ISO 18172-1:2007

INTERNATIONAL ISO
STANDARD 18172-1
First edition
2007-03-01
Gas cylinders — Refillable welded
stainless steel cylinders —
Part 1:
Test pressure 6 MPa and below
Bouteilles à gaz — Bouteilles soudées en acier inoxydable
rechargeables —
Partie 1: Pression d'épreuve de 6 MPa et inférieure

Reference number
©
ISO 2007
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©  ISO 2007
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ii © ISO 2007 – All rights reserved

Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols. 2
3.1 Terms and definitions. 2
3.2 Symbols . 3
4 Materials and heat treatment . 4
4.1 General. 4
4.2 Categories . 5
4.3 Heat treatment. 5
4.4 Test requirements. 5
5 Design . 5
5.1 General requirements. 5
5.2 Calculation of cylindrical shell wall thickness . 6
5.3 Design of convex ends. 6
5.4 Minimum wall thickness. 9
5.5 Ends of other shapes . 9
5.6 Design of openings. 9
6 Construction and workmanship. 9
6.1 General. 9
6.2 Welding procedures . 10
6.3 Cryoforming procedure. 10
6.4 Welded joints of pressure-containing parts . 10
6.5 Non-pressure-containing attachments.10
6.6 Valve protection. 11
6.7 Neck threads . 11
6.8 Visual examination . 11
7 New design tests. 12
7.1 General requirements. 12
7.2 Verifications and tests. 13
7.3 Descriptions of tests . 13
7.4 Design testing certificate . 14
8 Batch tests. 14
8.1 General. 14
8.2 Information . 15
8.3 Tensile test . 15
8.4 Bend test. 18
8.5 Macroscopic examination of weld cross-sections. 20
8.6 Checks and verifications . 20
9 Tests on every cylinder. 21
9.1 Pressure test . 21
9.2 Hardness test . 21
9.3 Leakage test . 21
10 Failure to meet test requirements. 21
11 Markings . 22
12 Certificate. 22
Annex A (normative) Radiographic examination of welds. 23
Annex B (normative) Description and evaluation of manufacturing defects and conditions
for rejection of welded stainless steel gas cylinders at time of visual inspection . 25
Annex C (informative) Examples of design and batch testing certificates. 27
Annex D (normative) Manufacturer's markings for LPG . 32
Bibliography . 33

iv © ISO 2007 – 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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 18172-1 was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 3, Cylinder
design.
ISO 18172 consists of the following parts, under the general title Gas cylinders — Refillable welded stainless
steel cylinders:
⎯ Part 1: Test pressure 6 MPa and below
⎯ Part 2: Test pressure greater than 6 MPa
Introduction
The purpose of this part of ISO 18172 is to provide a specification for the design, manufacture and testing of
refillable transportable welded stainless steel gas cylinders with a test pressure up to 6 MPa (60 bar).
The specifications given are based on knowledge of, and experience with, materials, design requirements,
manufacturing processes and control during manufacture of cylinders in common use.
ISO 18172 has been prepared to address the general requirements in Section 6.2.1 of the UN model
regulations for the transportation of dangerous goods ST/SG/AC.10/1/Rev.13. It is intended to be used under
a variety of regulatory regimes, but has been written so that it is suitable for use with the conformity
assessment system in paragraph 6.2.2.5 of the above-mentioned model regulations.

vi © ISO 2007 – All rights reserved

INTERNATIONAL STANDARD ISO 18172-1:2007(E)

Gas cylinders — Refillable welded stainless steel cylinders —
Part 1:
Test pressure 6 MPa and below
1 Scope
This part of ISO 18172 specifies minimum requirements concerning material, design, construction and
workmanship, manufacturing processes and testing of refillable transportable welded stainless steel gas
cylinders, of water capacities from 0,5 l up to and including 500 l, for compressed, liquefied and dissolved
gases. This part of ISO 18172 is applicable only to cylinders manufactured from stainless steels with test
pressures up to 6 MPa (60 bar).
If required, transportable large cylinders of water capacity above 150 l and up to 500 l may be manufactured
and certified to this part of ISO 18172, providing that handling facilities are provided (see 6.5.5).
For acetylene service, additional requirements for the cylinder and the basic requirements for the porous mass
are given in ISO 3807-1 and ISO 3807-2.
2 Normative references
The following referenced documents are indispensable for the application 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 2504:1973, Radiography of welds and viewing conditions for films — Utilization of recommended patterns
of image quality indicators (I.Q.I.)
ISO 3651-2, Determination of resistance to intergranular corrosion of stainless steels — Part 2: Ferritic,
austenitic and ferritic-austenitic (duplex) stainless steels — Corrosion test in media containing sulfuric acid
ISO 5817, Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding
excluded) — Quality levels for imperfections
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6892, Metallic materials — Tensile testing at ambient temperature
ISO 7438, Metallic materials — Bend test
ISO 9328-7:2004, Steel flat products for pressure purposes — Technical delivery conditions — Part 7:
Stainless steels
ISO 9606-1, Approval testing of welders — Fusion welding — Part 1: Steels
ISO 9956-1, Specification and approval of welding pro
...