ISO 11119-4:2016
(Main)Gas cylinders — Refillable composite gas cylinders — Design, construction and testing — Part 4: Fully wrapped fibre reinforced composite gas cylinders up to 150 l with load-sharing welded metallic liners
Gas cylinders — Refillable composite gas cylinders — Design, construction and testing — Part 4: Fully wrapped fibre reinforced composite gas cylinders up to 150 l with load-sharing welded metallic liners
ISO 11119-4:2016 specifies requirements for composite gas cylinders with load-sharing welded liners between 0,5 l and 150 l water capacity and a maximum test pressure of 450 bar for the storage and conveyance of compressed or liquefied gases. NOTE 1 1 bar = 105Pa = 105N/m2. The cylinders are constructed in the form of a welded stainless steel liner or welded ferritic steel liner or welded aluminium alloy liner and overwrapped with carbon fibre or aramid fibre or glass fibre (or a mixture thereof) in a matrix to provide longitudinal and circumferential reinforcement. The cylinders in this part of ISO 11119 are type 3 fully wrapped cylinders with a load-sharing metal liner and composite reinforcement on both the cylindrical portion and the dome ends. Cylinders produced in accordance with this part of ISO 11119 have a minimum design life of 15 years. Cylinders with test pressure of up to 60 bar have an unlimited design life. ISO 11119-4:2016 does not address the design, fitting, and performance of removable protective sleeves. ISO 11119-4:2016 does not apply to cylinders with seamless liners. For seamless liners, ISO 11119‑2 applies. NOTE 2 ISO 11623 covers periodic inspection and re-testing of composite cylinders.
Bouteilles à gaz — Bouteilles à gaz rechargeables en matériau composite et tubes — Conception, construction et essais — Partie 4: Bouteilles à gaz composites entièrement bobinées renforcées par des fibres et tubes d'une contenance allant jusqu'à 150 l avec liners métalliques transmettant la charge
General Information
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Standards Content (Sample)
DRAFT INTERNATIONAL STANDARD
ISO/DIS 11119-4
ISO/TC 58/SC 3 Secretariat: BSI
Voting begins on: Voting terminates on:
2013-10-15 2014-01-15
Gas cylinders — Refillable composite gas cylinders and
tubes — Design, construction and testing —
Part 4:
Fully wrapped fibre reinforced composite gas cylinders
and tubes up to 450 L with load-sharing welded metallic
liners
Bouteilles à gaz composites — Spécifications et méthodes d’essai
ICS: 23.020.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 11119-4:2013(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2013
ISO/DIS 11119-4:2013(E)
Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as
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ii © ISO 2013 – All rights reserved
Contents Page
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 3
4 Symbols . 5
5 Inspection and testing . 5
6 Materials . 5
6.1 General . 5
6.2 Composite materials . 7
7 Design and manufacture . 7
7.1 General . 7
7.2 Design submission . 7
7.3 Manufacturing . 9
8 Type approval procedure. 10
8.1 General requirements . 10
8.2 Prototype tests . 10
8.3 New design . 11
8.4 Design variants . 12
8.5 Type approval test procedures and criteria . 16
8.5.1 Proof pressure test . 16
8.5.2 Hydraulic volumetric expansion test . 16
8.5.3 it shows a permanent expansion (i.e. volumetric expansion after the pressure has been
released) in excess of 5 % of the total expansion.Liner Burst test . 17
8.5.4 Liner Integrity test . 17
8.5.5 Cylinder burst test . 18
8.5.6 Ambient cycle test . 18
8.5.7 Environmental cycle test . 20
8.5.8 Flaw test . 21
8.5.9 Drop test . 24
8.5.10 High velocity impact (Gunfire) test . 25
8.5.11 Fire resistance test . 26
8.5.12 Salt water immersion test . 27
8.5.13 Torque test . 28
8.5.14 Environmentally assisted stress rupture test . 28
8.5.15 Failure of type approval tests . 29
9 Batch inspection and testing . 29
9.1 Liner . 30
9.1.1 Each batch of liners shall be examined and dimensionally checked to ensure compliance
with the design specification. The following inspections shall be conducted: . 30
9.2 Failure of liner batch tests . 31
9.3 Overwrap materials . 31
9.4 Composite cylinder . 31
9.5 Cylinder failure during type approval or batch testing . 32
10 Cylinder marking . 33
10.1 General . 33
10.2 Additional marking . 33
ISO/DIS 11119-4
Annex A (informative) Examples of design approval certificate . 34
Annex B (informative) Specimen test reports . 36
Annex C (normative) Prototype, design variant and production testing . 39
Bibliography . 42
iv © ISO 2013 – All rights reserved
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11119-4 was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 3, Cylinder
design.
This is a first edition.
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 composite gas cylinders and tubes up to 450L
Part 2: Fully-wrapped fibre reinforced composite gas cylinders and tubes up to 450L with load-sharing metal
liners
Part 3: Fully-wrapped fibre reinforced composite gas cylinders and tubes up to 450L with non-load-sharing
metallic or non-metallic liners
Part 4: Fully-wrapped fibre reinforced composite gas cylinders and tubes up to 450L with load-sharing welded
metallic liners
ISO/DIS 11119-4
Introduction
The purpose of this part 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 is not to be construed as reflecting on the suitability
of the practice of any nation or region.
Some procedures and tests may require that precautions be taken for the health and/or safety of operator(s).
Safety, health and environmental concerns are not addressed and should be addressed by those who wish to
implement this standard.
ISO 11119-4 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 cylinders are intended to be used that might override the
requirements given in this International Standard
Annexes A and B of this part of ISO 11119 are for information only.
Annex C of this part of ISO 11119 is normative.
vi © ISO 2013 – All rights reserved
DRAFT INTERNATIONAL STANDARD ISO/DIS 11119-4
Gas cylinders – Refillable composite gas cylinders and tubes —
Design, construction and testing — Part 4: Fully wrapped fibre
reinforced composite gas cylinders and tubes up to 450L with
load-sharing welded metallic liners
1. Scope
This part of ISO 11119 specifies requirements for composite gas cylinders and tubes with load sharing welded
liners between 0.5 l and 450 l water capacity and a maximum test pressure of 450 bar, for the storage and
conveyance of compressed or liquefied gases.
The cylinders are constructed in the form of a welded stainless steel liner or welded ferritic steel liner or
welded aluminum alloy liner and- over-wrapped with carbon fibre or aramid fibre or glass fibre (or a mixture
thereof) in a matrix to provide longitudinal and circumferential reinforcement.
The cylinders and tubes in this standard are 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.
Cylinders produced in accordance with the standard have a minimum design life of 15 years. Cylinders with
test pressure up to 60 bar have an unlimited design life.
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 seamless liners. For seamless liners ISO11119-2
applies
NOTE ISO 11623 covers periodic inspection and re-testing of composite cylinders.
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 75.3; Plastics -- Determination of temperature of deflection under load -- Part 3: High-strength
thermosetting laminates and long-fibre-reinforced plastics
ISO 3341, Textile glass – Yarns – Determination of breaking force and breaking elongation
ISO 4706, Gas cylinders -- Refillable welded steel cylinders -- Test pressure 60 bar and below ISO 6506-1,
Metallic materials — Brinell hardness test — Part 1: Test method
ISO 5817; Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded)
— Quality levels for imperfections
ISO 6506-1; Metallic materials - Brinell hardness test -- Part 1: Test method
ISO 6508-1; Metallic materials -- Rockwell hardness test -- Part 1: Test method (scales A, B, C, D, E, F, G, H,
K, N, T)
ISO/DIS 11119-4
ISO 8521; Plastics piping systems -- Glass-reinforced thermosetting plastics (GRP) pipes -- Test methods for
the determination of the apparent initial circumferential tensile strength
ISO 10042; Welding -- Arc-welded joints in aluminium and its alloys -- Quality levels for imperfections
ISO 10618: Carbon Fibre – Determination of tensile properties of resin impregnated yarn
ISO 10460; Gas cylinders -- Welded carbon-steel gas cylinders -- Periodic inspection and testing
ISO 10464; Gas cylinders -- Refillable welded steel cylinders for liquefied petroleum gas (LPG) -- Periodic
inspection and testing
ISO 11114-1, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas contents
— Part 1: Metallic materials
ISO 13341, Transportable gas cylinders — Fitting of valves to gas cylinders
ISO 13769, Gas cylinders — Stampmarking
ISO 13919-1; Welding - Electron and laser-beam welded joints - Guidance on quality levels for imperfections -
Part 1: Steel
ISO 13919-2; Welding - Electron and laser-beam welded joints - Guidance on quality levels for imperfections -
Part 2: Aluminium and its weldable alloys
ISO 14130 – Fibre-reinforced plastic composites -- Determination of apparent interlaminar shear strength by
short-beam method
ISO 18172-2, Gas cylinders -- Refillable welded stainless steel cylinders -- Part 2: Test pressure greater than
6 MPa
ISO 20703, Gas cylinders -- Refillable welded aluminium-alloy cylinders -- Design, construction and testing
ISO/CD 21172-1 – Gas cylinders – Welded steel pressure drums for the transport of gases. Design and
construction. Part 1: Capacities up to 1000 litres
ASTM D2290, Standard Test Method for Apparent Hoop Tensile Strength of Plastic or Reinforced Plastic Pipe
ASTM D2291; Standard Practice for Fabrication of Ring Test Specimens for Glass-Resin Composites
ASTM D2343; Standard Test Method for Tensile Properties of Glass Fiber Strands, Yarns, and Rovings Used
in Reinforced Plastics
ASTM D2344; Standard Test Method for Short-Beam Strength of Polymer Matrix Composite Materials and
Their Laminates
ASTM D4018; Standard Test Methods for Properties of Continuous Filament Carbon and Graphite Fiber Tows
ASTM D3418; Standard Test Method for Transition Temperatures and Enthalpies of Fusion and
Crystallization of Polymers by Differential Scanning Calorimetry
ASTM D2196; Standard Test Methods for Rheological Properties of Non-Newtonian Materials by Rotational
(Brookfield type) Viscometer
EN14638-3, Transportable gas cylinders. Refillable welded receptacles of a capacity not exceeding 150 litres.
Welded carbon steel cylinders made to a design justified by experimental methods
2 © ISO 2013 – All rights reserved
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 (if applicable) 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 (pb) or liner (pb ) during a burst test
l
3.7
calculated linerproof pressure
pressure used for the liner integrity test and derived from the test pressure of the relevant liner design
standard
NOTE The liner design standards are given in table 1.
3.8
carbon fibre
continuous filaments of carbon laid up in tow form
3.9
composite overwrap
combination of fibres and matrix
3.10
dedicated gas service
service in which a cylinder is to be used only with a specified gas or group of gases
3.11
equivalent fibre
fibre equivalent to a fibre used in a previously prototype tested cylinder
ISO/DIS 11119-4
3.12
equivalent liner
-equivalent liners are manufactured from raw materials with the same specification, 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
3.13
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.
3.23
test pressure (ph)
required pressure applied during the pressure test of the composite cylinder
4 © ISO 2013 – All rights reserved
4. Symbols
Symbols and their designations
Symbol Designation Unit
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
pbl Burst pressure of the liner
N Number of cycles with pressurization to test pressure
Nd Number of cycles with a pressurization to maximum developed pressure
Y Number of years of design life
pl Calculated liner proof pressure for liner integrity test
5. Inspection and testing
To ensure that the cylinders conform to this part of ISO 11119, they shall be subject to the requirements,
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 aspects to the appropriate standards (as per table 1).
6.1.2 Relevant sections are those covering materials, thermal treatments, neck design, construction and
workmanship and, mechanical tests. Design requirements are excluded since these are specified by the
manufacturer for the design of the composite cylinder (7.2. 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 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 required to be manufactured from a metal or alloy suitable for the gas to be
contained as required by 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.
Table 1 — Liner material requirements
Type Type of liner Liner material Liner heat treatment Applicable standard Relevant sections of Capacity
the applicable
standard
Cylinders Welded steel liner Carbon steel Yes ISO 4706:2008 5, 6.3, 8, 9 Up to 150L
No EN 14638-3:2010 4, 5.4,6,8 Up to 150L
Stainless steel As defined in the ISO 18172-2:2007 4,5.6,6,8 Up to 150L
standard (yes or no)
Welded Aluminium Aluminium alloy ISO 20703:2006 4,5.4,6,7 Up to 150L
Alloy liner
Drums Welded steel drums Carbon steel, [ISO/CD 21172-1] ? 150 up to 450L
austenitic stainless
steel
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 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.
7. . Design and manufacture
7.1 General
7.1.1 A Type 3 fully-wrapped composite gas cylinder with load sharing welded liner shall comprise of:
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 adversive reaction or interaction (e.g. epoxy
coating with epoxy matrix) between the liner and the reinforcing fibre by the application of a suitable protective
coating to the liner prior to the wrapping process.
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 or have sufficient
threads to allow proper engagement of the valve. Only manufacturing processes covered by the standards
listed in table 1 are permissible.The cylinder may also include additional parts such as neck rings, bases,
etc…
7.1.2 Examples of certificates are shown in informative 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;
ISO/DIS 11119-4
d) the weld profile including the manufacturing procedure, dimensions and tolerances and the maximum
limits for excess weld metal as described in ISO 5817, table 1, §1.9; or ISO 10042, table 1, §1.11; or ISO
13919-1, table 2, §11 or ISO 13919-2, table 2 §12.
Table 2 — Excess weld metal limits
Standard Figure Limits for imperfections for quality
level
ISO 5817, table 1, §1.9 • h ≤ 1 mm + 0,1 b,
but max. 5 mm
h ≤ 1,5 mm + 0,1 b,
ISO 10042, table 1, §1.11
but max. 6 mm
ISO 13919-1, table 2, §11 • h ≤ 0.2 mm + 0,15
t, or 5 mm,
whichever is the
smaller
• h ≤ 0.2 mm + 0,15
ISO 13919-2, table 2 §12
t, maximum 5 mm
e) heat-treatment, temperatures, duration and tolerances, if applicable;
f) inspection procedures (in addition to those specified on the referred liner standard as per table 1);
g) material properties including minimum mechanical properties and hardness ranges, where applicable;
h) calculated proof pressure of the liner for liner integrity test (p ) (as per 8.5.4)
l
i) minimum design burst pressure (pb ) ;
l
j) dimensional details of valve threads and any other permanent features.
8 © ISO 2013 – All rights reserved
7.2.3 Documentation for the composite overwrap shall include (but not be limited to):
a) fibre material, specification and mechanical properties requirements. The mechanical properties shall be
as specified by the manufacturer;
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 and layer orientation and
tensioning of the fibre at wrapping; this tension can be either a process tension to aid the wrapping
process, or the much higher pre-tensioning to actively change the final stresses in the finished cylinder.
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 at 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 2/3 times the test pressure;
w
f) maximum developed pressure at 65 ºC for specific dedicated gas(es) p ;
max
g) minimum design burst pressure (pb);
h) design life in years; cylinders with a test pressure of less than 60 bar shall have a non-limited design life;
i) autofrettage pressure approximate duration , or details of the fibre tensioning and
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 (e.g. neck
rings, protective boots etc).
l) additional test requirements for special applications
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).
a) the weld profile shall not exceed the dimensions and tolerances and the maximum limits for excess weld
metal as documented in 7.2.2d
b) Welded joints shall conformto ISO5817 quality level B or ISO10042 (for Aluminium and its alloys) quality
level B or ISO13919-1 (for steel quality level C or ISO13919-2 quality level C (for Aluminium and its
alloys)
ISO/DIS 11119-4
7.3.2 The composite cylinder shall be fabricated from a load sharing liner fully over-wrapped 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
over-wrapped if it has been damaged or scored by the stripping process.
7.3.3 After wrapping is completed the composite shall be cured (if appropriate) using a c ontrolled
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 pre-stressing or fibre tensioning during wrapping in order to actively
change the final stresses in the finished cylinder, the tension shall be as specified in the documentation
referred to in 7.2.3 and 7.2.4 and 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.
Annex C, specify the prototype tests to be conducted under the supervision of the inspector and specifies the
test frequency.
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, enough 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 3, 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 In the course of prototype testing the inspector shall verify that the material and design meet the
requirements of clauses 6 and 7 and randomly select the cylindersnecessary for destructive testing. A
dimensional check for conformance to the drawing and the parameters as specified in the design submission
(see 7.2) shall be carried out on all liners and cylinders selected for destructive testing.
The tests shall consist of:
a) hydraulic or pneumatic proof pressure test, in accordance with 8.5.1 or, hydraulic volumetric expansion
test, in accordance with 8.5.2;
10 © ISO 2013 – All rights reserved
b) liner burst tests, in accordance with 8.5.3;
c) liner integrity test, in accordance with 8.5.4
d) cylinder burst test, in accordance with 8.5.5
e) ambient temperature cycle test, in accordance with 8.5.6. A cylinder with the maximum limit for excess
weld metal shall be chosen and used for ambient cycle test during prototype testing. Perform leak test, in
accordance with 8.5.15, immediately after finishing the minimum required cycles.;
f) environmental cycle test, in accordance with 8.5.7;
g) flaw test, in accordance with 8.5.8;
h) drop test, in accordance with 8.5.9;
i) high velocity impact (gunfire) test, in accordance with 8.5.10
j) torque test, in accordance with 8.5.13.
k) leak test, in accordance with 8.5.15;
l) composite materials mechanical properties tests, in accordance with 8.5.16;
8.2.6 Tests that are optional (as for 8.511, 8.5.12 and 8.5.13) depending upon the design and intended use
of the cylinder are :
a) fire resistance test, in accordance with 8.5.11
b) salt water immersion test, in accordance with 8.5.12;
c) environmentally assisted stress rupture test, in accordance with 8.5.14;
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 3 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 used in drop test 8.5.9 can be used to perform the burst test given in 8.5.5.
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 rendered unserviceable.
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, for example:
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
ISO/DIS 11119-4
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
(mass per unit length) shall not be considered a new fibre type.
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 clause 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.
8.3.3 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, for example:
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.
d) Different welding technology is used
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 Table3. A cylinder shall be considered to be a design variant if changes are limited to:
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 or pre-
stressing parameters have changed by more than 5%;
d) there is a change in the design test pressure up to and including 60 %;
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%;
12 © ISO 2013 – All rights reserved
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.
Where a new equivalent fibre has been successfully 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 shall be manufactured by the same welding procedure resulting in the same
weld configuration (same materials and parameters)
2) The equivalent liner material shall be subjected to the material tests specified in 9.2.3 and the
liner burst test specified in 8.5.3 and in both cases shall meet the requirements specified in 7.2.2.
3) Where a new equivalent liner has been successfully 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 inlet thread has changed;
When a cylinder design has only a different thread compared to an approved design only the torque test,
in accordance with 8.5.13, 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.
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 Table3, 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)
Table 3 — Type approval tests
Design Variant changes
Liner Auto-
Nominal Length Nominal Diameter Equiv. Test pressure Composite Equiv.’ Equiv.
New
Test Test
thickness frettage
liner thick’ or fibre Matrix
> 5% > 50 % ≤ 20 % >20% ≤ ≤ 20 % (c). >20 % ≤
Design
No. change or pre-
Liner base
≤ 50 % 50 % 60 %
tension
form
Liner material test
9.2 X X X
Composite material
9.4 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 Liner integrity test X X X X X X X
8.5.5 Hydraulic bur
...
INTERNATIONAL ISO
STANDARD 11119-4
First edition
2016-02-15
Gas cylinders — Refillable composite
gas cylinders — Design, construction
and testing —
Part 4:
Fully wrapped fibre reinforced
composite gas cylinders up to 150 l
with load-sharing welded metallic
liners
Bouteilles à gaz — Bouteilles à gaz rechargeables en matériau
composite et tubes — Conception, construction et essais —
Partie 4: Bouteilles à gaz composites entièrement bobinées renforcées
par des fibres et tubes d’une contenance allant jusqu’à 150 l avec
liners métalliques transmettant la charge
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 4
5 Inspection and testing . 4
6 Materials . 5
6.1 Liner materials . 5
6.2 Composite materials . 5
7 Design and manufacture . 6
7.1 General . 6
7.2 Design submission . 6
7.3 Manufacturing . 7
8 Type approval procedure . 9
8.1 General requirements . 9
8.2 Prototype tests . 9
8.3 New design .10
8.4 Design variants .11
8.5 Type approval test procedures and criteria .14
8.5.1 Proof pressure test .14
8.5.2 Hydraulic volumetric expansion test .14
8.5.3 Liner burst test .15
8.5.4 Liner integrity test .15
8.5.5 Cylinder burst test .16
8.5.6 Ambient cycle test .16
8.5.7 Environmental cycle test.18
8.5.8 Flaw test .20
8.5.9 Drop test .22
8.5.10 High velocity impact (gunfire) test .23
8.5.11 Fire resistance test .24
8.5.12 Salt water immersion test .25
8.5.13 Torque test .26
8.5.14 Environmentally assisted stress rupture test .26
8.5.15 Leak test .27
8.5.16 Composite material mechanical properties tests .27
8.5.17 Failure of type approval tests .27
9 Batch inspection and testing .28
9.1 General .28
9.2 Liner .28
9.3 Failure of liner batch tests .29
9.4 Overwrap materials .29
9.5 Composite cylinder.29
9.6 Cylinder failure during type approval or batch testing .31
10 Cylinder marking .31
10.1 General .31
10.2 Additional marking .31
Annex A (informative) Examples of design approval certificate .33
Annex B (informative) Specimen test reports .35
Annex C (normative) Prototype, design variant, and production testing .38
Bibliography .40
iv © ISO 2016 – All rights reserved
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 58, Gas cylinders, Subcommittee SC 3,
Cylinder design.
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 450L with non-load-
sharing metallic or non-metallic liners
— Part 4: Fully wrapped fibre reinforced composite gas cylinders up to 150 l with load-sharing welded
metallic liners
Introduction
The purpose of this part of ISO 11119 is to provide a specification for the design, manufacture,
inspection, and testing of a cylinder for worldwide usage. The objective is to balance design and
economic efficiency against international acceptance and universal utility.
This part of ISO 11119 aims to eliminate the concern about climate, duplicate inspection, and restrictions
currently existing because of a lack of definitive International Standards and is not to be construed as
reflecting on the suitability of the practice of any nation or region.
It is possible that some procedures and tests will require precautions to be taken for the health and/or
safety of the operator(s). Safety, health, and environmental concerns are not addressed and is to be
addressed by those who wish to implement this International Standard.
This part of ISO 11119 is intended to be used under a variety of national and international regulatory
regimes. Where there is any conflict between this part of ISO 11119 and any applicable regulation, the
regulation always takes precedence.
This part of ISO 11119 has been written so that it is suitable to be referenced in the UN Model
[1]
Regulations.
Annexes A and B of this part of ISO 11119 are for information only.
Annex C of this part of ISO 11119 is normative.
vi © ISO 2016 – All rights reserved
INTERNATIONAL STANDARD ISO 11119-4:2016(E)
Gas cylinders — Refillable composite gas cylinders —
Design, construction and testing —
Part 4:
Fully wrapped fibre reinforced composite gas cylinders up
to 150 l with load-sharing welded metallic liners
1 Scope
This part of ISO 11119 specifies requirements for composite gas cylinders with load-sharing welded
liners between 0,5 l and 150 l water capacity and a maximum test pressure of 450 bar for the storage
and conveyance of compressed or liquefied gases.
5 5 2
NOTE 1 1 bar = 10 Pa = 10 N/m .
The cylinders are constructed in the form of a welded stainless steel liner or welded ferritic steel liner
or welded aluminium alloy liner and overwrapped with carbon fibre or aramid fibre or glass fibre (or a
mixture thereof) in a matrix to provide longitudinal and circumferential reinforcement.
The cylinders in this part of ISO 11119 are type 3 fully wrapped cylinders with a load-sharing metal
liner and composite reinforcement on both the cylindrical portion and the dome ends.
Cylinders produced in accordance with this part of ISO 11119 have a minimum design life of 15 years.
Cylinders with test pressure of up to 60 bar have an unlimited design life.
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 seamless liners. For seamless liners,
ISO 11119-2 applies.
NOTE 2 ISO 11623 covers periodic inspection and re-testing of composite cylinders.
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 3341, Textile glass — Yarns — Determination of breaking force and breaking elongation
ISO 4706:2008, Gas cylinders — Refillable welded steel cylinders — Test pressure 60 bar and below
ISO 5817:2014, Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding
excluded) — Quality levels for imperfections
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
ISO 8521, Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes — Test methods
for the determination of the apparent initial circumferential tensile strength
ISO 10042:2005, Welding — Arc-welded joints in aluminium and its alloys — Quality levels for imperfections
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
ISO 13919-1:1996, Welding — Electron and laser-beam welded joints — Guidance on quality levels for
imperfections — Part 1: Steel
ISO 13919-2:2001, Welding — Electron and laser beam welded joints — Guidance on quality levels for
imperfections — Part 2: Aluminium and its weldable alloys
ISO 14130, Fibre-reinforced plastic composites — Determination of apparent interlaminar shear strength
by short-beam method
ISO 18172-2:2007, Gas cylinders — Refillable welded stainless steel cylinders — Part 2: Test pressure
greater than 6 MPa
ISO 20703:2006, Gas cylinders — Refillable welded aluminium-alloy cylinders — Design, construction and
testing
ASTM D2290-12,Standard test method for apparent hoop tensile strength of plastic or reinforced plastic pipe
ASTM D2291-09, Standard practice for fabrication of ring test specimens for glass-resin composites
ASTM D2343-09, Standard test method for tensile properties of glass fiber strands, yarns, and rovings used
in reinforced plastics
ASTM D2344/D2344M-13, Standard test method for short-beam strength of polymer matrix composite
materials and their laminates
ASTM D4018-11, Standard test methods for properties of continuous filament carbon and graphite fiber tows
EN 14638-3:2010, Transportable gas cylinders. Refillable welded receptacles of a capacity not exceeding
150 litres. Welded carbon steel cylinders made to a design justified by experimental methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
fibre
continuous filaments laid up in tow form
3.2
autofrettage
pressure application procedure that 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 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 welding procedure, and design
from the same material cast and heat treated (if applicable) at the same temperature and for the same
period of time
2 © ISO 2016 – All rights reserved
3.4
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
3.5
burst pressure
highest pressure reached in a cylinder, p , or liner, p , during a burst test
b bl
3.6
calculated liner proof pressure
pressure derived from the test pressure of the relevant liner design standard
Note 1 to entry: The liner design standards are given in Table 1. The calculated liner proof pressure is used for
the liner integrity test.
3.7
composite overwrap
combination of fibres and matrix
3.8
dedicated gas service
service in which a cylinder is to be used only with a specified gas or group of gases
3.9
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
3.10
equivalent liner
liner that is manufactured from the same nominal raw materials, using the same process(es) of
manufacture and having the same physical structure and the same nominal physical properties as in an
approved cylinder design
3.11
exterior coating
layers of material applied to the cylinder as protection or for cosmetic purposes
Note 1 to entry: The coating can be clear or pigmented.
3.12
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
3.13
load-sharing liner
liner that has a burst pressure greater than or equal to 5 % of the nominal burst pressure of the finished
composite cylinder
3.14
thermoplastic material
plastics capable of being repeatedly softened by increase of temperature and hardened by decrease
of temperature
3.15
thermosetting material
plastics that hardens permanently into a substantially infusible and insoluble product when cured by
the application of heat or chemical means
3.16
working pressure
settled pressure of a compressed gas at a reference temperature of 15 °C in a full gas cylinder
3.17
nominal outside diameter
diameter of the cylinder specified by the manufacturer for the type approval including tolerances
EXAMPLE Tolerances could be ±1 %.
3.18
type 3 cylinder
fully wrapped cylinder with a load-sharing metal liner and composite reinforcement on both cylindrical
and dome ends
3.19
test pressure
p
h
required pressure applied during the pressure test of the composite cylinder
4 Symbols
Symbols and their designations
Symbol Designation Unit
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
P burst pressure of the liner bar
bl
P calculated liner proof pressure for liner integrity test bar
l
N number of cycles with pressurization to test pressure units
N number of cycles with a pressurization to maximum developed pressure units
d
Y number of years of design life units
B width of weld reinforcement mm
h height or width of imperfection mm
t wall or plate thickness (nominal size) mm
5 Inspection and testing
Evaluation of conformity shall be carried out in accordance with the applicable regulations of the
countries of use.
4 © ISO 2016 – All rights reserved
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.
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 requirements are given in Table 1.
Table 1 — Liner requirements
Type of liner Liner material Liner heat treatment Applicable standard Relevant sections
of the applicable
standard
Welded steel liner Carbon steel Yes ISO 4706:2008 5, 6.3, 8, 9
No EN 14638-3:2010 4, 5.4, 6, 8
Stainless steel As defined in the ISO 18172-2:2007 4, 5.6, 6, 8
standard
Welded aluminium Aluminium alloy As defined in the ISO 20703:2006 4, 5.4, 6, 7
Alloy liner standard
Design requirements are excluded as these are specified by the manufacturer for the design of the
composite cylinder (7.2.4).
6.1.2 The composite cylinder manufacturer shall verify that each new batch of materials has the correct
properties and is of satisfactory quality and records shall be maintained 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.
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 filament material and the matrix system component materials shall be accompanied with
sufficient documentation to be able to fully identify the batch of materials used in the manufacture of
each cylinder.
6.2.4 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 conformity from the material
manufacturer is considered acceptable for the purposes of verification.
6.2.5 Batches of materials shall be identified and documented.
7 Design and manufacture
7.1 General
7.1.1 A type 3 fully wrapped composite gas cylinder with load-sharing welded liner shall comprise of
the following:
a) an internal metal liner which carries part of the longitudinal and circumferential load. For
cylinders with test pressure above 60 bar, the maximum permissible load share by the liner shall
be 30 %, which results in a maximum liner burst pressure of 30 % of minimum burst pressure of
the finished cylinder;
b) a composite overwrap formed by layers of continuous fibres in a matrix;
c) an optional external protection system.
There shall be no adverse reaction or interaction (e.g. epoxy coating with epoxy matrix) between the
liner and the reinforcing fibre by the application of a suitable protective coating to the liner prior to the
wrapping process.
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.
Construction and workmanship requirements shall be in accordance with those in the standards listed
in Table 1. If the cylinder includes permanently attached components (e.g. neck rings), they shall be
considered as an integral part of the cylinder and form part of the qualified design.
NOTE Examples of certificates are shown in Annexes A and B.
7.1.2 Cylinders with a test pressure less than 60 bar shall have a non-limited design life
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 specified 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) the following:
a) the material, including limits of chemical analysis;
b) the dimensions, minimum wall thickness, straightness, and out-of-roundness with tolerances;
c) the process and specification of manufacture;
d) the weld profile including the manufacturing procedure, dimensions and tolerances, and the
maximum limits for excess weld metal as specified in 7.3.1 a);
e) the heat treatment, temperatures, duration, and tolerances, if applicable;
f) the inspection procedures (in addition to those specified on the referred liner standard in
accordance with Table 1);
g) the material properties including minimum mechanical properties and hardness ranges, where
applicable;
h) the calculated proof pressure of the liner for liner integrity test, P (in accordance with 8.5.4);
l
6 © ISO 2016 – All rights reserved
i) the minimum design burst pressure, P ;
bl
j) the 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) the following:
a) the fibre material, specification, and mechanical properties requirements (the mechanical
properties shall be as specified by the manufacturer);
b) the minimum composite thickness;
c) the thermosetting matrix – specifications (including resin, curing agent, and accelerator) and resin
bath temperature where applicable;
d) the thermoplastic matrix system – main component materials, specifications, and process
temperatures;
e) the overwrap construction including the number of strands used, number of layers, and layer
orientation and tensioning of the fibre at wrapping; this tension can be either a process tension to
aid the wrapping process or the much higher pre-tensioning to actively change the final stresses in
the finished cylinder;
f) the curing process, temperatures, duration, and tolerances, where applicable.
7.2.4 Documentation for the composite cylinder shall include (but not be limited to) the following:
a) the nominal water capacity in litres at ambient conditions;
b) the dimensions with tolerances;
c) the list of intended contents if intended for dedicated gas service;
d) the test pressure, P ;
h
e) the working pressure, P (if applicable), that shall not exceed 2/3 × P test pressure;
w h
f) the maximum developed pressure at 65 °C for specific dedicated gas(es), P ;
max
g) the minimum design burst pressure, P ;
b
h) the design life in years;
i) the autofrettage pressure and approximate duration or details of the fibre tensioning, if applicable;
j) the nominal mass of the finished composite cylinder, including tolerances;
k) the details of components which are permanently attached and form part of the qualified design
(e.g. neck rings, protective boots);
l) the additional test requirements for special applications.
7.3 Manufacturing
7.3.1 The liner shall be manufactured in accordance with the manufacturer’s design (see 7.2.2) and
standard for the relevant liner requirements (as specified in 6.1.1).
a) The weld profile shall not exceed the dimensions and tolerances and the maximum limits for excess
weld metal as specified in Table 2.
Table 2 — Excess weld metal limits
Standard Figure Limits for imperfections for
quality level
ISO 5817:2014, Table 1 No. 1.9, for h ≤ 1 mm + 0,1 b, but max. 5 mm
fusion welded joint in steel, nickel,
titanium and their alloys
ISO 10042:2005, Table 1 No. 1.11, for h ≤ 1,5 mm + 0,1 b, but max. 6 mm
arc welded joints in aluminium and
their alloys
ISO 13919-1:1996, Table 2 No. 11, h ≤ 0,2 mm + 0,15 t, or 5 mm, which-
for electron and laser beam joints ever is the smaller
in steel
ISO 13919-2:2001, Table 2 No. 12, h ≤ 0,2 mm + 0,15 t, max. 5 mm
for electron and laser beam joints in
aluminum and its weldable alloys
b) Welded joints shall conform to ISO 5817 quality level B (for steel, nickel, and titanium and their
alloys) or ISO 10042 (for aluminium and its alloys) quality level B or ISO 13919-1 (for steel) quality
level C or ISO 13919-2 quality level C (for aluminium and its alloys).
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 may 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.
7.3.3 After wrapping is completed, the composite shall be cured (if applicable) using a controlled
temperature profile as specified in 7.2.3. The cure process 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
8 © ISO 2016 – All rights reserved
by appropriate measurement technique(s). The liners for cylinders subject to autofrettage shall be
heat treated.
7.3.5 If cylinders are subjected to a pre-stressing or fibre tensioning during wrapping in order
to actively change the final stresses in the finished cylinder, the tension shall be as specified in the
documentation referred to in 7.2.3 and 7.2.4 and shall be monitored and recorded.
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 on each new cylinder design or design variant.
Annex C specifies the prototype tests to be conducted and specifies the test frequency.
8.2 Prototype tests
8.2.1 A minimum of 30 cylinders that are representative of the new design in their finish form shall be
made available for prototype testing. Upon successful completion of all prototype tests, the remaining
untested cylinders from the prototype qualification batch may be used for service.
8.2.2 Where, 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. In this case, the approval
validity shall be limited to this batch only.
For a limited design change (design variant), in accordance with Table 3, a reduced number of cylinders
shall be selected.
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 9.2.
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 9.4.
8.2.5 Verify that the material and design meet the requirements of Clauses 6 and 7 and the cylinders
necessary for destructive testing shall be randomly selected. A dimensional check for conformity to the
drawing and the parameters as specified in the design submission (see 7.2) shall be performed on all
liners and cylinders selected for destructive testing.
The tests shall consist of the following:
a) the hydraulic or pneumatic proof pressure test, in accordance with 8.5.1, or hydraulic volumetric
expansion test, in accordance with 8.5.2;
b) the liner burst tests, in accordance with 8.5.3;
c) the liner integrity test, in accordance with 8.5.4;
d) the cylinder burst test, in accordance with 8.5.5;
e) the ambient temperature cycle test, in accordance with 8.5.6;
f) the environmental cycle test, in accordance with 8.5.7;
g) the flaw test, in accordance with 8.5.8;
h) the drop test, in accordance with 8.5.9;
i) the high velocity impact (gunfire) test, in accordance with 8.5.10;
j) the torque test, in accordance with 8.5.13;
k) the leak test, in accordance with 8.5.15;
l) the composite materials mechanical properties tests, in accordance with 8.5.16.
8.2.6 Tests that are optional depending upon the design and intended use of the cylinder are the
following:
a) the fire resistance test, in accordance with 8.5.11;
b) the salt water immersion test, in accordance with 8.5.12;
c) the environmentally assisted stress rupture test, in accordance with 8.5.14.
8.2.7 For approval of a design variant as specified in 8.4, it is only necessary to perform the tests as
specified in Table 3 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 may be used as
applicable (see 8.4.2).
8.2.8 Tests may be combined such that one cylinder can be used for more than one test. For example,
the cylinder used in drop test (see 8.5.9) may be used to perform the burst test specified in 8.5.5.
8.2.9 If the results of the prototype tests are satisfactory, the inspector shall issue a type approval
certificate.
NOTE A typical example of a type approval certificate is given in Annex A.
8.2.10 After completion of the tests, the cylinders shall be destroyed or rendered unserviceable.
8.3 New design
8.3.1 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, for example:
a) The cylinder 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. These conditions shall be verified by the inspector.
b) The cylinder 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. The
cylinder is manufactured with a new fibre type. A fibre of the same specification classification
and mechanical properties but with a different linear density (mass per unit length) shall not be
considered a new fibre type. A fibre shall be considered to be of a new fibre type when:
1) the fibre is of a different type (e.g. glass, aramid, or carbon);
2) the fibre is produced from a different precursor (e.g. polyacrylonitrile (PAN) or pitch for carbon);
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3) the fibre is not equivalent (see 8.4.1 i)) to the fibre in the original design.
d) The matrix materials (i.e. resin, curing agent, and accelerator) are different and not chemically
equivalent to the original design (e.g. a change from an epoxy to a polyester).
e) The test pressure has increased by more than 60 % from the qualified design.
8.3.2 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, for example:
a) The liner 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. These conditions shall be verified by the inspector.
b) The liner 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.
d) Different welding technology is used, e.g. weld configuration.
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 3. A cylinder shall be considered to be a design variant if changes are
limited to the following:
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) the pre-stressing parameters have changed by more than 5 %;
e) there is a change in the design test pressure up to and including 60 %; 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) 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;
g) the minimum wall thickness of the liner has changed by more than 5 %;
h) 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;
i) the matrix materials (i.e. resin, curing agent, and accelerator) are chemically equivalent to the
original design;
j) when equivalent overwrapping fibres are used;
1) 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.
NOTE Carbon fibres made from the same precursor can be equivalent. Aramid, carbon, and glass fibres
are not equivalent.
2) Where a new equivalent fibre has been successfully 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.
k) when an equivalent liner is used;
1) Equivalent liners shall be manufactured by the same welding procedure resulting in the same
weld configuration (same materials and parameters).
2) The equivalent liner material shall be subjected to the material tests specified in 9.2.3 and the
liner burst test specified in 8.5.3 and in both cases shall meet the requirements specified in 7.2.2.
3) Where a new equivalent liner has been successfully 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.
l) when the cylinder inlet thread has changed.
When a cylinder design has only a different thread compared with an approved design, only the torque
test, in accordance with 8.5.13, 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.
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 3, 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).
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