ISO 11515:2013

Gas cylinders - Refillable composite reinforced tubes of water capacity between 450 L and 3000 L - Design, construction and testing

ISO 11515:2013 specifies minimum requirements for the design, construction and performance testing of composite reinforced tubes between 450 l and 3 000 l water capacity, for transport, storage and use of compressed or liquefied gases with test pressures up to and including 1600 bar with a design life of at least 15 years and less than or equal to 30 years. The expected service temperatures are between -40 °C and +65 °C. The tubes defined are one of three types: Type 2 - a hoop wrapped tube with a load sharing metal liner and composite reinforcement on the cylindrical portion only. Type 3 - a fully wrapped tube with a load sharing metal liner and composite reinforcement on both the cylindrical portion and the dome ends. Type 4 - a fully wrapped tube with a non-load sharing liner and composite reinforcement on both the cylindrical portion and the dome ends. The Type 4 tubes are not intended to contain toxic, oxidizing or corrosive gases. ISO 11515:2013 is limited to tubes with composite reinforcement of carbon fibre or aramid fibre or glass fibre (or a mixture thereof) in a matrix. Composite tubes can be used alone or in batteries to equip trailers or skids (ISO modules) or multiple element gas containers (MEGC) for the transportation and distribution of gases. ISO 11515:2013 does not include consideration of any additional stresses that can occur during service or transport, (e.g. torsional / bending stresses). However it is important that the stresses associated with mounting the tube are considered by the assembly manufacturer and the tube manufacturer. The design life of tubes according to ISO 11515:2013 for transport of dangerous goods can be limited by the applicable regulations.

Bouteilles à gaz — Bouteilles tubulaires en composite renforcé rechargeables d'une capacité de 450 L à 3000 L — Conception, construction et essais

General Information

• Status: Withdrawn
• Publication Date: 21-Jul-2013
• ICS: 23.020.30 - Pressure vessels, gas cylinders
• ICS: 23.020.35 - Gas cylinders
• Technical Committee: ISO/TC 58/SC 3 - Cylinder design
• Drafting Committee: ISO/TC 58/SC 3/WG 32 - Refillable composite reinforced tubes of water capacity between 150l and 3 000l – Design, construction and testing
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 24-Aug-2022
• Completion Date: 13-Dec-2025

Relations

• Amended By: ISO 11515:2013/Amd 1:2018 - Gas cylinders - Refillable composite reinforced tubes of water capacity between 450 L and 3000 L - Design, construction and testing - Amendment 1
• Effective Date: 28-Aug-2021
• Revised: ISO 11515:2022 - Gas cylinders - Refillable composite reinforced tubes of water capacity between 450 l and 3000 l - Design, construction and testing
• Effective Date: 23-Apr-2020

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 11515
First edition
2013-07-15
Gas cylinders — Refillable composite
reinforced tubes of water capacity
between 450 L and 3000 L — Design,
construction and testing
Bouteilles à gaz — Bouteilles tubulaires en composite renforcé
rechargeables d’une capacité de 450 L à 3000 L — Conception,
construction et essais
Reference number
©
ISO 2013
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 5
5 Inspection and testing . 5
6 Materials . 5
6.1 Liner materials . 5
6.2 Composite overwrap . 6
7 Design and manufacture . 6
7.1 General . 6
7.2 Design submission . 7
7.3 Manufacturing . 8
8 Type approval procedure . 9
8.1 General . 9
8.2 Prototype tests . 9
8.3 New design .10
8.4 Design variants .11
8.5 Type approval test procedures and criteria .12
8.6 Failure of type approval tests .29
9 Inspection and testing at time of manufacture .29
9.1 Liners for Type 2 and Type 3 tubes .29
9.2 Liners for Type 4 tubes .29
9.3 Failure of liner batch tests .30
9.4 Overwrap materials .30
9.5 Composite tube .31
9.6 Failure of batch tests .31
10 Tube marking .32
10.1 General .32
10.2 Additional marking .32
Annex A (informative) Examples of design approval certificate .33
Annex B (informative) Specimen test reports .34
Annex C (normative) Ultrasonic inspection for seamless steel liners and metal tubing .36
Bibliography .41
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. 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. 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.
The committee responsible for this document is ISO/TC 58, Gas cylinders, Subcommittee SC 3, Cylinder design.
iv © ISO 2013 – All rights reserved

Introduction
The purpose of ISO 11515 is to provide a specification for the design, manufacture, inspection and testing
of composite tubes for worldwide usage. The objective is to balance design and economic efficiency
against international acceptance and universal utility.
ISO 11515 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.
ISO 11515 addresses the general requirements on design, construction and initial inspection and testing
of pressure receptacles of the United Nations Recommendations on the Transport of Dangerous Goods
Model Regulations.
Annexes A and B of ISO 11515 are for information only.
INTERNATIONAL STANDARD ISO 11515:2013(E)
Gas cylinders — Refillable composite reinforced tubes
of water capacity between 450 L and 3000 L — Design,
construction and testing
1 Scope
This International Standard specifies minimum requirements for the design, construction and
performance testing of composite reinforced tubes between 450 l and 3 000 l water capacity, for
transport, storage and use of compressed or liquefied gases with test pressures up to and including
1600 bar with a design life of at least 15 years and less than or equal to 30 years. The expected service
temperatures are between −40 °C and +65 °C.
The tubes defined are one of three types:
Type 2: a hoop wrapped tube with a load sharing metal liner and composite reinforcement on the
cylindrical portion only.
Type 3: a fully wrapped tube with a load sharing metal liner and composite reinforcement on both the
cylindrical portion and the dome ends.
Type 4: a fully wrapped tube with a non-load sharing liner and composite reinforcement on both the
cylindrical portion and the dome ends.
The Type 4 tubes manufactured and tested to this International Standard are not intended to contain
toxic, oxidizing or corrosive gases.
This International Standard is limited to tubes with composite reinforcement of carbon fibre or aramid
fibre or glass fibre (or a mixture thereof) in a matrix.
Composite tubes can be used alone or in batteries to equip trailers or skids (ISO modules) or multiple
element gas containers (MEGC) for the transportation and distribution of gases. This International
Standard does not include consideration of any additional stresses that can occur during service or
transport, (e.g. torsional / bending stresses). However it is important that the stresses associated with
mounting the tube are considered by the assembly manufacturer and the tube manufacturer.
NOTE The design life of tubes according to this International Standard for transport of dangerous goods can
be limited by the applicable regulations.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 306, Plastics — Thermoplastic materials — Determination of Vicat softening temperature (VST)
ISO 527-1, Plastics — Determination of tensile properties — Part 1: General principles
ISO 527-2, Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and
extrusion plastics
ISO 3341, Textile glass — Yarns — Determination of breaking force and breaking elongation
ISO 4624, Paints and varnishes — Pull-off test for adhesion
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 7225, Gas cylinders — Precautionary labels
ISO 7866, Gas cylinders — Refillable seamless aluminium alloy gas cylinders — Design, construction and testing
ISO 9227:2012, Corrosion tests in artificial atmospheres — Salt spray tests
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
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 11114-2, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 2:
Non-metallic materials
ISO 11120, Gas cylinders — Refillable seamless steel tubes of water capacity between 150 l and 3000 l —
Design construction and testing
ISO 13341, Gas cylinders — Fitting of valves to gas cylinders
ISO 13769, Gas cylinders — Stamp marking
ASTM D 522-93a, Standard Test Methods for Mandrel Bend Test of Attached Organic Coatings
ASTM D1308, Standard Test Method for Effect of Household Chemicals on Clear and Pigmented Organic Finishes
ASTM D2794, Standard Test Method for Resistance of Organic Coatings to the Effects of Rapid
Deformation (Impact)
ASTM D3170, Standard Test Method for Chipping Resistance of Coatings
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.
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
2 © ISO 2013 – All rights reserved

3.3
batch
collective term for a set of homogeneous items or material
Note 1 to entry: The number of items in a batch can vary according to the context in which the term is used.
3.4
batch of load sharing liners
quantity of up to 30 liners of the same nominal diameter, length, thickness and design, made successively
from the same material cast (heat) and processed in the same heat treatment equipment (i.e. a continuous
furnace process or a single furnace charge) using the same heat treatment parameters
3.5
batch of non-metallic liners
quantity of non-metallic liners of the same nominal diameter, length, thickness and design, made
successively and subjected to the same continuous manufacturing process
3.6
batch of non-load sharing metal liners or metal bosses
quantity of non-load sharing metal liners or metal bosses of the same nominal diameter, length,
thickness and design, made successively from the same material cast (heat) and processed in the same
heat treatment equipment using the same heat treatment parameters
3.7
batch of finished tubes
production quantity of up to 200 finished tubes successively produced (plus finished tubes required for
destructive testing), of the same nominal diameter, length, thickness and design
Note 1 to entry: The batch of finished tubes can contain different batches of liners, fibres and matrix materials.
3.8
burst pressure
highest pressure reached in a tube or liner during a burst test
3.9
carbon fibre
continuous filaments of carbon laid up in tow form, used for reinforcement
3.10
composite overwrap
combination of fibres and matrix used to reinforce the tube, including any barrier or protective layers
that are a permanent part of the design
3.11
dedicated gas service
service in which a tube is to be used only with specified gas or gases
3.12
equivalent fibre
fibre equivalent to a fibre used in a previously prototype tested tube
3.13
exterior coating
layers of material applied to the tube as protection or for cosmetic purposes
Note 1 to entry: The coating can be transparent or opaque.
3.14
equivalent liner
liner 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 (within ± 5 %) of the
approved liner design
3.15
glass fibre
continuous filaments of glass laid up in tow form, used for reinforcement
3.16
leak
-3
escape of gas at a rate greater than 5×10 mbar.l/s through a defect rather than permeation
3.17
liner
inner portion of the composite tube, whose purpose is both to contain the gas and transmit the gas
pressure to the fibres
3.18
load sharing liner
liner that has a burst pressure greater than or equal to 5 % of the nominal burst pressure of the finished
composite tube
3.19
non-load-sharing liner
liner which has a burst pressure less than 5 % of the nominal burst pressure of the finished composite tube
3.20
matrix
material that is used to bind and hold the fibres in place
3.21
minimum design burst pressure
minimum burst pressure specified by the manufacturer and that shall be achieved during a burst test
3.22
tube
transportable pressure receptacle of a water capacity exceeding 150 litres
3.23
representative composite tube
a shorter tube with the same nominal diameter, and manufactured using the same materials and
manufacturing technique, and using a representative wrapping pattern (same number of strands and
same number of layers) so as to represent an equivalent stress compared to a full scale prototype
3.24
tubing
hollow cylindrical body of metal or other material, used for conveying or containing liquids or gases
3.25
Type 2 tube
hoop wrapped tube with a load sharing metal liner and composite reinforcement on the cylindrical
portion only
3.26
Type 3 tube
fully wrapped tube with a load sharing metal liner and composite reinforcement on both cylindrical
portion and dome ends
4 © ISO 2013 – All rights reserved

3.27
Type 4 tube
fully wrapped tube with a non-load sharing liner and composite reinforcement on both cylindrical
portion and dome ends
4 Symbols
p Burst pressure of finished tube 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
ISO 11515 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 UN Model Regulations for the
Transportation of Dangerous Goods. Attention is drawn to requirements in specified relevant national
regulations of the country (countries) where the tubes are intended to be used that might override the
requirements given in this International Standard. To ensure that the tubes conform to this International
Standard, 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.
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 Load sharing liner materials shall conform in all relevant respects to the appropriate
International Standards:
a) seamless steel liners: ISO 9809-1, ISO 9809-2, ISO 9809-3 or ISO 11120 as appropriate;
b) seamless aluminium alloy liners: ISO 7866.
Relevant sections are those covering materials, thermal treatments, neck design, construction and
workmanship, mechanical tests. Design requirements are excluded since these are specified by the
manufacturer for the design of the composite tube (see 7.2.2).
6.1.1.1 The composite tube manufacturer shall verify that each new batch of materials has the specified
properties and qualities, and shall maintain records so that the cast of material and the heat treatment
batch (where applicable) used for the manufacture of each tube can be identified. A certificate of
conformance from the liner material manufacturer is considered acceptable for the purposes of
verification.
6.1.1.2 The liner shall be manufactured from a metal or alloy suitable for the gas to be contained in
accordance with ISO 11114-1.
6.1.1.3 When a neck ring is provided, it shall be of a material compatible with that of the tube, and shall
be securely attached by a method appropriate to the liner material.
Non-load sharing liner materials shall conform in all relevant respects to the appropriate standards, as
follows:
a) The liner (including metal boss) shall be manufactured from a material suitable for the gas to be
contained in accordance with ISO 11114-1 and ISO 11114-2.
b) Metal bosses attached to a non-metallic liner shall fulfil the performance requirements of this
International Standard.
c) The tensile yield strength and ultimate elongation of plastic liner material shall be determined at
−50 °C in accordance with ISO 527-2.The test results shall demonstrate the ductile properties of
the plastic liner material at temperatures of −50 °C or lower by meeting the values specified by the
manufacturer.
d) Polymeric materials from finished liners shall be tested in accordance with a method described in
ISO 306. The softening temperature shall be at least 100 °C.
6.2 Composite overwrap
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 matrix system component materials shall
provide sufficient documentation for the composite tube manufacturer to be able to identify fully the
batch of materials used in the manufacture of each tube.
6.2.4 The composite tube 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 tube 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, e.g. by the application of a suitable protective coating to the liner prior to the wrapping process
(if necessary).
NOTE Glass fibre reinforced composite tubes can be susceptible to chemical attack and degradation after
being in contact with aggressive acids (e.g. battery acid).
7 Design and manufacture
7.1 General
7.1.1 A Type 2 composite tube shall comprise:
a) an internal metal liner with one or two openings along the central axis only, which carries all the
longitudinal load and part of the circumferential load;
b) the liner, designed to withstand a burst pressure greater than 0,85 of the test pressure of the
finished tube.
c) a composite overwrap formed by layers of continuous fibres in a matrix along the parallel portions
of the tube sidewall;
6 © ISO 2013 – All rights reserved

d) an optional exterior coating to provide external protection. When this is an integral part of the
design it shall be permanent.
7.1.2 A Type 3 composite tube shall comprise:
a) an internal metal liner with one or two openings along the central axis only, 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 exterior coating to provide external protection. When this is an integral part of the
design it shall be permanent.
7.1.3 A Type 4 composite tube shall comprise:
a) an internal metal or non-metallic non-load sharing liner with one or two openings along the
central axis only;
b) metallic boss(es) for thread connections, where these are part of the design;
c) a composite overwrap formed by layers of continuous fibres in a matrix;
d) an optional exterior coating to provide external protection. When this is an integral part of the
design it shall be permanent.
7.2 Design submission
7.2.1 The design submission for each new design of tube 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.
The design submission will cover a design family of composite tubes of the same diameter and pressure
with different cylindrical lengths from 2× diameter and up to 5× the length of the representative
composite tube and with a water capacity between 450 and 3 000 litre.
7.2.2 Documentation for the liner and/or metal boss(es) shall include:
a) Material details, 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 (where applicable);
e) inspection procedures (minimum requirements);
f) material properties (including hardness for Type 2 and Type 3 tubes);
g) minimum design burst pressure (for Type 2 and Type 3 tube liners);
h) dimensional details of valve threads;
i) method of sealing boss to liner for Type 4 tubes.
7.2.3 Documentation for the composite overwrap shall include:
a) fibre material, specification and mechanical properties requirements;
b) minimum composite thickness;
c) resin system - main components and resin bath temperature where applicable;
d) thermoplastic matrix system – main component materials, specifications and process temperatures;
e) thermosetting matrix – specifications (including resin, curing agent and accelerator), and resin bath
temperature where applicable;
f) overwrap construction including the number of strands used, number of layers, and layer orientation;
g) curing process, temperatures, duration and tolerances.
7.2.4 Documentation for the composite tube shall include:
a) water capacity in litres;
b) dimensions, minimum thickness, straightness and out of roundness with tolerances;
c) list of intended contents if intended for dedicated gas service;
d) working pressure p which shall not exceed 2/3 test pressure;
w
e) composite tube test pressure, p ;
h
f) allowable range of elastic expansions and permanent expansions (if appropriate) for the design
when volumetric expansion test is used (See 9.5.4), to the satisfaction of the Competent Authority;
g) maximum developed pressure at 65 °C for specific dedicated gas(es) p ;
max
h) minimum design burst pressure;
i) design life in years between 15 and 30 years;
j) autofrettage pressure and approximate duration (where applicable);
k) tensioning of the fibre at winding (where applicable);
l) weight and manufacturing tolerance;
m) details of components which are permanently attached and form part of the qualified design (e.g.
neck rings, protective boots etc.).
7.3 Manufacturing
7.3.1 The liner and metal bosses, where incorporated, shall be manufactured in accordance with the
manufacturer’s design (see 7.2.2).
7.3.2 The composite tube shall be fabricated from a load sharing or non-load sharing liner over-
wrapped with resin impregnated continuous fibres. Winding shall be applied under controlled conditions
to develop the design composite thickness and as 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 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 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 tubes 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 tubes are subjected to a pre-stressing or fibre tensioning during winding to actively change
the final stresses in the finished tube, the level of stress shall be as specified in 7.2.4 and levels of stress
of tensioning shall be recorded or monitored.
8 © ISO 2013 – All rights reserved

8 Type approval procedure
8.1 General
The design submission of each new design of composite tube 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 sufficient number of tubes shall be made available to complete the prototype testing or testing
of the design variant.
8.2.2 The inspector shall verify that the batch of liners, prior to being wrapped, conforms to the design
requirements and are inspected and tested in accordance with 9.1 or 9.2, as appropriate.
8.2.3 The inspector shall verify that the composite material(s), prior to the tubes being wrapped,
conform to the design requirements and are tested in accordance with 9.4.
8.2.4 The inspector shall verify that all tubes in the batch produced for new design approval conform
to the design submission and are tested in accordance with 9.5. Except for the cases identified in 8.2.5,
the inspector shall supervise the tests shown in Table 1. An “A” in the relevant column of Table 1 shows
that the test is required for the appropriate tube category. An “O” in the relevant column of Table 1
shows that the test is required for particular designs, materials and uses. The relevant clause for each
test describes when the test is required.
Table 1 — Prototype Testing for New Designs
Design Tests Type 2 Type 3 Type 4
8.5.1 Hydraulic proof pressure test, or A A A
8.5.2 Hydraulic volumetric expansion test
8.5.3 Liner burst test A A
8.5.4 Tube burst test A A A
8.5.5 Ambient temperature cycling test A A A
8.5.6 Environmental cycling test A A A
8.5.7 Flaw test A A
8.5.8 Blunt impact test A A A
8.5.9 Fire resistance test A A A
8.5.10 Neck strength test A
8.5.11 Leak test A
8.5.12 Accelerated stress rupture test O O O
8.5.13 Permeability test O
8.5.14 Gas cycling test A
a b
8.5.15 Coatings test (where applicable) O O O
8.5.16 Salt Spray test O O O
KEY
A – All tubes tested.
O – Only required for particular designs, materials and uses.
a
Tubes being used for other tests may be used.
b
Coating tests can be carried out on sections/domes of tubes as appropriate.
Table 1 (continued)
Design Tests Type 2 Type 3 Type 4
8.5.17 Acid environment test O O O
8.5.18 Vacuum test O
KEY
A – All tubes tested.
O – Only required for particular designs, materials and uses.
a
Tubes being used for other tests may be used.
b
Coating tests can be carried out on sections/domes of tubes as appropriate.
8.2.5 For variations in design from the new design tube as specified in 8.4, it is only necessary to carry
out the tests as prescribed in Tables 2 to 4 as appropriate. A tube 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).
8.2.6 If the results of the verifications and tests according to 8.2.2, 8.2.3 and 8.2.4 as modified by 8.2.5
if application, are satisfactory, the inspector shall issue a type approval certificate, a typical example of
which is given in Annex A.
8.2.7 After completion of the tests the tubes shall be destroyed or made incapable of holding pressure.
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 written prior agreement of the inspector.
8.3.2 A new tube design requires full type approval testing. A tube shall be considered to be of a new
design compared to an existing approved design if:
a) It is manufactured in a different factory. A relocation of a factory does not require a new cylinder
design approval provided all materials, 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 tube. 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) 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 tube shall also be considered to be of a new design compared to an existing approved design if:
a) The liner manufactured from a material of different composition or composition limits from that
used in the original type tests;
b) The liner material properties are outside the original design limits
10 © ISO 2013 – All rights reserved

8.4 Design variants
8.4.1 For tubes similar to an approved design a reduced type approval testing programme is allowed.
A tube shall be considered to be a design variant if:
a) The outside diameter has changed by 50 % or less;
b) The autofrettage pressure has changed by more than 5 %;
c) The base profile and/or base thickness of the liner has changed relative to the tube diameter and
minimum wall thickness;
d) There is a change in the design test pressure up to and including 60 %;
Where a tube 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) When changes in diameter or pressure are made the structural wall elements must be operating at
the same, or lower nominal stress levels as the original design (e.g. if pressure or diameter increase
the wall thickness must increase proportionally);
f) The composite thickness has changed by more than 5 % for reasons other than a change in test
pressure or diameter;
g) The minimum wall thickness of the liner has changed by more than 5 %;
h) When 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 tube design. Carbon fibres made from the same precursor can be equivalent. Aramid,
carbon and glass fibres are not equivalent.
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 equivalent liner is used;
Equivalent liners 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, are
within ± 5 % of the approved cylinder design and fulfil the requirements of the relevant standard.
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 tube thread has changed.
When a tube design has only a different thread compared to an approved design only the torque
test, in accordance with 8.5.10, shall be carried out.
8.4.2 A tube 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 program. 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, 3 or 4 for the
appropriate tube category, 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
The manufacturer can conduct more than one of the type approval tests on a particular tube with the
agreement of the inspector.
Each completed tube shall be subjected to either a hydraulic proof test (in accordance with 8.5.1) or a
volumetric expansion test (in accordance with 8.5.2) at the design test pressure specified in 7.2.4
8.5.1 Hydraulic proof pressure test
8.5.1.1 Procedure
When carrying out the pressure test, a suitable fluid (e.g. normally water) shall be used as the test
medium. This test requires that the pressure in the tube be increased gradually and regularly until the
test pressure, p , is reached. The test pressure shall be held for at least 2 min with the tube isolated from
h
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 tube shall be re-tested after repairing such leakages.
The limit deviation on attaining test pressure shall be test pressure +3 % / −0 or +10 bar whichever is
the lower. Pressure gauges with the appropriate accuracy shall be used.
All internal surfaces of tubes shall be dried (to ensure no free water) immediately after testing.
Where tubes are subjected to autofrettage the hydraulic proof pressure test can be part of, or immediately
follow, the autofrettage process.
8.5.1.2 Criteria
The tube shall be rejected if there are leaks, failure to hold pressure or visible permanent deformation
after the tube is depressurised.
NOTE Cracking of resin is not necessarily a sign of permanent deformation.
8.5.2 Hydraulic volumetric expansion test
8.5.2.1 Procedure
When carrying out the pressure test, a suitable fluid (e.g. normally water) shall be used as the test
medium. This test requires that the pressure in the tube be increased gradually and regularly until the
test pressure, p , is reached. The tube test pressure shall be held for at least 2 min with the tube isolated
h
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 tube shall be re-tested after repairing such leakages.
The limit deviation on attaining test pressure shall be test pressure +3 % / −0 or +10 bar whichever is
the lower. Pressure gauges with the appropriate accuracy shall be used.
All internal surfaces of tubes shall be dried (to ensure no free water) immediately after testing.
12 © ISO 2013 – All rights reserved

Table 2 — Type approval tests for Type 2 tubes
Design variant
Nominal Diameter Equiv. Liner Test pressure Composite Equiv. Autofrettage
Test No. Test New Design liner thickness thick’ fibre
≤ 20 % > 20 % >5% ≤ 20 % > 20 % >5% >5%
≤ 50 % ≤ 60 %
9.1 Liner material test
X X X
9.5 Composite material tests X X
8.5.1/8.5.2 Hydraulic pressure test X X X X X X X X X X
8.5.3 Liner burst test X X X X X
8.5.4 Tube burst test X X X X X X X X X X
8.5.5 Ambient cycle test X X X X X X X X X X
8.5.6 Environmental cycle test X
a b
8.5.8 Blunt impact test X X X X X X
b
8.5.9 Fire resistance test X X X X
8.5.12 Stress rupture test X X X X
c
8.5.16 Salt Spray Test X X
d
8.5.17 Acid Environment Test X X X X
a
Test to be conducted for reduction in diameter only.
b
Test to be conducted on tubes for a reduction in liner thickness of 10 % or more.
c
Test to be conducted on tubes with steel liners.
d
Test to be conducted on tubes with load bearing glass fibre.

14 © ISO 2013 – All rights reserved
Table 3 — Type approval tests for Type 3 tubes
Design changes
Nominal Diameter Equiv. Liner Test pressure Composite Equiv. Autofrettage
Test No. Test New Design liner thickness thick’ or pattern fibre
≤ 20 % > 20 % >5% ≤ 20 % > 20 % >5%
≤ 50 % ≤ 60 %
9.1
Liner material test X X X
9.5 Composite material tests X X
a
8.5.1/8.5.2 Hydraulic pressure test
...