ISO 12991:2012
(Main)Liquefied natural gas (LNG) — Tanks for on-board storage as a fuel for automotive vehicles
Liquefied natural gas (LNG) — Tanks for on-board storage as a fuel for automotive vehicles
ISO 12991:2012 specifies the construction requirements for refillable fuel tanks for liquefied natural gas (LNG) used in vehicles as well as the testing methods required to ensure that a reasonable level of protection from loss of life and property resulting from fire and explosion is provided. It is applicable to fuel tanks intended to be permanently attached to land vehicles but can be used as a guide for other modes of transport.
Gaz naturel liquéfié (GNL) — Réservoirs pour le stockage à bord comme carburant pour véhicules automobiles
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INTERNATIONAL ISO
STANDARD 12991
First edition
2012-11-15
Liquefied natural gas (LNG) — Tanks
for on-board storage as a fuel for
automotive vehicles
Gaz naturel liquéfié (GNL) — Réservoirs pour le stockage à bord
comme carburant pour véhicules automobiles
Reference number
©
ISO 2012
© ISO 2012
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 either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Requirements .3
4.1 General requirements . 3
4.2 Mechanical stresses . 3
4.3 Thermal stresses . 4
4.4 Materials . 5
4.5 Design . 5
4.6 Insulation .
General requirements . 6
4.7 Accessories . 6
4.8 Manufacturing and assembly. 7
5 Type tests .7
5.1 Approval of new designs . 7
5.2 Inner tank burst pressure test . 8
5.3 Holding time test . 8
5.4 Maximum fuelling level test . 8
5.5 Accessory type tests . 8
6 Routine tests and inspection .8
6.1 General . 8
6.2 Pressure test . 9
6.3 Leak test . 9
6.4 Verification of the dimensions . 9
6.5 Destructive and non-destructive tests of welded joints . 9
6.6 Visual inspection .10
7 Marking and labelling .10
7.1 Marking method .10
7.2 Inner tank markings .10
7.3 Outer jacket markings . .10
7.4 Temporary markings for first fuelling .10
Annex A (normative) Fuel tank type tests .12
Annex B (normative) Accessory type tests .14
Bibliography .16
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 12991 was prepared by Technical Committee ISO/TC 220, Cryogenic vessels.
iv © ISO 2012 – All rights reserved
Introduction
The fuel tanks described in this International Standard are intended to be used in conjunction with the
fuelling system interface described in ISO 12617, which is under preparation.
INTERNATIONAL STANDARD ISO 12991:2012(E)
Liquefied natural gas (LNG) — Tanks for on-board storage
as a fuel for automotive vehicles
1 Scope
This International Standard specifies the construction requirements for refillable fuel tanks for liquefied
natural gas (LNG) used in vehicles as well as the testing methods required to ensure that a reasonable
level of protection from loss of life and property resulting from fire and explosion is provided.
This International Standard is applicable to fuel tanks intended to be permanently attached to land
vehicles but can be used as a guide for other mode of transport.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 1176, Road vehicles — Masses — vocabulary and codes
ISO 1431-1, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static and
dynamic strain testing
ISO 2768-1, General tolerances — Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications
ISO 6957, Copper alloys — Ammonia test for stress corrosion resistance
ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests
ISO 21013-3, Cryogenic vessels — Pressure-relief accessories for cryogenic service — Part 3: Sizing and
capacity determination
ISO 21014, Cryogenic vessels — Cryogenic insulation performance
ISO 21028-1, Cryogenic vessels — Toughness requirements for materials at cryogenic temperature — Part 1:
Temperatures below -80 degrees C
ISO 21029-1:2004, Cryogenic vessels — Transportable vacuum insulated vessels of not more than 1 000
litres volume — Part 1: Design, fabrication, inspection and tests
ISO 23208, Cryogenic vessels — Cleanliness for cryogenic service
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
accessory
device fixed directly to the inner tank or outer jacket of a fuel tank such as a pressure relief valve, shut-
off valve, non-return valve or level gauge
3.2
boil-off management system
system that controls the boil-off of gas under normal conditions
3.3
burst pressure
pressure that causes the rupture of a pressure vessel subjected to a constant increase of pressure during
a destructive test
3.4
design temperature
temperature of the inner tank, the outer jacket and all other accessories to which fabrication drawings,
inspections and physical measurements such as volume are referred
3.5
fuel tank
vessel used for the storage of cryogenic liquefied natural gas (LNG) fuel
3.7
impermissible fault range
pressure range within which an unwanted event is to be expected
3.8
inner tank
part of the fuel tank that contains liquefied natural gas (LNG)
3.9
level gauge
device that measures the level of liquefied natural gas (LNG) in the fuel tank
3.10
maximum allowable working pressure
MAWP
maximum pressure to which a component is designed to be subjected to and which is the basis for
determining the strength of the component under consideration
3.11
normal operating range
range planned for the process values
NOTE In the case of inner tanks, the normal operating range of the inner tank pressure is from 0 bar to the
set pressure of the primary pressure relief valve, which is lower than or equal to the maximum allowable working
pressure (MAWP) of the inner tank.
3.12
outer jacket
part of the fuel tank that encases the inner tank(s) and its insulation system
3.13
outer pressure
pressure acting on the outside of the inner tank or outer jacket
3.14
permissible fault range
range between the normal operating range and the impermissible fault range
3.15
pressure
pressure for which the value is equal to the algebraic difference between the absolute pressure and the
atmospheric pressure
NOTE This is also known as gauge pressure.
2 © ISO 2012 – All rights reserved
3.16
holding time
time of the pressure increase in the inner tank measured from a starting pressure of 0 bar at the
corresponding boiling point of liquefied natural gas (LNG) (−164° C) up to the maximum allowable
working pressure (MAWP) of the inner tank
NOTE The holding time is a measure of the insulation performance of the fuel tank.
3.17
batch inner tank heads
number (no more than 100) of tank heads produced by the same manufacturer, from the same material,
and having the same dimensions
3.18
maximum mass
a maximum authorized total mass, as defined
...
INTERNATIONAL ISO
STANDARD 12991
First edition
2012-11-15
Liquefied natural gas (LNG) — Tanks
for on-board storage as a fuel for
automotive vehicles
Gaz naturel liquéfié (GNL) — Réservoirs pour le stockage à bord
comme carburant pour véhicules automobiles
Reference number
©
ISO 2012
© ISO 2012
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 either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Requirements .3
4.1 General requirements . 3
4.2 Mechanical stresses . 3
4.3 Thermal stresses . 4
4.4 Materials . 5
4.5 Design . 5
4.6 Insulation .
General requirements . 6
4.7 Accessories . 6
4.8 Manufacturing and assembly. 7
5 Type tests .7
5.1 Approval of new designs . 7
5.2 Inner tank burst pressure test . 8
5.3 Holding time test . 8
5.4 Maximum fuelling level test . 8
5.5 Accessory type tests . 8
6 Routine tests and inspection .8
6.1 General . 8
6.2 Pressure test . 9
6.3 Leak test . 9
6.4 Verification of the dimensions . 9
6.5 Destructive and non-destructive tests of welded joints . 9
6.6 Visual inspection .10
7 Marking and labelling .10
7.1 Marking method .10
7.2 Inner tank markings .10
7.3 Outer jacket markings . .10
7.4 Temporary markings for first fuelling .10
Annex A (normative) Fuel tank type tests .12
Annex B (normative) Accessory type tests .14
Bibliography .16
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 12991 was prepared by Technical Committee ISO/TC 220, Cryogenic vessels.
iv © ISO 2012 – All rights reserved
Introduction
The fuel tanks described in this International Standard are intended to be used in conjunction with the
fuelling system interface described in ISO 12617, which is under preparation.
INTERNATIONAL STANDARD ISO 12991:2012(E)
Liquefied natural gas (LNG) — Tanks for on-board storage
as a fuel for automotive vehicles
1 Scope
This International Standard specifies the construction requirements for refillable fuel tanks for liquefied
natural gas (LNG) used in vehicles as well as the testing methods required to ensure that a reasonable
level of protection from loss of life and property resulting from fire and explosion is provided.
This International Standard is applicable to fuel tanks intended to be permanently attached to land
vehicles but can be used as a guide for other mode of transport.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 1176, Road vehicles — Masses — vocabulary and codes
ISO 1431-1, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static and
dynamic strain testing
ISO 2768-1, General tolerances — Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications
ISO 6957, Copper alloys — Ammonia test for stress corrosion resistance
ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests
ISO 21013-3, Cryogenic vessels — Pressure-relief accessories for cryogenic service — Part 3: Sizing and
capacity determination
ISO 21014, Cryogenic vessels — Cryogenic insulation performance
ISO 21028-1, Cryogenic vessels — Toughness requirements for materials at cryogenic temperature — Part 1:
Temperatures below -80 degrees C
ISO 21029-1:2004, Cryogenic vessels — Transportable vacuum insulated vessels of not more than 1 000
litres volume — Part 1: Design, fabrication, inspection and tests
ISO 23208, Cryogenic vessels — Cleanliness for cryogenic service
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
accessory
device fixed directly to the inner tank or outer jacket of a fuel tank such as a pressure relief valve, shut-
off valve, non-return valve or level gauge
3.2
boil-off management system
system that controls the boil-off of gas under normal conditions
3.3
burst pressure
pressure that causes the rupture of a pressure vessel subjected to a constant increase of pressure during
a destructive test
3.4
design temperature
temperature of the inner tank, the outer jacket and all other accessories to which fabrication drawings,
inspections and physical measurements such as volume are referred
3.5
fuel tank
vessel used for the storage of cryogenic liquefied natural gas (LNG) fuel
3.7
impermissible fault range
pressure range within which an unwanted event is to be expected
3.8
inner tank
part of the fuel tank that contains liquefied natural gas (LNG)
3.9
level gauge
device that measures the level of liquefied natural gas (LNG) in the fuel tank
3.10
maximum allowable working pressure
MAWP
maximum pressure to which a component is designed to be subjected to and which is the basis for
determining the strength of the component under consideration
3.11
normal operating range
range planned for the process values
NOTE In the case of inner tanks, the normal operating range of the inner tank pressure is from 0 bar to the
set pressure of the primary pressure relief valve, which is lower than or equal to the maximum allowable working
pressure (MAWP) of the inner tank.
3.12
outer jacket
part of the fuel tank that encases the inner tank(s) and its insulation system
3.13
outer pressure
pressure acting on the outside of the inner tank or outer jacket
3.14
permissible fault range
range between the normal operating range and the impermissible fault range
3.15
pressure
pressure for which the value is equal to the algebraic difference between the absolute pressure and the
atmospheric pressure
NOTE This is also known as gauge pressure.
2 © ISO 2012 – All rights reserved
3.16
holding time
time of the pressure increase in the inner tank measured from a starting pressure of 0 bar at the
corresponding boiling point of liquefied natural gas (LNG) (−164° C) up to the maximum allowable
working pressure (MAWP) of the inner tank
NOTE The holding time is a measure of the insulation performance of the fuel tank.
3.17
batch inner tank heads
number (no more than 100) of tank heads produced by the same manufacturer, from the same material,
and having the same dimensions
3.18
maximum mass
a maximum authorized total mass, as defined
...
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