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1、BRITISH STANDARD BS EN 1797:2001 Incorporating corrigendum November 2008 Cryogenic vessels Gas/material compatibility ICS 23.020.40 ? BS EN 1797:2001 Committee on 28 August 2001 BSI 2008 ISBN 978 0 580 63473 4 National foreword This British Standard is the UK implementation of EN 1797:2001. It super
2、sedes BS EN 1797-1:1998 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee PVE/18, Cryogenic vessels. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the
3、necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments/corrigenda issued since publication DateComments 30 November 2008 Addition of supersession information to national forwo
4、rd This British Standard was published under the authority of the Standards Policy and Strategy EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 1797 July 2001 ICS 23.020.40Supersedes EN 1797-1:1998 English version Cryogenic vessels - Gas/material compatibility Rcipients cryogniques - Compatibil
5、it entre gaz et matriaux Kryo-Behlter - Vertrglichkeit von Gas/Werkstoffen This European Standard was approved by CEN on 9 June 2001. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national st
6、andard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other l
7、anguage made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
8、 Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2001 CENAll rights of exploi
9、tation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1797:2001 E EN 1797:2001 (E) 2 Contents page Foreword3 1Scope 4 2Normative references 4 3Compatibility of materials with gases other than oxygen.4 4General requirements for oxygen service.5 4.1Evaluation of
10、materials for oxygen service.5 4.2Evaluation of metallic materials.5 4.3Evaluation of non metallic materials .6 4.4Test methods and acceptance criteria 6 4.4.1Ignition tests.6 4.4.2Mechanical impact test in liquid oxygen (LOX)7 Annex A (normative) Spontaneous ignition test (Bomb test).8 Annex B (nor
11、mative) Pressure surge test 13 Annex C (informative) Ignition test - Advantages and disadvantages of the two alternative methods16 Annex ZA (informative)Clauses of this European Standard addressing essential requirements or other provisions of EU directives.17 Bibliography18 BS EN 1797:2001 EN 1797:
12、2001 (E) 3 Foreword This European Standard has been prepared by Technical Committee CEN/TC 268, “Cryogenic vessels“, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at th
13、e latest by January 2002, and conflicting national standards shall be withdrawn at the latest by January 2002. This document replaces EN 1797-1:1998. For relationship with EU Directives, see informative annex ZA, which is an integral part of this document. This document has been prepared under a man
14、date given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directives. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard
15、: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. BS EN 1797:2001 EN 1797:2001 (E) 4 1 Scope This European Standard specifies requirements for gas/mater
16、ials compatibility for cryogenic vessels (such as chemical resistance) but it does not cover mechanical properties (e.g. for low temperature application). It gives guidance for compatibility with gases other than oxygen and it gives detailed requirements for oxygen and oxygen enriched atmosphere com
17、patibility and defines the testing methods for establishing oxygen compatibility of materials (metallic and non-metallic) to be used for cryogenic vessels and associated equipment. It mainly deals with materials that are normally or could be in contact with liquid/gaseous oxygen e.g., materials for
18、cryogenic vessels used for the storage and/or transport of liquid oxygen. It also deals with the materials which can be in contact with oxygen enriched environment e.g. insulating materials used for nitrogen, neon, hydrogen and helium cryogenic vessels in case of air condensation. 2 Normative refere
19、nces This European Standard incorporates by dated or undated references provisions from other publications. These normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of the
20、se publication apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies (including amendments). EN 849: 1996, Transportable gas cylinder Cylinder valves - Specification and type testing. E
21、N 12300, Cryogenic vessels - Cleanliness for cryogenic service. EN ISO 11114-1,Transportable gas cylinders - Compatibility of cylinder and valve materials with gas contents - Part 1 : Metallic materials (ISO 11114-1:1997). prEN ISO 11114-2:1997, Transportable gas cylinders - Compatibility of cylinde
22、r and valve materials with gas contents - Part 2 : Non-metallic materials (ISO/DIS 11114-2). 3 Compatibility of materials with gases other than oxygen The cryogenic vessels are used in a range of temperature from very low temperature to ambient temperature. The problems of compatibility with gases o
23、ther than oxygen such as corrosion, hydrogen embrittlement normally occur at ambient temperature and become negligible at cryogenic temperature. So, in case of gases other than oxygen, EN ISO 11114-1 and prEN ISO 11114-2:1997 may be used as a guide for cryogenic vessels. BS EN 1797:2001 EN 1797:2001
24、 (E) 5 4 General requirements for oxygen service 4.1 Evaluation of materials for oxygen service The selection of a material for use with oxygen and/or in an oxygen enriched atmosphere is primarily a matter of understanding the circumstances that cause oxygen to react with the material. Most material
25、s in contact with oxygen will not ignite without a source of ignition energy. When an energy input rate, as converted to heat, is greater than the rate of heat dissipation, and the resulting heat increase is continued for sufficient time, ignition and combustion will occur. Thus, two things shall be
26、 considered ?the materials minimum ignition temperature ; ?the energy sources that will produce a sufficient increase in the temperature of the material. These should be viewed in the context of the entire system design so that the specific factors listed below will assume the proper relative signif
27、icance. The specific factors are : ?the properties of the materials, including the factors affecting ease of ignition and the conditions affecting potential resulting damage (heat of reaction) ; ?the operating conditions : pressure, temperature, gas velocity, oxygen concentrations and oxygen state (
28、gaseous or liquid), surface contamination in accordance with EN 12300 ; ?the potential sources of ignition (friction, heat of compression, heat from mass impact, heat from particle impact, static electricity, electrical arc, resonance, internal flexing etc.) ; ?the reaction effect (consequence on th
29、e surroundings etc.) ; ?additional factors (performance requirements, prior experience, availability and cost). CAUTION This European Standard specifies the minimum acceptance requirements for materials in oxygen and enriched air service. In the cases of severe conditions and when the operating pres
30、sure is above 40 bar, additional tests to those specified should be considered. The use of materials in cryogenic vessels which do not pass the tests outlined in 4.4.1 and/or 4.4.2 shall be supported by a favourable risk assessment and/or documented evidence of previous long term satisfactory servic
31、e in use. 4.2 Evaluation of metallic materials Metallic materials normally used for the construction of cryogenic vessels i.e. low alloy steels, nickel steels, stainless steels, copper and copper alloys, aluminium and aluminium alloys do not normally present any incompatibility when in contact with
32、oxygen. The cases in which some ignitions or violent reactions may occur are when very thin materials are used with high surface/volume ratio, and when high ignition energy is available e.g. pump failure. Thin materials e.g. thinner than 0,1 mm shall be tested in accordance with 4.4.2 in conditions
33、as close as possible to the real operational conditions (e.g. for multi-layer insulations use similar number of layers and configuration). Materials to be used in applications where the ignition energy is potentially high should be subjected to special consideration. For cryogenic vessels intended f
34、or oxygen service the test shall be performed with oxygen. For cryogenic vessels intended for nitrogen, hydrogen or helium service, when materials are located in an area where contact with condensed enriched air is a risk, the test described in 4.4.2 shall be performed with cryogenic O/N mixtures co
35、ntaining at least 50 % oxygen. BS EN 1797:2001 EN 1797:2001 (E) 6 4.3 Evaluation of non metallic materials Non metallic materials include, for example, plastics, elastomers, lubricants, ceramics, glasses and glues. Some of these materials present a high risk of ignition when in contact with oxygen a
36、nd should be avoided or carefully selected and used in limited quantity. Some fully oxidised materials such as ceramics and glass present no risk of ignition provided they are not contaminated. Any non metallic materials, other than fully oxidised materials, in contact with liquid oxygen shall be te
37、sted in accordance with 4.4.1 and 4.4.2. Consideration shall be given to testing materials used in those parts of the system where liquid oxygen accumulation may incidentally occur (e.g. in the insulation). For cryogenic vessels intended for oxygen service the test shall be performed with oxygen. Fo
38、r cryogenic vessels intended for nitrogen, hydrogen or helium service, when materials are located in an area where contact with condensed enriched air is a risk, the test described in 4.4.2 shall be performed with cryogenic O/N mixtures containing at least 50 % oxygen. Any non metallic materials, ot
39、her than fully oxidised materials, in contact with gaseous oxygen shall be tested in accordance with 4.4.1. Consideration shall be given to testing materials used in those parts of the system where gaseous oxygen accumulation may incidentally occur (e.g. in the insulation). 4.4 Test methods and acce
40、ptance criteria Each material to be tested shall be clearly identified, normally by the commercial name and the manufacturers name. 4.4.1 Ignition tests Two alternative test methods are described in 4.4.1.1 or 4.4.1.2. The advantages and disadvantages of each are given in annex C. Materials not sati
41、sfying the requirements of 4.4.1.1 or 4.4.1.2 can still be used providing they successfully pass, in their actual operating configuration, the “Oxygen pressure surge test“ described in 5.3.8 of EN 849:1996 (e.g. for a valve sealing material, the entire valve or a representative assembly shall be tes
42、ted). 4.4.1.1 Spontaneous ignition test (“Bomb test“) 4.4.1.1.1 Test procedure The test procedure is given in annex A. BS EN 1797:2001 EN 1797:2001 (E) 7 4.4.1.1.2 Acceptance criteria The spontaneous ignition temperature determined in accordance with 4.4.1.1.1 shall be not less than the values given
43、 in Table 1. Table 1 Minimum spontaneous ignition temperature Maximum working pressure Bar (gauge) Minimum Spontaneous Ignition Temperature (SIT) C Remark 3200 10230 20250 40300 100350 150375 207400 Above 207 up to 345400 Complementary test may be advisable (see 4.1) NOTE Intermediate values can be
44、determined by linear interpolation. 4.4.1.2 Pressure surge test 4.4.1.2.1 Test procedure The test procedure is given in annex B. 4.4.1.2.2 Acceptance criteria No reaction shall be observed during 5 consecutive pressure surge impacts at the intended maximum working pressure. 4.4.2 Mechanical impact t
45、est in liquid oxygen (LOX) 4.4.2.1 Test procedure The mechanical impact test shall be performed at atmospheric pressure in liquid oxygen generally as described in the bibliography. This is an example of preferred test equipment but the details are not mandatory. The test shall be conducted : ?on mat
46、erial with the surface condition that is intended for use ; ?on material in a physical form delivered for use (i.e. solid, powder etc.) ; ?at an impact energy per unit contact area of 79 J/cm. 4.4.2.2 Acceptance criteria No reaction shall be detected within a series of 20 tests. BS EN 1797:2001 EN 1
47、797:2001 (E) 8 Annex A (normative) Spontaneous ignition test (Bomb test) A.1 General This annex defines a test method to determine the spontaneous ignition temperature of non-metallic materials in pressurised gaseous oxygen. Spontaneous ignition temperature is a criterion for the comparison and the
48、classification of materials, and can be used as an aid in the choice of materials used in the presence of pressurised gaseous oxygen. A.2 Principle A small quantity of the test material is slowly heated in oxygen under pressure. The continuous recording of pressure and temperature is used to determi
49、ne spontaneous ignition, which is seen as a sudden increase in temperature and pressure. A.3 Preparation of test pieces Test pieces shall be prepared by procedures that prevent contamination. Test pieces can be in liquid or solid form. In the case of solids, the materials shall be cut into a minimum of 6 pieces. The total mass of the pieces used in each test shall be at least 60 mg. A.4 Test equipment Figure A.1 shows the basic principle of the test equipment. When others methods of heating a