2015, Clause 5. ISO 15156-3:2015 is not necessarily suitable for application to equipment used in refining or downstream processes and equipment.

Industries du pétrole et du gaz naturel — Matériaux pour utilisation dans des environnements contenant de l'hydrogène sulfuré (H2S) dans la production de pétrole et de gaz — Partie 3: ARC (alliages résistants à la corrosion) et autres alliages résistants à la fissuration

General Information

• Status: Withdrawn
• Publication Date: 19-Aug-2015
• Withdrawal Date: 19-Aug-2015
• ICS: 75.180.01 - Equipment for petroleum and natural gas industries in general
• Technical Committee: ISO/TC 67 - Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries
• Drafting Committee: ISO/TC 67/WG 7 - Corrosion resistant materials
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 17-Nov-2020
• Completion Date: 13-Dec-2025

Relations

• Consolidated By: ISO 9863-1:2016/Amd 1:2019 - Geosynthetics - Determination of thickness at specified pressures - Part 1: Single layers - Amendment 1
• Effective Date: 06-Jun-2022
• Revised: ISO 15156-3:2020 - Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production - Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys
• Effective Date: 23-Apr-2020
• Revises: ISO 15156-3:2009 - Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production - Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys
• Effective Date: 24-May-2014

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15156-3
Third edition
2015-09-01
Petroleum and natural gas
industries — Materials for use in H2S-
containing environments in oil and
gas production —
Part 3:
Cracking-resistant CRAs (corrosion-
resistant alloys) and other alloys
Industries du pétrole et du gaz naturel — Matériaux pour utilisation
dans des environnements contenant de l’hydrogène sulfuré (H2S)
dans la production de pétrole et de gaz —
Partie 3: ARC (alliages résistants à la corrosion) et autres alliages
résistants à la fissuration
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
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Tel. [phone]
Fax [phone]
[e-mail]
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 3
4 Symbols and abbreviated terms . 4
5 Factors affecting the cracking-resistance of CRAs and other alloys in H S-
containing environments . 5
6 Qualification and selection of CRAs and other alloys with respect to SSC, SCC, and
GHSC in H S-containing environments. 5
6.1 General . 5
6.2 Evaluation of materials properties . 6
6.2.1 Hardness of parent metals . 6
6.2.2 Cracking-resistance properties of welds. 6
6.2.3 Cracking-resistance properties associated with other fabrication methods . 8
6.3 PREN . 8
7 Purchasing information and marking . 8
7.1 Information that should be supplied for material purchasing . 8
7.2 Marking, labelling, and documentation . 9
Annex A (normative) Environmental cracking-resistant CRAs and other alloys (including
Table A.1 — Guidance on the use of the materials selection tables) .10
Annex B (normative) Qualification of CRAs for H S-service by laboratory testing .56
Annex C (informative) Information that should be supplied for material purchasing .66
Annex D (informative) Materials chemical compositions and other information .68
Annex E (informative) Nominated sets of test conditions .84
Bibliography .85
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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries.
This third edition cancels and replaces the second edition (ISO 15156-3:2009), which has been
technically revised with the following changes:
— replacement in the Scope of the term “conventional elastic design criteria” by the term “load
controlled design methods”;
— refinements to 6.3 to require the use of absolute values when F is calculated for use in this part
PREN
of ISO 15156;
— acceptance of the environmental limits for low carbon 300 series stainless steels also for their dual
certified grades;
— changes to some of the tables of Annex A to more conservatively reflect the current knowledge of
the limits of use of some materials;
— changes to the definition of acceptable limits to in situ production environment pH in some
tables of Annex A;
— additions to a number of tables of Annex A of new sets of acceptable environmental limits for (new)
materials and their associated metallurgical requirements.
ISO 15156 consists of the following parts, under the general title Petroleum and natural gas industries —
Materials for use in H2S-containing environments in oil and gas production:
— Part 1: General principles for selection of cracking-resistant materials
— Part 2: Cracking-resistant carbon and low-alloy steels, and the use of cast irons
— Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys
iv © ISO 2015 – All rights reserved

Introduction
The consequences of sudden failures of metallic oil and gas field components associated with their
exposure to H S-containing production fluids led to the preparation of the first edition of NACE MR0175
which was published in 1975 by the National Association of Corrosion Engineers, now known as NACE
International.
The original and subsequent editions of NACE MR0175 established limits of H S partial pressure above
which precautions against sulfide stress-cracking (SSC) were always considered necessary. They
also provided guidance for the selection and specification of SSC-resistant materials when the H S
thresholds were exceeded. In more recent editions, NACE MR0175 has also provided application limits
for some corrosion-resistant alloys in terms of environmental composition and pH, temperature, and
H S partial pressures.
In separate developments, the European Federation of Corrosion issued EFC Publication 16 in 1995 and
EFC Publication 17 in 1996. These documents are generally complementary to those of NACE, though
they differed in scope and detail.
In 2003, the publication of the ISO 15156-series and NACE MR0175/ISO 15156 was completed for the
first time. These technically identical documents utilized the above sources to provide requirements
and recommendations for materials qualification and selection for application in environments
containing wet H S in oil and gas production systems. They are complemented by NACE TM0177 and
NACE TM0284 test methods.
The revision of this part of ISO 15156 involves a consolidation of all changes agreed and
published in the Technical Circular 1, ISO 15156-3:2009/Cir.1:2011(E), Technical Circular 2,
ISO 15156-3:2009/Cir.2:2013(E), Technical Circular 3, ISO 15156-3:2009/Cir.3:2014(E), and Technical
Circular 4, ISO 15156-3:2009/Cir.4:2014(E), published by the ISO 15156 Maintenance Agency secretariat
at DIN, Berlin.
The changes were developed by and approved by the ballot of representative groups from within the oil
and gas production industry. The great majority of these changes stem from issues raised by document
users. A description of the process by which these changes were approved can be found at the ISO 15156
maintenance website: www.iso.org/iso15156maintenance.
Technical Circular ISO 15156-3:2009/Cir.2:2013 and Technical Circular
ISO 15156-3:2009/Cir.3:2014 intend that an informative Annex F should be published for this part of
ISO 15156 that was to give an alternative presentation of the information contained in the materials
selection tables of Annex A.
During final editing of this part of ISO 15156, a number of technical errors were found in the transfer of
information between the materials selection tables of Annex A and Table F.1. In order not to delay the
publication of the new edition of this part of ISO 15156, the ISO 15156 Maintenance Agency agreed that
the proposed Annex F should not be published at this time.
When found necessary by oil and gas production industry experts, future interim changes to this part of
ISO 15156 will be processed in the same way and will lead to interim updates to this part of ISO 15156
in the form of Technical Corrigenda or Technical Circulars. Document users should be aware that such
documents can exist and can impact the validity of the dated references in this part of ISO 15156.
The ISO 15156 Maintenance Agency at DIN was set up after approval by the ISO Technical Management
Board given in document 34/2007. This document describes the make up of the agency which includes
experts from NACE, EFC and ISO/TC 67, and the process for approval of amendments. It is available from
the ISO 15156 maintenance website and from the ISO/TC 67 Secretariat. The website also provides
access to related documents that provide more detail of ISO 15156 maintenance activities.
INTERNATIONAL STANDARD ISO 15156-3:2015(E)
Petroleum and natural gas industries — Materials for use in
H2S-containing environments in oil and gas production —
Part 3:
Cracking-resistant CRAs (corrosion-resistant alloys) and
other alloys
WARNING — CRAs (corrosion-resistant alloys) and other alloys selected using this part of ISO 15156
are resistant to cracking in defined HS-containing environments in oil and gas production,
but not necessarily immune to cracking under all service conditions. It is the equipment user’s
responsibility to select the CRAs and other alloys suitable for the intended service.
1 Scope
This part of ISO 15156 gives requirements and recommendations for the selection and qualification of
CRAs (corrosion-resistant alloys) and other alloys for service in equipment used in oil and natural gas
production and natural gas treatment plants in H S-containing environments whose failure can pose
a risk to the health and safety of the public and personnel or to the environment. It can be applied to
help avoid costly corrosion damage to the equipment itself. It supplements, but does not replace, the
materials requirements of the appropriate design codes, standards, or regulations.
This part of ISO 15156 addresses the resistance of these materials to damage that can be caused by
sulfide stress-cracking (SSC), stress-corrosion cracking (SCC), and galvanically induced hydrogen
stress cracking (GHSC).
This part of ISO 15156 is concerned only with cracking. Loss of material by general (mass loss) or
localized corrosion is not addressed.
Table 1 provides a non-exhaustive list of equipment to which this part of ISO 15156 is applicable,
including permitted exclusions.
This part of ISO 15156 applies to the qualification and selection of materials for equipment designed and
constructed using load controlled design methods. For design utilizing strain-based design methods,
see ISO 15156-1:2015, Clause 5.
This part of ISO 15156 is not necessarily suitable for application to equipment used in refining or
downstream processes and equipment.
Table 1 — List of equipment
ISO 15156 is applicable to materials used for the Permitted exclusions
following equipment
Drilling, well construction, and well-servicing Equipment exposed only to drilling fluids of controlled
a
equipment composition
Drill bits
b
Blowout-preventer (BOP) shear blades
Drilling riser systems
Work strings
c
Wireline and wireline equipment
Surface and intermediate casing
d
Wells including subsurface equipment, gas lift Sucker rod pumps and sucker rods
equipment, wellheads, and christmas trees
Electric submersible pumps
Other artificial lift equipment
Slips
Flow-lines, gathering lines, field facilities, and field Crude oil storage and handling facilities operating at
processing plants a total absolute pressure below 0,45 MPa (65 psi)
Water-handling equipment Water-handling facilities operating at a total absolute
pressure below 0,45 MPa (65 psi)
Water injection and water disposal equipment
Natural gas treatment plants —
Transportation pipelines for liquids, gases, and Lines handling gas prepared for general commercial
multi-phase fluids and domestic use
For all equipment above Components loaded only in compression
a
See ISO 15156-2:2015, A.2.3.2.3 for more information.
b
See ISO 15156-2:2015, A.2.3.2.1 for more information.
c
Wireline lubricators and lubricator connecting devices are not permitted exclusions.
d
For sucker rod pumps and sucker rods, reference can be made to NACE MR0176.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 7539-7, Corrosion of metals and alloys — Stress corrosion testing — Part 7: Method for slow strain rate
testing
ISO 10423, Petroleum and natural gas industries — Drilling and production equipment — Wellhead and
christmas tree equipment
ISO 11960, Petroleum and natural gas industries — Steel pipes for use as casing or tubing for wells
ISO 15156-1:2015, Petroleum and natural gas industries — Materials for use in H2S-containing environments
in oil and gas production — Part 1: General principles for selection of cracking-resistant materials
2 © ISO 2015 – All rights reserved

ISO 15156-2:2015, Petroleum and natural gas industries — Materials for use in H2S-containing
environments in oil and gas production — Part 2: Cracking-resistant carbon and low alloy steels, and the
use of cast irons
1)
ASTM A747/A747M , Standard Specification for Steel Castings, Stainless, Precipitation Hardening
ASTM E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with
Specifications
ASTM E562, Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count
2)
EFC Publications Number 17 , Corrosion resistant alloys for oil and gas production: guidelines on general
requirements and test methods for H2S service
3)
NACE CORROSION/95 , Paper 47, Test methodology for elemental sulfur-resistant advanced materials for
oil and gas field equipment
NACE CORROSION/97 Paper 58, Rippled strain rate test for CRA sour service materials selection
NACE TM0177, Laboratory testing of metals for resistance to sulfide stress cracking and stress corrosion
cracking in H2S environments
NACE TM0198, Slow strain rate test method for screening corrosion resistant alloys (CRAs) for stress
corrosion cracking in sour oilfield service
SAE AMS-2430, Shot Peening, Automatic
4)
SAE — ASTM, Metals and alloys in the Unified Numbering System, ISBN 0-7680-04074
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15156-1, ISO 15156-2, and the
following apply.
3.1
ageing
change in metallurgical properties that generally occurs slowly at room temperature (natural ageing)
and more rapidly at higher temperature (artificial ageing)
3.2
anneal
heat to and hold at a temperature appropriate for the specific material and then cool at a suitable rate
for such purposes as reducing hardness, improving machineability, or obtaining desired properties
3.3
austenite
face-centred cubic crystalline phase of iron-based alloys
3.4
duplex stainless steel
austenitic/ferritic stainless steel
stainless steel (3.13) whose microstructure at room temperature consists primarily of a mixture of
austenite (3.3) and ferrite (3.5)
1) ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, USA.
2) European Federation for Corrosion, available from The Institute of Materials, 1 Carlton House Terrace, London
SW1Y 5DB, UK [ISBN 0-901716-95-2].
3) NACE International, P.O. Box 2183140, Houston, TX 77218-8340, USA.
4) Society of Automotive Engineers (SAE), 400 Commonwealth Drive, Warrendale, PA 15096-0001, USA.
3.5
ferrite
body-centred cubic crystalline phase of iron-based alloys
3.6
ferritic stainless steel
stainless steel (3.13) whose microstructure at room temperature consists predominantly of ferrite (3.5)
3.7
galvanically induced hydrogen stress cracking
GHSC
cracking that results due to the presence of hydrogen in a metal induced in the cathode of a galvanic
couple and tensile stress (residual and/or applied)
3.8
martensite
hard, supersaturated solid solution of carbon in iron characterized by an acicular (needle-like)
microstructure
3.9
martensitic steel
steel in which a microstructure of martensite (3.8) can be attained by quenching at a cooling rate fast
enough to avoid the formation of other microstructures
3.10
pitting-resistance equivalent number
PREN
F
PREN
number developed to reflect and predict the pitting resistance of a CRA based upon the proportions of
the elements Cr, Mo, W, and N in the chemical composition of the alloy
Note 1 to entry: See 6.3 for further information.
3.11
production environment
natural occurring produced fluids without contamination from chemicals that will temporarily or
continuously reduce the in situ pH
Note 1 to entry: Flow back of chemicals for stimulation and scale removal may temporarily reduce the pH
significantly and some continuously injected chemicals, such as scale inhibitors, can continuously reduce pH.
3.12
solid solution
single crystalline phase containing two or more elements
3.13
stainless steel
steel containing 10,5 % mass fraction or more chromium, possibly with other elements added to secure
special properties
4 Symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms shown in ISO 15156-1 and
ISO 15156-2 apply, some of which are repeated for the purpose of convenience, together with the following:
AYS actual yield strength
CR c-ring
CRA corrosion-resistant alloy
4 © ISO 2015 – All rights reserved

HBW Brinell hardness
HRB Rockwell hardness (scale B)
HRC Rockwell hardness (scale C)
pCO partial pressure of CO
2 2
pH S partial pressure of H S
2 2
PWHT post-weld heat treatment
S elemental sulfur
RSRT rippled strain rate test
SSRT slow strain rate test
UNS unified (alloy) numbering system
5 Factors affecting the cracking-resistance of CRAs and other alloys in H S-
containing environments
The cracking behaviour of CRAs and other alloys in H S-containing environments can be affected by
complex interactions of parameters including the following:
— chemical composition, strength, heat treatment, microstructure, method of manufacture, and
finished condition of the material;
— H S partial pressure or equivalent dissolved concentration in the water phase;
— acidity (in situ pH) of the water phase;
— chloride or other halide ion concentration;
— presence of oxygen, sulfur, or other oxidants;
— exposure temperature;
— pitting resistance of the material in the service environment;
— galvanic effects;
— total tensile stress (applied plus residual);
— exposure time.
These factors shall be considered when using this part of ISO 15156 for the selection of materials
suitable for environments containing H S in oil and gas production systems.
6 Qualification and selection of CRAs and other alloys with respect to SSC, SCC,
and GHSC in H S-containing environments
6.1 General
CRAs and other alloys shall be selected for their resistance to SSC, SCC, and/or GHSC as required by the
intended service.
Compliance of a CRA or other alloy with this part of ISO 15156 implies cracking-resistance within defined
environmental service limits. These limits are dependent on the material type or the individual alloy.
To enable qualification and/or selection of CRAs and other alloys, the equipment purchaser can be
required to provide information on the proposed conditions of exposure to the equipment supplier.
In defining the severity of H S-containing environments, exposures that can occur during system
upsets or shutdowns, etc. shall also be considered. Such exposures can include unbuffered, low pH
condensed water. The limits given in the tables in Annex A are for production environments and do not
cover conditions occurring during injection or flowback of chemicals that can reduce the in situ pH.
CRAs and other alloys shall be selected using Annex A or following qualification by successful
laboratory testing in accordance with Annex B. Qualification based on satisfactory field experience is
also acceptable. Such qualification shall comply with ISO 15156-1.
In Annex A, materials are identified by materials groups. Within each group, alloys are identified by
materials type (within compositional limits) or as individual alloys. Acceptable metallurgical conditions
and environmental limits are given for which alloys are expected to resist cracking. Environmental
limits are given for H S partial pressure, temperature, chloride concentration, and elemental sulfur.
A CRA or other alloy can be qualified by testing for use under operating conditions that are more
severe than the environmental limits given in Annex A. Similarly, a CRA or other alloy can be qualified
for use in different metallurgical conditions (higher strength, alternative heat treatment, etc.) to those
given in Annex A.
The documentation of qualifications performed in accordance with Annex B shall meet the requirements
in ISO 15156-1:2015, Clause 9.
The equipment user shall verify qualifications (see B.2.2) and retain documentation supporting the
materials selections made.
6.2 Evaluation of materials properties
6.2.1 Hardness of parent metals
If hardness measurements on parent metal are specified, sufficient hardness tests shall be made
to establish the actual hardness of the CRA or other alloy being examined. Individual HRC readings
exceeding the value permitted by this part of ISO 15156 may be considered acceptable if the average
of several readings taken within close proximity does not exceed the value permitted by this part
of ISO 15156 and no individual reading is greater than 2 HRC above the specified value. Equivalent
requirements shall apply to other methods of hardness measurement when specified in this part of
ISO 15156 or referenced in a manufacturing specification.
The conversion of hardness readings to or from other scales is material-dependent. The user may
establish the required conversion tables.
NOTE The number and location of hardness tests on parent metal are not specified in ISO 15156 (all parts).
6.2.2 Cracking-resistance properties of welds
6.2.2.1 General
The metallurgical changes that occur when welding CRAs and other alloys can affect their susceptibility
to SSC, SCC, and/or GHSC. Welded joints can have a greater susceptibility to cracking than the parent
material(s) joined.
The equipment user may allow the cracking susceptibility of weldments to govern the limits of safe
service conditions for a fabricated system.
Processes and consumables used in welding should be selected in accordance with good practice and to
achieve the required corrosion and cracking resistances.
6 © ISO 2015 – All rights reserved

Welding shall be carried out in compliance with appropriate codes and standards as agreed between
the supplier and the purchaser. Welding procedure specifications (WPSs) and procedure qualification
records (PQRs) shall be available for inspection by the equipment user.
Welding PQRs shall include documented evidence demonstrating satisfactory cracking resistance
under conditions at least as severe as those of the proposed application. Such evidence shall be based
upon one or more of the following:
— compliance with the requirements and recommendations for the specific materials group of Annex A
(see also 6.2.2.2 and 6.2.2.3);
— weld cracking-resistance qualification testing in accordance with Annex B;
— documented field experience modelled upon that specified for parent materials in ISO 15156-1.
The requirements and recommendations given in Annex A might not be appropriate for all combinations
of parent and weld metals used in the fabrication of equipment and components. The equipment user
may require evidence of successful cracking-resistance testing as part of the welding procedure
qualification to ensure the weldment produced provides adequate resistance to SSC, SCC, and GHSC for
the application.
6.2.2.2 Qualification of welding procedures in accordance with Annex A based upon hardness
6.2.2.2.1 General
The qualification of welding procedures for sour service shall, if specified in Annex A, include hardness
testing in accordance with 6.2.2.2.2, 6.2.2.2.3 and 6.2.2.2.4.
6.2.2.2.2 Hardness testing methods for welding procedure qualification
Hardness testing for welding procedure qualification shall be carried out using Vickers HV 10 or HV 5
methods in accordance with ISO 6507-1 or the Rockwell 15N method in accordance with ISO 6508-1.
NOTE For the purposes of this part of ISO 15156, ASTM E384 is equivalent to ISO 6507-1 and ASTM E18 is
equivalent to ISO 6508-1.
The use of other methods shall require explicit user approval.
6.2.2.2.3 Hardness surveys for welding procedure qualification
Hardness surveys for butt welds, fillet welds, repair, and partial penetration welds and overlay welds
shall be carried out as described in ISO 15156-2:2015, 7.3.3.3.
6.2.2.2.4 Hardness acceptance criteria for welds
Weld hardness acceptance criteria for CRAs or other alloys given in Annex A shall apply to alloys
selected using Annex A.
Hardness acceptance criteria can also be established from successful cracking-resistance testing of
welded samples. Testing shall be in accordance with Annex B.
6.2.2.3 Qualification of welding procedures in accordance with Annex A by other means of testing
Where appropriate, requirements and recommendations to ensure adequate cracking-resistance of
welds using other means of testing are provided in the materials groups of Annex A.
6.2.3 Cracking-resistance properties associated with other fabrication methods
For CRAs and other alloys that are subject to metallurgical changes caused by fabrication methods
other than welding, cracking-resistance qualification testing of the material affected by fabrication
shall be specified as part of the qualification of the fabrication process.
Qualification testing shall be specified as part of the qualification of burning and cutting processes if
any HAZ remains in the final product.
The requirements and acceptance criteria of 6.2.2 shall apply to the qualification testing of both
fabrication methods and burning/cutting processes subject to the suitable interpretation of the
hardness survey requirements of 6.2.2.2.3 for the fabrication method or burning/cutting process.
The form and location of the samples used for evaluation and testing shall be acceptable to the
equipment user.
6.3 PREN
For the purpose of determining conformance with the requirements of this part of ISO 15156, all F
PREN
limits specified in this part of ISO 15156 shall be considered absolute limits as defined in ASTM Practice
E29. With the absolute method, an observed value or a calculated value is not to be rounded, but is
to be compared directly with the specified limiting value. Conformance or non-conformance with the
specification is based on this comparison.
The F calculation is based on actual composition, not nominal composition. Nominal composition
PREN
is used for general classification only.
The PREN (F ) shall be calculated as given in Formula (1):
PREN
Fw=+33,,ww+05 +16w (1)
()
PREN Cr Mo WN
where
w is the mass fraction of chromium in the alloy, expressed as a percentage mass fraction of
Cr
the total composition;
w is the mass fraction of molybdenum in the alloy, expressed as a percentage mass fraction
Mo
of the total composition;
w is the mass fraction of tungsten in the alloy, expressed as a percentage mass fraction of the
W
total composition;
w is the mass fraction of nitrogen in the alloy, expressed as a percentage mass fraction of the
N
total composition.
NOTE There are several variations of the PREN. All were developed to reflect and predict the pitting
resistance of Fe/Ni/Cr/Mo CRAs in the presence of dissolved chlorides and oxygen, e.g. in sea water. Though
useful, these indices are not directly indicative of corrosion resistance in H S-containing oil field environments.
7 Purchasing information and marking
7.1 Information that should be supplied for material purchasing
7.1.1 The preparation of material purchasing specifications can require cooperation and exchange of
data between the equipment user, the equipment supplier, and the material manufacturer to ensure that
the material purchased complies with ISO 15156-1 and this part of ISO 15156.
7.1.2 The following information shall be provided:
8 © ISO 2015 – All rights reserved

— preferred materials types and/or grades (if known);
— equipment type (if known);
— reference to this part of ISO 15156;
— acceptable bases for selection of materials for cracking-resistance (see Clause 6).
7.1.3 The equipment user and the equipment supplier/material manufacturer may agree that CRAs
and other alloys other than those described and or listed in Annex A may be selected subject to suitable
qualification testing.
If the purchaser intends to make use of such agreements, extensions, and qualifications, the appropriate
additional information shall be clearly indicated in the materials purchasing specification. This
information includes the following:
— requirements for SSC, SCC, and/or GHSC testing (see Clause 6 and Annex B);
— service conditions for the specific sour service application.
7.1.4 The information required for material purchasing shall be entered on suitable data sheets.
Suggested formats are given in Annex C.
7.2 Marking, labelling, and documentation
Materials complying with this part of ISO 15156 shall be made traceable, preferably by marking, before
delivery. Suitable labelling or documentation is also acceptable.
For materials qualified and selected for a special application in accordance with Annex B, traceability
shall include reference to the environmental conditions of the special application.
The equipment user may request the equipment or materials supplier to provide documentation of the
materials used in equipment or components and their environmental service limits as defined in this
part of ISO 15156.
The tables in Annex C provide designations that can be used.
Annex A
(normative)
Environmental cracking-resistant CRAs and other alloys
(including Table A.1 — Guidance on the use of the materials
selection tables)
A.1 General
A.1.1 Materials groups
The materials groups used to list CRAs or other alloys (see 6.1) are as follows:
— austenitic stainless steels (identified as material type and as individual alloys) (see A.2);
— highly alloyed austenitic stainless steels (identified as material types and as individual alloys) (see
A.3);
— solid-solution nickel-based alloys (identified as material types and as individual alloys) (see A.4);
— ferritic stainless steels (identified as material type) (see A.5);
— martensitic stainless steels (identified as individual alloys) (see A.6);
— duplex stainless steels (identified as material types) (see A.7);
— precipitation-hardened stainless steels (identified as individual alloys) (see A.8);
— precipitation-hardened nickel-based alloys (identified as individual alloys) (see A.9);
— cobalt-based alloys (identified as individual alloys) (see A.10);
— titanium and tantalum (identified as individual alloys) (see A.11);
— copper, aluminium (identified as materials types) (see A.12).
Subject to A.1.2, A.1.3, A.1.4, and A.1.5 below, the CRAs and other alloys listed in Table A.1 to
Table A.42 may be used without further testing for SSC, SCC, and GHSC cracking-resistance within the
environmental limits shown.
Information on the use of copper and aluminium alloys is contained in A.12.
A.13 contains recommendations on the use of cladding, overlays, and wear-resistant alloys.
NOTE The materials listed and the restrictions shown are those originally listed in NACE MR0175:2003 (no
longer available) except for balloted changes introduced since 2003.
A.1.2 Limits of chemical composition
The user of a CRA or other alloy shall ensure that the chemical analysis of the material used meets the
material analysis requirements shown for the material in SAE — ASTM, Metals and alloys in the Unified
Numbering System.
To comply with this part of ISO 15156, the material shall also meet any provision shown in the text
and/or tables of its materials group.
10 © ISO 2015 – All rights reserved

A.1.3 Environmental and metallurgical limits for cracking-resistance
A.2.2 to A.11.2 contain materials selection tables showing the environmental limits of the materials
when used for any equipment or component. These subclauses also often contain materials selection
tables showing the less restrictive environmental limits of the materials when used for named
equipment or components.
− 0
The tables show the application limits with respect to temperature, pH S, Cl , pH, S . These limits apply
collectively. The pH used in the tables corresponds to the minimum in situ pH.
NOTE 1 In the tables of this Annex, the SI unit “milligrams per litre” is used for mass concentration. In US
Customary units, these are commonly expressed in parts per million (ppm).
NOTE 2 Guidance on the calculation of p is given in ISO 15156-2:2015, Annex C.
H2S
NOTE 3 Guidance on the calculation of pH is given in ISO 15156-2:2015, Annex D.
NOTE 4 In preparing the materials selection tables, it is assumed that no oxygen is present in the service
environment.
Where no specified limit for a variable can be defined in a table, explanatory remarks that reflect
current knowledge have been included in the table.
The environmental limits for an alloy are valid only within any additional metallurgical limits given for
the alloy in the text of the same table. Where tempering of a material is required, the tempering time
shall be sufficient to ensure the achievement of the required through-thickness hardness.
When purchasing materials, metallurgical properties known to affect the materials’ performance in
H S-containing oil and gas environments in addition to those specifically listed in this Annex should
also be considered. ISO 15156-1:2015, 8.1 lists such properties.
A.1.4 Requirements and recommendations on welding
The clauses for the materials groups contain requirements and recommendations for welding the
materials of the group to achieve satisfactory cracking-resistance in the weldment produced.
A.1.5 Other requirements and recommendations on CRAs and other alloys
A.1.5.1 Requirements for overlays, surface treatments, plating, coatings, linings, etc.
For the composition, cracking-resistance and use of overlays, see A.13.
Metallic coatings (electroplated and electroless plated), conversion coatings, plastic coatings, or linings
may be used, but are not acceptable for preventing cracking.
The effect of their application on the cracking-resistance of the substrate shall be considered.
Nitriding with a maximum case depth of 0,15 mm (0,006 in) is an acceptable surface treatment if
conducted at a temperature below the lower critical temperature of the alloy being treated. The use of
nitriding as a means of preventing cracking in sour service is not acceptable.
A.1.5.2 Threading
Threads produced using a machine-cutting process are acceptable.
Threads produced by cold forming (rolling) are acceptable on CRAs and other alloys if the material and
the limits of its application otherwise comply with this part of ISO 15156.
A.1.5.3 Cold deformation of surfaces
Cold deformation of surfaces is acceptable if caused by processes such as burnishing that do not impart
more cold work than that incidental to normal machining operations (such as turning or boring, rolling,
threading, drilling, etc.).
Cold deformation by controlled shot-peening is acceptable if applied to base materials that comply with
this part of ISO 15156 and if restricted to a maximum shot size of 2,0 mm (0,080 in) and an Almen
intensity not exceeding 10C. The process shall be controlled in accordance with SAE AMS-2430.
A.1.5.4 Identification stamping
The use of identification stamping using low-stress (dot, vibratory, and round-V) stamps is acceptable.
The use of conventional sharp V-stamping is acceptable in low-stress areas such as the outside diameter
of flanges. Conventional sharp V-stamping shall not be performed in high-stress areas unless agreed
with the equipment user.
A.1.6 Use of materials selection tables
Table A.1 provides a guide to the materials selection tables for any equipment or component. It also
provides a guide to additional materials selection tables for specific named equipment or components
when other, less restrictive, environmental, or metallurgical limits may be applied.
NOTE See Note in introduction of this part of ISO 15156 regarding Annex F of Technical Circular
ISO 15156-3:2009/Cir.2:2013 and Technical Circular ISO 15156-3:2009/Cir.3:2014.
A.2 Austenitic stainless steels (identified as material type and as individual alloys)
A.2.1 Materials analyses
Austenitic stainless steels of this material type shall contain the following elements in the following
proportions, expressed as mass fractions: C, 0,08 % max; Cr, 16 % min; Ni, 8 % min; P, 0,045 % max; S,
0,04 % max; Mn, 2,0 % max; and Si, 2,0 % max. Other alloying elements are permitted.
Higher carbon contents for UNS S30900 and S31000 are acceptable up to the limits of their respective
specifications.
The alloys listed in Table D.1 can, but do not necessarily, meet the requirements above. In some cases,
more restrictive chemistries are required to comply with the requirements of this materials group.
See also A.3.1.
It is common industry practice to dual certify 300 series stainless steels as standard grade and low
carbon grade such as S31600 (316) and S31603 (316L). The environmental limits given for low carbon
300 series stainless steels are acceptable for the dual certified grades.
Free-machining austenitic stainless steel products shall not be used.
12 © ISO 2015 – All rights reserved

Table A.1 — Guidance on the use of the materials selection tables of Annex A based on
equipment or component type
A.2.2 Environmental and materials limits for the uses of austenitic stainless steels
Table A.2 — Environmental and materials limits for austenitic stainless steels used for any
equipment or components
Materials
Partial
type/
pressure Chloride Sulfur-
individual Temperature pH Remarks
H S conc. resistant?
alloy UNS
p
H2S
number
max max max
°C (°F) kPa (psi) mg/l
60 (140) 100 (15) See See No Any combination of chloride
“Remarks” “Remarks” concentration and in situ pH
column column occurring in production
environments is acceptable.
Austenitic
stainless
These materials have been used
steel
without restrictions on temperature,
from
pH S, or in situ pH in
...