ISO/FDIS 18742

Ship and marine technology — High manganese austenitic steel — Specification for high manganese austenitic steel welded fittings for cryogenic temperature

This specification covers wrought high manganese austenitic steel welded fittings for pressure piping cryogenic temperature. The specification of high manganese austenitic steel welded fittings can be applicable to all pressure retaining components and any non-pressure retaining component for hull systems and onshore projects.

Navires et technologie maritime — Acier austénitique à haute teneur en manganèse — Spécification pour les raccords soudés en acier austénitique à haute teneur en manganèse pour température cryogénique

General Information

• Status: Not Published
• ICS: 47.020.05 - Materials and components for shipbuilding
• Technical Committee: ISO/TC 8/SC 4 - Outfitting and deck machinery
• Drafting Committee: ISO/TC 8/SC 4 - Outfitting and deck machinery
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 03-Nov-2025
• Completion Date: 03-Nov-2025

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/TC 8/SC 4
Ship and marine technology —
Secretariat: SAC
High manganese austenitic steel —
Voting begins on:
Specification for high manganese
2025-11-03
austenitic steel welded fittings for
Voting terminates on:
cryogenic temperature
2025-12-29
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 8/SC 4
Ship and marine technology —
Secretariat: SAC
High manganese austenitic steel —
Voting begins on:
Specification for high manganese
austenitic steel welded fittings for
Voting terminates on:
cryogenic temperature
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Abbreviated terms . 3
5 Health, safety and quality requirements . 3
5.1 Health and safety requirements .3
5.2 Quality requirements .3
6 Material designation . . 4
7 Manufacture . 4
8 Chemical composition . 4
9 Forming and welding . 5
10 Heat treatment . 6
11 Mechanical properties . 7
11.1 Preparation of test specimens and extent of testing .7
11.2 Mechanical properties .7
11.2.1 General .7
11.2.2 Tensile testing .8
11.2.3 Impact testing .8
11.2.4 Bend testing .8
11.2.5 Hardness testing.9
11.3 Retesting .9
12 Inspection . 9
12.1 General requirements .9
12.2 Visual inspection .9
12.3 RT and UT .10
12.4 PT . .10
12.5 Hydrostatic testing .11
13 Repairs .11
14 Dimension inspection .12
15 Traceability, handling and packing .12
16 Documentation .12
Annex A (normative) Hardness of Hi-Mn steel welded fittings . 14
Bibliography .15

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 TC 8, Ships and marine technology, Subcommittee SC
4, Outfitting and deck machinery.
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.

iv
Introduction
The aim of this document is to provide a set of common requirements for metallic materials used in cryogenic
[1] [2]
applications, in alignment with the IGC Code and IGF Code adopted by the International Maritime
Organization (IMO).
The newly developed, high manganese austenitic steel is expected to possess mechanical properties
including Charpy impact energy values comparable to those materials for cryogenic service listed in both the
IGC Code and IGF Code. Consequently, high manganese steel is intended to satisfy the strength requirements
of the structure of cargo tanks, fuel tanks and piping systems.
In addition, upon agreement with a purchaser, this document can be applied to piping systems for liquefied
hydrogen.
This document provides a standard specification of high manganese austenitic steel welded fittings
for material suppliers, ship owners, ship yards, manufacturers and shipping companies with regard to
producing, purchasing and using such materials.

v
FINAL DRAFT International Standard ISO/FDIS 18742:2025(en)
Ship and marine technology — High manganese austenitic
steel — Specification for high manganese austenitic steel
welded fittings for cryogenic temperature
1 Scope
This document provides requirements for wrought high manganese austenitic steel welded fittings used for
pressure piping at cryogenic temperature.
The specification of high manganese austenitic steel welded fittings is applicable to all pressure retaining
components and any non-pressure retaining components used in hull systems for marine technology and in
onshore projects.
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 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method
ISO 2566-1, Steel — Conversion of elongation values — Part 1: Carbon and low-alloy st
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Date: 2025-04-2310-20
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ShipsShip and marine technology — High manganese austenitic steel
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— Specification for high manganese austenitic steel welded fittings
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for cryogenic temperature
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St l D fi iti
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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: + 41 22 749 01 11
Formatted: English (United Kingdom)
Formatted: English (United Kingdom)
Fax: [phone]
EmailE-mail: [e-mail]
Formatted: German (Germany)
Website: www.iso.orgwww.iso.org
Formatted: zzCopyright address, Adjust space between
Latin and Asian text, Adjust space between Asian text
Published in Switzerland
and numbers
Formatted: German (Germany)
Formatted: Font: 11 pt
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0 pt, Line spacing: single
ii © ISO 18742 2025 – All rights reserved
ii
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Formatted: HeaderCentered, Left
Contents Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Abbreviated terms . 3
5 Health, safety and quality requirements . 4
5.1 Health and safety requirements . 4
5.2 Quality requirements . 4
6 Material designation . 4
7 Manufacture . 5
8 Chemical composition . 5
9 Forming and welding . 6
10 Heat treatment . 7
11 Mechanical properties . 8
11.1 Preparation of test specimens and extent of testing . 8
11.2 Mechanical properties . 8
11.3 Retesting . 10
12 Inspection . 11
12.1 General requirements . 11
12.2 Visual inspection . 11
12.3 RT and UT . 11
12.4 PT . 12
12.5 Hydrostatic testing . 13
13 Repairs . 13
14 Dimension inspection. 14
15 Traceability, handling and packing . 14
16 Documentation . 14
Annex A (normative) Hardness of Hi-Mn steel welded fittings . 16
Bibliography . 17

Foreword . iv
Introduction . v
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1 Scope . 1
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2 Normative references . 1
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3 Terms and definitions . 2
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4 Abbreviated terms . 3
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5 Health, safety and quality requirements . 4
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© ISO 2025 – All rights reserved
iii
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Formatted: HeaderCentered
5.2 Quality Requirements . 4
6 Material designation . 4
7 Manufacture . 4
8 Chemical composition . 5
9 Forming and welding . 6
10 Heat treatment . 6
11 Mechanical properties . 7
11.1 Preparation of test specimens and extend of testing . 7
11.2 Mechanical properties . 8
11.3 Retesting . 9
12 Inspection . 10
12.1 General requirements . 10
12.2 Visual inspection . 10
12.3 RT and UT . 10
12.4 PT . 11
12.5 Hydrostatic testing . 12
13 Repairs . 12
14 Dimension inspection. 13
15 Traceability, handling and packing . 13
16 Documentation . 13
Annex A (informative) Hardness of Hi-Mn steel welded fittings . 14
Bibliography . 15
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Formatted: FooterPageRomanNumber, Space Before:
0 pt, Line spacing: single
iv © ISO 18742 2025 – All rights reserved
iv
Formatted: Font: Bold
Formatted: HeaderCentered, Left
Foreword Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers
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 document 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).
Formatted: English (United Kingdom)
Formatted: Default Paragraph Font, English (United
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
Kingdom)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
Field Code Changed
in respect thereof. As of the date of publication of this document,
...