ISO 18154:2017

INTERNATIONAL ISO
STANDARD 18154
First edition
2017-03
Ships and marine technology — Safety
valve for cargo tanks of LNG carriers
— Design and testing requirements
Navires et technologie maritime — Soupape de sûreté pour les
réservoirs de cargaison des méthaniers — Exigences de conception
et d’essai
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Main valve components . 2
4.1 Body . 2
4.2 Nozzle. 2
4.3 Disk . 2
4.4 Cover . 2
4.5 Diaphragm . 2
5 Design . 3
6 Materials . 4
7 Production testing and inspection . 4
7.1 Purpose . 4
7.2 Impact test . 4
7.3 Non-destructive inspection . 4
7.4 Pressure test . 5
7.4.1 General requirement . 5
7.4.2 Fluid . 5
7.4.3 Duration. 5
7.4.4 Test equipment . 5
7.5 Surface inspection . 5
7.6 Visual inspection . 5
8 Performance test . 6
8.1 Performance test in ambient temperature . 6
8.1.1 Purpose . 6
8.1.2 Number of test times . 6
8.1.3 Fluid . 6
8.1.4 Acceptance criteria . 6
8.2 Leakage test in ambient temperature . 6
8.2.1 Purpose . 6
8.2.2 Fluid . 6
8.2.3 Test pressure . 6
8.2.4 Duration. 6
8.2.5 Acceptance leakage rate . 6
8.2.6 Test equipment . 7
8.3 Performance test in low temperature . 7
8.3.1 Purpose . 7
8.3.2 Number of test times . 7
8.3.3 Fluid . 7
8.3.4 Acceptance criteria . 7
8.4 Preparation for the performance test in low temperature . 7
8.4.1 Start temperature for the test . 7
8.4.2 Safety requirement . 7
8.4.3 Test system . 7
8.5 Leakage test in low temperature . 8
8.5.1 Purpose . 8
8.5.2 Fluid . 8
8.5.3 Test pressure . 8
8.5.4 Duration. 8
8.5.5 Acceptance tolerance . 9
8.5.6 Test equipment . 9
9 Vacuum test . 9
9.1 Purpose . 9
9.2 Vacuum condition . 9
9.2.1 Test temperature . 9
9.2.2 Vacuum set test . 9
9.2.3 Number of test times . 9
9.2.4 Fluid . 9
10 Type test . 9
11 Determination of pilot operated safety valve performance . 9
12 Sizing of pilot operated safety valves .10
13 Marking and sealing .10
Bibliography .11
iv © ISO 2017 – All rights reserved

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
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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 wit
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