ISO 11119-2:2002

INTERNATIONAL ISO
STANDARD 11119-2
First edition
2002-05-15
Gas cylinders of composite construction —
Specification and test methods —
Part 2:
Fully wrapped fibre reinforced composite
gas cylinders with load-sharing metal liners
Bouteilles à gaz composites — Spécifications et méthodes d'essai —
Partie 2: Bouteilles à gaz composites entièrement bobinées renforcées par
des liners métalliques transmettant la charge

Reference number
©
ISO 2002
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©  ISO 2002
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ii © ISO 2002 – 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
7 Design and manufacture.5
8 Type approval procedure.8
9 Batch inspection and testing .21
10 Cylinder marking .24
Annex A (informative) Examples of design approval certificate.25
Annex B (informative) Specimen test reports .26
Bibliography.29

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 3.
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 part of ISO 11119 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.
ISO 11119 consists of the following parts, under the general title Gas cylinders of composite construction —
Specification and test methods:
— Part 1: Hoop wrapped composite gas cylinders
— Part 2: Fully wrapped fibre reinforced composite gas cylinders with load-sharing metal liners
— Part 3: Fully wrapped fibre reinforced composite gas cylinders with non-metallic and non-load-sharing metal
liners
Annexes A and B of this part of ISO 11119 are for information only.
iv © ISO 2002 – All rights reserved

Introduction
The purpose of ISO 11119 is to provide a specification for the design, manufacture, inspection and testing of a
cylinder for world-wide usage. The objective is to balance design and economic efficiency against international
acceptance and universal utility.
ISO 11119 aims to eliminate the concern about climate, duplicate inspection and restrictions currently existing
because of lack of definitive International Standards and should not be construed as reflecting on the suitability of
the practice of any nation or region.

INTERNATIONAL STANDARD ISO 11119-2:2002(E)

Gas cylinders of composite construction — Specification
and test methods —
Part 2:
Fully wrapped fibre reinforced composite gas cylinders with
load-sharing metal liners
1 Scope
This part of ISO 11119 specifies requirements for composite gas cylinders up to and including 450 litres water
capacity, for the storage and conveyance of compressed or liquefied gases with test pressures up to and including
1)
650 bar . The cylinders are constructed in the form of a seamless metallic liner over-wrapped with carbon fibre or
aramid fibre or glass fibre (or a mixture thereof) in a resin matrix, to provide circumferential reinforcement.
This part of ISO 11119 addresses fully wrapped composite cylinders with a load-sharing liner (i.e. a liner that
shares the load of the overall cylinder design) and a design life from 10 a to non-limited life. For cylinders with
design life in excess of 15 a, and in order for these cylinders to remain in service beyond 15 a, requalification of
these cylinders is recommended.
This part of ISO 11119 does not address the design, fitting and performance of removable protective sleeves.
Where these are fitted they should be considered separately.
NOTE 1 ISO 11439 applies to cylinders intended for use as fuel containers on natural gas vehicles.
NOTE 2 ISO 11623 covers periodic inspection and retesting of composite cylinders.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 11119. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 11119 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
ISO 6506-1:1999, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6508-1:1999, Metallic materials — Rockwell hardness test — Part 1: Test method (scales A, B, C, D, E, F, G,
H, K, N, T)
ISO 7225:1994, Gas cylinders — Precautionary labels
ISO 7866:1999, Gas cylinders — Refillable seamless aluminium alloy gas cylinders — Design, construction and
testing
1) 1 bar = 10 Pa.
ISO 9809-1:1999, 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 9809-2:2000, 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 11114-1:1997, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas
contents — Part 1: Metallic materials
ISO 11439:2000, Gas cylinders — High pressure cylinders for the on-board storage of natural gas as a fuel for
automotive vehicles
ISO 13341:1997, Transportable gas cylinders — Fitting of valves to gas cylinders
2)
ISO 13769 , Gas cylinders — Stamp marking
EN 1964-3:2000, 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 D 2343, Standard Test Method for Tensile Properties of Glass Fiber Strands, Yarns, and Rovings Used in
Reinforced Plastics
ASTM D 4018, Standard Test Methods for Properties of Continuous Filament Carbon and Graphite Fiber Tows
SACMA SRM 16R-94, Recommended Test Method for Tow Tensile Testing of Carbon Fibers
3 Terms and definitions
For the purposes of this part of ISO 11119, the following terms and definitions apply.
3.1
aramid fibre
continuous filaments of aramid laid up in tow form, used for reinforcement
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
collective term for a set of homogeneous items or material
NOTE The number of items in a batch may vary according to the context in which the term is used.
3.3.1
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

2) To be published.
2 © ISO 2002 – All rights reserved

3.3.2
batch of finished cylinders
production quantity of up to 200 finished cylinders successively produced (plus finished cylinders required for
destructive testing), of the same nominal diameter, length, thickness and design
NOTE The batch of finished cylinders may contain different batches of liners, fibres and matrix materials.
3.4
burst pressure
highest pressure reached in a cylinder during a burst test
3.5
carbon fibre
continuous filaments of carbon laid up in tow form, used for reinforcement
3.6
composite overwrap
the combination of fibres and matrix
3.7
dedicated gas service
service in which a cylinder is to be used only with specified gas or gases
3.8
equivalent fibre
fibre 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
NOTE Carbon fibres made from the same precursor can be equivalent, but aramid, carbon and glass fibres are not
equivalent.
3.9
equivalent liner
liner equivalent to a liner in a previously prototype tested cylinder when any of the following apply:
 the liner is of the prototype tested design except that it is manufactured in a different factory;
 the liner is of the prototype tested design except that it is manufactured using a significantly different process
from that used to produce the prototype tested design;
 the liner is of the prototype tested design except that it is given a heat treatment outside the limits specified in
the prototype tested design
3.10
exterior coating
layers of material applied to the cylinder as protection or for cosmetic purposes
NOTE The coating may be clear or pigmented.
3.11
fully wrapped cylinder
cylinder reinforced with fibres in a resin matrix to take both circumferential and longitudinal stress
3.12
glass fibre
continuous filaments of glass laid up in tow form, used for reinforcement
3.13
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
3.14
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
3.15
matrix
material which is used to bind and hold the fibres in place
4 Symbols
See Table 1.
Table 1 — Symbols and their designations
Symbol Designation Unit
p
Burst pressure of finished cylinder bar
b
p
Burst pressure of liner bar
bl
p
Test pressure bar
h
p
Maximum developed pressure at 65°C bar
max
p
Working pressure bar
W
5 Inspection and testing
Evaluation of conformity is required to be performed in accordance with the relevant regulations of the country(ies)
where the cylinders are used. In order 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 authorized inspection body
(hereafter referred to as “the inspector”) recognized in the country(ies) of use. The inspector shall be competent for
the inspection of cylinders.
6 Materials
6.1 Liner materials
6.1.1 The liner materials shall conform in all relevant respects to the appropriate standard, as follows:
a) seamless steel liners: ISO 9809-1 or ISO 9809-2, as appropriate;
b) seamless stainless steel liners: EN 1964-3;
c) seamless aluminium alloy liners: ISO 7866.
This excludes the design requirements, since these are specified by the manufacturer for the design of the
composite cylinder (see 7.2.2).
NOTE For liners with water a capacity > 150 l the relevant sections of the above standards also apply.
4 © ISO 2002 – All rights reserved

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 from which the batch of materials used for the manufacture of each cylinder can be identified. A certificate
of conformance from the liner material manufacturer is considered acceptable for the purposes of verification.
6.1.3 The cast shall be identified to the satisfaction of the inspector.
6.1.4 The liner shall be manufactured from a metal or alloy suitable for containing the gas (see ISO 11114-1).
Furthermore the liner material shall be evaluated by the manufacturer as suitable for the specific application. If the
liner material is not covered by ISO 11114-1 for a particular gas/commodity, the responsibility for the approval of
material selection should reside with the authority having jurisdiction in the country of use.
6.1.5 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.
6.2 Composite materials
6.2.1 The overwrap filament materials shall be carbon fibre or aramid fibre or glass fibre (or any mixture thereof).
6.2.2 The resin matrix shall be a polymer suited to the application, environment and intended life of the product;
e.g., epoxy or modified epoxy with amine or anhydride curing agent, vinyl esters and polyesters.
6.2.3 The supplier of the filament material and the resin system component material shall provide sufficient
documentation for the composite cylinder manufacturer to be able to fully identify 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 conformance 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.
6.2.6 The manufacturer shall ensure 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 (if necessary).
7 Design and manufacture
7.1 General
7.1.1 A fully wrapped composite gas cylinder with load-sharing liner shall comprise the following parts:
 an internal metal liner, which carries part of the longitudinal and circumferential load;
 a composite overwrap formed by layers of continuous fibres in a matrix;
 an optional exterior coating to provide external protection. When this is an integral part of the design it shall be
permanent.
7.1.2 Cylinders may be designed with one or two openings along the central axis only. Parallel threads shall
extend completely through the neck or have sufficient threads to allow full engagement of the valve.
7.1.3 The cylinder may also include additional parts such as rings, bases, etc.
7.1.4 The composite cylinder shall be certified by the inspector. The inspector shall certify that the design,
manufacture, inspection and testing were carried out in accordance with this part of ISO 11119. Example forms of
certificates are shown in annexes A and B.
7.1.5 The cylinders shall be designed for high reliability under sustained load and cyclic loading. Therefore it is
necessary to take account of the properties of the individual composite fibres and to establish their respective
minimum fibre stress ratios.
The fibre stress ratio is defined as the fibre stress at calculated design minimum burst pressure divided by the fibre
stress at × 2/3 test pressure.
The minimum fibre stress ratios shall be as follows:
 for glass — 3,4
 for aramid — 3,1
 for carbon — 2,4
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 stress analysis, manufacturing and inspection particulars as detailed in
7.2.2, 7.2.3, 7.2.4 and 7.2.5.
7.2.2 Documentation for the liner shall include:
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 (mechanical properties requirements);
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:
a) fibre material, specification and mechanical properties requirements;
b) fibre construction, strand-geometry and treatment;
c) resin system, main components and resin bath temperature where applicable;
d) resin system, curing agent, materials and specifications where applicable;
e) resin system, accelerator, materials and specifications where applicable;
f) overwrap construction including the number of strands used;
g) curing process, temperatures, duration and tolerances.
6 © ISO 2002 – All rights reserved

7.2.4 Documentation for the composite cylinder shall include:
a) water capacity in litres;
b) list of intended contents if intended for dedicated gas service;
c) working pressure, p (if applicable and which shall not exceed test pressure × 2/3);
w
d) composite cylinder test pressure, p ;
h
e) maximum developed pressure at 65 °C for specific dedicated gas(es), p ;
max
f) design life in years; cylinders with a test pressure of less than 60 bar shall have a non-limited design life;
g) autofrettage pressure and approximate duration (where applicable);
h) tensioning of the fibre at winding (where applicable);
i) weight.
7.2.5 Stress analysis shall be carried out and documentation provided in accordance with the following.
The stresses in the composite material(s) and in the liner shall be calculated using appropriate finite element stress
analysis or other stress analysis programmes, which take into account the non-linear material behaviour of the
liner. The nominal thickness and nominal properties of the respective materials shall be used for the calculations.
A table summarizing the stresses at zero, test pressure × 2/3, test pressure and design minimum burst pressure
shall be provided.
The fibre stress ratio(s) for the design shall exceed those stated in 7.1.5.
NOTE There is no standardized calculation method for the stress analysis. Therefore the objective of this clause is to
demonstrate only that the design stress ratios have been met.
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 over-wrapped with resin-
impregnated continuous fibres. Winding shall be applied in the longitudinal and circumferential directions under
controlled tension to in order to develop the design composite thickness and as specified in the documentation in
7.2.3.
Liners may be stripped and re-wound, provided that the overwrap has not been cured. The liner shall not be over-
wrapped if it has been damaged or scored by the stripping process.
7.3.3 After winding is completed, the composite shall be cured (if appropriate) using a controlled temperature
profile as specified in the documentation 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 the documentation 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 winding 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
The design submission of each new design of cylinder shall be submitted by the manufacturer to the inspector. The
type approval tests detailed in 8.2 shall be carried out on each new design or design variant under the supervision
of the inspector.
8.2 Prototype tests
8.2.1 A minimum of 30 cylinders that are guaranteed by the manufacturer to be representative of the new design
shall be made available for prototype testing.
8.2.2 However, if for special applications the total number of cylinders required is less than 30, enough cylinders
shall be made to complete the prototype tests required, in addition to the production quantity. Then the approval
validity is limited to this batch only.
8.2.3 For a limited design change (design variant), in accordance with Table 2, a reduced number of cylinders
may be selected by the inspector.
8.2.4 The inspector shall verify that the batch of liners, prior to being wrapped, conforms to the design
requirements and is inspected and tested in accordance with 9.1. Where specified in Table 2, one liner shall be
selected and subjected to a burst test in accordance with 8.5.3.
8.2.5 The inspector shall verify that the composite material(s), prior to the cylinders being wrapped, conform to
the design requirements and are tested in accordance with 9.3.
8.2.6 The inspector shall verify that all cylinders in the batch produced for new design approval conform to the
design submission and are tested in accordance with 9.4.
8.2.7 Except for the cases identified in 8.2.8, the inspector shall supervise the following tests on the cylinders
selected:
a) hydraulic proof pressure test, in accordance with 8.5.1 or hydraulic volumetric expansion test, in accordance
with 8.5.2;
b) burst test, in accordance with 8.5.4;
c) ambient cycle test, in accordance with 8.5.5;
d) environmental cycle test, in accordance with 8.5.6;
e) flaw test, in accordance with 8.5.7;
f) drop test, in accordance with 8.5.8;
g) high velocity impact (gunfire) test, in accordance with 8.5.9;
h) fire resistance test, if a pressure relief device is fitted to prevent failure in case of fire in service, in accordance
with 8.5.10;
i) salt water immersion test, in accordance with 8.5.11;
j) torque test, in accordance with 8.5.12;
k) high temperature creep test, in accordance with 8.5.13.
8 © ISO 2002 – All rights reserved

8.2.8 For variations in design from the new design cylinder as specified in 8.4, it is only necessary to carry out
the tests as prescribed in Table 2. 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).
8.2.9 If the results of the verifications in accordance with 8.2.4, 8.2.5, 8.2.6 and either 8.2.7 or 8.2.8, as
applicable, are satisfactory, the inspector shall issue a design approval certificate, a typical example of which is
given in annex A.
8.2.10 All test cylinders shall be rendered unserviceable after testing has been completed.
8.3 New design
8.3.1 No alteration shall be made to the design or the method of manufacture after approval unless such
alteration has received the prior agreement of the inspector.
8.3.2 A new cylinder design requires full qualification testing. A cylinder shall be considered to be of a new
design compared with an existing approved design if the method of cylinder manufacture or design has changed to
a significant extent, e.g.
a) It is manufactured in a different factory.
The testing required for cylinders after relocation of an existing factory shall be evaluated by the inspector.
b) It is manufactured by a process that is significantly different from the process used in the design qualification.
NOTE A significant change is regarded as a change that would give rise to measurable change in the performance of the
liner and/or finished cylinder. The inspector determines 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) The composite overwrap materials are significantly different from the qualified design, e.g. different resin
system or fibre type.
e) The test pressure has increased more than 60 % from the qualified design.
8.3.3 A cylinder shall also be considered to be of a new design compared with an existing approved design if the
method of liner manufacture or design has changed to a significant extent, e.g.
a) It is manufactured in a different factory.
The testing required for liners after relocation of an existing factory shall be evaluated by the inspector.
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 qualification testing programme may only be
required. A cylinder shall be considered to be a design variant if changes are limited to the following conditions:
a) the nominal length of the cylinder has changed;
b) the nominal outside diameter has changed by less than 50 %;
c) the autofrettage pressure has changed by more than 5 % or 10 bar, whichever is the lower;
d) the base profile and/or base thickness of the liner has changed relative to the cylinder diameter and minimum
wall thickness;
e) there is an increase 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.
f) there is a minor change in the composite overwrapping thickness (up to 5 %) or the wrapping pattern has
changed;
g) the nominal wall thickness of the liner has changed;
h) matrix materials (i.e. resin, curing agent, accelerator) are different but are chemically equivalent to the original
design;
i) when equivalent overwrapping fibres are used;
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 material is used the new liner shall
1) be subjected to the material tests specified in 9.1.3 and
2) meet the minimum requirements specified in 7.2.2 and the liner burst test, in accordance with 8.5.3, and
shall also meet the minimum requirements of the prototype tested design.
NOTE 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.
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 carried out.
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 2, 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 Qualification test procedures and criteria
8.5.1 Hydraulic proof pressure test
8.5.1.1 Procedure
This test requires that the hydraulic pressure in the cylinder be increased gradually and regularly until the test
pressure, p , is reached. The cylinder test pressure shall be held for a sufficiently long period (at least 30 s) in order
h
to ascertain that there are no leaks and no failure. If leakage occurs in the piping or fittings, the cylinders may be
retested after repairing such leakages.
Where cylinders are subjected to autofrettage, the hydraulic proof pressure test may be part of or immediately
follow the autofrettage process.
10 © ISO 2002 – All rights reserved

Table 2 — Qualification tests
Design changes
Length Diameter  Test pressure
Test New
Liner Composite
Test
Equiv. Equiv. Equiv.
No. design
a
u 50 % > 50 % u 20 % > 20 % thickness u 20 % > 20 % thick or Thread
liner fibre matrix
change pattern
u 50 %  u 60 %
9.1 Liner material test ×   × ×
9.4 Composite material tests ×     × × ×
8.5.1/2
Hydraulic pressure × × × × × × × × × × ×
b b
8.5.3 Liner burst × × × × × × × ×
8.5.4 Cylinder burst × × × × × × × × × × ×
8.5.5
Ambient cycle × × × × × × × × × × ×
8.5.6 Environmental cycle
×
8.5.7 Flaw ×  ×
c
8.5.8 Drop test × × ×  × ×
×
High velocity impact
d c
8.5.9 ×   ×
× ×
(gunfire)
c
8.5.10 Fire resistance × × ×  ×
×
8.5.11 Salt water ×
8.5.12 Torque test ×      ×
b b b
8.5.13 High temp. creep ×
× × ×
a
Also applies for change in autofrettage pressure.
b
Where burst pressure to test pressure ratio of design variant is over 20 % greater than the same ratio for the approved design.
c
Conducted with a liner thickness decrease only.
d
Test to be conducted for reduction in diameter only

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.
8.5.2 Hydraulic volumetric expansion test
8.5.2.1 Procedure
This test requires that the hydraulic pressure in the cylinder be increased gradually and regularly until the test
pressure, p , is reached. The cylinder test pressure shall be held for a sufficiently long period (at least 30 s) in order
h
to ascertain that there are no leaks and no failure. If leakage occurs in the piping or fittings, the cylinders may be
retested 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 can then be established for each cylinder.
Where cylinders are subjected to autofrettage, the hydraulic volumetric expansion test may be part of or
immediately follow the autofrettage process.
8.5.2.2 Criteria
The cylinder shall be rejected if either:
a) there are leaks or failure to hold pressure or
b) it shows a permanent expansion at zero pressure in excess of 5 % of the total expansion.
8.5.3 Liner burst test
8.5.3.1 Procedure
One cylinder 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.
Parameters to monitor and record 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 of the liner, p , shall be not less than the minimum 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 2002 – 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 5 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.
Parameters to monitor and record are
a) burst pressure;
b) description of failure;
c) pressure/time curve or pressure/volume curve.
8.5.4.2 Criteria
The burst pressure of the finished cylinder, p , shall be not less than the test pressure, p , × 2 of the composite
b h
cylinder design.
8.5.5 Ambient cycle test
NOTE It is recommended that no air be trapped within the system prior to the commencement of the 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 may 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 that 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 cycles per min).
The temperature on the outside surface of the cylinder shall not exceed 50 °C during the test.
Parameters to monitor and record are
a) 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
The cylinders shall withstand N pressurization cycles to test pressure, p , or N pressurization cycles to maximum
h d
developed pressure, p , without failure by burst or leakage, where:
max
N = y × 250 cycles per year of design life
N = y × 500 cycles per year of design life
d
y is the number of years of design life
y shall be a whole number which is not less than 10 years.
The test shall continue for a further N or N cycles, or until the cylinder fails by leakage, whichever is the sooner. In
d
either case the cylinder shall be deemed to have passed the test. However, should failure during this second part
of the test be by burst, then the cylinder shall have failed the test (see Table 3).
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.
NOTE For cylinder without limit in design life the actual service life of the design is subject to conformity assessment.
Table 3 — Criteria for 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 carried out using a non-corrosive fluid under ambient conditions, subjecting the cylinders to
successive reversals at an upper cyclic pressure that 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 pressure shall not exceed 0,25 Hz (15 cycles per min). The temperature on the outside surface of the
cylinder shall not exceed 50 °C during the test.
Parameters to monitor and record are
a) temperature of the cylinder;
b) number of cycles achieving upper cyclic pressure;
c) minimum and maximum cyclic pressures;
d) cycle frequency;
14 © ISO 2002 – All rights reserved

e) test medium used;
f) mode of failure, if appropriate.
8.5.5.2.2 Criteria
The cylinders shall withstand 12 000 pressurization cycles to test pressure, p . If the cylinder is designed to pass
h
12 000 hydraulic cycles to test pressure and achieves this level consistently in the test, it is not necessary to limit
the design life of the cylinder.
NOTE For cylinders without limit in design life, the actual service life of the design is subject to conformity assessment.
8.5.6 Environmental cycle test
8.5.6.1 Procedure
One cylinder, as wrapped and without paint or removable protective coating, shall be tested as follows.
Condition cylinder and contained pressurizing medium for 48 h at atmospheric pressure, at a temperature between
60 °C and 70 °C and at a relative humidity greater than or equal to 95 %.
The hydraulic pressurizing medium external to the cylinder under test shall commence the cycle testing at ambient
temperature. Hydraulically apply 5 000 cycles from a pressure source approximately equal to atmospheric pressure
to two-thirds of the test pressure, p . The cylinder skin temperature shall be maintained at between 60 °C and
h
70 °C by regulating the environmental chamber and the cycling frequency. The cycling frequency shall not exceed
5 cycles per min.
Release pressure and stabilize cylinder at 20 °C approximately.
Stabilize the cylinder and the contained pressurizing medium until the temperature is between – 50 °C and – 60 °C.
The hydraulic pressurizing medium external to the cylinder under test shall commence the cycle testing at ambient
temperature. Apply 5 000 cycles from a pressure source approximately equal to atmospheric pressure to two-thirds
of the test pressure, p . The cylinder skin temperature shall be maintained at between – 50 °C and – 60 °C by
h
regulating the environmental chamber and the cycling frequency. The cycling frequency shall not exceed 5 cycles
per min. The fluid shall also be selected to ensure that it functions at the temperatures specified in the various cycle
tests.
Release pressure and stabilize the cylinder at approximately 20 °C. Hydraulically apply 30 cycles from a pressure
source approximately equal to atmospheric pressure to the test pressure, p .
h
On completion of these tests, the cylinder is subjec
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