ISO 4978:2018

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
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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
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electrotechnical standardization.
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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
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.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 specified in this document and are listed below. If the purchaser does not
indicate any of these options at the time of enquiry and order, products shall be supplied at the discretion
of the manufacturer:
a) heat treatment condition of supply (see 5.2);
b) if a product analysis is required (see 6.1.2 and 9.1.2);
c) maximum carbon equivalent value (see 6.1.3);
d) surface condition of supply (see 6.5);
e) others (see 6.7).
5 Manufacturing process
5.1 Steelmaking
5.1.1 Unless otherwise stated at the time of enquiry and order, the steelmaking process and the
deoxidation practice within the provisions of 5.1.2 and 5.1.3 shall be left to the discretion of the
manufacturer.
5.1.2 The steel shall be produced by electric or one of the basic oxygen processes. Other steelmaking
processes may be used by agreement between the parties concerned. On request, the purchaser shall be
informed of the steelmaking process used.
NOTE Other parties include the user, purchaser and manufacturer of the equipment, the producer of the
material supplied and the inspection and/or certifying authority.
5.1.3 The deoxidation procedure shall ensure that the steel has acceptable non-aging properties. The
steel shall therefore be killed with aluminium so that Al is equal to or greater than 0,015 %. However,
sol
other elements which, by binding the nitrogen, have a similar effect may also be used instead of, or in
addition to, aluminium (see also Table 1).
If the manufacturer intends, however, to supply steels with such additions in contents higher than
0,05 %, this addition shall conform to the restriction
...