prEN 15047

Transportable gas cylinders - Specification for the design and construction of refillable seamless steel cylinders for portable fire extinguishers and bottles for breathing apparatus of water capacities from 0,5 litre up to 15 litres

This standard specifies minimum requirements for the material, design, construction and workmanship, manufacturing processes and tests at manufacture of refillable seamless steel gas cylinders fitted with bursting disc devices for portable fire extinguishers and breathing apparatus of water capacities from 0,5 litre up to 15 litres. This standard is applicable to cylinders manufactured from steel with an Rm value of less than 1 100 MPa.

Ortsbewegliche Gasflaschen - Gestaltung und Konstruktion von wiederbefüllbaren nahtlosen Flaschen aus Stahl für tragbare Feuerlöscher und Atemgeräte mit einem Fassungsraum von 0,5 Liter bis einschließlich 15 Liter

Bouteilles à gaz transportables - Spécification pour la conception et la fabrication de bouteilles à gaz rechargeables et transportables en acier sans soudure d'extincteurs d'incedie portatif et bouteilles d'appareil respiratoir de capacité de l'eau comprise entre 0,5 l et 15 l inclus

Prenosni plinski valji - Specifikacija za zasnovo in konstrukcijo ponovno polnljivih nevarjenih jeklenk za prenosne gasilne naprave in za dihalne aparate z vodno prostornino od 0,5 litra do 150 litrov

General Information

• Status: Not Published
• ICS: 23.020.35 - Gas cylinders
• Technical Committee: CEN/TC 23 - Transportable gas cylinders
• Drafting Committee: CEN/TC 23/SC 1/WG 1 - Seamless steel cylinders
• Current Stage: 4098 - Decision to abandon - Enquiry
• Start Date: 01-Feb-2007
• Completion Date: 01-Feb-2007
• 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)
• Directive: 97/23/EC - Directive 97/23/EC of the European Parliament and of the Council of 29 May 1997 on the approximation of the laws of the Member States concerning pressure equipment
• Mandate: M/071 - Mandate to CEN for standardization in the field of Pressure equipment
• Mandate: M/086 - Mandate to CEN for standardization in the field of transport of dangerous goods
• Ref Project: OSIST prEN 15047:2004 - Transportable gas cylinders - Specification for the design and construction of refillable seamless steel cylinders for portable fire extinguishers and bottles for breathing apparatus of water capacities from 0,5 litre up to 15 litres

Overview

prEN 15047 (CEN) specifies minimum requirements for the design, construction, material selection and manufacturing tests of refillable, seamless steel transportable gas cylinders used in portable fire extinguishers and breathing apparatus. It covers cylinders with water capacities from 0.5 litre up to 15 litres, manufactured from steels with tensile strength (Rm) below 1 100 MPa, and fitted with bursting disc devices. The draft standard aligns with the Pressure Equipment Directive (PED) and provides type-approval and production test guidance for safe, durable cylinders.

Key topics and technical requirements

• Scope and Applicability: Refillable seamless steel cylinders for portable extinguishers and breathing sets, capacities 0.5–15 L; Rm < 1 100 MPa.
• Material controls: Chemical composition limits (C, Mn, Si, S, P and alloying elements), cast analysis certificates and non-ageing steel requirements.
• Heat treatment: Requirements for normalizing, quenching, tempering; documentation of heat treatment and crack-control measures for rapid quenching media.
• Design calculations: Wall thickness calculation tied to guaranteed yield stress (Re) and design stress factor (F ≤ 0.875); minimum thickness rules and examples (see Annex B).
• Ends and heads: Criteria for convex head/base thickness and geometries to ensure satisfactory stress distribution.
• Testing at manufacture: New design (type) tests, burst tests, hydraulic tests, tensile and hardness testing, non-destructive inspection when required, and tests on every cylinder (e.g., visual, leak/hydro test).
• Marking and certification: Requirements for cylinder identification, marking (including stamping per prEN ISO 13769) and production certificates; Annex ZA links to PED essential requirements.
• Failure and rejection criteria: Visual inspection defects and conditions for rejection (Annex A).

Applications and who uses this standard

• Cylinder manufacturers designing and producing refillable seamless steel gas cylinders for fire safety and respiratory protection.
• Fire extinguisher and breathing apparatus OEMs specifying compliant pressure vessels.
• Testing laboratories and conformity assessment bodies performing type approval, burst and hydraulic testing.
• Regulatory authorities, procurement specialists and quality managers ensuring compliance with CEN requirements and the PED.
• Design engineers calculating wall thickness, head geometry and selecting appropriate steel grades compatible with gas service (see EN ISO 11114-1).

Related standards

• EN ISO 11114-1 (compatibility of cylinder/valve materials with gas contents)
• EN 629 series (25E taper thread valves)
• EN 10002-1, EN 10003-1 (tensile & hardness tests)
• EN 10204 (inspection documents)
• prEN ISO 13769 (stamp marking), prEN ISO 15245 (parallel threads)
• Annex ZA of prEN 15047 maps to the Pressure Equipment Directive (97/23/EC)

Keywords: transportable gas cylinders, refillable seamless steel cylinders, portable fire extinguishers, breathing apparatus, prEN 15047, cylinder design, wall thickness, burst test, hydraulic test, CEN, PED.

Standards Content (Sample)

SLOVENSKI OSIST prEN 15047:2004

PREDSTANDARD
december 2004
Prenosni plinski valji – Specifikacija za zasnovo in konstrukcijo ponovno
polnljivih nevarjenih jeklenk za prenosne gasilne naprave in za dihalne
aparate z vodno prostornino od 0,5 litra do 150 litrov
Transportable gas cylinders - Specification for the design and construction of
refillable seamless steel cylinders for portable fire extinguishers and bottles for
breathing apparatus of water capacities from 0,5 litre up to 15 litres
ICS 23.020.30 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD
DRAFT
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2004
ICS
English version
Transportable gas cylinders - Specification for the design and
construction of refillable seamless steel cylinders for portable
fire extinguishers and bottles for breathing apparatus of water
capacities from 0,5 litre up to 15 litres
Bouteilles à gaz transportables - Spécification pour la Ortsbewegliche Gasflaschen - Gestaltung und Konstruktion
conception et la fabrication de bouteilles à gaz von wiederbefüllbaren ortsbeweglichen nahtlosen
rechargeables et transportables en acier sans soudure Gasflaschen aus Stahl für Tragbare Feuerlösche und
d'extincteurs d'incedie portatif et bouteilles d'appareil Atmungapparat mit einem Fassungsraum von 0,5 l bis
respiratoir de capacité de l'eau comprise entre 0,5 l et 15 l einschließlich 15 l
inclus
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 23.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 15047:2004: E
worldwide for CEN national Members.

Contents
Foreword.3
Introduction .4
1 Scope .5
2 Normative references .5
3 Terms, definitions and symbols.5
4 Material requirements .7
5 Design requirements .9
6 Construction and workmanship requirements.13
7 New design tests.19
8 Tests for steel cylinders.20
9 Tests on every cylinder.28
10 Failure to meet test requirements.29
11 Markings .30
12 Certificate .30
Annex A (normative) Description, evaluation of manufacturing defects and conditions for rejection of
seamless steel gas cylinders at time of visual inspection.31
Annex B (informative) Examples of wall thickness calculations.39
Annex C (informative) Examples of new design (type) approval and production testing certificates .41
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 97/23/EC (PED) .46
Bibliography .48

Foreword
This document (prEN 15047:2004) has been prepared by Technical Committee CEN/TC 23 “Transportable gas
cylinders”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This document has been prepared under a mandate given to CEN by the European Commission and the European
Free Trade Association, and supports essential requirements of EU Directive(s).
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document.
This European standard has been prepared to address the essential requirements of the Pressure Equipment
Directive (PED) for portable, refillable seamless steel (with a high F-factor) fire extinguishers and breathing
apparatus of water capacities from 0,5 litre up to and including 15 litres.
Annex A is normative. Annexes B, C and ZA are informative.
Introduction
The purpose of this standard is to provide a specification for the design, manufacture, inspection and approval of
refillable seamless high F-factor steel for use in portable fire extinguishers and breathing apparatus
The specification given is based upon 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.
This standard draws upon established practice as outlined in the ADR (European Agreement Concerning the
International Carriage of Dangerous Goods by Road) for determining the test pressure of gas cylinders (ADR, P200
4.1.4.1).
1 Scope
This standard specifies minimum requirements for the material, design, construction and workmanship,
manufacturing processes and tests at manufacture of refillable seamless steel gas cylinders fitted with bursting disc
devices for portable fire extinguishers and breathing apparatus of water capacities from 0,5 litre up to 15 litres. This
standard is applicable to cylinders manufactured from steel with an R value of less than 1 100 MPa.
m
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references,
only the edition cited applies. For undated references, the latest edition of the referenced document (including any
amendments) applies.
EN 629-1, Transportable gas cylinders — 25E taper thread for connection of valves to gas cylinders — Part 1:
Specification
EN 629-2, Transportable gas cylinders — 25E taper thread for connection of valves to gas cylinders — Part 2:
Gauge inspection
EN 10002-1, Metallic materials — Tensile testing — Part 1: Test method
EN 10003-1, Metallic materials — Brinell hardness test — Part 1: Test method
EN 10204:1991, Metallic Products — Types of inspection documents
EN 10028-1, Flat products made of steels for pressure purposes - Part 1: General requirements
EN ISO 11114-1:1997, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas
contents - Part 1: Metallic materials (ISO 11114-1:1997)
EN ISO 13341, Transportable gas cylinders — Fitting of valves to gas cylinders
prEN ISO 13769: 2004, Gas cylinders — Stamp marking
prEN ISO 15245-1, Transportable gas cylinders — Parallel threads for connection of valves to gas cylinders — Part
1: Specification
prEN ISO 15245-2, Transportable gas cylinders — Parallel threads for connection of valves to gas cylinders — Part
2: Gauge Inspection
EURONORM 6-55, Bend test for steel
3 Terms, definitions and symbols
For the purpose of this standard the following terms, definitions and symbols apply:
3.1 Terms and definitions
3.1.1
yield stress
value corresponding to the lower yield stress Re or, for steels that do not exhibit defined yield, the 0,2 % proof
L
stress Rp
0,2
3.1.2
normalizing
heat treatment in which a cylinder is heated to a uniform temperature above the upper critical point (AC , as
defined in EN 10052) of the steel and then cooled in still air
3.1.3
quenching
hardening heat treatment in which a cylinder, which has been heated to a uniform temperature above the upper
critical point (AC , as defined in EN 10052) of the steel, is cooled rapidly in a suitable medium
3.1.4
tempering
softening heat treatment which follows quenching (or in some cases normalizing), in which the cylinder is heated to
a uniform temperature below the lower critical point (AC , as defined in EN 10052) of the steel
3.1.5
batch
a quantity of up to 200 cylinders, plus cylinders for destructive testing, of the same nominal diameter, thickness,
length and design made from the same steel cast and subjected to the same heat treatment for the same duration
of time
3.1.6
burst pressure
highest pressure reached in a cylinder during a burst test
3.1.7
working pressure
settled pressure at a uniform temperature of 15 °C and full gas content
3.1.8
test pressure
required pressure applied during a pressure test
3.1.9
design stress factor (F) (variable)
the ratio of equivalent wall stress at test pressure (p ) to guaranteed minimum yield stress (R )
h e
3.1.10
mass
the weight of a cylinder, expressed in kilograms, comprising the combined weight of cylinder and permanently
attached parts (eg foot ring, neck ring, etc) but without valve
3.2 Symbols
a Calculated minimum thickness, in millimetres, of the cylindrical shell
a' Guaranteed minimum thickness, in millimetres, of the cylindrical shell
A Percentage elongation, determined by the tensile test 7.2.2.2
b Guaranteed minimum thickness, in millimetres, at the centre of a convex base (see figure 1)
d Diameter of former, in millimetres figure 4
D Nominal outside diameter of the cylinder, in millimetres see figure 1
F Design stress factor (variable) see 3.1.9
H Outside height of domed part (convex head or base end), in millimetres (see figure 1)
n The ratio of the diameter of the bend test former to actual thickness of test piece (t)
1)
P Measured burst pressure, in bar above atmospheric pressure
b
1)
P Lower cyclic pressure, in bar above atmospheric pressure
lc
1)
P Hydraulic test pressure, in bar above atmospheric pressure
h
P Maximum allowable pressure in bar for which the cylinder is designed, as specified in 5.2.
S
r Inside knuckle radius, in millimetres (see figure 1)
r Inside crown radius, in millimetres (see figure 1)
i
R Minimum guaranteed value of yield stress (see 3.1.1) in megapascals, for the finished cylinder
e
R Actual value of yield stress, in megapascals, determined by the tensile test 8.1.2.1
ea
R Minimum guaranteed value of tensile strength, in megapascals, for the finished cylinder
g
R Actual value of tensile strength, in megapascals, determined by the tensile test 8.1.2.1
m
S Original cross sectional area of tensile test piece, in square millimetres, according to EN 10002-1
o
T Maximum allowable temperature °C
s
t Actual thickness of test specimen, in millimetres
4 Material requirements
4.1 General provisions
4.1.1 Steels for the manufacture of gas cylinders shall meet the requirements of this standard.
4.1.2 The steel used for the fabrication of gas cylinders shall have acceptable non-ageing properties and shall
not be rimming quality. In cases where examination of this non-ageing property is required, the criteria by which it is
to be specified shall be agreed between the parties.
4.1.3 The cylinder manufacturer shall identify the cylinders with the cast of steel from which they are made.
4.1.4 Grades of steel used for cylinder manufacture shall be compatible with the intended gas service, e.g.
corrosive gases, embrittling gases. (See EN ISO 11114-1).
4.2 Controls on chemical composition
4.2.1 The chemical composition of all steels shall be specified and recorded, including:
– maximum sulfur and phosphorus content;
– carbon, manganese and silicon content;
– nickel, chromium, molybdenum and all other alloying elements intentionally added.

1)
1bar = 10 Pa = 0.1MPa
The content of carbon, manganese, silicon and where appropriate, nickel, chromium and molybdenum shall be
given, with tolerances, such that the differences between the maximum and minimum values of the cast do not
exceed the values shown in table 1.
Table 1 — Chemical composition tolerances
Element Nominal content in % Maximum permissible range in %
Carbon < 0,30 % 0,06 %
0,07 %
≥ 0,30 %
Manganese All values 0,30 %
Silicon All values 0,30 %
Chromium < 1,50 % 0,30 %
0,50 %
≥ 1,50 %
Nickel All values 0,40 %
Molybdenum All values 0,15 %
NOTE The maximum permissible range for each element is not required to be centred on its
nominal content. As an example, for a steel with nominal carbon content of 0,10 %, the following
three maximum permissible ranges are equally acceptable:
+0,00 %, -0,06 % +0,00 %, -0,06 %
+0,06 %, -0,00 %
+0,03 %, -0,03 % +0,03 %, -0,03 %

The combined content of the following elements: V, Nb, Ti, B, Zr, shall not exceed 0,15 %.
4.2.2 Sulfur and phosphorus in the cast analysis of material used for the manufacture of gas cylinders shall not
exceed the values shown in table 2.
Table 2 — Sulfur and phosphorus limits

R in MPa
m
R < 950 950 ≤ R < 1 100
m m
Sulfur 0,020 % 0,010 %
Phosphorus 0,020 % 0,020 %
Sulfur + phosphorus 0,030 % 0,025 %

4.2.3 The cylinder manufacturer shall obtain and provide certificates of cast analyses of the steels supplied for
the manufacture of gas cylinders. Should check analyses be required, they shall be carried out either on specimens
taken during manufacture from material in the form as supplied by the steel maker to the cylinder manufacturer, or
from finished cylinders avoiding decarbonised zones from the cylinder surface. In any check analysis, the maximum
permissible deviation from the limits specified for cast analyses shall conform to the values specified in EN 10028-
1.
4.3 Heat treatment
4.3.1 The cylinder manufacturer shall provide a certificate stating the heat treatment process applied to the
finished cylinders.
4.3.2 Quenching in media other than mineral oil is permissible provided that the method produces cylinders free
of cracks. If the rate of cooling in the medium is greater than 80 % of that in water at 20 °C without additives, every
production cylinder shall be subjected to a non-destructive test to prove freedom from cracks.
4.3.3 The tempering process for quenched and tempered cylinders and for normalized and tempered cylinders
shall achieve the required mechanical properties. The actual temperature to which a type of steel is subjected for a
given tensile strength shall not deviate by more than 30 °C from the temperature specified by the cylinder
manufacturer.
5 Design requirements
5.1 General provisions
5.1.1 The calculation of the wall thickness of the pressure containing parts shall be related to the yield stress (R ) of
e
the material.
5.1.2 For calculation purposes the value of the yield stress (R ) is limited to a maximum of 0,90 R .
e g
5.1.3 The internal pressure upon which the calculation of wall thickness is based shall be the hydraulic test
pressure (P ).
h
5.2 Calculation of cylindrical wall thickness
The guaranteed minimum thickness of the cylindrical shell (a') shall not be less than the thickness calculated using
the equation:
 
D 10.F.Re− 3.Ph
 
a = 1−
 
2 10.F.Re
 
where the value of F shall not exceed 0,875.
R / R shall be limited to 0,90.
e g
The calculated minimum thickness shall also satisfy the equation:
a ≥ D + 1 mm
With an absolute minimum of a = 1,5 mm.
Cylinders for CO fire extinguishers applications shall be designed for hydraulic test pressures related to selected
filling ratios. The test pressure shall not be less than the developed pressure at 65°C (see Table 3). For breathing
apparatus applications the test pressure shall not be less than 1,5 x working pressure (see 3.1.7).
Table 3 — Test pressure versus filling ratio for CO
Filling
P Minimum test pressure P
S h
(kg/l)
(bar) (bar)
0,667 136,8 200
0,675 138,4 200
0,750 173,5 250
When choosing the minimum guaranteed value of the thickness of the cylindrical shell (a'), the manufacturer shall
take into account all requirements for type and production testing, particularly the burst test requirements of 8.2.
For examples of wall thickness calculations see annex B.
5.3 Calculation of convex ends (heads and base ends)
5.3.1 The shapes shown in figure 1 are typical for convex heads and base ends. Shapes A and B are base ends
formed from tubing, shapes D and E are base ends formed during the piercing of a billet, and shapes C and F are
heads.
5.3.2 The thickness (b) at the centre of the convex end shall be not less than that required by the following
criteria:
Where the inside knuckle radius (r) is not less than 0,075 D, then
b ≥ 1,5a for 0,40 > H/D ≥ 0,20
b ≥ a for H/D ≥ 0,40
In order to obtain a satisfactory stress distribution in the region where the end joins the cylindrical part, any
thickening of the end that may be required, shall be gradual from the point of juncture. For the application of this
rule, the point of juncture between the cylindrical part and the end is defined by the horizontal line indicating
dimension H in figure 1.
Shape B shall not be excluded from this requirement.
The cylinder manufacturer shall prove by the pressure cycling test as required in 8.3 that the design is satisfactory.
Key
1 Cylindrical part
Figure 1 — Typical convex ends
5.4 Calculation of concave base ends
When concave base ends are used, the dimensions defined in figure 2 shall be not less than the following
calculated values:
a = 2a ; a = 2a ; h = 0,12D ; r = 0,075D
1 2
Figure 2 — Concave base ends
In order to obtain a satisfactory stress distribution, the thickness of the cylinder shall increase progressively in the
transition area region between the cylindrical part and the base, and the wall shall be free from defects.
The cylinder manufacturer shall prove by the pressure cycling test for a new design as required in 7.1 that the
design is satisfactory.
5.5 Neck design
5.5.1 The external diameter and thickness of the formed neck end of the cylinder shall be designed for the torque
applied in fitting the valve to the cylinder. The torque may vary according to the diameter of thread, the form, and
the sealant used in the fitting of the valve. The torques specified in EN ISO 13341 shall not be exceeded, since this
could result in permanent damage to the cylinder. Where the cylinder manufacturer specifies a lower torque this
also shall not be exceeded. The manufacturer shall notify any such requirements to the purchaser of aluminium or
aluminium alloy cylinders for portable CO fire extinguishers.
5.5.2 The thickness of the wall in the cylinder neck shall be sufficient to prevent permanent expansion of the neck
during initial and subsequent fitting of the valve into the cylinder. Where the cylinder is specifically designed to be
fitted with neck reinforcement, such as a neck ring or shrunk-on collar this may be taken into account (see
EN ISO 13341).
5.5.3 Cylinders for portable CO fire extinguishers may be designed with one or two opening(s) along the central
cylinder axis only.
5.6 Foot-rings
When a foot-ring is provided, it shall be sufficiently strong to support the cylinder in a vertical orientation and made
of material compatible with that of the cylinder. The shape should be cylindrical and shall give the cylinder sufficient
stability. The foot-ring shall be secured to the cylinder by a method other than welding, brazing or soldering. Any
gaps which may form water traps shall be sealed to prevent ingress of water, by a method other than welding,
brazing or soldering.
5.7 Neck-rings
When a neck-ring is provided, it shall be made of a material that is compatible with that of the cylinder, and shall be
securely attached by a method other than welding, brazing or soldering.
The manufacturer shall ensure that the axial load required to remove the neck-ring is greater than 10 times the
weight of the empty cylinder and not less than 1 000 N, also that the minimum torque required to turn the neck-ring
is greater than 100 N⋅m.
5.8 Design drawing
A fully dimensioned drawing shall be prepared which includes the specification of the material, and details of the
permanent fittings.
6 Construction and workmanship requirements
6.1 General
The cylinder shall be produced by:
— forging or drop forging from a solid ingot or billet; or
— manufacturing from seamless tube; or
— pressing from a flat plate.
Metal shall not be added in the process of closure of the end. Manufacturing defects shall not be corrected by
plugging of bases. Welding of seamless steel cylinders shall not be permitted under any circumstances.
Once the manufacturing route has been established and new design approval obtained, no other significant
changes to the process shall be permitted unless the product is submitted for re-approval.
6.2 Wall thickness
Each cylinder shall be examined for thickness and for external and internal surface defects. The wall thickness at
any point shall not be less than the minimum design thickness.
6.3 Surface defects
The internal and external surfaces of the finished cylinder shall be free from defects that would adversely affect the
safe working of the cylinder. See annex A. Such defects shall be removed by local dressing. The wall thickness of
any dressed area shall not be less than the minimum thickness specified.
6.4 Ultrasonic examination
6.4.1 General
Except as identified in 6.4.6, all cylinders shall be ultrasonically examined for defects. These tests are based on
techniques used by cylinder manufacturers. Other techniques of ultrasonic examination may be used, provided
these have been demonstrated to be suitable for the manufacturing method.
6.4.2 Equipment and personnel requirements
The ultrasonic testing equipment shall be capable of at least detecting the reference standard as described in
6.4.3.2. It shall be serviced regularly in accordance with the manufacturers operating instructions to ensure that its
accuracy is maintained. Inspection records and approval certificates for the equipment shall be maintained.
The operation of the test equipment shall be by personnel certified at least to level 1 of EN 473 and supervised by
personnel certified at least to level 2 of EN 473.
The inner and outer surfaces of any cylinder which is to be tested ultrasonically shall be in a condition suitable for
an accurate and reproducible test.
For flaw detection the pulse echo system shall be used. For thickness measurement either the resonance method
or the pulse echo system shall be used. Either contact or immersion techniques of testing shall be used.
A coupling method which ensures adequate transmission of ultrasonic energy between the testing probe and the
cylinder shall be used.
6.4.3 Flaw detection of the cylindrical part
6.4.3.1 Procedure
The cylinders to be inspected and the search unit shall have a rotating motion and translation relative to one
another such that a helical scan of the cylinder will be described. The velocity of rotation and translation shall be
constant within ± 10 %. The pitch of the helix shall be less than the width covered by the probe (at least a 10 %
overlapping shall be guaranteed) and be related to the effective beam width such as to ensure 100 % coverage at
the velocity of rotation and translation used during the calibration procedure.
An alternative scanning method may be used for transverse defect detection, in which the scanning or relative
movement of the probes and the work piece is longitudinal, the sweeping motion being such as to ensure a 100 %
surface coverage with 10 % overlapping of the sweeps.
The cylinder wall shall be tested for longitudinal defects with the ultrasonic energy transmitted in both
circumferential directions and for transverse defects in both longitudinal directions.
For concave based cylinders where hydrogen embrittlement or stress corrosion may occur (see EN ISO 11114-1)
the transition region between the cylindrical part and cylinder base shall also be tested for transverse defects in the
direction of the base. For the area to be considered, see figure 3. The ultrasonic sensitivity shall be set at + 6 dB in
order to improve the detection of defects equivalent to 5 % of the cylindrical wall thickness in this thickened portion.
In this case, or when optional testing is carried out on the transition areas between the cylindrical part and neck
and/or cylindrical part and base, this may be conducted manually if not carried out automatically.
The effectiveness of the equipment shall be periodically checked by passing a reference standard through the test
procedure. This check shall be carried out at least at the beginning and end of each shift. If during this check the
presence of the appropriate reference notch is not detected then all cylinders tested subsequent to the last
acceptable check shall be retested once the equipment has been adjusted.
Figure 3 — Base/cylindrical part transition region
6.4.3.2 Reference standard
A reference standard of convenient length shall be prepared by the manufacturer. The cylinder selected by the
manufacturer for the reference standard shall be dimensionally and acoustically representative of the cylinder to be
inspected, as demonstrable by the manufacturer. The reference standard shall be free from discontinuities which
may interfere with the detection of the reference notches.
Reference notches both longitudinal and transverse, shall be machined on the outer and inner surface of the
reference standard. The notches shall be separated such that each notch can be clearly identified.
Dimensions and shape of notches are of crucial importance for the adjustment of the equipment (see figures 4 and
5).
– The length of the notches (E) shall not be greater than 50 mm.
– The width (W) shall not be greater than twice the nominal depth (T). However, where this condition cannot be
met a maximum width of 1,0 mm is acceptable.
– The depth of the notches (T) shall be equal to 5 % ± 0,75 % of the nominal wall thickness (S), with a minimum
of 0,3 mm and a maximum of 1,0 mm, over the full length of the notch. Runouts at each end are permissible.
– The notch shall be sharp edged at its intersection with the surface of the cylinder wall. The cross section of the
notch shall be rectangular except where spark erosion machining methods are employed; then it is
acknowledged that the bottom of the notch will be rounded.
– The shape and dimensions of the notch shall be verified by an appropriate method.
Key
1 Outside reference notch
2 Inside reference notch
NOTE. T ≤ (5 ± 0,75)% S but ≤ 1,0 mm and ≥ 0,3 mm
W ≤ 2T, but if not possible then ≤ 1,0 mm
E ≤ 50 mm
Figure 4 — Design details and dimensions of the reference notches for longitudinal defects
NOTE.  T ≤ (5 ± 0,75)% S but ≤ 1,0 mm and ≥ 0,3 mm
W ≤ 2T, but if not possible then ≤ 1,0 mm
E ≤ 50 mm
Figure 5 — Schematic representation of the reference notches for circumferential defects

6.4.3.3 Calibration of equipment
Using the reference standard described in 6.4.3.2 the equipment shall be adjusted to produce clearly identifiable
indications from inner and outer surface notches. The amplitude of the indications shall be as near equal as
possible. The indication of smallest amplitude shall be used as the rejection level and for setting visual, audible,
recording or sorting devices. The equipment shall be calibrated with the reference standard or probe, or both,
moving in the same manner, in the same direction and at the same speed as will be used during the inspection of
the cylinder. All visual, audible, recording or sorting devices shall operate satisfactorily at the test speed.
6.4.4 Wall thickness measurement
If the measurement of the wall thickness is not carried out in another stage of production, the cylindrical part shall
be 100 % examined to ensure that the thickness is not less than the guaranteed minimum value (a').
6.4.5 Interpretation of results
Cylinders with indications which are equal to or greater than the lowest of the indications from the reference
notches shall be withdrawn. This comparison shall be made between the indications from the cylinder and those
from the reference notch in the same orientation and on the same face e.g. a transverse inside defect shall be
compared with the transverse inside reference notch. The cause of the indication shall be identified and if possible
removed. After removal the cylinders shall be re-subjected to ultrasonic flaw detection and thickness measurement.
Any cylinder which is shown to be below the guaranteed minimum wall thickness (a') shall be rejected.
6.4.6 Requirements for ultrasonic examination
For small cylinders with a cylindrical length of less than 200mm or where the product of p .V is less than 400,
w
ultrasonic examination is not necessary.
For all other cylinders, ultrasonic examination shall be carried out on the cylindrical part of each cylinder. For
cylinders to be used for hydrogen service, examination shall be carried out at the completion of cylinder
manufacture. For cylinders for other gases, examination shall be carried out during the manufacturing process.
In addition to these requirements optional examinations may be carried out at any stage.
6.4.7 Certification
The ultrasonic examination shall be certified by the cylinder manufacturer.
Every cylinder, which has passed the ultrasonic examination in accordance with this standard shall be stamp
marked ‘UT’ in accordance with prEN ISO 13769: 2004 (see clause 11) and optionally with the symbol shown in
figure 6.
NOTE The company logo or initials may be included in this symbol
Figure 6 — Optional stamp marking for ultrasonic examination
6.5 Neck threads
The internal neck threads shall conform to a recognized standard (e.g. EN 629-1 or EN ISO 15245-1) to permit the
use of a corresponding valve thus minimizing neck stresses following the valve torquing operation. Internal neck
threads may be checked using gauges corresponding to the agreed neck thread. For example, where the neck
thread is specified to be in accordance with EN 629-1, the corresponding gauges are specified in EN 629-2.
Particular care shall be taken to ensure that neck threads are accurately cut, are of full form and free from any
sharp profiles e.g. burrs.
6.6 Out-of roundness
The out-of-roundness of the cylindrical shell, i.e. the difference between the maximum and minimum outside
diameters at the same cross-section, shall not exceed 2 % of the mean of these diameters.
6.7 Mean diameter
The mean external diameter shall not deviate more than ± 1 % from the nominal design diameter.
6.8 Straightness
The maximum deviation of the cylindrical part of the shell from a straight line shall not exceed 3 mm per metre
length.
6.9 Stability
For a cylinder designed to stand on its base, the variation from vertical shall be less than 1 % of its height, and the
outer diameter of the surface in contact with the ground shall be greater than 75 % of the nominal outside diameter.
7 New design tests
7.1 New design (type) approval testing
7.1.1 Testing shall be carried out for each new design of cylinder. A previously approved cylinder shall be
considered to be of a new design when any of the following conditions apply:

a) it is manufactured in a different factory;
b) it is manufactured by a different process (this includes the case when major process changes are made
during the production period e.g. end forging to spinning, change in type of heat treatment etc.);
c) it is manufactured from a steel of different specified composition limits from that used in the original type
test;
d) it is given a different heat treatment, that is outside the tolerance specified in 4.3.3;
e) the base profile has changed, e.g. concave, convex, hemispherical or there is a change in the base
thickness/cylinder diameter ratio;
f) the overall length of the cylinder has increased by more than 50 % (cylinders with a length/diameter ratio
less than 3 shall not be used as reference cylinders for any new design with this ratio greater than 3);
g) the nominal outside diameter has changed;
h) the design wall thickness has changed;
i) the hydraulic test pressure has increased;
j) the guaranteed minimum yield stress (R ) and/or the guaranteed minimum tensile strength (R ) have
e g
changed.
7.1.2 A technical specification of each new design of cylinder, including design drawing, design calculations,
steel details and heat treatment, shall be submitted by the manufacturer to the relevant authority. The new design
(type) approval tests referred to in 7.1.3 shall be carried out on each new cylinder design by the relevant authority.
A minimum of 50 finished cylinders which shall be guaranteed by the manufacturer to be representative of the new
design shall be made available for prototype testing.
However, if the total production is less than 50 cylinders, enough cylinders shall be made to complete the prototype
tests required, in addition to the production quantity, but in this case the approval validity is limited to this particular
production batch.
7.1.3 In the course of new design testing, it shall be verified that:
– the design conforms to the requirements of clause 5;
– the thicknesses of the walls and ends on two of the cylinders taken for tests meet the requirements of 5.3 to
5.6, the measurements being taken on three transverse sections of the cylindrical part and over the whole of a
longitudinal section of the base and the head;
– the requirements of clause 4 (material) and 5.7 (foot-ring) are complied with;
– the geometrical requirements of 6.6 to 6.9 are complied with for all cylinders selected by the relevant authority;
– the internal and external surfaces of the cylinders are free of any defect which might make them unsafe to use
(see annex A).
7.1.4 Witness the following tests on the cylinders selected:
– the tests specified in 8.1 (mechanical tests) on 2 cylinders, the test pieces being identifiable with the batch;
– the test specified in 8.2 (hydraulic burst test) on 2 cylinders, the cylinders bearing representative stamp
marking;
– the test specified in 8.3 (pressure cycling test) on 2 cylinders, the cylinders bearing representative stamp
marking;
– the test specified in 8.6 (base check) on all the sample cylinders.
If the results of the checks are satisfactory, the relevant authority shall issue a type approval certificate a typical
example of which is given in C.1.
8 Tests for steel cylinders
8.1 Mechanical tests
8.1.1 General requirements
All tests for checking the material properties of gas cylinders shall be carried out on material from heat treated
cylinders.
8.1.2 Location of test pieces
For location of test pieces, see figure 7.

Key
1 Bend test pieces
2 Transverse impact test pieces
3 Longitudinal impact test pieces (alternative positions shown dotted)
4 Tensile test pieces
Figure 7 — Location of test pieces
8.1.3 Tensile test
8.1.3.1 A tensile test shall be carried out on material taken from the cylindrical part of the cylinder by adopting
either of the following procedures:
a) Rectangular specimens prepared in accordance with 8.1.3.2, acceptance values for elongation being in
accordance with 8.1.3.3;
b) Machined round specimens having the maximum diameter practicable, the elongation measured on a
gauge length of 5 times the specimen diameter being no less than 16 %. It is recommended that
machined round specimens are not used for wall thickness less than 3 mm.
8.1.3.2 The tensile test shall be carried out according to EN 10002-1 on a test piece shaped in accordance
with figure 8 and with a gauge length L = 5,65 S .
o o
The two faces of the test piece representing the inside and the outside surfaces of the cylinder shall not be
machined.
Dimensions in millimetres
Figure 8 — Tensile test piece
8.1.3.3 The percentage elongation (A) shall not be less than the following values:
A =
2R
m
with an absolute minimum of 14 %.
NOTE Attention is drawn to the method of measurement of elongation described in EN 10002-1, particularly in cases
where the tensile test piece is tapered, resulting in a point of fracture away from the middle of the gauge length.
8.1.4 Bend test
8.1.4.1 The bend test shall be carried out in accordance with EURONORM 6-55 on four test pieces obtained
by cutting either one or two rings of width 25 mm or 4t, whichever is the greater into equal parts. Each test piece
shall be of sufficient length to permit the bend test to be carried out correctly. Only the edges of each strip may be
machined.
8.1.4.2 The test piece shall not crack when bent inwards around the former until the inside edges are not
further apart than the diameter of the former (see figure 9).

Figure 9 — Illustration of bend test
8.1.4.3 The diameter of the former (D ) shall be established from table 4.
F
For the actual tensile strength (R ) given in table 3, D = n⋅t.
m F
8.1.5 Flattening test
The flattening test shall be carried out on two rings 25 mm wide taken from the cylinder body. Only the edges of the
rings may be machined. The rings shall be flattened between platens until the required distance between platens is
achieved. For the actual tensile strength (R ) given in table 4, the distance between the platens shall be a
m
maximum of u⋅t.The flattened rings shall remain visually uncracked.
Table 4 — Bend test and flattening test requirements
Actual tensile Bend test Flattening test
MPa
Value of Value of
n u
R ≤ 440 26
m
3 6
440 < R ≤ 520
m
4 6
520 < R ≤ 600
m
5 7
600 < R ≤ 700
m
6 8
700 < R ≤ 800
m
7 9
800 < R ≤ 900
m
R > 900 8 9
m
8.1.6 Impact test
8.1.6.1 Except for the requirements set out below the test shall be carried out in accordance with EN 10045-1.
The impact test pieces shall be taken in the direction as required in table 5 from the wall of the cylinder. The notch
shall be perpendicular to the face of the cylinder wall. For longitudinal tests the test piece shall be machined all
over (on six faces); if the wall thickness does not permit a final test piece width of 10 mm, the width shall be as near
as practicable to the nominal thickness of the cylinder wall. The test pieces taken in the transverse direction shall
be machined on four faces only, the inner and outer faces of the cylinder wall shall be un-machined.
8.1.6.2 The minimum acceptable values are specified in table 5.
Table 5 — Minimum acceptable impact strength values
> 140
≤ 140
Cylinder diameter D,mm
Direction of testing TransverseLongitudinal
Width of test piece, mm >3 to >5 to
>7,5 to ≤10 >3 to ≤5
Test temperature, °C - 50 - 50
Impact strength J/cm
Quenched and Mean of 3 specimens 30 35 40 60
tempered steels Individual specimen 24 28 32 48

Normalized, or
normalized and Mean of 3 specimens 20 40
tempered Individual specimen 16 32
steels with
R ≤ 750 MPa
m
8.2 Hydraulic burst test
8.2.1 Procedure
8.2.1.1 Test installation
The test equipment as shown in figure 10 shall be capable of operation in accordance with the test conditions
specified in 8.2.1.2 and of producing accurately the information required by 8.2.2 and 8.2.3.
8.2.1.2 Test conditions
As the cylinder and test equipment are being filled with water, care shall be taken to ensure that no air is trapped in
the circuit by operating the hydraulic pump until water is discharged from the vent or air-release valve.
During the test, pressurization shall be carried out in two successive stages:
a) In the first stage, the strain rate in the elastic range shall not exceed that in the tensile test up to a pressure
value corresponding to the initiation of plastic deformation;
b) In the second stage, the pump discharge rate shall be maintained at as constant a level as is possible until the
cylinder bursts.
Key
1 Test fluid reservoir
2 Tank for measurement of test fluid. (The test fluid reservoir may be used as a measuring tank)
3 Pump
4 Pressure gauge
5 Pressure/volumetric expansion curve recorder
6 Vent or air release valve
7 Test well
Figure 10 — Typical hydraulic burst test installation
8.2.2 Interpretation of test
8.2.2.1 The interpretation of the burst test shall involve:
– Determination of the burst pressure (p ) and of the yield pressure (p ) attained during the test.
b y
– Examination of the tear and of the shape of its edges.
8.2.2.2 The measured burst pressure (p ) shall be:
b
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