ISO/TR 4673:2022
(Main)Gas cylinders — Service life performance of composite cylinders and tubes
Gas cylinders — Service life performance of composite cylinders and tubes
This document collects history and experience of composite cylinders and tubes to be used under the International Regulations for the Transport of Dangerous Goods: — with a water capacity up to 3 000 l; — with a design life greater than 15 years. In particular the document reviews the topic of the service life performance of existing composite cylinders and tubes and provides information and data for the following items: — history of cylinder design; — current testing regimes; — significance of the tests on their performance; — service performance including pre-fill and periodic inspection and tests. NOTE In this document, for “cylinder/tube”, only the term “cylinder” is used.
Titre manque
General Information
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 4673
First edition
2022-10
Gas cylinders — Service life
performance of composite cylinders
and tubes
Reference number
ISO/TR 4673:2022(E)
© ISO 2022
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ISO/TR 4673:2022(E)
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ISO/TR 4673:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 History of composite cylinder design . 2
5 Current testing regimes . 2
5.1 General . 2
5.2 Requirements at the design, construction and testing stage . 2
5.3 Requirements at Pre-fill inspection . 5
5.4 Requirements at Periodic inspection and testing . 6
6 Significance of cylinder test on their performance . 6
7 Service performance including pre-fill and periodic inspection and test .8
8 Summary and conclusions . 8
Bibliography . 9
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ISO/TR 4673:2022(E)
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 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 3,
Cylinder design.
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.
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ISO/TR 4673:2022(E)
Introduction
Composite gas cylinders have been manufactured for more than 50 years. Over that time, several
specifications have been developed at the national, regional and international levels.
The following ISO standards cover the design of composites cylinders and tubes:
— ISO 11119 series (cylinders and tubes up to 450 l);
— ISO 11515 (tubes from 450 l to 3 000 l).
When the above-mentioned standards were proposed for reference in the UN Model Regulations, a
lot of discussion took place because the two main regions using composite gas cylinders (Europe and
North America) had different approaches. In Europe, regulations permitted non-limited lifetime for
composite cylinders, while in North America, the lifetime was limited to 15 years by the US Department
of Transportation.
To reach consensus, the concept of a service life test programme for composite cylinders and composite
tubes of more than 15 years design life time was incorporated into the United Nations Recommendations
th
on the Transport of Dangerous Goods (The Orange Book), as adopted in the 19 revision, in NOTE 2 of
6.2.2.1.1 and 6.2.2.1.2. This statement has raised several questions over the years:
— When are the tests to be performed?
— On which cylinders are the tests to be performed? How will the sampling be established?
— What tests are to be performed?
— Are all the tests really needed?
— Can the service life test programme be included in the design standard?
To answer these questions, ISO/TC 58/SC 3/WG 36 developed ISO/TR 19811. Indeed, to understand
what testing programmes are in use by ISO P-member countries, competent authorities were asked to
provide information regarding the composite cylinder approvals that are accepted in their country and
any service life test programmes currently practiced.
The information received from the competent authorities was used to determine the similarities and
differences in the service life test programmes used.
In 2018, ISO/TC 58/SC 3/AHG 1 concluded that there is no standardized global test protocol, and the
worldwide feasibility of such programmes was difficult to put in place.
Finally in 2019, taking into account the previous work of ISO/TC 58/SC 3/WG 36 and ISO/TC 58/SC 3/
AHG 1, ISO/TC 58/SC 3 asked WG 36 to develop a document to support the removal of service life test
programme from the UN Model Regulations.
The aim of this proposed Technical Report was to build a rationale to answer the following question:
“Is a service life test programme needed to guarantee the safe and reliable performance of cylinders
with a design life longer than 15 years?”
It is important to note that the current document deals only with the need (or not) of having a service
life test programme for a cylinder with design life of more than 15 years or non-limited life to guarantee
its “safety”.
NOTE The aim of the current document is not to discuss the merit of the tests performed to extend the life
beyond its design life nor the frequency of periodic inspections
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TECHNICAL REPORT ISO/TR 4673:2022(E)
Gas cylinders — Service life performance of composite
cylinders and tubes
1 Scope
This document collects history and experience of composite cylinders and tubes to be used under the
International Regulations for the Transport of Dangerous Goods:
— with a water capacity up to 3 000 l;
— with a design life greater than 15 years.
In particular the document reviews the topic of the service life performance of existing composite
cylinders and tubes and provides information and data for the following items:
— history of cylinder design;
— current testing regimes;
— significance of the tests on their performance;
— service performance including pre-fill and periodic inspection and tests.
NOTE In this document, for “cylinder/tube”, only the term “cylinder” is used.
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 10286, Gas cylinders — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10286 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
design life
maximum life (in years) for which the composite cylinder is designed and approved in accordance with
the applicable standard
3.2
service life
number of years the cylinder is permitted to be in service
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ISO/TR 4673:2022(E)
4 History of composite cylinder design
Composite cylinders have been used in commercial service for over 50 years. The first well-known
standards were:
— DOT FRP-1, type 3FC composite cylinders published in 1981;
— DOT FRP-2, type 3HW composite cylinders published in 1982.
Both of the above were developed by the Compressed Gas Association (CGA) in cooperation with DOT.
DOT FRP-1 and FRP-2 were limited to a service life of 15 years.
— HSE-AL-FW1, 1st published in January 1991. 15-year service life with possibility to extend;
— HSE-AL-HW1, 1st published in January 1991. 15-year service life with possibility to extend;
— DOT-CFFC, published on 1996 with the possibility of extending the 15-year service life up to a total
service life of 30 years;
— ISO 11119, Parts 1, 2 & 3, published in 2002;
— EN 12245 and EN 12257, both published in 2002;
— ISO 11515, published in 2013.
ISO 11119 series, ISO 11515, EN 12245 and 12257 are for limited life and non-limited life designs.
Technical reports collected data and specific design factors, test protocols and cylinder performance
are summarized in the ISO/TR 13086 series of documents.
Approximately 12 million composite cylinders have been manufactured for compressed gases and
20 million for liquefied gases (mainly liquid propane gas (LPG)).
The vast majority of cylinders with a design life in excess of 15 years have been designed, manufactured
and tested as non-UN approved cylinders thus allowing a service life greater than 15 years without a
service life test programme.
The initial limitation of service life to 15 years was imposed in some countries because of lack of service
experience of composite materials and cylinders.
5 Current testing regimes
5.1 General
The UN Model Regulations refer to ISO standards for the design, construction, testing, pre-fill inspection
and periodic inspection and testing for composite cylinders and tubes:
— At the manufacturing stages the relevant standards are ISO 11119 (series) and ISO 11515.
— At time of filling the relevant standard is ISO 24431.
— At periodic inspection and testing the relevant standard is ISO 11623.
5.2 Requirements at the design, construction and testing stage
Tests are carried out during Type Approval, during production on a batch-by batch basis and on
individual cylinders to ensure that the cylinders will provide satisfactory in-service performance.
The tests and the main requirements specified in the ISO 11119 series are summarised in Tables 1 and
2.
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ISO/TR 4673:2022(E)
Table 1 — Type approval testing ISO 11119
Test ISO 11119-1 ISO 11119-2- ISO 11119-3 ISO 11119-4 Sampling
Rate
Liner material tests X X X X 1
Liner integrity test N/A N/A N/A X 1
Composite material X X X X 1
tests
Proof pressure test or X X X X 100 %
hydraulic expansion test
Liner burst test X X X X 1
Hydraulic burst test X X X X 3/30
Ambient cycle test X X X X 2/30
Environmental cycling X X X X 1/30
test
Flaw test N/A X X X 2/30
Drop test O X X X 2
...
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