ISO 4978:2018

Steel sheet and strip for welded gas cylinders

This document specifies the characteristics of hot-rolled steel sheet and strip with a thickness up to 12 mm inclusive of the non-alloyed steels listed in Table 1, which are intended for welded gas cylinders in accordance with ISO 4706.

Produit en acier laminé à plat pour bouteilles à gaz soudées

General Information

• Status: Published
• Publication Date: 02-Aug-2018
• ICS: 77.140.30 - Steels for pressure purposes
• Technical Committee: ISO/TC 17/SC 10 - Steel for pressure purposes
• Drafting Committee: ISO/TC 17/SC 10 - Steel for pressure purposes
• Current Stage: 9060 - Close of review
• Completion Date: 04-Mar-2029

Relations

• Revises: ISO 4978:1983 - Flat rolled steel products for welded gas cylinders
• Effective Date: 13-Feb-2016

Overview

ISO 4978:2018 - Steel sheet and strip for welded gas cylinders defines the material and delivery requirements for hot-rolled steel sheet and strip (thickness up to 12 mm) intended for welded gas cylinders manufactured in accordance with ISO 4706. The standard sets out chemical composition, mechanical properties, grain size, weldability, surface condition, dimensions, inspection and testing requirements specific to non-alloyed steel grades (Table 1: P235 to P365).

Key topics and technical requirements

• Scope and materials: Hot-rolled steel sheet and strip for welded gas cylinders, thickness ≤ 12 mm. Grades and chemical limits are given in Table 1.
• Chemical composition: Heat analysis limits for C, Si, Mn, P, S and aluminium (Alsol ≥ 0.015 %). Microalloy additions (Nb, V, Ti) permitted within specified maxima; purchaser can require product analysis and a maximum carbon-equivalent value (CEV, optional up to 0.45 %).
• Mechanical properties: Yield strength, tensile strength, elongation and impact energy requirements are specified (transverse direction). Impact testing required for thickness > 6 mm with defined sub-sized specimens; average of three specimens must meet the specified energy, allowing one to be as low as 70% of the limit.
• Grain size: Ferritic grain size Index 6 or finer (ISO 643).
• Weldability: Designed to be weldable by common fusion welding processes; CEV option addresses weldability concerns.
• Surface and internal quality: Supply options include rolled or descaled/oiled surfaces; general quality requirements referenced to ISO 404.
• Delivery and testing: Delivery condition (hot-rolled, normalized, normalizing rolling) and inspection documents must be agreed at order. Tests include chemical analysis, tensile, impact, bend, grain size and non-metallic inclusion assessment (as per referenced ISO methods).
• Additional requirements: Options such as impact testing at −40 °C, maximum yield/tensile ratio (≤ 0.8), and bend test acceptance criteria can be specified by the purchaser.

Applications and users

ISO 4978:2018 is used by:

• Steel producers specifying hot-rolled sheet and strip for cylinder service
• Gas cylinder manufacturers (welded refillable cylinders) selecting material compliant with ISO 4706
• Welding engineers and fabricators assessing weldability and CEV limits
• Quality assurance, inspection and procurement teams defining acceptance tests and inspection documents
• Regulatory and certification bodies verifying material conformity for pressure equipment

Keywords: ISO 4978:2018, steel sheet and strip, welded gas cylinders, hot-rolled steel, chemical composition, mechanical properties, weldability, material specification.

Related standards

• ISO 4706 (refillable welded steel cylinders)
• ISO 404 (general technical delivery requirements)
• ISO 16160 (dimensional tolerances for hot-rolled sheet)
• ISO 148-1, ISO 643, ISO 4967, ISO 6892-1, ISO 10474 (test and inspection methods)

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 4978
Second edition
2018-08
Steel sheet and strip for welded gas
cylinders
Produit en acier laminé à plat pour bouteilles à gaz soudées
Reference number
©
ISO 2018
© ISO 2018
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 2018 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Information to be supplied by the purchaser. 2
5 Manufacturing process . 2
5.1 Steelmaking . 2
5.2 Delivery condition . 2
6 Technical requirements . 3
6.1 Chemical composition . 3
6.2 Mechanical properties . 4
6.3 Grain size . 4
6.4 Weldability . 4
6.5 Surface condition and soundness . 4
6.6 Dimensions and tolerances . 5
6.7 Other requirements . 5
7 Inspection . 5
7.1 Types of inspection and inspection documents . 5
7.2 Test frequency . 6
7.3 Visual inspection . 6
8 Sampling . 6
9 Test methods . 7
9.1 Chemical analysis . 7
9.2 Tensile test . 7
9.3 Impact test . 7
9.4 Bend test . 7
9.5 Grain size . 7
9.6 Non-metallic inclusion . 7
9.7 Retests . 7
10 Marking . 7
Bibliography . 8
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
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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
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Any trade name used in this document is information given for the convenience of users and does not
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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 17, Steel, SC 10, Steel for pressure purposes.
This second edition cancels and replaces the first edition ISO 4978:1983, which has been technically
revised. The following main changes have been made:
— the title has been changed from “flat rolled steel products” to “steel sheet and strip”;
— the Scope has been changed from “flat rolled steel products with a thickness up to 6 mm” to “hot-
rolled steel sheet and strip with a thickness up to 12 mm”;
— the normative references have been updated;
— a new option c) for maximum carbon equivalent value has been added to the list of options for the
purchaser in 4.2;
— statements concerning the surface condition under 6.5.1 and internal quality under 6.5.3 have been
revised;
— the tables and statements concerning chemical composition, mechanical properties, testing and
assessment of non-metallic inclusions have been completely revised or added;
— the Bibliography has been added.
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 © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 4978:2018(E)
Steel sheet and strip for welded gas cylinders
1 Scope
This document specifies the characteristics of hot-rolled steel sheet and strip with a thickness up to
12 mm inclusive of the non-alloyed steels listed in Table 1, which are intended for welded gas cylinders
in accordance with ISO 4706.
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 377, Steel and steel products — Location and preparation of samples and test pieces for mechanical testing
ISO 404, Steel and steel products — General technical delivery requirements
ISO 643, Steels — Micrographic determination of the apparent grain size
ISO 4706, Gas cylinders — Refillable welded steel cylinders — Test pressure 60 bar and below
ISO 4967:2013, Steel — Determination of content of non-metallic inclusions — Micrographic method using
standard diagrams
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 7438, Metallic materials — Bend test
ISO 10474, Steel and steel products — Inspection documents
ISO 16160, Hot-rolled steel sheet products — Dimensional and shape tolerances
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
normalizing rolling
rolling process in which the final deformation process is carried out in a certain temperature range,
leading to a material condition equivalent to that obtained after normalizing so that the specified
values of the mechanical properties are retained even after normalizing
4 Information to be supplied by the purchaser
4.1 The following information shall be supplied by the purchaser at the time of enquiry and order:
a) the dimensions and tolerances of the product (see 6.6);
b) the steel grade (see Table 1);
c) the inspection procedures and type of the documents required.
4.2 A number of options are sp
...