1、 STD=BSI BS EN 12308-ENGL 1998 = Lb24bb7 0734474 320 D BRITISH STANDARD _ Installations and equipment for LNG - Suitability testing of gaskets designed for flanged joints used on LNG piping The European Standard EN 123081998 has the status of a British Standard ICs 23.040.80; 75.200 BS EN 12308:1998
2、 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW STD.BS1 BS EN L2308-ENGL 1998 Lb24669 0734475 267 direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 December 1998 Amd. No. BS EN 123081998 Dat
3、e Text affected National foreword This British Standard is the English language version of EN 123081998. The UK participation in its preparation was entrusted to Technical Committee GSES, hstabtions and equipment for LNG, which has the responsibility to: - aid enquirers to understand the te* - prese
4、nt to the responsible European committee any enquiries on the - monitor related international and European developments and promulgak interpretation, or proposals for change, and keep the UK interests informed; them in the UK. A iist of organizations represented on this committee can be obtained on
5、request to its secretary. Cross-references The British Stancards which implement international or European publications referred to in this document may be found in the BSI Sandards Catalogue under the section entitled “hternational Standards Correspondence Index”, or by using the “Find” facility of
6、 the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legai obligations.
7、Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 12, an inside back cover and a back cover. O BSI 1998 ISBN O 680 30073 O STD-BSI BS EN 1230d-ENGL 1778 m Lb24bb9 073447b IT3 m EUROPEAN STANDARD EN 12308 NORME EUR0PEE”E EuROP 75.200 Descript
8、ors: gas installation, gas valves, gas pipes, liquefied natural gas, pipe fittings, pipe joints, flange connections, pipe flanges, operating requirements, tests, testing conditions, clamping tests, mechanical strength, leak tests, acceptability English version Instaalations and equipment for LNG- Su
9、itability testing of gaskets designed for fianged joints used on LNG piping Installatons et quipements relatif% au GNL - Essais daptitude lemploi des joints destins aux assemblages par brides des tuyauteries GNL Anlagen und Ausrustung fr Flussigerdgas - Eignungspnifung von Flachdichtungen fr Flansch
10、verbindungen in Flussigerdgas - Rohrleitungen This European Standard was approved by CEN on 7 May 1998. CEN members are bound to comply with the CENKENELEC Internai Regulations which stipuiate the conditions for giving this European Standard the status of a national standard without any alteration.
11、Up-to-date lis and bibhographid references concerning such national standank 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 t
12、he responsibility of a CEN member into its own language and notified to the Central Secretanat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finla.nd, France, Germax Greece, Iceland, Ireland, Italy, Luxembour
13、g, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fur Normung Central Secretariat: rue de Stassart 36, B-1060 Brussels O 1998 CEN All rights of exploitation in any form and by
14、 any means reserved worldwide for CEN national Members. Ref. No. EN 123081998 E Page 2 EN 123W1998 Foreword Contents This European standard has been prepared by Technical Committee CEN/“C 282, Instahtion and equipment for LNG, the Secretariat of which is held by AFNOR. 1 Foreword This European Stand
15、ard shall be given the status of a nationai standard, either by pubiidon of an identical text or by endorsement, at the latest by December 1998 and conflictjng national standards shall be withdrawn at the latest by December 1998. According to the CENKENELEC Intend Regulations, the nationai standards
16、 organizations of the following countx-ies are bound to implement this European Standard: Austna, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Icelan, Ireland, Itaiy, Luxembourg, Netherlands, Nonva - class range from Class 150 to Class 900; - nominal diameter range for Class f
17、langes from NPS l/4 to NPS42. 2 Normative references This European Standard incorporates provisions from other publications, by dated or undated reference. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subs
18、equent amendments to or revisions of any of these publications shall apply to this European Standard only when incorporated hereto by amendment or revision. For undated references, the latest edition of the publication referred to applies. EN 764, Pressure equipment - Terminology and symbols - Press
19、ure, temperature, volume. EN 1160, Instauations and equipment for liquefied natural gas - General chamtemstics of liquefied natural gas. EN 1333, Pipework components - Definition and selectwn of PN. EN 15141, finges and theirjoints - LXmm-s of gaskets for PN-cksignated jlanges - Part 1: Non-rnetaUic
20、 it is a convenient round number for reference purposes which is normally only loosely related to the manufacturing dimensions in inches NOTE 1 It is designated by the letters NPS followed by a number. NOTE 2 The NPS cannot be subject to measurement and cannot be used for the purpose of calculation.
21、 3.6 class a numerical designation for reference purposes, used oniy for metricated flanges of ANSI origin NOTE 1 It is designated by the word “Class“, foilowed by the appropriate reference number. NOTE 2 The number following the word “Class“ does not represent a measurable value and therefore canno
22、t be used in calculations or foilowed by a unit. NOTE 3 The maximum allowable pressure depends upon the Class number, the material and design of the component. The corresponding allowable temperature etc. is given in the tables of the plT-ratings in the appropriate standards. 3.6 class of pressure t
23、he PN or class of a component 3.7 allowable pressure (ps) see EN 764 3.8 required bolting load (Fa the load to be applied to ensure the tightness of the joint in normal operating conditions 4 Design specincations of tested gaskets The gasket subjected to the suitabiity tests defined in this standard
24、 shall fuifil the requirements of EN 1514-1 to EN 1514-4, prEN 15151 and prEN 1515-2 and wherever necessary, the requirements of EN 1160. O BSI 1998 STDmBSI BS EN 12308-ENGL II998 IIb24bbY 0734479 902 W Joint intemal relative pressure Mechanical load Page 4 EN l23081998 1,15 X ps Fa Fa 1,15 X p, 6 %
25、chnical documentation by the gasket manufacturer The manufacturer shall supply the technical documentation applicable to the gasket, and in Pat-tiCW a) the dimensional characteristics of the gasket; b) the assembly drags for the gasket; c) the required bolting load Fa of the joint designed to ensure
26、 tightness under the following conditions: 1) operating temperature ranging from - 165 OC to + 60 OC; 2) operating pressure ranging hm O Pa to 1,15 times the allowable pressure (ps) of the joint. d) the thickness of the gasket and the stacking height, EI, of the fianges (see Fgure C.2) after tighten
27、ing with the required bolting load F,. When calculating the required bolting load Fa of the joint to the test conditions defined above, the manufacturer shall take into account the following: - the characteristics of the selected bolting - the reveisible loosening of the bolting due to the differenc
28、es in the thermai state of the joint components during cooldown; - the irreversible loosening of the bolting due to changes in the relative positioning of the joint components during the first few cooldowns. Annex A describes the thermal and mechanical siresses to which the gasket in a flanged joint
29、 is subjected, and suggests how the joint is tightened 6 Check of compatibility between bolting load and mechanical strength of joint components 6.1 Compatibility with flanges It is required to check with calculations of mechanid strength that the required bolting load Fa does not generate any perma
30、nent distortion of the fianges under the conitions of thermemechanical stress defined in ble 1. 6.2 Compatibility with bolting It is necessary to check with dculations of mechanical strength that the require bolting load Fa can be applied without generating any permanent distortion of the bolts. Com
31、patibility shall be regarded as demonstrated if the following condition is satisfied: where: n Fb Fa 5 n X Fb is the number of bolts; is the maximum allowable load of each bolt. The load Fa shall be calculated based on the assumption that the bolt is subjected to a pure traction load, to a deflectio
32、n load resulting from flaring-out of the Ilanges caused by the bolting, and possibly to a torsion load generated by the means of tightening the bolt. 7 Means and equipment required for testing 7.1 Test rig Attention is drawn to European safety reguiations for the design and operation of the test rig
33、. It shall consist of two assembled spool pieces between which the gasket to be tested is positioned. The spools shall be fitted with branch-tees providing for - LNG SUpplY; -draining of the test rig; - pressurising of the test rig; - measurement of temperature and pressure of the gas or LNG contain
34、ed in the spools. Annex B specifies the characteristics of the test rig. 7.2 Measuring equipment The foliowing devices shall be used to measure the conditions under which the gasket is tested NOTE Liquid nitrogen can replace LNG in the spools provided the appropriate detector is used to measure the
35、possible leakages. - a hydraulic tightener or torque wrench to tighten the bolts; - a micrometer graduated every 0,Ol mm to determine the bolting load when assembling the joint, or any other similar precision instrument; - a temperature probe to measure the gas or LNG temperature inside the test rig
36、; - a pressure transmitter or a mometer to measure the internal pressure of the rig; - a gas detector with a minimum threshold of at least 10 % of the methane low flammability limit in air to detect any gas leakage from the gasket during an LNG te* - a temperature probe arranged at the upper periphe
37、ry of one fiange to check the thermal state of the joint during cooldown. Table 1 - Stresses to be taken into account when checking the mechanical strength of flanges I Nature of stress I vdnes I Cool-do I l nmpe-e 15 OC From 15 OC to -165 OC for the following duration: 5 min when DN I 150; 15 min w
38、hen 150 c DN 5 300; 60min when300 e DN I loo0 O BSI 1998 STD-BSI BS EN 12308-ENGL 1998 .I Lb24bb9 0734480 624 = 8 Qsting 8.1 Application of bolting load The joint bolting shall be tightened at ambient temperature such that the relative deviation between the achieved bolting loads and the required bo
39、lting load of each bolt shall range between O % and + 10 %. The bolting load ddl be verified in accordance with annex C. 8.2 Leak testing at ambient temperature The gasket shd be checked for tightness with gas (air, nahiral gas, nitrogen) at 4 pressure stages for 5 min, corresponding to 0,25 X ps 0,
40、5 X ps 1 X ps and 1,15 X p,. At each of the above pressure stages, leak tightness shall be checked by applying soap suds between the flanges of the joint. The test shall be regarded as conclusive if no soap bubble forms. 8.3 Leak testing at cold temperature Five testing cycles shal be carried out at
41、 cold temperature in accordance with the following operational procedure: a) ll the test rig with LNG, with fig time as specified in ?cible 2; Table 2 - Test rig filling time as a function of the DN I l DN time t min I I DN 5 150 (5sts15 I I 150 DN 5 300 I151t160 I b) cooldown the test rig by circul
42、ating LNG; c) stop the LNG circulation once the joint cooling rate is less than 10 “C/h over a period of 15 min; d) check the leak tightness of the joint; The check of leak tightness at cold temperature shall consist of checking for the absence of any leakage with a gas detector over the entire oute
43、r circumference of the joint, at 4 pressure stages for 5 min, corresponding to 0,25 X ps, 0,5 X ps, 1 X ps and 1,15 X p,. e) drain the test rig to aliow warming up to ambient temperature; f) repeat the ambient temperature test in conformiy with 8.2. NOTE The pressure increase from one stage to the n
44、ext can be achieved by simple warming-up of the LNG contained in the rig. Page Fi EN 12308:1998 9 Acceptance criterion A gasket shall be regarded as suitable for use in flanged joints of LNG pipes provided that the leak tightness tests specified in 8.2 and 8.3 have proved conclusive. It is not neces
45、sary to cany out such tests on all gaskets presenting the same basic design, except the dimensions. Wle D.l specifies the allowable range of DN which are qualified for each DN tested. Table E.l specifies the allowable range of PN which are qualified for each PN tested 10 Bst report The results from
46、the above test shall be recorded in a test report listing the following data: a) name of testing company, name of tester and signature; b) date of test report; c) technical data sheet of gasket; d) tested gasket characteristics, in particular its DN or NPS and class of pressure; e) required bolting
47、load of the joint as supplied by manufacturer as well as the calculation details; f) achieved bolting load; g) the bolting load uncertainty; h) thermal conditions of test at cold temperature characterized by ambient temperature, LNG temperature and temperature at the upper periphery of the flange; i
48、) results from the leak tightness tests at ambient and cold temperatures and curves reporting the evolution of pressure during the tests; j) DN values of the gaskets qualified on the basis of this test; k) classes of pressure of the gaskets qualified on the basis of this test. O BSI 1998 STD-BSI BS
49、EN L2308-ENGL 3998 Lb24bb9 0734483 560 Page 6 EN 12308:1998 Annex A (informative) Thermo-mechanical behaviour of a flanged joint with gasket A.l General comments In cryogenic applications, a joint undergoes reversible and irreversible loosening processes resulting from the successive cooldown operations to which it is subjected. These loosening processes should be taken inta account when determining the bolting load which should in addition be compatible with the mechanical strength of the various components in the joint. A.2 Reversible loosening T
