EN ISO 9809-1:2019

SLOVENSKI STANDARD
01-december-2019
Nadomešča:
SIST EN ISO 9809-1:2010
Plinske jeklenke - Konstruiranje, izdelava in preskušanje ponovno polnljivih
plinskih jeklenk in velikih jeklenk iz celega iz jekla - 1. del: Jeklenke in velike
jeklenke iz jekel za poboljšanje z natezno trdnostjo, manjšo od 1100 MPa (ISO 9809
-1:2019)
Gas cylinders - Design, construction and testing of refillable seamless steel gas cylinders
and tubes - Part 1: Quenched and tempered steel cylinders and tubes with tensile
strength less than 1 100 MPa (ISO 9809-1:2019)
Gasflaschen - Gestaltung, Konstruktion und Prüfung von wiederbefüllbaren nahtlosen
Gasflaschen aus Stahl - Teil 1: Flaschen aus vergütetem Stahl mit einer Zugfestigkeit
kleiner als 1 100 MPa (ISO 9809-1:2019)
Bouteilles à gaz - Conception, construction et essais des bouteilles à gaz et des tubes
rechargeables en acier sans soudure - Partie 1: Bouteilles et tubes en acier trempé et
revenu ayant une résistance à la traction inférieure à 1 100 MPa (ISO 9809-1:2019)
Ta slovenski standard je istoveten z: EN ISO 9809-1:2019
ICS:
23.020.35 Plinske jeklenke Gas cylinders
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 9809-1
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 23.020.35 Supersedes EN ISO 9809-1:2010
English Version
Gas cylinders - Design, construction and testing of
refillable seamless steel gas cylinders and tubes - Part 1:
Quenched and tempered steel cylinders and tubes with
tensile strength less than 1 100 MPa (ISO 9809-1:2019)
Bouteilles à gaz - Conception, construction et essais des Gasflaschen - Auslegung, Herstellung und Prüfung von
bouteilles à gaz et des tubes rechargeables en acier wiederbefüllbaren nahtlosen Gasflaschen aus Stahl -
sans soudure - Partie 1: Bouteilles et tubes en acier Teil 1: Flaschen aus vergütetem Stahl mit einer
trempé et revenu ayant une résistance à la traction Zugfestigkeit kleiner als 1 100 MPa (ISO 9809-1:2019)
inférieure à 1 100 MPa (ISO 9809-1:2019)
This European Standard was approved by CEN on 25 July 2019.

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 CEN-CENELEC 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 CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9809-1:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 9809-1:2019) has been prepared by Technical Committee ISO/TC 58 "Gas
cylinders" in collaboration with 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 April 2020, and conflicting national standards shall be
withdrawn at the latest by April 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 9809-1:2010.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 9809-1:2019 has been approved by CEN as EN ISO 9809-1:2019 without any
modification.
INTERNATIONAL ISO
STANDARD 9809-1
Third edition
2019-08
Gas cylinders — Design, construction
and testing of refillable seamless steel
gas cylinders and tubes —
Part 1:
Quenched and tempered steel
cylinders and tubes with tensile
strength less than 1 100 MPa
Bouteilles à gaz — Conception, construction et essais des bouteilles à
gaz et des tubes rechargeables en acier sans soudure —
Partie 1: Bouteilles et tubes en acier trempé et revenu ayant une
résistance à la traction inférieure à 1 100 MPa
Reference number
ISO 9809-1:2019(E)
©
ISO 2019
ISO 9809-1:2019(E)
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 9809-1:2019(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 3
5 Inspection and testing . 4
6 Materials . 4
6.1 General requirements . 4
6.2 Controls on chemical composition . 4
6.3 Typical steels . 6
6.4 Heat treatment . 6
6.5 Failure to meet test requirements . 6
7 Design . 7
7.1 General requirements . 7
7.2 Limitation on tensile strength . 7
7.3 Design of cylindrical shell thickness . 7
7.4 Design of convex ends (heads and bases). 8
7.5 Design of concave base ends .10
7.6 Neck design .10
7.7 Foot rings .11
7.8 Neck rings .11
7.9 Design drawing .11
8 Construction and workmanship .11
8.1 General .11
8.2 Wall thickness .11
8.3 Surface imperfections .11
8.4 Ultrasonic examination .11
8.5 Out-of-roundness .12
8.6 Mean diameter .12
8.7 Straightness .12
8.8 Verticality and stability .12
8.9 Neck threads .12
9 Type approval procedure .13
9.1 General requirements .13
9.2 Prototype tests .14
9.2.1 General requirements .14
9.2.2 Pressure cycling test .15
9.2.3 Base check .15
9.2.4 Bend test and flattening test .15
9.2.5 Torque test for taper thread only .17
9.2.6 Shear stress calculation for parallel threads .17
9.3 Type approval certificate.17
10 Batch tests .17
10.1 General requirements .17
10.2 Tensile test .19
10.3 Impact test .20
10.4 Hydraulic burst test .22
10.4.1 Test installation . .22
10.4.2 Test conditions.23
ISO 9809-1:2019(E)
10.4.3 Interpretation of test results .24
10.4.4 Acceptance criteria .24
11 Tests/examinations on every cylinder .25
11.1 General .25
11.2 Hydraulic test .25
11.2.1 Proof pressure test .25
11.2.2 Volumetric expansion test .25
11.3 Hardness test .25
11.4 Leak test .26
11.5 Capacity check .26
12 Certification .26
13 Marking .26
Annex A (normative) Description and evaluation of manufacturing imperfections in
seamless gas cylinders .27
Annex B (normative) Ultrasonic examination .42
Annex C (informative) Example of type approval certificate .48
Annex D (informative) Example of acceptance certificate .49
Annex E (informative) Bend stress calculation.52
Annex F (informative) Chemical compositions of internationally-recognized steel .53
Annex G (informative) An example of shear strength calculation for parallel threads .54
Bibliography .56
iv © ISO 2019 – All rights reserved

ISO 9809-1:2019(E)
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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 3,
Cylinder design.
This third edition cancels and replaces the second edition (ISO 9809-1:2010), which has been technically
revised. The changes compared to the previous edition are as follows:
— water capacity extended from below 0,5 l and up to and including 450 l;
— batch size for tubes now introduced;
— bend test retained only for prototype tests;
— test requirements for check analysis (tolerances modified);
— new test requirements for threads introduced including an informative Annex G;
— original European Annexes now incorporated into the body of this document;
— Annex A "Manufacturing imperfections" now aligned with ISO/TR 16115.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
ISO 9809-1:2019(E)
Introduction
This document provides a specification for the design, manufacture, inspection and testing of a
seamless steel cylinder and tube. The objective is to balance design and economic efficiency against
international acceptance and universal utility.
ISO 9809 (all parts) aims to eliminate existing concerns about climate, duplicate inspections and
restrictions because of a lack of definitive International Standards.
[7]
This document has been written so that it is suitable to be referenced in the UN Model Regulations .
vi © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 9809-1:2019(E)
Gas cylinders — Design, construction and testing of
refillable seamless steel gas cylinders and tubes —
Part 1:
Quenched and tempered steel cylinders and tubes with
tensile strength less than 1 100 MPa
1 Scope
This document specifies minimum requirements for the material, design, construction and
workmanship, manufacturing processes, examination and testing at time of manufacture for refillable
seamless steel gas cylinders and tubes with water capacities up to and including 450 l.
It is applicable to cylinders and tubes for compressed, liquefied and dissolved gases and for quenched
and tempered steel cylinders and tubes with a maximum actual tensile strength R of less than
ma
1 100 MPa.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
ISO 10286, Gas cylinders — Terminology
ISO 11114-1, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 1:
Metallic materials
ISO 11114-4, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas
contents — Part 4: Test methods for selecting steels resistant to hydrogen embrittlement
ISO 13341, Gas cylinders — Fitting of valves to gas cylinders
ISO 13769, Gas cylinders — Stamp marking
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10286 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
ISO 9809-1:2019(E)
3.1
batch
quantity of up to 200 for cylinders and up to 50 for tubes, plus cylinders/tubes for destructive testing
of the same nominal diameter, thickness, length and design made successively on the same equipment,
from the same cast of steel and subjected to the same heat treatment for the same duration of time
Note 1 to entry: In this document where not specifically mentioned for “cylinder/tube” only the term “cylinder”
will be used.
3.2
burst pressure
p
b
highest pressure reached in a cylinder during a burst test
3.3
design stress factor
F
ratio of equivalent wall stress at test pressure, p , to guaranteed minimum yield strength, R
h eg
3.4
quenching
hardening heat treatment in which a cylinder, which has been heated to a uniform temperature above
the upper critical point, Ac , of the steel, is cooled rapidly in a suitable medium
3.5
reject
cylinder that has been set aside (Level 2 or Level 3) and not allowed to enter into service
3.6
rendered unserviceable
cylinder that has been treated in such a way as to render it impossible for it to enter into service
Note 1 to entry: Examples for acceptable methods to render cylinders unserviceable can be found in ISO 18119.
Any actions on cylinders rendered unserviceable are outside the scope of this document.
3.7
repair
action to return a rejected cylinder to a Level 1 condition
3.8
tempering
toughening heat treatment which follows quenching, in which the cylinder is heated to a uniform
temperature below the lower critical point, Ac , of the steel
3.9
test pressure
p
h
required pressure applied during a pressure test
Note 1 to entry: Test pressure is used for cylinder wall thickness calculation.
3.10
working pressure
settled pressure of a compressed gas at a uniform reference temperature of 15 °C in a full gas cylinder
3.11
yield strength
stress value corresponding to the upper yield strength, R , or for steels which do not exhibit a defined
eH
yield, the 0,2 % proof strength (non-proportional extension), R
p0,2
Note 1 to entry: See ISO 6892-1.
2 © ISO 2019 – All rights reserved

ISO 9809-1:2019(E)
4 Symbols
A percentage elongation after fracture
a calculated minimum thickness, in millimetres, of the cylindrical shell
a′ guaranteed minimum thickness, in millimetres, of the cylindrical shell
a guaranteed minimum thickness, in millimetres, of a concave base at the knuckle (see Figure 2)
a guaranteed minimum thickness, in millimetres, at the centre of a concave base (see Figure 2)
b guaranteed minimum thickness, in millimetres, at the centre of a convex base (see Figure 1)
c maximum permissible deviation of burst profile, in millimetres (see Figure 11)
D nominal outside diameter of the cylinder, in millimetres (see Figure 1)
D diameter, in millimetres, of former (see Figure 4)
f
F design stress factor (variable) (see 3.3)
H outside height, in millimetres, of domed part (convex head or base end) (see Figure 1)
h outside depth (concave base end), in millimetres (see Figure 2)
L original gauge length, in millimetres, as defined in ISO 6892-1 (see Figure 6)
o
n ratio of the diameter of the bend test former to actual thickness of test piece, t
p measured burst pressure, in bar, above atmospheric pressure
b
NOTE 1 bar = 10 Pa = 0,1 MPa.
p hydraulic test pressure, in bars, above atmospheric pressure
h
p observed pressure when cylinder starts yielding during hydraulic burst test, in bars, above
y
atmospheric pressure
r inside knuckle radius, in millimetres (see Figures 1 and 2)
R minimum guaranteed value of the yield strength (see 7.1.1), in megapascals, for the finished
eg
cylinder
R actual value of the yield strength, in megapascals, as determined by the tensile test (see 10.2)
ea
R minimum guaranteed value of the tensile strength, in megapascals, for the finished cylinder
mg
R actual value of tensile strength, in megapascals, as determined by the tensile test (see 10.2)
ma
S original cross-sectional area of tensile test piece, in square millimetres, in accordance with
o
ISO 6892-1
t actual thickness of the test specimen, in millimetres
t average cylinder wall thickness at position of testing during the flattening test, in millimetres
m
ISO 9809-1:2019(E)
u ratio of distance between knife edges or platens in the flattening test to average cylinder wall
thickness at the position of test
V water capacity of cylinder, in litres
w width, in millimetres, of the tensile test piece (see Figure 6)
5 Inspection and testing
Assessment of conformity to this international standard shall take into account the applicable
regulations of the countries of use.
To ensure that cylinders conform to this document, they shall be subject to inspection and testing in
accordance with Clauses 9, 10 and 11.
Tests and examinations performed to demonstrate compliance with this document shall be conducted
using instruments calibrated before being put into service and thereafter according to an established
programme.
6 Materials
6.1 General requirements
6.1.1 Materials for the manufacture of gas cylinders shall fall within one of the following categories:
a) internationally recognized cylinder steels;
b) nationally recognized cylinder steels;
c) new cylinder steels resulting from technical progress.
For all categories, the relevant conditions specified in 6.2 and 6.3 shall be satisfied.
6.1.2 The material used for the manufacture of gas cylinders shall be steel, other than rimming quality,
with non-ageing properties and shall be fully killed with aluminium and/or silicon.
In cases where examination of this non-ageing property is required by the customer, the criteria by
which it is to be specified should be agreed with the customer and inserted in the order.
6.1.3 The cylinder manufacturer shall establish means to identify the cylinders with the cast of steel
from which they are made.
6.1.4 Grades of steel used for cylinder manufacture shall be compatible with the intended gas service,
e.g. corrosive gases and embrittling gases (see ISO 11114-1).
6.1.5 Wherever continuously cast billet material is used, the manufacturer shall ensure that there are
no deleterious imperfections (porosity) in the material to be used for making cylinders (see 9.2.3).
6.2 Controls on chemical composition
6.2.1 The chemical composition of all steels shall be defined at least by:
— the carbon, manganese and silicon contents in all cases;
— the chromium, nickel and molybdenum contents or other alloying elements intentionally added to
the steel;
4 © ISO 2019 – All rights reserved

ISO 9809-1:2019(E)
— the maximum sulfur and phosphorus contents in all cases.
The carbon, manganese and silicon contents and, where appropriate, the chromium, nickel and
molybdenum contents 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.
The combined content of the following elements: vanadium, niobium, titanium, boron and zirconium
shall not exceed 0,15 %.
The actual content of any element deliberately added shall be reported and their maximum content
shall be representative of good steel making practice.
Table 1 — Chemical composition tolerances
Element Maximum content Permissible range Check analysis
(mass fraction) (mass fraction)
Deviation from the
limits specified for the
cast analyses
(mass fraction)
% % %
Carbon <0,30 0,06
±0,02
≥0,30 0,07
Manganese All values 0,30 ≤1,00 ± 0,04
>1,00 ≤ 1,70 ± 0,05
Silicon All values 0,30 ±0,03
Chromium <1,50 0,30 ≤2,00 ± 0,05
≥1,50 0,50
>2,00 ≤ 2,20 ± 0,10
Nickel All values 0,40 ≤2,00 ± 0,05
>2,00 ≤ 4,30 ± 0,07
Molybdenum All values 0,15 ≤0,30 ± 0,03
>0,30 ≤ 0,60 ± 0,04
6.2.2 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 — Maximum sulfur and phosphorus limits in % (mass fraction)
Sulfur 0,010
Phosphorus 0,020
Sulfur and phosphorus 0,025
6.2.3 The cylinder manufacturer shall obtain and make available certificates of cast (heat) analyses of
the steels supplied for the construction of gas cylinders.
Should check analyses be required, they shall be carried out either on specimens taken during
manufacture from the material in the form as supplied by the steel maker to the cylinder manufacturer
or from finished cylinders. In any check analysis, the maximum permissible deviation from the limits
specified for the cast analyses shall conform to the values in Table 1.
ISO 9809-1:2019(E)
6.3 Typical steels
Two typical internationally recognized steel types which have provided safe performance over many
years are:
a) chromium molybdenum steel (quenched and tempered);
b) carbon manganese steel (quenched and tempered).
The chemical compositions of these steels, subject to the controls specified in 6.2.1, are given in Annex F.
6.4 Heat treatment
6.4.1 The cylinder manufacturer shall certify the heat treatment process applied to the finished
cylinders.
6.4.2 Quenching in media other than mineral oil is permissible provided that:
— the method produces cylinders free of cracks.
— the manufacturer ensures that the rate of cooling does not produce any cracks in the cylinder.
— every production cylinder is subjected to a method of non-destructive testing to prove freedom
from cracks, if the average rate of cooling in the medium is greater than 80 % of that in water at
20 °C without additives.
— during the production of cylinders, the concentration of the quenchant is checked and recorded
during every shift to ensure that the limits are maintained. Further documented checks shall be
carried out to ensure that the chemical properties of the quenchant are not degraded.
6.4.3 The tempering process 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.
6.5 Failure to meet test requirements
In the event of failure to meet the test requirements, retesting or reheat treatment and retesting shall
be carried out as follows to the satisfaction of the inspector.
a) If there is evidence of a fault in carrying out a test or an error of measurement, a further test shall
be performed. If the result of this test is satisfactory, the first test shall be ignored.
b) If the test has been carried out in a satisfactory manner, the cause of test failure shall be identified.
1) If the failure is considered to be due to the heat treatment applied, the manufacturer may
subject all the cylinders implicated by the failure to only one further heat treatment, e.g. if
the failure is in a test representing the prototype or batch cylinders. Test failure shall require
reheat treatment of all the represented cylinders prior to retesting.
This reheat treatment shall consist of either re-tempering or complete reheat treatment.
Whenever cylinders are reheat treated, the minimum guaranteed wall thickness shall be
maintained.
Only the relevant prototype or batch tests needed to prove the acceptability of the new batch
shall be performed again. If one or more tests prove even partially unsatisfactory, all cylinders
of the batch shall be rejected.
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ISO 9809-1:2019(E)
2) If the failure is due to a cause other than the heat treatment applied, all cylinders with
imperfections shall be either rejected or repaired such that the repaired cylinders pass the
test(s) required for the repair. They shall then be re-instated as part of the original batch.
7 Design
7.1 General requirements
7.1.1 The calculation of the wall thickness of the pressure-containing parts shall be related to the
guaranteed minimum yield strength, R , of the material in the finished cylinder.
eg
7.1.2 Cylinders shall be designed with one or two openings along the central cylinder axis only.
7.1.3 For calculation purposes, the value of R shall not exceed 0,90 R .
eg mg
7.1.4 The internal pressure upon which the calculation of wall thickness is based shall be the hydraulic
test pressure p .
h
7.2 Limitation on tensile strength
7.2.1 Where there is no risk of hydrogen embrittlement, the maximum value of the tensile strength is
limited by the ability of the steel to meet the requirements of Clauses 9 and 10, but the maximum actual
tensile strength, R , shall always be less than 1 100 MPa for chrome-molybdenum steels and in no case
ma
exceed 1 030 MPa for carbon manganese steels.
7.2.2 Where there is a risk of hydrogen embrittlement (see ISO 11114-1), the maximum value of the
tensile strength, as determined in 10.2, shall either be 880 MPa or, where the ratio R /R does not
ea ma
exceed 0,9, be 950 MPa. Alternatively, the maximum tensile strength shall be established using data
derived from the tests carried out in accordance with ISO 11114-4.
7.2.3 Other gas/material compatibility risks, including stress corrosion and hydrogen embrittlement
mechanism by gases other than hydrogen, shall be assessed in accordance with ISO 11114-1 and
ISO 11114-4.
7.3 Design of cylindrical shell thickness
The guaranteed minimum thickness of the cylindrical shell, a′, shall not be less than the thickness
calculated using Formulae (1) and (2), and additionally, Formula (3) shall be satisfied.
 
10 FR − 3 p
D eg
h
 
a= 1− (1)
 
2 10 FR
 
eg
 
0,65
where the value of F is the lesser of  or 0,85.
RR
eg mg
R /R shall not exceed 0,90.
eg mg
The wall thickness shall also satisfy Formula (2):
D
a≥+1 (2)
with an absolute minimum of a = 1,5 mm.
ISO 9809-1:2019(E)
The burst ratio shall be satisfied by test as given in Formula (3):
pp/,≥16 (3)
bh
NOTE 1 It is generally assumed that p = 1,5 times working pressure for compressed gases for cylinders
h
designed and manufactured to conform with this document.
NOTE 2 For some applications, such as tubes assembled in batteries to equip trailers or skids (ISO modules)
or MEGCs for the transportation and distribution of gases, it is important that stresses associated with mounting
the tube (e.g. bending stresses, see Annex E, torsional stresses, dynamic loadings) are considered by the assembly
manufacturer and the tube manufacturer.
NOTE 3 In addition, during hydraulic pressure testing, tubes could be supported or lifted by their necks;
therefore, potential bending stresses are considered. For general guidance, see Annex E.
7.4 Design of convex ends (heads and bases)
7.4.1 When convex base ends (see Figure 1) are used the thickness, b, at the centre of a convex end
shall be not less than that required by the following criteria: where the inside knuckle radius, r, is not less
than 0,075D then:
b ≥ 1,5 a for 0,40 > H/D ≥ 0,20;
b ≥ a for H/D ≥ 0,40.
To obtain a satisfactory stress distribution in the region where the end joins the shell, any thickening
of the end when required shall be gradual from the point of juncture, particularly at the base. For the
application of this rule, the point of juncture between the shell and the end is defined by the horizontal
lines indicating dimension H in Figure 1.
Shape b) in Figure 1 shall not be excluded from this requirement.
7.4.2 The cylinder manufacturer shall prove by the pressure cycling test detailed in 9.2.2 that the
design is satisfactory.
The shapes shown in Figure 1 are typical of convex heads and base ends. Shapes a), b), d) and e) are
base ends and shapes c) and f) are heads.
8 © ISO 2019 – All rights reserved

ISO 9809-1:2019(E)
a) b) c)
d) e) f)
Key
1 cylindrical part
Figure 1 — Typical convex ends
ISO 9809-1:2019(E)
7.5 Design of concave base ends
7.5.1 When concave base ends (see Figure 2) are used, the following design values are recommended:
a ≥ 2a
a ≥ 2a
h ≥ 0,12D
r ≥ 0,075D
The design drawing shall at least show values for a , a , h and r.
1 2
To obtain a satisfactory stress distribution, the thickness of the cylinder shall increase progressively in
the transition region between the cylindrical part and the base.
7.5.2 The cylinder manufacturer shall in any case prove by the pressure cycling test detailed in 9.2.2
that the design is satisfactory.
Figure 2 — Concave base end
7.6 Neck design
7.6.1 The external diameter and thickness of the formed neck end of the cylinder shall be adequate for
the torque applied in fitting the valve to the cylinder. The torque may vary according to the valve/fitting
type (e.g. plugs) diameter of thread, the form of thread and the sealant used in the fitting of the valve.
NOTE For information on torques, see ISO 13341.
7.6.2 In establishing the minimum thickness, the thickness of wall in the cylinder neck shall prevent
permanent expansion of the neck during the initial and subsequ
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