SIST EN 12257:2002

Transportable gas cylinders - Seamless, hoop-wrapped composite cylinders

This European Standard specifies minimum requirements for the materials, design, construction, prototype testing and routine manufacturing inspections of composite gas cylinders with a water capacity up to and including 450 litres for compressed, liquefied and dissolved gases.
NOTE   For the purposes of this standard, the word "cylinder" includes tubes up to 450 litres water capacity.
This standard is applicable to cylinders that comprise a seamless metal liner reinforced over a substantial part of the parallel length by wound composite fibres of glass, carbon, aramid, or wire.
This standard is not applicable to gas cylinders which are almost totally covered with fibres and commonly called "fully-wrapped" cylinders. For fully-wrapped composite cylinders see prEN 12245.
NOTE   The specification does not address the design, fitting and performance of removable protective sleeves. Where these are fitted they should be considered separately.

Ortsbewegliche Gasflaschen - Nahtlose umfangsgewickelte Flaschen aus Verbundwerkstoffen

Diese Norm enthält Mindestanforderungen an die Werkstoffe, die Gestaltung, Konstruktion, die Bauartzulassungen, Baureihen- und Abnahmeprüfungen von Flaschen aus Verbundwerkstoffen mit einem Fassungsraum bis zu 450 Litern für verdichtete, verflüssigte und unter Druck gelöste Gase.
ANMERKUNG   Für die Anwendung dieser Norm umfasst das Wort "Flasche" auch Großflaschen mit einem Fassungsraum bis zu 450 Litern.
Diese Norm ist auf Flaschen anwendbar, die aus einem nahtlosen Liner aus Metall bestehen, und die über den größten Teil der parallelen Länge mit einem Wickelverbund aus Glas-, Kohlenstoff-, Aramid- oder Stahl (Draht) verstärkt sind.
Die vorliegende Norm gilt nicht für Gasflaschen, die mit Faserwerkstoffen vollumwickelt sind und allgemein als "vollumwickelte" Flaschen bezeichnet werden. Für diese gilt EN 12245.
ANMERKUNG   Diese Festlegungen beinhalten nicht die Gestaltung, Montage und das Verhalten von abnehmbaren Schutzhüllen. Dies sollte separat betrachtet werden.

Bouteilles a gaz transportables - Bouteilles sans soudure, frettées composites

La présente Norme européenne spécifie les exigences minimales relatives aux matériaux, a la conception, a la construction, aux essais de prototype et aux contrôles courants en fabrication, des bouteilles a gaz composites, d'une contenance en eau inférieure ou égale a 450 litres, pour gaz comprimés, liquéfiés et dissous.
NOTE 1   Pour les besoins de la présente norme, le mot « bouteille » englobe les tubes d'une contenance en eau inférieure ou égale a 450 l.
La présente norme s'applique aux bouteilles constituées d'un liner métallique sans soudure renforcé sur une portion substantielle de sa partie cylindrique par un enroulement composite en fibres de verre, de carbone, d'aramide ou par un fil métallique.
La présente norme ne s'applique pas aux bouteilles a gaz presque totalement recouvertes de fibres, couramment appelées "bouteilles entierement bobinées". Pour les bouteilles composites entierement bobinées, voir l'EN 12245.
NOTE 2   Cette spécification ne traite pas de la conception, du montage et des performances des gaines de protection amovibles. Lorsque celles-ci sont montées, il convient de les considérer séparément.

Premične plinske jeklenke - Jeklenke iz celega, obročasto obvite s kompozitno maso

General Information

• Status: Published
• Publication Date: 31-Oct-2002
• ICS: 23.020.35 - Gas cylinders
• Technical Committee: TLP - Pressure vessels
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Nov-2002
• Due Date: 01-Nov-2002
• Completion Date: 01-Nov-2002
• Directive: 94/55/EC - Transport of dangerous goods by road
• Directive: 96/49/EC - Transport of dangerous goods by rail
• Directive: 96/86/EC - Transport of dangerous goods by road (94/55/EC Dir. amendment)
• Directive: 96/87/EC - Transport of dangerous goods by rail (96/49/EC Dir. amendment)
• Mandate: M/086 - Mandate to CEN for standardization in the field of transport of dangerous goods
• Ref Project: EN 12257:2002 - Transportable gas cylinders - Seamless, hoop-wrapped composite cylinders

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 12257:2002
01-november-2002
3UHPLþQHSOLQVNHMHNOHQNH-HNOHQNHL]FHOHJDREURþDVWRREYLWHVNRPSR]LWQR
PDVR
Transportable gas cylinders - Seamless, hoop-wrapped composite cylinders
Ortsbewegliche Gasflaschen - Nahtlose umfangsgewickelte Flaschen aus
Verbundwerkstoffen
Bouteilles a gaz transportables - Bouteilles sans soudure, frettées composites
Ta slovenski standard je istoveten z: EN 12257:2002
ICS:
23.020.30 7ODþQHSRVRGHSOLQVNH Pressure vessels, gas
MHNOHQNH cylinders
SIST EN 12257:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 12257:2002

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SIST EN 12257:2002
EUROPEAN STANDARD
EN 12257
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2002
ICS 23.020.30
English version
Transportable gas cylinders - Seamless, hoop-wrapped
composite cylinders
Bouteilles à gaz transportables - Bouteilles sans soudure, Ortsbewegliche Gasflaschen - Nahtlose umfangsgewickelte
frettées composites Flaschen aus Verbundwerkstoffen
This European Standard was approved by CEN on 9 November 2001.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12257:2002 E
worldwide for CEN national Members.

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SIST EN 12257:2002
EN 12257:2002 (E)
Contents
page
Foreword .3
Introduction .4
1 Scope.5
2 Normative references.5
3 Terms, definitions and symbols .6
4 Design and manufacture .7
5 Cylinder and material tests .10
6 Conformity evaluation .21
7 Marking.21
Annex A (normative)  Prototype testing, design variant testing and production testing .22
Annex B (informative)  Examples of type approval and production testing certificates .33
Bibliography .37
2

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SIST EN 12257:2002
EN 12257:2002 (E)
Foreword
This document EN 12257:2002 has been prepared by Technical Committee CEN/TC 23
"Transportable gas cylinders", the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2002, and conflicting national standards shall
be withdrawn at the latest by August 2002.
This European Standard has been prepared under a mandate given to CEN by the European
Commission and the European Free Trade Association, and supports the objectives of the framework
Directives on Transport of Dangerous Goods.
This European Standard has been submitted for reference into the RID and/or the technical annexes
of the ADR. Therefore in this context the standards listed in the normative references and covering
basic requirements of the RID/ADR not addressed within the present standard are normative only
when the standards themselves are referred to in the RID and/or the technical annexes of the ADR.
Annex A is normative and annex B is informative.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Czech
Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.
3

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SIST EN 12257:2002
EN 12257:2002 (E)
Introduction
The purpose of this standard is to provide a specification for the design, manufacture, inspection and
testing of refillable transportable seamless, hoop wrapped composite cylinders.
The specifications given are based on knowledge of, and experience with, materials, design
requirements, manufacturing processes and control during manufacture of cylinders in common use in
the countries of the CEN members.
4

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SIST EN 12257:2002
EN 12257:2002 (E)
1 Scope
This European Standard specifies minimum requirements for the materials, design, construction,
prototype testing and routine manufacturing inspections of composite gas cylinders with a water
capacity up to and including 450 litres for compressed, liquefied and dissolved gases.
NOTE For the purposes of this standard, the word “cylinder” includes tubes up to 450 litres water capacity.
This standard is applicable to cylinders that comprise a seamless metal liner reinforced over a
substantial part of the parallel length by wound composite fibres of glass, carbon, aramid, or wire.
This standard is not applicable to gas cylinders which are almost totally covered with fibres and
commonly called "fully-wrapped" cylinders. For fully-wrapped composite cylinders see EN 12245.
NOTE The specification does not address the design, fitting and performance of removable protective
sleeves. Where these are fitted they should be considered separately.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate place in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this European Standard only when incorporated in it by amendment or revision. For undated
references the latest edition of the publication referred to applies (including amendments).
EN 1089-1, Transportable gas cylinders— Gas cylinder identification (excluding LPG) –
Part 1: Stampmarking.
EN 1964-1, Transportable gas cylinders — Specification for the design and construction of refillable
transportable seamless steel gas cylinders of water capacities from 0,5 litre up to and including 150
litres — Part 1: Cylinders made of seamless steel with an R value of less than 1 100 MPa.
m
prEN 1964-2, Transportable gas cylinders — Specification for the design and construction of refillable
transportable seamless steel gas cylinders from 0,5 litres up to and including 150 litres — Part 2:
Tensile strength (R max)
1 100 MPa.
m
EN 1964-3, Transportable gas cylinders — Specification for the design and construction of refillable
transportable seamless steel gas cylinders of capacity from 0,5 litres up to 150 litres — Part 3:
Stainless steel cylinders.
EN 1975, Transportable gas cylinders — Specification for the design and construction of refillable
transportable seamless aluminium and aluminium alloy gas cylinders of capacity from 0,5 l up to 150 l.
EN 10002-1, Metallic materials — Tensile testing — Part 1: Method of test (at ambient temperature)
EN ISO 11114-1, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas
contents — Part 1: Metallic Materials (ISO 11114-1:1997).
EN ISO 11120, Gas Cylinders — Refillable seamless steel tubes of water capacity between 150 l
and 3000 l — Design, construction and testing (ISO 11120:1999).
EN ISO 13341, Transportable gas cylinders — Fitting of valves to gas cylinders (ISO 13341:1997).
5

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EN 12257:2002 (E)
ASTM D 2290-92, Test method for apparent tensile strength of ring or tubular plastics and reinforced
plastics by split disk method.
ASTM D 2291-83, Fabrication of ring test specimens for glass-resin composites.
ASTM D 2343-95, Test method for tensile properties of glass fibre strands, yarns and rovings used in
reinforced plastics.
ASTM D 4018-93, Test methods for tensile properties of continuous filament carbon and graphite fiber
tows.
3 Terms, definitions and symbols
For the purposes of this European Standard, the following terms, definitions and symbols apply.
3.1 Terms and definitions
3.1.1
ambient temperature
temperature of surroundings varying between 10 °C and 35 °C (for test purposes only)
3.1.2
autofrettage
pressure application procedure which strains the metal liner past its yield point sufficiently to cause
permanent plastic deformation, and results in the liner having compressive stresses and the fibres
having tensile stresses internally when at zero internal gauge pressure
3.1.3
batch, (of fibres, wires or components of the resin system)
homogeneous quantity of material, identified and certified as such by the supplier
3.1.4
batch, (of metallic liners)
quantity of liners of the same nominal diameter, thickness, length and design, made successively from
the same material cast and subjected to the same heat treatment for the same length of time
3.1.5
batch, (of finished cylinders with liners)
quantity of up to 200 finished cylinders plus finished cylinders required for destructive testing, of the
same nominal diameter, thickness, length and design. The batch may contain different batches of
liners (providing the batches are nominally the same and have had the same treatments), fibres and
matrix materials
3.1.6
burst pressure
highest pressure reached in a cylinder or liner during the relevant burst test
3.1.7
composite overwrap
fibres and matrix taken together as a combined unit, or wire reinforcement
3.1.8
exterior coating
layer of clear or pigmented material applied to the cylinder for protection or for cosmetic purposes
6

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EN 12257:2002 (E)
3.1.9
fibre or strand
load-carrying part of the composite overwrap e.g. glass, aramid or carbon
3.1.10
hoop-wrapped cylinder
cylinder with composite overwrap along the cylindrical portion of the liner which carries part of the
circumferential stress
3.1.11
liner
metallic cylinder that contains the gas and provides a substantial structural strength to the composite
cylinder
3.1.12
matrix
material which is used to bind and hold the fibres in place
3.1.13
rejected cylinder
cylinder which in its present condition has not passed the test requirements
3.1.14
wire reinforcement
load carrying overwrap, using a metallic wire (e.g. steel), that does not require a matrix
3.2 Symbols
1)
p actual burst pressure of composite cylinder, in bar above atmospheric pressure
b
1)
p burst pressure of liner, in bar above atmospheric pressure
bL
1)
p minimum burst pressure of composite cylinder obtained during design variant testing, in bar
bmin
above atmospheric pressure
1)
p hydraulic test pressure of composite cylinder, in bar above atmospheric pressure
h
4 Design and manufacture
4.1 General
A hoop-wrapped composite gas cylinder shall comprise the following parts:
4.1.1

An internal metal liner, which carries the total longitudinal load and a substantial circumferential
load; and either

a composite overwrap formed by layers of continuous fibres in a matrix; or

wire reinforcement.

An optional exterior coating to provide external protection. When this is an integral part of the
design it shall be permanent.

5
1) 1 bar = 10 Pa = 0,1 MPa.
7

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EN 12257:2002 (E)
The cylinder can also include additional parts such as rings, bases, etc.
4.1.2 Cylinders shall be designed with one or two openings along the central axis only.
4.2 Liner
4.2.1 Liner materials
The liners shall be manufactured in accordance with the relevant sections of the following European
standards:
a) seamless steel liners: EN 1964-1 or prEN 1964-2 as appropriate;
b) seamless stainless steel liners: EN 1964-3;
c) seamless aluminium alloy liners: EN 1975;
d) steel tubes (i.e. >150 l): EN ISO 11120.
The relevant sections are: materials, thermal treatments, neck design, construction and workmanship,
mechanical tests.
NOTE This excludes the design requirements, since these are specified by the manufacturer for the design
of the composite cylinder. For liners with water capacity above 150 l manufactured of stainless steel or aluminium
alloy the relevant sections of the appropriate standard also apply.
The liner material shall be compatible with the gases intended to be used as determined by
EN ISO 11114-1.
4.2.2 Design drawing
A fully dimensioned drawing of the liner shall be supplied which includes the specification of the
material and material properties. The following material properties shall be specified:

minimum yield stress;

minimum tensile strength;

minimum elongation;

minimum burst pressure;

compatibility with the contained gas as determined by EN ISO 11114-1.
4.2.3 Design of ends (heads and bases)
The design of the ends shall be in accordance with the general requirements of the relevant cylinder
standard (as identified in 4.2.1). In order to achieve satisfactory stress distribution, the liner wall
thickness shall increase progressively in the transition zone between the cylindrical shell and the
ends, particularly the base.
The external diameter and thickness of the formed neck end of the liner shall be designed to
withstand the torque applied in fitting the valve to the cylinder, and the tests specified in Test No 12
(see 5.2.12) and Test No 13 (see 5.2.13).
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4.2.4 Neck ring
When a neck ring is provided, it shall be of a material compatible with that of the cylinder, and shall be
securely attached by a method appropriate to the liner material.
4.3 Composite overwrap
4.3.1 Materials
Material requirements for the fibre and the matrix, and for the wire where appropriate, shall be as
specified by the cylinder manufacturer.
4.3.2 Winding
Appropriate procedures shall be defined for the winding and curing process to ensure good
repeatability and traceability.
The following parameters shall be defined and monitored:

percentages of the components of the matrix system and their batch numbers;

the batch numbers of the fibres or wire used;

the number of strands used;

the winding tension per strand or wire, (if applicable);

the winding speed(s);

the winding angle and/or pitch for each layer;

resin bath temperature range, (if applicable);

the number of layers;

the procedure used to obtain correct impregnation (e.g. wet winding or pre-impregnation);

the polymerisation cycle;

the polymerisation process (e.g., thermal cycle, ultrasonic, ultraviolet, or radiation).
For thermal polymerisation, the temperature and the length of the polymerisation cycle of the resin
system shall be such that they do not affect the mechanical characteristics of the liner. In addition,
tolerances for holding time and temperature at each stage shall be defined.
4.4 Finished cylinder
4.4.1 Design drawings
A fully dimensioned drawing of all parts that constitute the finished cylinder shall be supplied. The
design drawing shall also include tolerances on all dimensions, including out-of-roundness,
straightness, weight and water capacity.
The drawing shall include the specification of the material(s), the material properties and the
reinforcement pattern. The specifications and the reinforcement patterns may be given in a technical
specification enclosed with the drawing.
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The test pressure, autofrettage pressure (if applicable) and minimum burst pressure for the design
shall be specified. The minimum burst pressure shall be at least 1,67  test pressure (p ).
h
Any special characteristics or special limitations (e.g. design life, underwater suitability and/or
maximum fitting torque restrictions) shall also be stated.
4.4.2 Autofrettage
Internal pressurisation to autofrettage pressure of cylinders with metallic liners can be part of the
manufacturing process; if so this operation shall be executed after polymerisation of the composite for
thermosetting resins.
During the autofrettage operation, the following parameters shall be recorded:

autofrettage pressure;

length of application of this pressure.
If autofrettage is performed, a check shall be made that the procedure has been effectively performed on
all cylinders (e.g. through measurement of autofrettage expansions or other equivalent methods).
4.4.3 Manufacturing requirements for the finished cylinder
The internal and external surfaces of the finished cylinder shall be free of defects which could
adversely affect the safe working of the cylinder. In addition there shall be no visible foreign matter
present inside the cylinder (e.g. resin, swarf or other debris).
5 Cylinder and material tests
5.1 General
This clause describes tests to be conducted on seamless, hoop-wrapped composite cylinders,
cylinder liners and the materials used in manufacture of cylinders for prototype testing of new cylinder
designs, design variant testing and batch acceptance tests. The tests listed may be required or
optional, as identified in the schedule of testing and inspections in annex A.
No tests shall be performed with a removable protective sleeve fitted to the cylinder.
5.2 Test procedures and test requirements
5.2.1 Test No 1 - Composite material tests
Procedure:
Tests on the composite materials to establish their mechanical properties shall be carried out
in accordance with the following procedures:
a) Tensile properties of fibres:
For glass, aramid: - ASTM D 2290-92 and ASTM 2291-83;
- ASTM D 2343-95;
For carbon: - ASTM D 4018-93.
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EN 12257:2002 (E)
b) Tensile properties of wires: - EN 10002-1
Equivalent tests in accordance with alternative standards or test specifications acceptable to
the inspection body may be applied.
Criteria:
The mechanical properties shall meet the minimum requirements for the design as specified by
the manufacturer.
5.2.2 Test No 2 - Liner material tests
Procedure:
Tests on the liner material shall be carried out following the test procedures of the appropriate
standards as follows:
a) Seamless steel - as described in EN 1964-1, prEN 1964-2, or EN ISO 11120, as appropriate;
b) Seamless stainless steel - as described in EN 1964-3;
c) Seamless aluminium - as described in EN 1975.
Criteria:
The material properties shall meet the minimum requirements for the design as specified by the
manufacturer.
5.2.3 Test No 3 - Liner burst test at ambient temperature
Procedure:
The hydraulic burst test shall be carried out using a test rig, which allows pressure to be
increased at a controlled rate.
The test shall be carried out in ambient conditions and the temperature on the external
surface of the liner shall be maintained at less than 50 °C. The rate of pressurization shall not
exceed 10 bar/s and the duration of the test shall be at least 40 s.
The cylinder shall be pressurized at a controlled rate until failure. The pressure against time
curve or pressure against volume curve shall be plotted.
The maximum pressure achieved during the test shall be recorded as the burst pressure.
Criteria:

burst pressure of the liner (p ) shall be greater than or equal to 0,85 times test pressure (p ) and
bl h
to the minimum specified in 4.2.2;

burst initiation shall be in the cylindrical part and the liner shall remain in one piece.
Parameters to monitor and record:

burst pressure;
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the number of pieces;

description of failure;

pressure/time curve or pressure/volume curve.
5.2.4 Test No 4 - Hydraulic (proof) test of finished cylinders at ambient temperature
Procedure:
Where cylinders are subjected to autofrettage the hydraulic proof pressure test may
immediately follow or be part of the autofrettage operation.
The water pressure in the cylinder shall increase at a controlled rate until the test pressure
(p ) is reached. The cylinder shall remain at the test pressure (p ) for at least 30 s.
h h
3%
The limit deviation on attaining test pressure shall be test pressure (p ).
h
0
Criteria:

pressure shall remain steady;

there shall be no leaks;

after the test the cylinder shall show no visible permanent deformation.
Parameters to monitor during the test:

pressure.
5.2.5 Test No 5 – Cylinder burst test at ambient temperature
Procedure:
The hydraulic pressure burst test shall be carried out using a test rig, which allows pressure to
be increased at a controlled rate.
The test shall be carried out in ambient conditions and the temperature on the external
surface of the cylinder shall be maintained at less than 50 °C. The rate of pressurisation shall
not exceed 10 bar /s and the duration of the test shall be at least 40 s.
The cylinder shall be pressurised at a controlled rate until failure. The pressure against time
curve or pressure against volume curve shall be plotted.
The maximum pressure achieved during the test shall be recorded as the burst pressure.
Criteria:

burst pressure shall be greater than or equal to the manufacturer's minimum specified design
burst pressure and 1,67  test pressure (p  1,67 p );
b h

burst initiation shall be by longitudinal failure in the cylindrical part and the liner shall remain in
one piece.
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EN 12257:2002 (E)
Parameters to monitor and record:

burst pressure;

the number of pieces;

description of failure;

pressure/time curve or pressure/volume curve.
5.2.6 Test No 6 - Resistance to pressure cycles at test pressure (p ) and ambient temperature
h
a) For non-limited life
Procedure:
The cycle test shall be carried out using a test rig, which allows pressure to be increased and
decreased at a controlled rate and automatically suspend the test when the cylinder has
failed, either by leakage or rupture.
The test shall be carried out with a non-corrosive liquid subjecting the cylinder to successive
reversals at an upper cyclic pressure equal to the hydraulic test pressure (p ). The value of
h
the lower cyclic pressure shall not exceed 10 % of the upper cyclic pressure and shall have
an absolute maximum of 30 bar.
The cylinder shall actually experience the maximum and minimum cyclic pressures during this
test.
The cycle tests shall be carried out in ambient conditions and the temperature on the outside
surface of the cylinder shall not exceed 50 °C during the test. The frequency of reversals of
pressure shall not exceed 0,25 Hz (15 cycles per minute).
The temperature of the external surface of the cylinder shall be monitored at least twice a
day.
The number of cycles achieved during the test shall be recorded.
After completion of this test the cylinder shall then be destroyed (e.g. by bursting), or made
incapable of holding pressure.
Criteria:

the cylinder shall withstand 12 000 cycles to test pressure (p ) without failure by burst or leakage.
h
Parameters to monitor and record:

the temperature of the cylinder;

number of cycles achieving upper cyclic pressure;

minimum and maximum cyclic pressures;

cycle frequency;

test medium used;

mode of failure, if appropriate.
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b) For limited life:
Procedure:
This test shall be conducted in accordance with the procedure as described in a) above and
shall consist of two parts run sequentially and continuously. Different criteria apply to the two
parts, as shown in Figure 1.
After completion of this test the cylinder shall then be destroyed (e.g. by bursting), or made
incapable of holding pressure.
Criteria:

the cylinder shall first withstand N cycles to test pressure (p ) without failure by burst or leakage,
h
where:
N = y  250
where
y is the number of years of design service life, and shall be a whole
number greater than 10;
N cycles, or until failure by leakage whichever is the sooner. In

the test shall continue for a further
either case the cylinder shall be deemed to have passed the test. However should failure during
this second half of the test be by burst, then the cylinder shall have failed Test No. 6.
st nd
1 part 2 part
Number of cycles 0 ‹---------------------------›NN ‹-------------------------›2N
Criteria No leakage/burst = Pass
No leakage or burst Leakage = Pass
st
Pass 1 part Burst = Fail
Figure 1 — Criteria for Test No 6
Parameters to monitor and record:

the temperature of the cylinder;

number of cycles, achieving upper cyclic pressure;

minimum and maximum cyclic pressures;

cycle frequency;

test medium used;

mode of failure, if appropriate.
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5.2.7 Test No 7 - Immersion in salt water
This test is required for all cylinder designs intended for diving and is optional for other applications.
Procedure:
The cylinder shall be finished as for the intended application and without external coating
unless this is an integral part of the design.
Two closed cylinders shall be immersed in an aqueous solution containing 35 g/l of sodium
chloride at (20 ± 5) °C for 90 days continuously.
The cylinders shall be immersed:

for 45 days at not less than 2/3 test pressure (p );
h

for 45 days without pressure.
The pressure shall be recorded at least at the beginning of the test and after 45 days, prior to
de-pressurisation.
Then, following the 90 day immersion:

one of the two cylinders shall be subjected to Test No 5 (see 5.2.5);

the other cylinder shall be subjected to Test No 6 (see 5.2.6);
After completion of Test No.6, the cylinder shall then be destroyed (e.g. by bursting), or made
incapable of holding pressure.
Criteria:

for the first cylinder, burst pressure shall be greater than or equal to 1,67  test pressure (p  1,67
b
p ), burst initiation shall be by longitudinal failure in the cylindrical part and the liner shall remain
h
in one piece;

for the second cylinder, criteria shall be as for Test No. 6 (see 5.2.6), as appropriate for the
design life.
Parameters to monitor and record:

the temperature of the solution, at least twice a day;

filling pressure;

duration of immersion;

parameters specified in Test No 5 (see 5.2.5);

parameters specified in Test No 6 (see 5.2.6).
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5.2.8 Test No 8 - Exposure to elevated temperature at test pressure
This test is not required for cylinders wound with wire.
Procedure:
For a design service life of up to 20 years, one cylinder shall be hydraulically pressurised to
test pressure (p ), and shall be maintained at this pressure for 1 000 h.
h
For a design service life of greater than 20 years, including non-limited life, the test shall run for
2 000 h.
The test shall be conducted at (70 ± 5) C and a relative humidity of less than 50 %. After this
test, the cylinder shall be subjected to Test No 5 (see 5.2.5).
Criteria:

burst pressure shall be greater than or equal to 1,67  test pressure (p  1,67 p ), burst initiation
b h
shall be by longitudinal failure in the cylindrical part and the liner shall remain in one piece;
Parameters to monitor and record:

measurement of the water capacity before and after test;

temperature and relative humidity, at least twice a day;

cylinder pressure at least twice a day;

parameters specified in Test No 5 (see 5.2.5).
5.2.9 Test No 9 - Extreme temperature cycle test
a) Pressure cycling stages
Procedure:
The cylinder and the contained pressurising medium shall be conditioned for 48 h at
atmospheric pressure, at between 60 °C and 70 °C and at a relative humidity greater than or
equal to 95 %.
The hydraulic pressurising medium, located in the circuit external to the cylinder under test,
shall commence the cycle testing at ambient temperature. 5 000
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