1、BS ISO 18154:2017Ships and marine technology Safety valve for cargo tanksof LNG carriers Design andtesting requirementsBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 18154:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of
2、 ISO 18154:2017. The UK participation in its preparation was entrusted to TechnicalCommittee SME/32, Ships and marine technology - Steeringcommittee.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the n
3、ecessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2017. Published by BSI Standards Limited 2017ISBN 978 0 580 88215 9ICS 47.020.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard
4、was published under the authority of theStandards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate Text affectedBS ISO 18154:2017 ISO 2017Ships and marine technology Safety valve for cargo tanks of LNG carriers Design and testing requirementsNavires e
5、t technologie maritime Soupape de sret pour les rservoirs de cargaison des mthaniers Exigences de conception et dessaiINTERNATIONAL STANDARDISO18154First edition2017-03Reference numberISO 18154:2017(E)BS ISO 18154:2017ISO 18154:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2
6、017, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission
7、. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 18154:2017ISO 18154:2017
8、(E)Foreword v1 Scope . 12 Normative references 13 Terms and definitions . 14 Main valve components . 24.1 Body 24.2 Nozzle 24.3 Disk . 24.4 Cover 24.5 Diaphragm 25 Design 36 Materials . 47 Production testing and inspection . 47.1 Purpose 47.2 Impact test 47.3 Non-destructive inspection 47.4 Pressure
9、 test 57.4.1 General requirement 57.4.2 Fluid 57.4.3 Duration. 57.4.4 Test equipment 57.5 Surface inspection 57.6 Visual inspection . 58 Performance test 68.1 Performance test in ambient temperature . 68.1.1 Purpose 68.1.2 Number of test times 68.1.3 Fluid 68.1.4 Acceptance criteria 68.2 Leakage tes
10、t in ambient temperature . 68.2.1 Purpose 68.2.2 Fluid 68.2.3 Test pressure . 68.2.4 Duration. 68.2.5 Acceptance leakage rate 68.2.6 Test equipment 78.3 Performance test in low temperature . 78.3.1 Purpose 78.3.2 Number of test times 78.3.3 Fluid 78.3.4 Acceptance criteria 78.4 Preparation for the p
11、erformance test in low temperature . 78.4.1 Start temperature for the test . 78.4.2 Safety requirement 78.4.3 Test system . 78.5 Leakage test in low temperature . 88.5.1 Purpose 88.5.2 Fluid 88.5.3 Test pressure . 88.5.4 Duration. 88.5.5 Acceptance tolerance . 98.5.6 Test equipment 9 ISO 2017 All ri
12、ghts reserved iiiContents PageBS ISO 18154:2017ISO 18154:2017(E)9 Vacuum test 99.1 Purpose 99.2 Vacuum condition . 99.2.1 Test temperature . 99.2.2 Vacuum set test . 99.2.3 Number of test times 99.2.4 Fluid 910 Type test 911 Determination of pilot operated safety valve performance 912 Sizing of pilo
13、t operated safety valves .1013 Marking and sealing .10Bibliography .11iv ISO 2017 All rights reservedBS ISO 18154:2017ISO 18154:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing In
14、ternational 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
15、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 Directiv
16、es, 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 som
17、e 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 declara
18、tions 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 on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information a
19、bout ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.This document was prepared by ISO Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee SC 3, Piping and machinery
20、. ISO 2017 All rights reserved vBS ISO 18154:2017BS ISO 18154:2017Ships and marine technology Safety valve for cargo tanks of LNG carriers Design and testing requirements1 ScopeThis document specifies the requirements of design, test and inspection methods for diaphragm-type pilot operated safety va
21、lves, which are used in cargo tanks of LNG carriers in order to keep the pressure inside the tank below maximum allowable working pressure.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this docume
22、nt. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 4126-4, Safety devices for protection against excessive pressure Part 4: Pilot operated safety valvesIMO, The International Code for
23、the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code)API STD 527, Seat Tightness of Pressure Relief ValvesASME B16.34, Valves-Flanged, Threaded and Welding End3 Terms and definitionsFor the purpose of this document, the following terms and definitions apply.ISO and IEC
24、maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp3.1blowdowndifference between the set and reseating pressuresNote 1 to en
25、try: Blowdown is normally stated as a percentage of set pressure, except for pressures of less than 3 bar, when the blowdown is expressed in bar.3.2flow areacross-sectional area (but not the curtain area) between inlet and seat that is used to calculate the theoretical flow capacity of the main valv
26、e, with no deduction for any obstruction3.3liftactual travel of the main valve disk away from the closed positionINTERNATIONAL STANDARD ISO 18154:2017(E) ISO 2017 All rights reserved 1BS ISO 18154:2017ISO 18154:2017(E)3.4pilot operated safety valveautomatic, self-actuated device comprising a main va
27、lve and an attached pilot valveNote 1 to entry: The pilot responds to the pressure of the fluid without any other energy source than the fluid itself, and controls the operation of the main valve. The valve opens when the fluid pressure increases to the pilot valve set point. The valve re-closes whe
28、n the fluid pressure is reduced to reseating pressure. See Figure 1.3.5reseating pressurevalue of the inlet static pressure at which the disk re-establishes contact with the seat or at which the lift becomes zero3.6set pressuretank pressure at which the main valve of a pilot operated safety valve un
29、der operating conditions begins to open3.7theoretical discharge capacitycalculated capacity expressed in mass or volumetric units of a theoretically perfect nozzle having a cross-sectional flow area equal to the flow area of a main valve3.8vacuum setnegative tank pressure value at which the valve st
30、arts to open under working conditions4 Main valve components4.1 BodyThe body inlet is connected directly to the tank, and the exit is connected to a discharge pipe. It keeps the pressure contained and endures the reaction of pressurized fluid discharged from the system.4.2 NozzleIt jets out pressuri
31、zed fluid to the discharge pipe.4.3 DiskIt works with the seat to provide sealing function to prevent leakage when it is closed. It is in direct contact with the working fluid, and may be damaged part if the fluid contains solids or foreign material.4.4 CoverIt is connected to the body and makes a p
32、ressure space where flow can occur.4.5 DiaphragmIt is a main component assembled between the main valve body and the cover. It delivers the fluid pressure to the disk.2 ISO 2017 All rights reservedBS ISO 18154:2017ISO 18154:2017(E)Key1 pilot spring 9 boost diaphragm2 pilot valve 10 sense cavity3 pil
33、ot seat 11 boost cavity4 fixed orifice 12 spindle seal diaphragm5 dome 13 blowdown adjustment orifice (variable)6 main valve 14 main valve diaphragm7 main valve seat 15 pilot pickup8 sense diaphragmFigure 1 Main components of pilot operated safety valve (Diaphragm type)5 Design5.1 The design shall i
34、ncorporate guiding arrangements necessary to ensure consistent operation and seat tightness.5.2 The nozzle of the main valve, other than when it is an integral part of the valve body, shall be fastened securely to prevent the seat from becoming loose in service.5.3 Valve operation shall be designed
35、to provide consistent, proper function in very low pressure and cryogenic services. ISO 2017 All rights reserved 3BS ISO 18154:2017ISO 18154:2017(E)5.4 Means shall be provided to lock and/or to seal all external adjustments to prevent unauthorized adjustments of the pilot operated safety valve.5.5 I
36、n the case of main valves with restricted lift, the lift restricting device shall limit the main valve lift but shall not otherwise interfere with the operation of the main valve. The lift restricting device shall be designed, installed and sealed by the valve manufacturer.5.6 Pilot operated safety
37、valves for flammable fluids shall discharge to a non-hazardous location.5.7 Valves shall be designed so that tear or damage to the diaphragm can be checked without disassembly.5.8 It shall be designed that fluid can be fully released under 1,1 times of the maximum allowable pressure of the protectio
38、n system.5.9 The fitting of any additional device to a pilot and valve combination shall not prevent the pressurized system from being protected under any circumstances.6 Materials6.1 Materials of the valve used near slippery surfaces, such as disk, disk guide and holder/spindle, shall be corrosion
39、resistant and wear resistant. These materials shall also have durability in very low temperature environments.6.2 Gaskets that have sealing functions shall be constructed of materials having durability in 163 C environment.6.3 Materials of the body and nozzle that are directly exposed to very low te
40、mperature environments shall be equal to CF3M.6.4 The spring materials shall be equal to CF3M for durability in very low temperatures.6.5 The materials of all other components shall have durability in very low temperatures.7 Production testing and inspection7.1 PurposeThe purpose of these tests is t
41、o ensure that pressure retaining components, especially castings, meet the requirements for which they have been designed and manufactured without exhibiting any form of quality defect.7.2 Impact testCastings, such as body and nozzle etc., shall satisfy the V-notch criteria of Charpy impact testing
42、in accordance with IGC code 6.1.4.7.3 Non-destructive inspectionIf the material is casting, the inside or outside of the material shall be tested by non-destructive inspection. Normally, a radiographic test (RT) is conducted, but alternative non-destructive inspection can be conducted by requirement
43、 of the purchasers.4 ISO 2017 All rights reservedBS ISO 18154:2017ISO 18154:2017(E)7.4 Pressure test7.4.1 General requirementIt is conducted on castings such as the nozzle, body and cover. These components shall not have deformation, leakage or any other unusual condition when 1,5 times of set press
44、ure is applied according to ASME B16.34.7.4.2 FluidPressure test shall be conducted by water or air pressure. The working fluid shall be fresh water and conducted in ambient temperature.7.4.3 DurationIt shall be for 15 min after applying test pressure.7.4.4 Test equipmentAn example of the equipment
45、is shown in Figure 2.Key1 body and cover2 nozzleFigure 2 Water pressure test equipment7.5 Surface inspectionIt shall be checked and verified that there are no shrinkage cavities, burrs, sand inclusions or cracks on the inside and outside of the casting surface. If there are cracks, the decision shal
46、l satisfy ISO 4126-4.7.6 Visual inspection7.6.1 Forgings shall be checked for evidence of cracks.7.6.2 There shall not be any defects on machined surfaces directly contacting the gasket. Corners or edges shall be rounded out and chamfered. ISO 2017 All rights reserved 5BS ISO 18154:2017ISO 18154:201
47、7(E)8 Performance test8.1 Performance test in ambient temperature8.1.1 PurposeThe purpose is to check that the valve is working well under set pressure and tolerance in ambient temperature.The set pressure and tolerance shall satisfy Table 1.Table 1 Tolerance of set pressureService Set pressure Tole
48、ranceCargo tank Set pressure 25 kPaab10 % of set pressureaActual set pressure shall satisfy purchasers specification.bTolerance for negative pressure is 25 %.8.1.2 Number of test timesThe manufacturers and the purchasers may reach an agreement for the number of performance test times, but the test s
49、hall be conducted at least 50 times for performance consistency.8.1.3 FluidInert gas and air shall be used.8.1.4 Acceptance criteriaThe valve shall be open under the tolerance of set pressure.8.2 Leakage test in ambient temperature8.2.1 PurposeThe purpose of this test is to verify the air tightness on the seat when the valve is closed in ambient temperature.8.2.2 FluidAir or N2shall be used.8.2.3 Test pressureIt shall be started at 90 % of the set pressure.8.2.4 DurationIt shall be retained for at least 5 min.8.2.5
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