Gas cylinders - Procedures for change of gas service (ISO 11621:1997)

This international Standard applies to seamless steel,  aluminium alloy and welded steel refillable cylinders of all  sizes, including large cylinders (water capacity greater then  150 l). It provides general requirements and procedures to be  considered whenever a cylinder is being transferred from one  gas service to another permanent and liquefied gases. It does  not apply to cylinders for dissolved acetylene, radioactive  gases or gases listed in group G of table 1.

Gasflaschen - Verfahren für den Wechsel der Gasart (ISO 11621:1997)

Diese Internationale Norm gilt für nahtlose Flaschen aus Stahl, Flaschen aus Aluminiumlegierung und
geschweißte Flaschen aus Stahl aller Größen, einschließlich von Großflaschen (Fassungsraum größer als 150 l).
Diese Internationale Norm legt allgemeine Anforderungen und Verfahren fest, die berücksichtigt werden müssen,
wann immer die Gasart einer Gasflasche geändert wird.
Diese Internationale Norm gilt nicht für gelöstes Acetylen, radioaktive Gase oder Gase der Gruppe G von
Tabelle 1.

Bouteilles a gaz - Mode opératoire pour le changement de service de gaz (ISO 11621:1997)

La présente Norme internationale s'applique aux bouteilles rechargeables de toutes dimensions, y compris celles de grande capacité (contenance en eau supérieure à 150 1), en acier sans soudure, en alliage d'aluminium et en acier soudé.
Elle fixe des prescriptions générales et des modes opératoires à prendre en compte lorsqu'on prévoit de transférer une bouteille d'un service de gaz à un autre pour les gaz permanents et liquéfiés.
Elle n'est pas applicable aux bouteilles devant contenir de l'acétylène dissous, des gaz radioactifs ou des gaz listés dans le groupe G du tableau 1.

Plinske jeklenke – Postopki za spremembo namembnosti (ISO 11621:1997)

General Information

Status
Published
Publication Date
28-Feb-2006
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Mar-2006
Due Date
01-Mar-2006
Completion Date
01-Mar-2006

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Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 11621:2006
01-marec-2006
Nadomešča:
SIST EN 1795:1999
Plinske jeklenke – Postopki za spremembo namembnosti (ISO 11621:1997)
Gas cylinders - Procedures for change of gas service (ISO 11621:1997)
Gasflaschen - Verfahren für den Wechsel der Gasart (ISO 11621:1997)
Bouteilles a gaz - Mode opératoire pour le changement de service de gaz (ISO
11621:1997)
Ta slovenski standard je istoveten z: EN ISO 11621:2005
ICS:
23.020.35 Plinske jeklenke Gas cylinders
SIST EN ISO 11621:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 11621:2006

---------------------- Page: 2 ----------------------
SIST EN ISO 11621:2006
EUROPEAN STANDARD
EN ISO 11621
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2005
ICS 23.020.30 Supersedes EN 1795:1997
English Version
Gas cylinders - Procedures for change of gas service (ISO
11621:1997)
Bouteilles à gaz - Mode opératoire pour le changement de Gasflaschen - Verfahren für den Wechsel der Gasart (ISO
service de gaz (ISO 11621:1997) 11621:1997)
This European Standard was approved by CEN on 22 September 2005.
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 Central Secretariat 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 Central Secretariat 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11621:2005: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
SIST EN ISO 11621:2006
EN ISO 11621:2005 (E)
Foreword
The text of ISO 11621:1997 has been prepared by Technical Committee ISO/TC 58 “Gas cylinders” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 11621:2005 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 April 2006, and conflicting national standards shall be withdrawn at the
latest by April 2006.
This document supersedes EN 1795:1997.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: 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.

Endorsement notice

The text of ISO 11621:1997 has been approved by CEN as EN ISO 11621:2005 without any modifications.
NOTE Normative references to International Standards are listed in annex ZA (normative).

2

---------------------- Page: 4 ----------------------
SIST EN ISO 11621:2006
EN ISO 11621:2005 (E)

Annex ZA
(normative)
Normative references to international publications with their
corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places 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).
NOTE When an International Publication has been modified by common modifications, indicated by (mod.), the
relevant EN/HD applies.
ISO Year Title EN/HD Year
Publication
ISO 5145 1990 Cylinder valve outlets for gases and gas mixtures — No EN equivalent
Selection and dimensioning (withdrawn, see
ISO 5145: 2004
ISO 6406 1992 Periodic inspection and testing of seamless steel EN 1968 2002
gas cylinders (Note: To be replaced by ISO/FDIS
6406 (2004-10))
ISO 10156 1996 Gases and gas mixtures - Determination of fire EN 720-2 1996
potential and oxidizing ability for the selection of
cylinder valve outlets (in revision)
To be replaced by
EN ISO 10156
ISO 10460 1993 Welded carbon steel gas cylinders — Periodic EN 1803 2002
inspection and testing (Note: To be replaced by
ISO/FDIS 10460 (2004-11))
ISO 11114-1 1997 Transportable gas cylinders — Compatibility of EN ISO 11114-1 1997
cylinder and valve materials with gas contents —
Part 1: Metallic materials

3

---------------------- Page: 5 ----------------------
SIST EN ISO 11621:2006
INTERNATIONAL
IS0
STANDARD
11621
First edition
1997-04-I 5
Gas cylinders - Procedures for change
of gas service
Bouteilles 2 gaz - Mode opkatoire pour le changement de service de gaz
Reference number
IS0 11621:1997(E)

---------------------- Page: 6 ----------------------
SIST EN ISO 11621:2006
IS0 11621:1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies
casting a vote.
International Standard IS0 11621 was prepared by Technical Committee
ISO/TC 58, Gas cylinders, Subcommittee SC 4, Operational requirements
for gas cylinders.
Annex A of this International Standard is for information only.
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
c=ch; a=400net; p=iso; o=isocs; s=central
x.400
Printed in Switzerland

---------------------- Page: 7 ----------------------
SIST EN ISO 11621:2006
@ IS0 IS0 11621:1997(E)
Introduction
It is occasionally desirable to change gas cylinders from one gas service to
another. Certain of these service changes can be made quite easily, while
others require a careful inspection of the interior and exterior of the cylinder
to detect the presence of corrosion products or contaminants, which must
be removed for safety reasons or to avoid undesirable contamination of the
contained gas.
This International Standard has been prepared to assist those engaged in
the filling of gas cylinders for changing cylinders from one gas service to
another.

---------------------- Page: 8 ----------------------
SIST EN ISO 11621:2006
This page intentionally left blank

---------------------- Page: 9 ----------------------
SIST EN ISO 11621:2006
IS0 11621:1997(E)
INTERNATIONAL STANDARD @ IS0
Procedures for change of gas service
Gas cylinders -
1 Scope
This International Standard applies to seamless steel, aluminium alloy and welded steel refillable cylinders of all
sizes, including large cylinders (water capacity greater than 150 I).
It provides general requirements and procedures to be considered whenever a cylinder is being transferred from
one gas service to another for permanent and liquefied gases.
It does not apply to cylinders for dissolved acetylene, radioactive gases or gases listed in group G of table I.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 5145:1990, Cylinder valve outlets for gases and gas mixtures - Selection and dimensioning.
IS0 6406: 1992, Periodic inspection and testing of seamless steel gas cylinders,
- Determination of fire potential and oxidizing ability for the selection of
IS0 10156:1996, Gases and gas mixtures
cylinder valve outlets.
IS0 10460:1993, Welded carbon steel gas cylinders - Periodic inspection and testing,
IS0 10461: 1993, Seamless aluminium-alloy gas cylinders - Periodic inspection and testing.
Isolll14-1: --1), Compatibility of cylinder and valve materials with gas contents - Part 1: Metallic materials.
1) To be published.

---------------------- Page: 10 ----------------------
SIST EN ISO 11621:2006
@ IS0
IS0 11621:1997(E)
3 Abbreviations
NDT = Non-destructive testing.
SCT = Stress corrosion testing.
4 General requirements
Cylinders are manufactured in accordance with international and/or national standards and are intended for use with
a variety of gases under specified filling conditions. Although some cylinders are restricted to specific gas services,
the majority of cylinders can be transferred from one gas service to another, provided applicable regulations are
observed and appropriate procedures are followed and material compatibilities are considered (see IS0 11114-l).
Cylinders which have been in service may have been exposed to conditions that render them unsafe during, or
when transferred to, a different gas service. These conditions could result in contamination, corrosion or residual
gases that may react. Therefore, it is essential that all procedures detailed in clause 5 and displayed in tables 1, 2
and 3 be carefully followed.
Particular attention shall be directed to assuring that purging or cleaning procedures, where specified, remove all
residual gas, contaminants or corrosion products and that cleaning agents are removed and cylinders dried and
sealed to prevent entry of dirt or moisture after cleaning.
Persons using this International Standard shall be knowledgeable in the handling of compressed gases and be
familiar with the chemical and physical properties of the commodities which they charge into cylinders and of the
contaminants which are likely to be found therein.
4.1 Grouping of gases
For the purposes of this International Standard, the gases for which cylinder transfers are most frequently desired
have been separated into several groups. This separation has taken into consideration the chemical and physical
reactivity of the gases and of the contaminants which are most frequently encountered.
The requirements in this International Standard may not be applicable to gases or mixtures which are not included in
the gas groups given in table 3. Recommendations for the cleaning of cylinders which have contained such gases
shall be obtained from the manufacturer of the cylinder and/or gas. The values quoted in table 1 for the FTSC code
are taken from IS0 5145 or IS0 10156.
4.2 Gases which may affect cylinder condition
Cylinders which have been in certain gas services may be subjected to conditions which could affect the future
serviceability of the cylinder or render it unsuitable for use in any other gas service. Cylinders in such services are
subject to rigid requalification procedures or may be prohibited from use in other gas services. Examples are:
steel cylinders in carbon monoxide/carbon monoxide mixture service which may be subject to stress corrosion
cracking;
steel cylinders which have been in hydrogen service but which were not designed and manufactured for this
gas (see IS0 11114-1).
5 Actions for change of service
5.1 General
Because of the potential safety problems (e.g. corrosion, contamin ation, compatibility), specific actions are required
when transferring a cylinder from one gas service to another. The steps (set of actions), denoted by a number, are
2

---------------------- Page: 11 ----------------------
SIST EN ISO 11621:2006
@ IS0 IS0 11621 :1997(E)
listed in table 3. Table 2 shows in tabular form all the steps to be taken for each transfer. It is important that each
step be taken. The gas groups are shown by name and letter in table 1. The actions given in table 3 are described in
detail in 53.1 to 53.10 inclusive.
5.2 Use of tables 1,2 and 3
EXAMPLE d
A nitrogen cylinder is to be transferred to hydrogen service. Determine the gas groups from table 1 (nitrogen = A;
hydrogen = E). Using table 2, find A in the left-hand column and proceed across the table to column E where you
will find the numbers 1, 4, 6. Go to table 3, which shows what actions are required by steps 1, 4 and 6 (for details,
see 53.1, 5.3.4 and 5.3.6).
EXAMPLE 2
An oxygen cylinder is to be transferred to 50 % oxygen and 50 % nitrous oxide. Determine the gas groups from
table 1 (oxygen and nitrous oxide = C). Using table 2, find C in the left-hand column and proceed ,across the table
to column C where you will find the number 1. Go to table 3, which shows what actions are required by step 1
(for details, see 5.3.1).
- Gas groups for change of service
Table ll
Description Gases
Group
I I
Inertl) Nitrogen, argon, helium, neon, krypton, xenon and all gases and gas mixtures
A
having FTSC code 01X*)0 (but excluding gases in group B).
B Inert/activea) Carbon dioxide, carbon dioxide mixtures and oxygen mixtures containing less
than 21 % oxygen having FTSC code 01X0 or 11X0.
C Oxidizing Oxygen, nitrous oxide, air and mixtures containing at least 21 % oxygen or more
than 60 % nitrous oxide having FTSC code 41 X0.
D Flammable Ethylene, methane, cyclopropane, other hydrocarbons, liquefied petroleum gases,
etc., and all gases and gas mixtures having FTSC code 21X0 (but excluding
flammable gases of groups E and F).
Embrittling Hydrogen and all non-toxic gases of group 2 of IS0 11114-1 having FTSC code
E
21 x0.
F SC@) Carbon monoxide and carbon monoxide mixtures.
I I
Very toxic (X3Xx), toxic (X2Xx), corrosive (XXXYS)) and pyrophoric (3XxX) gases
G Toxic
Corrosive (but excluding group F).
Pyrophoric
CAUTION - Some of these gases are also embrittling (see IS0 11114-I).
1) inert in terms of fire potential (see IS0 10156).
2) X equals any digit.
3) Inert in terms of fire potential, but corrosive in presence of moisture.
4) Stress corrosion cracking.
5) YZO
3

---------------------- Page: 12 ----------------------
SIST EN ISO 11621:2006
@ IS0
IS0 11621:1997(E)
Table 2 - Actions to be taken when transferring cylinders from one gas service to another
D
To + A B C E F G
Carbon
From
Inert/active Oxidizing Flammable Embrittling monoxide Toxic, etc.
Inert
Jf
A Inert 1 I, 2 I, 3 1 IA6 195
I, 4 3
B Inert/active I, 7 1
I, 3 197 19 4, 6, 7 I, 5 7 11 3,4, 6
C Oxidizing I, 7 1 1 I, &7 19 4, 67, 8 19 5 7, 8 19 3,4, 7, 8
D Flammable I, 8 I, 8 I, 893 1, 8” 1, 4, 6, 8” 1, 5, 8* 1 J 4, 5 8
E Embrittling 1, 8*, 9 I, &9 19 3,8, 9 I, 899 1, 6, 8*, 9 19 598, 9
19 3,4, 8, 9
F Carbon monoxide 1, 8, 10 1, 8, 10 1,8,3, 10 1, 8, 10 1,6,8,10 1,5,8*,10 1,3,4,8,10
m . m . .
. m .
Toxic, etc. Not covered by this International Standard. Only to be performed under tightly controlled .
G
conditions using special procedures.
I
Table 3 - List of actions for change of gas service
Step No. Action
1 External examination and preparation:
Verify contents/identification
Cylinder external surface
Valve outlet and operation
Check working pressure/specification
Ownership
retest if required resulting from change of service
Test date -
Reduce pressure (blow down) to atmospheric pressure using appropriate discharge
Remove all existing labels, stencils, etc., after cylinder has been emptied
Re-mark with service markings: label, paint, stamp, etc. (after gas has been removed from the
cylinder)
If the valve is removed do an internal visual inspection
2 Check for moisture contamination
Internal inspection for liquid and/or hydrocarbons If suspected, clean for oxygen service
3
Check materials compatibility in accordance with IS0 11114-1
4
5 Check moisture level for steel cylinders. Use moisture requirements of IS0 11114-1
Check for internal surface defects
6
7 Check for internal corrosion ,
8 Cylinder content evacuation
Pull vacuum or purge (only if valve is removed)
8”
Check previous service against IS0 11114-1 g If not compatible, perform appropriate NIX and hydrotest
9
10 If suspected that cylinder has been exposed to water, perform appropriate NDT and hydrotest
4

---------------------- Page: 13 ----------------------
SIST EN ISO 11621:2006
@ IS0 IS0 11621:1997(E)
5.3 Details of actions for change of service
The following gives details and/or explanations of the actions listed in table 3.
53.1 External examination and preparation (step 1)
This step is required for each cylinder transferred to any other gas service. Each action listed in this subclause shall
be taken for each cylinder. Prior to the following actions, the cylinder contents (gas or gas group) shall be verified to
determine actions required from table 2. The actions below do not necessarily have to be performed in the order
indicated. At all times, safety considerations shall be observed.
- Carry out an external visual inspection of the cylinder and valve to verify suitability for service. For guidance,
see IS0 6406, IS0 10460 and IS0 10461. Note that external contamination of the cylinder and especially the
valve may indicate internal contamination.
-
Check that the cylinder is equipped with a valve having an outlet connection conforming to IS0 5145 or national
standards for the new service. If not, see table 2 to determine if step 8 or step 8* is required, before replacing
the valve. Also, check that the valve operates satisfactorily.
- Determine that the pressure relief device, if present, is of an approved type for the intended gas and the
working/test pressure of the cylinder.
- Check the working pressure/cylinder design specification and applicable regulations to verify that the cylinder is
satisfactory and authorized for the new gas service.
- Check the cylinder ownership to verify that the owner has authorized the transfer to another gas service.
- Check the test date and determine whether or not it is within the specified test frequency for the old and new
gas service. Retest, if necessary.
- Reduce the pressure (blow down) to atmospheric pressure using appropriate equipment and discharge to be
safe and meet environmental requirements.
- Remove all means of identification concerning the former gas content, such as labels, colour coding and other
relevant identification. Stamp markings of the former gas content shall be either removed or crossed out.
- Identify for the new gas service: this includes painting, labelling, stencilling and possibly stamp marking of the
cylinder.
- If a valve is removed for any reason, the opportunity should be taken to perform an internal visual inspection.
The valve may not require replacement for transfers within the same gas group, but a valve may be replaced
because of damage or improper operation. An internal inspection shall always observe for defects, corrosion
and contamination. Only acceptable cylinders shall be kept in service. Contaminated cylinders may be cleaned
(see annex A). Internal inspection of cylinders having contained oxidizing gases can be performed without
evacuation provided that a safety lamp is used. However, evacuation/purging shall be carried out prior to
probing or working on the interior surface.
5.3.2 Check for moisture contamination (step 2)
When step 2 is required, it is not mandatory that the valve be removed. The point of concern is the presence of
moisture in the cylinder. The absence of liquid water and other aqueous substances can be verified either by a
visual examination or by a moisture test for dew point. If visual internal inspection is used, a dry surface appearance
is acceptable proof of satisfactory condition. If liquid is found, the cylinder shall be dried, and/or washe
...

SLOVENSKI STANDARD
SIST EN ISO 11621:2006
01-marec-2006
1DGRPHãþD
SIST EN 1795:1999
Plinske jeklenke – Postopki za spremembo namembnosti (ISO 11621:1997)
Gas cylinders - Procedures for change of gas service (ISO 11621:1997)
Gasflaschen - Verfahren für den Wechsel der Gasart (ISO 11621:1997)
Bouteilles a gaz - Mode opératoire pour le changement de service de gaz (ISO
11621:1997)
Ta slovenski standard je istoveten z: EN ISO 11621:2005
ICS:
23.020.30 7ODþQHSRVRGHSOLQVNH Pressure vessels, gas
MHNOHQNH cylinders
SIST EN ISO 11621:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 11621:2006

---------------------- Page: 2 ----------------------

SIST EN ISO 11621:2006
EUROPEAN STANDARD
EN ISO 11621
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2005
ICS 23.020.30 Supersedes EN 1795:1997
English Version
Gas cylinders - Procedures for change of gas service (ISO
11621:1997)
Bouteilles à gaz - Mode opératoire pour le changement de Gasflaschen - Verfahren für den Wechsel der Gasart (ISO
service de gaz (ISO 11621:1997) 11621:1997)
This European Standard was approved by CEN on 22 September 2005.
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 Central Secretariat 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 Central Secretariat 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11621:2005: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST EN ISO 11621:2006
EN ISO 11621:2005 (E)
Foreword
The text of ISO 11621:1997 has been prepared by Technical Committee ISO/TC 58 “Gas cylinders” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 11621:2005 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 April 2006, and conflicting national standards shall be withdrawn at the
latest by April 2006.
This document supersedes EN 1795:1997.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: 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.

Endorsement notice

The text of ISO 11621:1997 has been approved by CEN as EN ISO 11621:2005 without any modifications.
NOTE Normative references to International Standards are listed in annex ZA (normative).

2

---------------------- Page: 4 ----------------------

SIST EN ISO 11621:2006
EN ISO 11621:2005 (E)

Annex ZA
(normative)
Normative references to international publications with their
corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places 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).
NOTE When an International Publication has been modified by common modifications, indicated by (mod.), the
relevant EN/HD applies.
ISO Year Title EN/HD Year
Publication
ISO 5145 1990 Cylinder valve outlets for gases and gas mixtures — No EN equivalent
Selection and dimensioning (withdrawn, see
ISO 5145: 2004
ISO 6406 1992 Periodic inspection and testing of seamless steel EN 1968 2002
gas cylinders (Note: To be replaced by ISO/FDIS
6406 (2004-10))
ISO 10156 1996 Gases and gas mixtures - Determination of fire EN 720-2 1996
potential and oxidizing ability for the selection of
cylinder valve outlets (in revision)
To be replaced by
EN ISO 10156
ISO 10460 1993 Welded carbon steel gas cylinders — Periodic EN 1803 2002
inspection and testing (Note: To be replaced by
ISO/FDIS 10460 (2004-11))
ISO 11114-1 1997 Transportable gas cylinders — Compatibility of EN ISO 11114-1 1997
cylinder and valve materials with gas contents —
Part 1: Metallic materials

3

---------------------- Page: 5 ----------------------

SIST EN ISO 11621:2006
INTERNATIONAL
IS0
STANDARD
11621
First edition
1997-04-I 5
Gas cylinders - Procedures for change
of gas service
Bouteilles 2 gaz - Mode opkatoire pour le changement de service de gaz
Reference number
IS0 11621:1997(E)

---------------------- Page: 6 ----------------------

SIST EN ISO 11621:2006
IS0 11621:1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies
casting a vote.
International Standard IS0 11621 was prepared by Technical Committee
ISO/TC 58, Gas cylinders, Subcommittee SC 4, Operational requirements
for gas cylinders.
Annex A of this International Standard is for information only.
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
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SIST EN ISO 11621:2006
@ IS0 IS0 11621:1997(E)
Introduction
It is occasionally desirable to change gas cylinders from one gas service to
another. Certain of these service changes can be made quite easily, while
others require a careful inspection of the interior and exterior of the cylinder
to detect the presence of corrosion products or contaminants, which must
be removed for safety reasons or to avoid undesirable contamination of the
contained gas.
This International Standard has been prepared to assist those engaged in
the filling of gas cylinders for changing cylinders from one gas service to
another.

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SIST EN ISO 11621:2006
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SIST EN ISO 11621:2006
IS0 11621:1997(E)
INTERNATIONAL STANDARD @ IS0
Procedures for change of gas service
Gas cylinders -
1 Scope
This International Standard applies to seamless steel, aluminium alloy and welded steel refillable cylinders of all
sizes, including large cylinders (water capacity greater than 150 I).
It provides general requirements and procedures to be considered whenever a cylinder is being transferred from
one gas service to another for permanent and liquefied gases.
It does not apply to cylinders for dissolved acetylene, radioactive gases or gases listed in group G of table I.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 5145:1990, Cylinder valve outlets for gases and gas mixtures - Selection and dimensioning.
IS0 6406: 1992, Periodic inspection and testing of seamless steel gas cylinders,
- Determination of fire potential and oxidizing ability for the selection of
IS0 10156:1996, Gases and gas mixtures
cylinder valve outlets.
IS0 10460:1993, Welded carbon steel gas cylinders - Periodic inspection and testing,
IS0 10461: 1993, Seamless aluminium-alloy gas cylinders - Periodic inspection and testing.
Isolll14-1: --1), Compatibility of cylinder and valve materials with gas contents - Part 1: Metallic materials.
1) To be published.

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SIST EN ISO 11621:2006
@ IS0
IS0 11621:1997(E)
3 Abbreviations
NDT = Non-destructive testing.
SCT = Stress corrosion testing.
4 General requirements
Cylinders are manufactured in accordance with international and/or national standards and are intended for use with
a variety of gases under specified filling conditions. Although some cylinders are restricted to specific gas services,
the majority of cylinders can be transferred from one gas service to another, provided applicable regulations are
observed and appropriate procedures are followed and material compatibilities are considered (see IS0 11114-l).
Cylinders which have been in service may have been exposed to conditions that render them unsafe during, or
when transferred to, a different gas service. These conditions could result in contamination, corrosion or residual
gases that may react. Therefore, it is essential that all procedures detailed in clause 5 and displayed in tables 1, 2
and 3 be carefully followed.
Particular attention shall be directed to assuring that purging or cleaning procedures, where specified, remove all
residual gas, contaminants or corrosion products and that cleaning agents are removed and cylinders dried and
sealed to prevent entry of dirt or moisture after cleaning.
Persons using this International Standard shall be knowledgeable in the handling of compressed gases and be
familiar with the chemical and physical properties of the commodities which they charge into cylinders and of the
contaminants which are likely to be found therein.
4.1 Grouping of gases
For the purposes of this International Standard, the gases for which cylinder transfers are most frequently desired
have been separated into several groups. This separation has taken into consideration the chemical and physical
reactivity of the gases and of the contaminants which are most frequently encountered.
The requirements in this International Standard may not be applicable to gases or mixtures which are not included in
the gas groups given in table 3. Recommendations for the cleaning of cylinders which have contained such gases
shall be obtained from the manufacturer of the cylinder and/or gas. The values quoted in table 1 for the FTSC code
are taken from IS0 5145 or IS0 10156.
4.2 Gases which may affect cylinder condition
Cylinders which have been in certain gas services may be subjected to conditions which could affect the future
serviceability of the cylinder or render it unsuitable for use in any other gas service. Cylinders in such services are
subject to rigid requalification procedures or may be prohibited from use in other gas services. Examples are:
steel cylinders in carbon monoxide/carbon monoxide mixture service which may be subject to stress corrosion
cracking;
steel cylinders which have been in hydrogen service but which were not designed and manufactured for this
gas (see IS0 11114-1).
5 Actions for change of service
5.1 General
Because of the potential safety problems (e.g. corrosion, contamin ation, compatibility), specific actions are required
when transferring a cylinder from one gas service to another. The steps (set of actions), denoted by a number, are
2

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SIST EN ISO 11621:2006
@ IS0 IS0 11621 :1997(E)
listed in table 3. Table 2 shows in tabular form all the steps to be taken for each transfer. It is important that each
step be taken. The gas groups are shown by name and letter in table 1. The actions given in table 3 are described in
detail in 53.1 to 53.10 inclusive.
5.2 Use of tables 1,2 and 3
EXAMPLE d
A nitrogen cylinder is to be transferred to hydrogen service. Determine the gas groups from table 1 (nitrogen = A;
hydrogen = E). Using table 2, find A in the left-hand column and proceed across the table to column E where you
will find the numbers 1, 4, 6. Go to table 3, which shows what actions are required by steps 1, 4 and 6 (for details,
see 53.1, 5.3.4 and 5.3.6).
EXAMPLE 2
An oxygen cylinder is to be transferred to 50 % oxygen and 50 % nitrous oxide. Determine the gas groups from
table 1 (oxygen and nitrous oxide = C). Using table 2, find C in the left-hand column and proceed ,across the table
to column C where you will find the number 1. Go to table 3, which shows what actions are required by step 1
(for details, see 5.3.1).
- Gas groups for change of service
Table ll
Description Gases
Group
I I
Inertl) Nitrogen, argon, helium, neon, krypton, xenon and all gases and gas mixtures
A
having FTSC code 01X*)0 (but excluding gases in group B).
B Inert/activea) Carbon dioxide, carbon dioxide mixtures and oxygen mixtures containing less
than 21 % oxygen having FTSC code 01X0 or 11X0.
C Oxidizing Oxygen, nitrous oxide, air and mixtures containing at least 21 % oxygen or more
than 60 % nitrous oxide having FTSC code 41 X0.
D Flammable Ethylene, methane, cyclopropane, other hydrocarbons, liquefied petroleum gases,
etc., and all gases and gas mixtures having FTSC code 21X0 (but excluding
flammable gases of groups E and F).
Embrittling Hydrogen and all non-toxic gases of group 2 of IS0 11114-1 having FTSC code
E
21 x0.
F SC@) Carbon monoxide and carbon monoxide mixtures.
I I
Very toxic (X3Xx), toxic (X2Xx), corrosive (XXXYS)) and pyrophoric (3XxX) gases
G Toxic
Corrosive (but excluding group F).
Pyrophoric
CAUTION - Some of these gases are also embrittling (see IS0 11114-I).
1) inert in terms of fire potential (see IS0 10156).
2) X equals any digit.
3) Inert in terms of fire potential, but corrosive in presence of moisture.
4) Stress corrosion cracking.
5) YZO
3

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SIST EN ISO 11621:2006
@ IS0
IS0 11621:1997(E)
Table 2 - Actions to be taken when transferring cylinders from one gas service to another
D
To + A B C E F G
Carbon
From
Inert/active Oxidizing Flammable Embrittling monoxide Toxic, etc.
Inert
Jf
A Inert 1 I, 2 I, 3 1 IA6 195
I, 4 3
B Inert/active I, 7 1
I, 3 197 19 4, 6, 7 I, 5 7 11 3,4, 6
C Oxidizing I, 7 1 1 I, &7 19 4, 67, 8 19 5 7, 8 19 3,4, 7, 8
D Flammable I, 8 I, 8 I, 893 1, 8” 1, 4, 6, 8” 1, 5, 8* 1 J 4, 5 8
E Embrittling 1, 8*, 9 I, &9 19 3,8, 9 I, 899 1, 6, 8*, 9 19 598, 9
19 3,4, 8, 9
F Carbon monoxide 1, 8, 10 1, 8, 10 1,8,3, 10 1, 8, 10 1,6,8,10 1,5,8*,10 1,3,4,8,10
m . m . .
. m .
Toxic, etc. Not covered by this International Standard. Only to be performed under tightly controlled .
G
conditions using special procedures.
I
Table 3 - List of actions for change of gas service
Step No. Action
1 External examination and preparation:
Verify contents/identification
Cylinder external surface
Valve outlet and operation
Check working pressure/specification
Ownership
retest if required resulting from change of service
Test date -
Reduce pressure (blow down) to atmospheric pressure using appropriate discharge
Remove all existing labels, stencils, etc., after cylinder has been emptied
Re-mark with service markings: label, paint, stamp, etc. (after gas has been removed from the
cylinder)
If the valve is removed do an internal visual inspection
2 Check for moisture contamination
Internal inspection for liquid and/or hydrocarbons If suspected, clean for oxygen service
3
Check materials compatibility in accordance with IS0 11114-1
4
5 Check moisture level for steel cylinders. Use moisture requirements of IS0 11114-1
Check for internal surface defects
6
7 Check for internal corrosion ,
8 Cylinder content evacuation
Pull vacuum or purge (only if valve is removed)
8”
Check previous service against IS0 11114-1 g If not compatible, perform appropriate NIX and hydrotest
9
10 If suspected that cylinder has been exposed to water, perform appropriate NDT and hydrotest
4

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SIST EN ISO 11621:2006
@ IS0 IS0 11621:1997(E)
5.3 Details of actions for change of service
The following gives details and/or explanations of the actions listed in table 3.
53.1 External examination and preparation (step 1)
This step is required for each cylinder transferred to any other gas service. Each action listed in this subclause shall
be taken for each cylinder. Prior to the following actions, the cylinder contents (gas or gas group) shall be verified to
determine actions required from table 2. The actions below do not necessarily have to be performed in the order
indicated. At all times, safety considerations shall be observed.
- Carry out an external visual inspection of the cylinder and valve to verify suitability for service. For guidance,
see IS0 6406, IS0 10460 and IS0 10461. Note that external contamination of the cylinder and especially the
valve may indicate internal contamination.
-
Check that the cylinder is equipped with a valve having an outlet connection conforming to IS0 5145 or national
standards for the new service. If not, see table 2 to determine if step 8 or step 8* is required, before replacing
the valve. Also, check that the valve operates satisfactorily.
- Determine that the pressure relief device, if present, is of an approved type for the intended gas and the
working/test pressure of the cylinder.
- Check the working pressure/cylinder design specification and applicable regulations to verify that the cylinder is
satisfactory and authorized for the new gas service.
- Check the cylinder ownership to verify that the owner has authorized the transfer to another gas service.
- Check the test date and determine whether or not it is within the specified test frequency for the old and new
gas service. Retest, if necessary.
- Reduce the pressure (blow down) to atmospheric pressure using appropriate equipment and discharge to be
safe and meet environmental requirements.
- Remove all means of identification concerning the former gas content, such as labels, colour coding and other
relevant identification. Stamp markings of the former gas content shall be either removed or crossed out.
- Identify for the new gas service: this includes painting, labelling, stencilling and possibly stamp marking of the
cylinder.
- If a valve is removed for any reason, the opportunity should be taken to perform an internal visual inspection.
The valve may not require replacement for transfers within the same gas group, but a valve may be replaced
because of damage or improper operation. An internal inspection shall always observe for defects, corrosion
and contamination. Only acceptable cylinders shall be kept in service. Contaminated cylinders may be cleaned
(see annex A). Internal inspection of cylinders having contained oxidizing gases can be performed without
evacuation provided that a safety lamp is used. However, evacuation/purging shall be carried out prior to
probing or working on the interior surface.
5.3.2 Check for moisture contamination (step 2)
When step 2 is required, it is not mandatory that the valve be removed. The point of concern is the presence of
moisture in the cylinder. The absence of liquid water and other aqueous substances can be verified either by a
visual examination or by a moisture test for dew point. If visual internal inspection is used, a dry surface appearance
is acceptable proof of satisfactory condition. If liquid is found, the cylinder shall b
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