ISO 11119-2:2012

INTERNATIONAL ISO
STANDARD 11119-2
Second edition
2012-07-15
Gas cylinders — Refillable composite
gas cylinders and tubes — Design,
construction and testing —
Part 2:
Fully wrapped fibre reinforced composite
gas cylinders and tubes up to 450 l with
load-sharing metal liners
Bouteilles à gaz — Bouteilles à gaz rechargeables en matériau
composite et tubes — Conception, construction et essais —
Partie 2: Bouteilles à gaz composites entièrement bobinées renforcées
par des fibres et tubes d’une contenance allant jusqu’à 450 l avec liners
métalliques transmettant la charge
Reference number
©
ISO 2012
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Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 4
5 Inspection and testing . 4
6 Materials . 4
6.1 Liner materials . 4
6.2 Composite materials . 5
7 Design and manufacture . 5
7.1 General . 5
7.2 Design submission . 5
7.3 Manufacturing . 6
8 Type approval procedure . 7
8.1 General requirements . 7
8.2 Prototype tests . 7
8.3 New design . 8
8.4 Design variants . 9
8.5 Type approval test procedures and criteria .10
9 Batch inspection and testing .22
9.1 Liner .22
9.2 Failure of liner batch tests .23
9.3 Overwrap materials .23
9.4 Composite cylinder .23
9.5 Cylinder failure during type approval or batch testing .24
10 Cylinder marking .25
10.1 General .25
10.2 Additional marking .25
Annex A (informative) Examples of design approval certificate .26
Annex B (informative) Specimen test reports .27
Bibliography .30
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 11119-2 was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 3, Cylinder design.
This edition cancels and replaces ISO 11119-2:2002.
ISO 11119 consists of the following parts, under the general title Gas cylinders — Refillable composite gas
cylinders and tubes — Design, construction and testing:
— Part 1: Hoop wrapped fibre reinforced composite gas cylinders and tubes up to 450 l
— Part 2: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with load-sharing
metal liners
— Part 3: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with non-load-sharing
metallic or non-metallic liners
The following part is under preparation:
— Part 4: Fully wrapped fibre reinforced composite gas cylinders with load-sharing welded metal liners
iv © ISO 2012 – All rights reserved

Introduction
The purpose of this International Standard is to provide a specification for the design, manufacture, inspection
and testing of cylinders for worldwide usage. The objective is to balance design and economic efficiency
against international acceptance and universal utility.
This International Standard aims to eliminate the concern about climate, duplicate inspection and restrictions
currently existing because of lack of definitive International Standards and is not to be construed as reflecting
on the suitability of the practice of any nation or region.
This part of ISO 11119 addresses the general requirements on design, construction and initial inspection
and testing of pressure receptacles of the Recommendations on the transport of dangerous goods: Model
regulations developed by the United Nations (Reference [16]).
INTERNATIONAL STANDARD ISO 11119-2:2012(E)
Gas cylinders — Refillable composite gas cylinders and
tubes — Design, construction and testing —
Part 2:
Fully wrapped fibre reinforced composite gas cylinders and
tubes up to 450 l with load-sharing metal liners
1 Scope
This part of ISO 11119 specifies requirements for composite gas cylinders and tubes between 0,5 l and 450 l
water capacity, for the storage and conveyance of compressed or liquefied gases.
This part of ISO 11119 applies to type 3 fully wrapped cylinders or tubes with a load-sharing metal liner and
composite reinforcement on both the cylindrical portion and the dome ends.
This part of ISO 11119 is limited to cylinders and tubes with composite reinforcement of carbon fibre, aramid
fibre or glass fibre (or a mixture thereof) within a matrix.
Cylinders complying with this part of ISO 11119 have a minimum design life of 15 years.
This part of ISO 11119 does not address the design, fitting, and performance of removable protective sleeves.
This part of ISO 11119 does not apply to cylinders with welded liners.
[6] [7]
NOTE ISO 11439 applies to cylinders intended for use as fuel containers on natural gas vehicles and ISO 11623
covers periodic inspection and re-testing of composite cylinders.
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 3341, Textile glass — Yarns — Determination of breaking force and breaking elongation
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method (scales A, B, C, D, E, F,
G, H, K, N, T)
ISO 7225, Gas cylinders — Precautionary labels
ISO 7866, Gas cylinders — Refillable seamless aluminium alloy gas cylinders — Design, construction and testing
ISO 9809-1, Gas cylinders — Refillable seamless steel gas cylinders — Design, construction and testing —
Part 1: Quenched and tempered steel cylinders with tensile strength less than 1 100 MPa
ISO 9809-2, Gas cylinders — Refillable seamless steel gas cylinders — Design, construction and testing —
Part 2: Quenched and tempered steel cylinders with tensile strength greater than or equal to 1 100 MPa
ISO 9809-3, Gas cylinders — Refillable seamless steel gas cylinders — Design, construction and testing —
Part 3: Normalized steel cylinders
ISO 10618, Carbon fibre — Determination of tensile properties of resin-impregnated yarn
ISO 11114-1, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 1:
Metallic materials
ISO 13341, Gas cylinders — Fitting of valves to gas cylinders
ISO 13769, Gas cylinders — Stamp marking
EN 1964-3, Transportable gas cylinders — Specification for the design and construction of refillable transportable
seamless steel gas cylinders of water capacities from 0,5 litre up to and including 150 litres — Part 3: Cylinders
made of seamless stainless steel with an R value of less than 1 100 MPa
m
ASTM D7269, Standard test methods for tensile testing of aramid yarns
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. References to cylinders are to
include composite tubes as appropriate
3.1
aramid fibre
continuous filaments of aramid laid up in tow form
3.2
autofrettage
pressure application procedure which strains the metal liner past its yield point sufficient to cause permanent
plastic deformation, and results in the liner having compressive stresses and the fibres having tensile stresses
when at zero internal gauge pressure
3.3
batch
set of homogeneous items or material
NOTE The number of items in a batch can vary according to the context in which the term is used.
3.4
batch of liners
production quantity of up to 200 finished liners successively produced (plus units required for destructive
testing) of the same nominal diameter, length, thickness and design, from the same material cast and heat
treated to the same conditions of temperature and time
3.5
batch of finished cylinders
production quantity of up to 200 finished cylinders successively produced by the same manufacturing process
plus finished cylinders required for destructive testing, of the same nominal diameter, length, thickness and design
3.6
burst pressure
highest pressure reached in a cylinder during a burst test
3.7
carbon fibre
continuous filaments of carbon laid up in tow form
3.8
composite overwrap
combination of fibres and matrix
3.9
dedicated gas service
service in which a cylinder is to be used only with a specified gas or gases
2 © ISO 2012 – All rights reserved

3.10
equivalent fibre
fibre equivalent to a fibre used in a previously prototype tested cylinder
3.11
equivalent liner
liner that has certified properties and performance so as to be a direct equivalent to a liner used in an already
approved cylinder
3.12
exterior coating
layers of material applied to the cylinder as protection or for cosmetic purposes
NOTE The coating can be clear or pigmented.
3.14
glass fibre
continuous filaments of glass laid up in tow form
3.15
liner
inner portion of the composite cylinder, comprising a metallic vessel, whose purpose is both to contain the gas
and transmit the gas pressure to the fibres
3.16
matrix
material that is used to bind and hold the fibres in place
3.17
load-sharing liner
liner which has a burst pressure greater than or equal to 5 % of the nominal burst pressure of the finished
composite cylinder
3.18
thermoplastic material
plastics capable of being repeatedly softened by increase of temperature and hardened by decrease of temperature
3.19
thermosetting material
plastics that, when cured by the application of heat or chemical means, harden permanently into a substantially
infusible and insoluble product
3.20
working pressure
settled pressure of a compressed gas at a reference temperature of 15 °C in a full gas cylinder
3.21
nominal outside diameter
Diameter of the cylinder specified by the manufacturer for the type approval including tolerances (e.g. ± 1%)
3.22
type 3 cylinder
fully wrapped cylinder with a load-sharing metal liner and composite reinforcement on both cylindrical and
dome ends.
4 Symbols
Symbols and their designations
p burst pressure of finished cylinder bar
b
p test pressure bar
h
p maximum developed pressure at 65 °C bar
max
p working pressure bar
w
5 Inspection and testing
This part of ISO 11119 is intended to be used under a variety of national regulatory regimes, but has been
written so that it is suitable for use with the conformity assessment system of the Recommendations on the
transport of dangerous goods: Model regulations developed by the United Nations (Reference [16]). Attention
is drawn to requirements in specified relevant national regulations of the country (countries) where the cylinders
are intended to be used that might override the requirements given in this part of ISO 11119.
To ensure that the cylinders conform to this part of ISO 11119, they shall be subject to inspection and testing
in accordance with Clauses 6, 7, 8, and 9 by an inspection body (hereafter referred to as “the inspector”)
authorized to do so. Example forms of certificates that can be used are shown in Annexes A and B.
Equipment used for measurement, testing, and examination during production shall be maintained and
calibrated within a documented quality management system.
6 Materials
6.1 Liner materials
6.1.1 The liner materials shall conform in all relevant respects to the appropriate standard:
a) seamless steel liners: ISO 9809-1, ISO 9809-2 or ISO 9809-3, as appropriate;
b) seamless stainless steel liners: EN 1964-3;
c) seamless aluminium alloy liners: ISO 7866.
Relevant sections are those covering materials, thermal treatments, neck design, construction and workmanship,
and mechanical tests. This excludes the design requirements, since these are specified by the manufacturer
for the design of the composite cylinder (see 7.2.2).
6.1.2 The materials used shall be of uniform and consistent quality. The composite cylinder manufacturer
shall verify that each new batch of materials has the correct properties and is of satisfactory quality, and shall
maintain records so that the cast of material and the heat treatment batch (where applicable) used for the
manufacture of each cylinder can be identified.
6.1.3 The liner shall be manufactured from a metal or alloy suitable for the gas to be contained in accordance
with ISO 11114-1.
6.1.4 When a neck ring is provided, it shall be of a material compatible with that of the cylinder, and shall be
securely attached by a method appropriate to the liner material.
4 © ISO 2012 – All rights reserved

6.2 Composite materials
6.2.1 The overwrap materials shall be carbon fibre or aramid fibre or glass fibre or any mixture thereof.
6.2.2 The matrix shall be a polymer suited to the application, environment, and intended life of the product.
6.2.3 The supplier of the filament material and the matrix system component materials shall provide sufficient
documentation for the composite cylinder manufacturer to be able to identify fully the batch of materials used in
the manufacture of each cylinder.
6.2.4 The materials used shall be of uniform and consistent quality. The composite cylinder manufacturer
shall verify that each new batch of materials has the correct properties and is of satisfactory quality, and
maintain records from which the batch of materials used for the manufacture of each cylinder can be identified. A
certificate of conformity from the material manufacturer is considered acceptable for the purposes of verification.
6.2.5 Batches of materials shall be identified and documented to the satisfaction of the inspector.
7 Design and manufacture
7.1 General
7.1.1 A Type 3 fully-wrapped composite gas cylinder with load-sharing liner shall comprise:
a) an internal metal liner, which carries part of the longitudinal and circumferential load;
b) a composite overwrap formed by layers of continuous fibres in a matrix;
c) an optional external protection system.
Where necessary, care shall be taken to ensure that there is no adverse reaction between the liner and the
reinforcing fibre by the application of a suitable protective coating to the liner prior to the wrapping process.
7.1.2 Cylinders shall be designed with one or two openings along the central axis only. Threads shall extend
completely through the neck or have sufficient threads to allow full engagement of the valve.
The cylinder can also include additional parts (e.g. neck rings, bases).
7.1.3 Examples of certificates are shown in Annexes A and B.
7.2 Design submission
7.2.1 The design submission for each new design of cylinder shall include a detailed drawing, along with
documentation of the design including manufacturing and inspection particulars as detailed in 7.2.2, 7.2.3, and 7.2.4.
7.2.2 Documentation for the liner shall include (but not be limited to):
a) material, including limits of chemical analysis;
b) dimensions, minimum thickness, straightness, and out-of-roundness, with tolerances;
c) process and specification of manufacture;
d) heat treatment, temperatures, duration, and tolerances;
e) inspection procedures (minimum requirements);
f) material properties including minimum mechanical properties and hardness ranges, where applicable;
g) minimum design burst pressure;
h) dimensional details of valve threads and any other permanent features.
7.2.3 Documentation for the composite overwrap shall include (but not be limited to):
a) fibre material, specification, and mechanical properties requirements;
b) minimum composite thickness ;
c) thermosetting matrix — specifications (including resin, curing agent and accelerator), and resin bath
temperature where applicable;
d) thermoplastic matrix system — main component materials, specifications and process temperatures;
e) overwrap construction including the number of strands used, number of layers, layer orientation, and
tensioning of the fibre at wrapping (where applicable);
f) curing process, temperatures, duration, and tolerances, where applicable.
7.2.4 Documentation for the composite cylinder shall include (but not be limited to):
a) nominal water capacity, in litres, under ambient conditions;
b) dimensions with tolerances
c) list of intended contents, if intended for dedicated gas service;
d) test pressure, p ;
h
e) working pressure, p (if applicable), that shall not exceed 0,67 × p ;
w h
f) maximum developed pressure at 65 °C for specific dedicated gas(es), p ;
max
g) minimum design burst pressure;
h) design life in years, although cylinders with a test pressure of less than 60 bar shall have a non-
limited design life;
i) autofrettage pressure and approximate duration (where applicable);
j) nominal mass of the finished composite cylinder, including tolerances;
k) details of components which are permanently attached and form part of the qualified design (neck rings,
protective boots, etc.).
7.3 Manufacturing
7.3.1 The liner shall be manufactured in accordance with the manufacturer’s design (see 7.2.2) and the
International Standard for the relevant metallic material (as listed in 6.1.1).
7.3.2 The composite cylinder shall be fabricated from a load-sharing liner fully overwrapped with layers of
continuous fibres in a matrix applied under a controlled tension to develop the design composite thickness
specified in 7.2.3.
Liners can be stripped and re-wound provided that the overwrap has not been cured. The liner shall not be
overwrapped if it has been damaged or scored by the stripping process.
6 © ISO 2012 – All rights reserved

7.3.3 After wrapping is completed the composite shall be cured (if appropriate) using a controlled temperature
profile as specified in 7.2.3. The maximum temperature shall be such that the mechanical properties of the liner
material are not adversely affected.
7.3.4 If cylinders are subjected to an autofrettage operation, the autofrettage pressure and duration shall be
as specified in 7.2.4. The manufacturer shall demonstrate the effectiveness of the autofrettage by appropriate
measurement technique(s) acceptable to the inspector.
7.3.5 If cylinders are subjected to a prestressing or fibre tensioning during wrapping in order to actively
change the final stresses in the finished cylinder, the level of stress shall be as specified in the documentation
in 7.2.4 and levels of stress of tensioning shall be recorded or monitored.
8 Type approval procedure
8.1 General requirements
Each new cylinder design shall be submitted by the manufacturer to the inspector. The type approval tests
detailed in 8.2 shall be performed, under the supervision of the inspector, on each new cylinder design or
design variant.
8.2 Prototype tests
8.2.1 A minimum of 30 cylinders that are representative of the new design shall be made available for prototype
testing. Upon successful completion of all prototype tests, the remaining untested cylinders from the prototype
qualification batch can be used for service.
8.2.2 If, for special applications, the total number of cylinders required is less than 30, sufficient cylinders
shall be made to complete the prototype tests required, in addition to the production quantity. In this case, the
approval validity is limited to this batch only.
For a limited design change (design variant), in accordance with Table 1, a reduced number of cylinders shall
be selected by the inspector.
8.2.3 The batch of liners, prior to being wrapped, shall conform to the design requirements and shall be
inspected and tested in accordance with 9.1.
8.2.4 The composite material(s), prior to the cylinders being wrapped, shall conform to the design requirements
and shall be tested in accordance with 9.3.
8.2.5 Tests for a new cylinder design shall be supervised by an inspector and shall consist of:
a) hydraulic proof pressure test, in accordance with 8.5.1 or, hydraulic volumetric expansion test, in
accordance with 8.5.2;
b) liner burst test, in accordance with 8.5.3;
c) cylinder burst test, in accordance with 8.5.4;
d) ambient temperature cycle test, in accordance with 8.5.5;
e) environmental cycle test, in accordance with 8.5.6;
f) flaw test, in accordance with 8.5.7;
g) drop test, in accordance with 8.5.8;
h) high velocity impact (gunfire) test, in accordance with 8.5.9
i) torque test, in accordance with 8.5.12.
8.2.6 Tests that are optional depending upon the design and intended use of the cylinder are:
a) fire resistance test, in accordance with 8.5.10;
b) salt water immersion test, in accordance with 8.5.11;
c) environmentally assisted stress rupture test, in accordance with 8.5.13;
8.2.7 For approval of a design variant as specified in 8.4, it s only necessary to carry out the tests as stated in
Table 1 under supervision of the inspector. A cylinder approval by a reduced series of tests shall not be used as
a basis for a second design variant approval with a reduced set of tests (i.e. multiple changes from an approved
design are not permitted), although individual test results can be used as applicable (see 8.4.2).
8.2.8 Tests can be combined such that one cylinder can be used for more than one test. For example, the
cylinder burst test in the drop test (8.5.12) can be used to satisfy the requirement of the burst test (8.5.4).
8.2.9 If the results of the above prototype tests are satisfactory, the inspector shall issue a type approval
certificate, a typical example of which is given in Annex A.
8.2.10 After completion of the tests, the cylinders shall be destroyed or made incapable of holding pressure.
8.3 New design
8.3.1 After approval, no alteration shall be made to the design or to the method of manufacture without
requalification
8.3.2 A new cylinder design requires full type approval testing. A cylinder shall be considered to be of a new
design compared with an existing approved design if the method of manufacture or cylinder design has changed
to a significant extent. Examples are given in a) to g).
a) It is manufactured in a different factory. A relocation of a factory does not require a new cylinder design
approval provided all equipment and procedures remain the same as for the original design approval.
b) It is manufactured by a process that is significantly different from the process used in the design type
approval. A significant change is regarded as a change that would have a measurable change in the
performance of the liner and/or finished cylinder. The inspector shall determine when a change in process
or design or manufacture is significantly different from the original qualified design.
c) The nominal outside diameter has changed more than 50 % from the qualified design.
d) A fibre of the same specification classification and mechanical properties, but with a different linear density
shall not be considered a new fibre type. Minor changes in the wrapping pattern shall not be considered
to be a new design.
e) The cylinder is manufactured with a new fibre type. A fibre shall be considered to be of a new fibre type when:
1) the fibre is of a different classification (e.g. glass, aramid or carbon);
2) the fibre is produced from a different precursor [e.g. polyacrylonitrile (PAN) or pitch for carbon];
3) the fibre is not equivalent [see 8.4.1 i)] to the fibre in the original design
f) The matrix materials (i.e. resin, curing agent, accelerator) are different and not chemically equivalent to the
original design (e.g. a change from an epoxy to a polyester).
g) The test pressure has increased more than 60 % from the qualified design.
8 © ISO 2012 – All rights reserved

8.3.3 A cylinder shall also be considered to be of a new design compared with an existing approved design if
the liner method of manufacture or design has changed to a significant extent. Examples are given in a) to c).
a) It is manufactured in a different factory. A relocation of a factory does not require a new cylinder design
approval provided all equipment and procedures remain the same as for the original design approval.
b) It is manufactured from a material of different composition or composition limits from that used in the
original type tests.
c) The material properties are outside the original design limits.
8.4 Design variants
8.4.1 For cylinders similar to an approved design, a reduced type approval testing programme is required as
specified in Table 1. A cylinder shall be considered to be a design variant if changes are limited to items a) to k).
a) The nominal length of the cylinder has changed by more than 5 %.
b) The nominal outside diameter has changed by 50 % or less.
c) The autofrettage pressure has changed by more than 5 % or 10 bar, whichever is the lower.
d) There is a change in the design test pressure up to and including 60 %.
NOTE Where a cylinder is to be used and marked for a lower test pressure than that for which design approval has
been given, it is not deemed to be of a new design or design variant.
e) The base profile and/or base thickness of the liner has changed relative to the cylinder diameter and
minimum wall thickness and outside the tolerances provided in the design submission.
f) The minimum wall thickness of the liner has changed by more than 5 %-
g) There have been changes to the composite thickness or wrap pattern other than the changes necessary
to accommodate the changes of diameter and/or length.
h) Matrix materials (i.e. resin, curing agent, accelerator) are chemically equivalent to the original design.
i) When equivalent overwrapping fibres are used.
Equivalent fibres are manufactured from the same nominal raw materials, using the same process of
manufacture and having the same physical structure and the same nominal physical properties, and where
the average tensile strength and modulus is within ± 5 % of the fibre properties in an approved cylinder
design. Carbon fibres made from the same precursor can be equivalent. Aramid, carbon and glass fibres
are not equivalent.
NOTE Where a new equivalent fibre has been prototype tested for an existing design, then all the manufacturer’s
existing prototype tested designs are regarded as prototype tested with the new fibre without the need for any additional
prototype testing.
j) When an equivalent liner is used:
1) equivalent liners are manufactured from the same nominal raw materials, using the same process
of manufacture and having the same physical structure and where the average tensile strength and
modulus is within ± 5 % of the approved cylinder design;
2) the equivalent liner material shall be subjected to the material tests specified in 9.1.3 and the liner
burst test specified in 8.5.3 and in both cases shall meet the minimum requirements specified in 7.2.2;
3) where a new equivalent liner has been prototype tested for an existing design, then all the manufacturer’s
existing prototype tested designs are regarded as prototype tested with the new liner without the need
for any additional prototype testing.
k) When the cylinder thread has changed:
1) when a cylinder design has only a different thread compared to an approved design, only the torque
test, in accordance with 8.5.12, shall be performed.
8.4.2 A cylinder approval by a reduced series of tests (a “design variant”) shall not be used as a basis for a
second design variant approval with a reduced set of tests (i.e. multiple changes from an approved design are
not permitted). If a test has been conducted on a design variant (A) that falls within the testing requirements
for a second variant (B), then the result for (A) can be applied to the new design variant (B) test programme.
However design variant (A) cannot be used as the reference for determining the testing required for any new
design variant.
8.4.3 Where a design variant involves more than one parameter change all the tests required by those
parameter changes shall be performed once only.
8.4.4 The inspector shall determine the level of reduced testing if not defined in Table 1, but a fully approved
design shall always be used as a reference for the new design variant (i.e. new design variants shall not be
approved by reference only to a previous design variant)
8.5 Type approval test procedures and criteria
8.5.1 Proof pressure test
8.5.1.1 Procedure
When carrying out the pressure test, a suitable fluid (normally water) shall be used as the test medium. This
test requires that the pressure in the cylinder be increased gradually and regularly until the test pressure, p , is
h
reached. The cylinder test pressure shall be held for at least 30 s with the cylinder isolated from the pressure
source, during which time there shall be no decrease in the recorded pressure or evidence of any leakage.
Adequate safety precautions shall be taken during the test.
If leakage occurs in the piping or fittings, the cylinders shall be re-tested after repairing such leakages.
Where cylinders are subjected to autofrettage, the proof pressure test can immediately follow the
autofrettage process.
+10
The limit deviation on attaining test pressure shall be test pressure (p + 3) % or p bar , whichever is the
h
()
h 0
lower. Pressure gauges with the appropriate accuracy shall be used.
All internal surfaces of cylinders shall be dried (to ensure no free water) immediately after testing.
Alternatively a pneumatic pressure test can be used provided that appropriate measures are taken to ensure safe
operation and to contain any energy that can be released, which is considerably more than in the hydraulic test.
8.5.1.2 Criteria
The cylinder shall be rejected if there are leaks, failure to hold pressure or visible permanent deformation after
the cylinder is depressurized.
NOTE Cracking of resin is not necessarily a sign of permanent deformation
10 © ISO 2012 – All rights reserved

Table 1— Type approval tests
Design variant changes
New
Nominal length Nominal diameter Equiv- Liner Test pressure Composite Equiv- Equiv- Auto-
Test
Test Des-
alent thickness thick’ or alent alent. frettage
No.
>5 % >50 % ≤20 % >20 % ≤20 % >20 %
ign
liner change liner base fibre matrix
≤50 % ≤50 % (c). ≤60 %
form
9.1 Liner material test x x x
9.4 Composite material
x x x
tests
8.5.1–2 Hydraulic pressure x x x x x x x x x x x x
8.5.3 Liner burst x x x x x x x
8.5.4 Hydraulic burst x x x x x x x x x x x x x
8.5.5 Ambient cycle x x x x x x x x x x x x x
8.5.6 Environmental cycle x x
8.5.7 Flaw x x
b
8.5.8 Drop x x x — x x
c b
8.5.9 High velocity impact x — — x
a b
8.5.10 Fire resistance x x x — x
a
8.5.11 Salt water x x
f
8.5.12 Torque test x
a d d d e
8.5.13 Stress rupture test x — — — —
a
Optional test required according to the design and intended use of the cylinder.
b
Conducted with a liner thickness decrease only.
c
Test to be conducted for reduction in diameter only.
d
Where burst pressure to test pressure ratio of design variant is over 20 % greater than the same ratio for the approved design.
e
For an increase in autofrettage pressure of greater than 15 %.
f
When a cylinder design has only a different thread compared to an approved design only the torque test, in accordance with 8.5.12 shall be performed.

8.5.2 Hydraulic volumetric expansion test
8.5.2.1 Procedure
When carrying out the pressure test, a suitable fluid ( normally water) shall be used as the test medium. This
test requires that the pressure in the cylinder be increased gradually and regularly until the test pressure, p , is
h
reached. The cylinder test pressure shall be held for at least 30 s with the cylinder isolated from the pressure
source, during which time there shall be no decrease in the recorded pressure or evidence of any leakage.
Adequate safety precautions shall be taken during the test.
If leakage occurs in the piping or fittings, the cylinders shall be re-tested after repairing such leakages.
The total volumetric expansion of each cylinder under the test pressure, p , and the permanent volumetric
h
expansion of the cylinder after the pressure is released shall be recorded. The elastic expansion (i.e. total
expansion less permanent expansion) under test pressure shall then be established for each cylinder.
Where cylinders are subjected to autofrettage, the hydraulic volumetric expansion pressure test can immediately
follow the autofrettage process.
+10
The limit deviation on attaining test pressure shall be (p + 3) % or p bar , whichever is the lower.
h
()h 0
All internal surfaces of cylinders shall be dried (to ensure no free water) immediately after testing.
8.5.2.2 Criteria
The cylinder shall be rejected if:
a) there are leaks or failure to hold pressure;
b) there is permanent expansion (i.e. volumetric expansion after the pressure has been released) in excess
of 5 % of the total expansion.
8.5.3 Liner burst test
8.5.3.1 Procedure
One liner shall be tested hydraulically to destruction by pressurizing at a rate of no more than 5 bar/s. The test
shall be carried out under ambient conditions.
The parameters that shall be monitored and recorded are:
a) burst pressure;
b) the number of pieces;
c) description of failure;
d) pressure–time curve or pressure–volume curve.
8.5.3.2 Criteria
The burst pressure, p , shall be not less than the minimum design burst pressure specified in the design
bl
submission (7.2.2). Failure shall initiate in the liner side wall and the liner shall remain in one piece.
12 © ISO 2012 – All rights reserved

8.5.4 Cylinder burst test
8.5.4.1 Procedure
Three cylinders shall be tested hydraulically to destruction by pressurizing at a rate of no more than 10 bar/s.
The test shall be carried out under ambient conditions. Prior to the commencement of the test, it shall be
ensured that no air is trapped within the system.
The parameters that shall be monitored and recorded are:
a) burst pressure;
b) description of failure;
c) pressure–time curve or pressure–volume curve.
8.5.4.2 Criteria
a) The burst pressure shall exceed the minimum design burst pressure specified by the cylinder
manufacturer (see 7.2.4).
b) The burst pressure, p , for cylinders with carbon fibre reinforcement shall be not less than 2,0 × p , where
b h
p is the test pressure.
h
c) The burst pressure, p , for cylinders with aramid fibre reinforcement shall be not less than 2,1 × p .
b h
d) The burst pressure, p , for cylinders with glass fibre reinforcement shall be not less than 2,4 × p .
b h
8.5.5 Ambient cycle test
8.5.5.1 For cylinders with test pressure equal to, or greater than, 60 bar
8.5.5.1.1 General
Where a cylinder is intended for use only with one or more specific gases the design can be designated for
dedicated gas use. The gases permitted in the cylinder shall be identified clearly on the cylinder label (see 10.2).
8.5.5.1.2 Procedure
Two cylinders shall be subjected to a hydraulic pressure cycle test to test pressure, p , for unspecified gas service
h
or maximum developed pressure at 65 °C, p , for the dedicated gas which has the greatest developed pressure.
max
The test shall be carried out using a non-corrosive fluid under ambient conditions, subjecting the cylinders to
successive reversals at an upper cyclic pressure which is equal to the hydraulic test pressure, p , or maximum
h
developed pressure at 65 °C, p , as appropriate.
max
The value of the lower cyclic pressure shall not exceed 10 % of the upper cyclic pressure, but shall have an
absolute maximum of 30 bar. The frequency of reversals of pressure shall not exceed 0,25 Hz (15 cycle/min).
The temperature on the outside surface of the cylinder shall not exceed 50 °C during the test.
The parameters that shall be monitored and recorded are:
a) the temperature of the cylinder;
b) number of cycles achieving upper cyclic pressure;
c) minimum and maximum cyclic pressures;
d) cycle frequency;
e) test medium used;
f) mode of failure, if appropriate.
8.5.5.1.3 Criteria
Both cylinders shall withstand N pressurization cycles to test pressure, p , or N pressurization cycles to
h d
maximum developed pressure, p without failure by burst or leakage, where:
max
N = t × 250 cycle/year of design life
N = t × 500 cycle/year of design life
d
where t is the number of years of design life, which shall be a whole number, not less than 15.
The test shall continue for a further N or N cycles, or until the cylinder fails by leakage, whichever is the sooner.
d
In either case the cylinder shall be deemed to have passed the test. However if failure during this second part
of the test is by burst, then the cylinder shall have failed the test (see Table 2).
If the cylinder is designed to pass 12 000 hydraulic cycles to test pressure or 24 000 cycles to maximum
developed pressure, and achieves this level consistently in the test it is not necessary to limit the design life of
the cylinder.
Table 2 — Criteria for the ambient cycle test
1st part 2nd part
0 to N N to 2N but 2N no more than 12 000
Number of cycles
0 to N N to 2N but 2N no more than 24 000
d d d d
No leakage/burst = Pass
Criteria No leakage or burst Leakage = Pass
Pass 1st part Burst = Fail
8.5.5.2 For cylinders with test pressure less than 60 bar
8.5.5.2.1 Procedure
Two cylinders shall be subjected to a hydraulic pressure cycle test to test pressure.
The test shall be performed using a non-corrosive fluid under ambient conditions, subjecting the cylinders to
successive reversals at an upper cyclic pressure which is equal to the hydraulic test pressure, p .
h
The value of the lower cyclic pressure shall not exceed 10 % of the upper cyclic pressure. The frequency of
reversals of pre
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