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© ISO 2017 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 carga[.]
INTERNATIONAL STANDARD ISO 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 18154:2017(E) © ISO 2017 ISO 18154:2017(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2017, Published in Switzerland All rights reserved Unless otherwise specified, no part o f 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 Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2017 – All rights reserved ISO 18154:2017(E) Page Contents Foreword v Scope Normative references Terms and definitions Main valve components 4.1 4.2 4.3 4.4 4.5 Design Materials Production testing and inspection 7.1 7.2 7.3 7.4 7.5 7.6 Nozzle Disk Cover Diaphragm Body Purpose Impact test Non-destructive inspection Pressure test 7.4.1 General requirement 7.4.2 Fluid 7.4.3 Duration 7.4.4 Test equipment Surface inspection Visual inspection Performance test Performance test in ambient temperature 8.1.1 Purpose 8.1.2 Number of test times 8.1.3 Fluid 8.1.4 Acceptance criteria 8.2 Leakage test in ambient temperature 8.2.1 Purpose 8.2.2 Fluid 8.2.3 Test pressure 8.2.4 Duration 8.2.5 Acceptance leakage rate 8.2.6 Test equipment 8.3 Performance test in low temperature 8.3.1 Purpose 8.3.2 Number of test times 8.3.3 Fluid 8.3.4 Acceptance criteria 8.4 Preparation for the performance test in low temperature 8.4.1 Start temperature for the test 8.4.2 Sa fety requirement 8.4.3 Test system 8.5 Leakage test in low temperature 8.5.1 Purpose 8.5.2 Fluid 8.5.3 Test pressure 8.5.4 Duration 8.5.5 Acceptance tolerance 8.5.6 Test equipment © ISO 2017 – All rights reserved iii 8.1 ISO 18154:2017(E) Vacuum test 10 Type test 11 12 13 9.1 9.2 Purpose Vacuum condition 9.2.1 Test temperature 9.2.2 Vacuum set test 9.2.3 Number of test times 9.2.4 Fluid Determination of pilot operated safety valve performance Sizing of pilot operated safety valves 10 Marking and sealing 10 Bibliography 11 iv © ISO 2017 – All rights reserved ISO 18154:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f 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 o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f 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 in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s 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 © ISO 2017 – All rights reserved v INTERNATIONAL STANDARD ISO 18154:2017(E) Ships and marine technology — Safety valve for cargo tanks of LNG carriers — Design and testing requirements Scope T h i s c ument s p e c i fie s the re qu i rements o f de s ign, te s t and i n s p e c tion me tho d s for d i aph ragm-typ e pi lo t op erate d s a fe ty va lve s , wh ich are u s e d i n c argo ta n ks o f L NG c arriers i n order to ke ep the pre s s u re inside the tank below maximum allowable working pressure T he Normative references fol lowi ng c u ments are re ferre d to i n the tex t i n s uch a way th at s ome or a l l o f thei r content s titute s re qu i rements o f th i s c u ment For date d re ference s , on ly the e d ition cite d appl ie s For u ndate d re ference s , the late s t e d ition o f the re ference d c ument (i nclud i ng a ny amend ments) appl ie s ISO 4126-4, Safety devices for protection against excessive pressure — Part 4: Pilot operated safety valves IMO, The International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code) API STD 527, Seat Tightness of Pressure Relief Valves ASME B16.34, Valves-Flanged, Threaded and Welding End Terms and definitions For the pu r p o s e o f th i s c u ment, the fol lowi ng term s and defi n ition s apply ISO and IEC maintain terminological databases for use in standardization at the following addresses: — IEC Electropedia: available at http://www.electropedia org/ — ISO Online browsing platform: available at http://www.iso org/obp 3.1 blowdown difference between the set and reseating pressures N o te to entr y: B lowdown i s no r m a l l y s tate d a s a p ercentage o f s e t p re s s u re , e xcep t bar, when the blowdown is expressed in bar for pre s s u re s o f le s s th a n 3.2 flow area cross-sectional area (but not the curtain area) between inlet and seat that is used to calculate the the ore tic a l flow c ap ac ity o f the mai n va lve, with no de duc tion for a ny ob s truc tion 3.3 lift ac tua l travel o f the mai n va lve d i sk away © ISO 2017 – All rights reserved from the clo s e d p o s ition ISO 18154:2017(E) 3.4 pilot operated safety valve automatic, self-actuated device comprising a main valve and an attached pilot valve N o te to entr y: T he p i lo t re s p o nd s to the pre s s u re o f the flu id without a ny o ther energ y s ou rce th a n the flu id its el f, a nd co ntro l s the op eration o f the m a i n va l ve T he va l ve o p en s when the flu id pre s s u re i nc re a s e s to the p i lo t va l ve s e t p oi nt T he va l ve re - clo s e s when the flu id pre s s u re i s re duce d to re s e ati ng pre s s u re S e e Figure 3.5 reseating pressure value of the inlet static pressure at which the disk re-establishes contact with the seat or at which the lift becomes zero 3.6 set pressure tan k pre s s ure at wh ich the ma i n va lve o f a pi lo t op erate d s a fe ty va lve u nder op erati ng cond ition s begins to open 3.7 theoretical discharge capacity ca lc u late d c ap acity expre s s e d i n mas s or volume tric u n its o f a the ore tic a l ly p er fe c t no z z le havi ng a cro s s - s e c tiona l flow are a e qua l to the flow a re a o f a ma i n va lve 3.8 vacuum set negative tank pressure value at which the valve starts to open under working conditions 4.1 Main valve components Body T he b o dy i n le t i s ne c te d d i re c tly to the ta n k, a nd the exit i s ne c te d to a d i s ch arge pip e I t ke ep s the pre s s u re conta i ne d a nd endu re s the re ac tion o f pre s s uri z e d flu id d i s ch arge d 4.2 from the s ys tem Nozzle I t j ets o ut p res s urized fluid to the dis charge p ip e 4.3 Disk It works with the seat to provide sealing function to prevent leakage when it is closed It is in direct contac t with the worki ng fluid, and may b e damage d p ar t i f the flu id contai n s s ol id s or 4.4 foreign materia l Cover I t is co nnected to the b o dy and makes a p res s ure s p ace where flo w can o ccur 4.5 Diaphragm I t i s a mai n comp onent as s emble d b e twe en the mai n va lve b o dy a nd the cover I t del ivers the fluid pressure to the disk © ISO 2017 – All rights reserved ISO 18154:2017(E) Key pilot spring pilot valve pilot seat 10 11 12 13 14 15 fixed o rifice dome main valve main valve seat sense diaphragm boost diaphragm s ens e cavity b o o s t cavity spindle seal diaphragm b lowdown adj us tment o rifice (variab le) main valve diaphragm pilot pickup Figure — Main components of pilot operated safety valve (Diaphragm type) Design 5.1 The des ign s hall inco rp o rate guiding arrangements neces s ary to ens ure co ns is tent o p eratio n and 5.2 The no zzle o f the main valve, o ther than when it is an integral p art o f the valve b o dy, s hall b e seat tightness fas tened 5.3 s ecurely to p revent the s eat fro m b eco ming lo o s e in s ervice Valve o p eratio n s hall b e des igned to p rovide co ns is tent, p ro p er functio n in very lo w p res s ure and cryo genic s ervices © ISO 2017 – All rights reserved ISO 18154:2017(E) 5.4 M eans s hall b e p rovided to lo ck and/o r to s eal all external adj us tments to p revent unautho rized adj us tments o f the p ilo t o p erated s a fety valve In 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 5.5 des igned, ins talled and s ealed by the valve manu facturer 5.6 Pilo t o p erated s a fety valves 5.7 Valves shall be designed so that tear or damage to the diaphragm can be checked without fo r flammab le fluids s hall dis charge to a no n- hazardo us lo catio n dis as s emb ly 5.8 I t s hall b e des igned that fluid can b e fully releas ed under , times o f the maximum allo wab le p res s ure o f the p ro tectio n sys tem 5.9 The fitting o f any p res s urized sys tem 6.1 fro m additio nal device to a p ilo t and valve co mb inatio n s hall no t p revent the b eing p ro tected under any circums tances Materials M aterials o f the valve us ed near s lip p ery s ur faces , s uch as dis k, dis k guide and ho lder/s p indle, s hall b e co rro s io n res is tant and wear res is tant Thes e materials s hall als o have durab ility in very low temperature environments 6.2 Gas kets that have s ealing 6.3 M aterials o f the b o dy and no zzle that are directly exp o s ed to very low temp erature enviro nments 6.4 The s p ring materials s hall b e equal to C F3 M 6.5 The materials o f all o ther co mp o nents s hall have durab ility in very lo w temp eratures environment functio ns s hall b e co ns tructed o f materials having durab ility in –1 63 °C shall be equal to CF3M 7.1 fo r durab ility in very low temp eratures Production testing and inspection Purpose T he pu rp o s e o f the s e te s ts i s to en s u re that pre s s u re re tai n i ng comp onents , e s p e c ia l ly c a s ti ngs , me e t the re qui rements for wh ich they have b e en de s igne d a nd manu fac tu re d without e xh ibiti ng any form of qua l ity de fe c t 7.2 Impact test C a s ti ngs , s uch as b o dy and no z z le e tc , sha l l s ati s fy the V-no tch c riteria o f C rp y i mp ac t te s ti ng i n accordance with IGC code 6.1.4 7.3 Non-destructive inspection I f the materi a l i s c as ti ng , the i n s ide or outs ide o f the materi a l sh a l l b e te s te d b y non- de s truc tive i n s p e c tion Norma l ly, a rad io graph ic te s t (RT ) i s conduc te d , but a lternative non- de s truc tive i n s p e c tion ca n b e conduc te d by re qu i rement o f the pu rchas ers © ISO 2017 – All rights reserved ISO 18154:2017(E) 7.4 Pressure test 7.4.1 It is General requirement conduc te d on c a s ti ngs s uch a s the no z z le , b o dy a nd cover T he s e comp onents s l l no t h ave de formation, le a kage or any o ther u nu s ua l cond ition when , ti me s o f s e t pre s s u re i s appl ie d accord i ng to ASME B16.34 7.4.2 Fluid P re s s ure te s t sh a l l b e conduc te d by water or a i r pre s s u re T he worki ng flu id s l l b e conducted in ambient temperature 7.4.3 water a nd Duration I t s l l b e 7.4.4 fre s h for m i n a fter applyi ng te s t pre s s u re Test equipment An example of the equipment is shown in Figure Key nozzle b o dy and cover Figure — Water pressure test equipment 7.5 Surface inspection I t sh a l l b e che cke d a nd veri fie d that there are no sh ri n kage c avitie s , bu rrs , s a nd i nclu s ion s or c racks on the i n s ide and outs ide o f the c a s ti ng s u r face I f there are cracks , the de ci s ion s l l s ati s fy I S O 41 - 7.6 Visual inspection 7.6.1 Forgings shall be checked for evidence of cracks 7.6.2 There s hall no t b e any de fects o n machined s ur faces directly co ntacting the gas ket C o rners o r edges shall be rounded out and chamfered © ISO 2017 – All rights reserved ISO 18154:2017(E) Performance test 8.1 Performance test in ambient temperature 8.1.1 Purpose The purpose is to check that the valve is working well under set pressure and tolerance in ambient temperature The set pressure and tolerance shall satis fy Table Table — Tolerance of set pressure Service a b Cargo tank Set pressure Set pressure Actual set pressure shall satis fy purchasers’ specification 25 kPaab Tolerance ±10 % of set pressure Tolerance for negative pressure is ±25 % 8.1.2 Number of test times The manu facturers and the purchasers may reach an agreement for the number o f per formance test times, but the test shall be conducted at least 50 times for per formance consistency 8.1.3 Fluid Inert gas and air shall be used 8.1.4 Acceptance criteria The valve shall be open under the tolerance of set pressure 8.2 8.2.1 Leakage test in ambient temperature Purpose The purpose o f this test is to veri fy the air tightness on the seat when the valve is closed in ambient temperature 8.2.2 Fluid Air or N2 shall be used 8.2.3 Test pressure It shall be started at 90 % of the set pressure 8.2.4 Duration It shall be retained for at least 8.2.5 Acceptance leakage rate Leakage rate o f the sa fety valve between the disk and seat shall be less than 0,06 ml/min/mm (1,5 cm3/min/inch diameter) © ISO 2017 – All rights reserved ISO 18154:2017(E) 8.2.6 Test equipment Inspection method is shown in Figure Leakage measurement shall be conducted using 1,0 mm wall thickness and 8,0 mm outer diameter pipe according to API STD 527 Figure — Leakage inspection method 8.3 8.3.1 Performance test in low temperature Purpose The purpose o f this test is to check that the valve is working accurately under the set pressure and the tolerance The set pressure and tolerance shall satis fy Table 8.3.2 Number of test times The manu facturers and the purchasers may reach an agreement for the number o f per formance test times, but the test shall be conducted at least three times 8.3.3 Fluid Helium gas shall be used 8.3.4 Acceptance criteria The valve shall open under the tolerance of set pressure 8.4 8.4.1 Preparation for the performance test in low temperature Start temperature for the test The test shall be started a fter the inside of the nozzle temperature reaches –163 °C; the temperature shall be measured by a thermocouple Also, the temperature shall be dropped by LN or similar liquid to LN 8.4.2 Safety requirement Protective gear must be used during the test 8.4.3 Test system The test system may be constructed as shown in Figure Other suitable test systems may be applied © ISO 2017 – All rights reserved ISO 18154:2017(E) Key pressure gauge thermocouple digital manometer temperature sensor POV He LN2 Figure — System for performance test in low temperature (example) 8.5 8.5.1 Leakage test in low temperature Purpose T he pu rp o s e o f th i s te s t i s to veri fy the r tightne s s on the s e at when the va lve i s clo s e d i n low temperatures 8.5.2 Fluid Hel iu m gas , wh ich i s b elow –16 ° C , s l l b e u s e d 8.5.3 Test pressure It shall be started at 90 % of the set pressure 8.5.4 Duration It shall be retained for at least © ISO 2017 – All rights reserved ISO 18154:2017(E) 8.5.5 Acceptance tolerance Leakage tolerance o f the sa fety valve between the disk and seat shall be less than 0,06 ml/min/mm (1,5 cm3/min/inch diameter) 8.5.6 Test equipment Inspection method is as shown in Figure Leakage measurement shall be conducted using 1,0 mm wall thickness and 8,0 mm outer diameter pipe according to API STD 527 Vacuum test 9.1 Purpose In the case o f sa fety valve for cargo tank o f LNG carriers, the function shall be satisfied in a vacuum environment The purpose of this test is to check the relief function of the valve under the given vacuum condition In the case o f sa fety valve for cargo tank o f LNG carriers, it is possible to check the result when the vacuum set is satisfied in a vacuum environment 9.2 Vacuum condition The degree o f vacuum and tolerance shall satis fy Table Table — Degree of vacuum and tolerance Service a Cargo tank Degree of vacuum Vacuum set Actual set pressure shall satis fy purchasers’ specification 9.2.1 kPa, Gauge a Tolerance ±25 % of Vacuum set Test temperature The test shall be conducted in ambient temperature 9.2.2 Vacuum set test The vacuum test shall be conducted at vacuum set pressure 9.2.3 Number of test times The manu facturers and the purchasers may reach an agreement for the number o f per formance test times, but the test shall be conducted at least three times 9.2.4 Fluid Air or inert gas shall be used 10 Type test It shall satis fy ISO 4126-4 11 Determination of pilot operated safety valve performance It shall satis fy ISO 4126-4 © ISO 2017 – All rights reserved ISO 18154:2017(E) 12 Sizing of pilot operated safety valves I t sh a l l s ati s fy I S O 41 - 13 Marking and sealing I t sh a l l s ati s fy I S O 41 - 10 © ISO 2017 – All rights reserved ISO 18154:2017(E) Bibliography [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] ISO 4126-1:2013, Safety devices for protection against excessive pressure — Part 1: Safety valves ISO 4126-7:2013, Safety devices for protection against excessive pressure — Part 7: Common data ISO 21028-1, Cryogenic vessels — Toughness requirements for materials at cryogenic temperature — Part 1: Temperatures below −80 °C ISO 21028-2, Cryogenic vessels - Toughness requirements for materials at cryogenic temperature - Part 2: Temperatures between −80 °C and −20 °C API RP 520, Sizing, Selection, and Installation of Pressure-relieving Devices API STD 526, Flanged Steel Pressure Relief Valves API STD 2000, Venting Atmospheric and Low-pressure Storage Tanks ASME B16.5, Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 ASTM A351/A351M, Standard Specification for Castings, Austenitic, for Pressure-Containing Parts ASTM E2248, Standard Test Method for Impact Testing of Miniaturized Charpy V-Notch Specimens MSS SP-55, Quality Standard for Steel Castings for Valves, Flanges and Fittings and Other Piping Components - Visual Method for Evaluation of Surface Irregularities SIGTTO, Sizing, Selection, and Installation of Pressure-Relieving Devices © ISO 2017 – All rights reserved 11 ISO 18154:2017(E) ICS 47.020.30 Price based on 11 pages © ISO 2017 – All rights reserved