EN ISO 20485-2018 en Non-destructive testing - Leak testing - Tracer gas method.pdf

1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Non-destructive testing - Leak testing - Tracer gas method (ISO 20485:2017)BS EN ISO 20485:2018National forewordThis British Standard is the UK implementation of EN ISO 20485:2018. It is identical to ISO 20485:2017. It

2、supersedes BS EN 13185:2001, which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee WEE/46, Non-destructive testing.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include

3、all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2018 Published by BSI Standards Limited 2018ISBN 978 0 580 92696 9ICS 19.100Compliance with a British Standard cannot confer immunity from legal obligations. This British

4、Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2018.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS EN ISO 20485:2018EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 20485February 2018ICS 19.100 Superse

5、des EN 13185:2001, EN 13185:2001/EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGCEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2018 CEN Ref. No. EN ISO 20485:2018: EAll rights of exploitation in any form and by any means reserved w

6、orldwide for CEN national MembersNon-destructive testing - Leak testing - Tracer gas method (ISO 20485:2017)Essais non destructifs - Contrle dtanchit - Mthode par gaz traceur (ISO 20485:2017)Zerstrungsfreie Prfung - Dichtheitsprfung - Prfgasverfahren (ISO 20485:2017)This European Standard was approv

7、ed by CEN on 26 November 2017.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 standard without any alteration. Up-to-date lists and bibliographical references concerning such national

8、standards may be obtained on application to the CEN-CENELEC Management Centre 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 the responsibility of a CEN member into its own language an

9、d notified to the CEN-CENELEC Management Centre has the same status as the official versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungar

10、y, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.English VersionEN ISO 20485:2018 (E)European forewordThis document (EN ISO 20485:2018) has been prepared

11、 by Technical Committee ISO/TC 135 “Non-destructive testing“ in collaboration with Technical Committee CEN/TC 138 “Non-destructive testing”, 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 o

12、r by endorsement, at the latest by August 2018, and conflicting national standards shall be withdrawn at the latest by August 2018.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying a

13、ny or all such patent rights.This document supersedes EN 13185:2001.According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark,

14、Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.Endorsement

15、noticeThe text of ISO 20485:2017 has been approved by CEN as EN ISO 20485:2018 without any modification.2BS EN ISO 20485:2018ISO 20485:2017(E)Foreword iv1 Scope . 12 Normative references 13 Terms and definitions . 14 Principles of detection 15 Generation and detection of tracer gas flow 25.1 Tracer

16、gas flows into the object (Group A techniques) 25.2 Tracer gas flows out of the object (Group B techniques) . 26 Apparatus . 27 Object preparation . 28 Group A techniques, tracer gas flows into the object. 38.1 General . 38.2 Initial system set-up procedure . 38.3 Vacuum technique (total) test proce

17、dure (A.1) 48.4 Vacuum technique (partial) test procedure (A.2) . 58.5 Vacuum technique (local) test procedure (A.3) 59 Group B techniques, tracer gas flows out of object . 69.1 General . 69.2 Initial system set up procedure 79.2.1 Ammonia test with colour-change reagents (B.1) 79.2.2 Tracer gas flo

18、wing out of the object (B.2, B.3, B.4, B.6) 79.2.3 Pressurisation Evacuation test (B.5) . 89.3 Ammonia test procedure (B.1) 89.3.1 General 89.3.2 Test object preparation 89.3.3 Reagent application . 89.3.4 Ammonia pressurization 89.3.5 Impregnation time 99.3.6 Visual examination . 99.3.7 Post test c

19、leaning . 99.4 Vacuum box test procedure (B.2.1, B.2.2) 99.4.1 General 99.4.2 Vacuum box technique for closed objects B.2.1 99.4.3 Vacuum box technique for open objects B.2.2 .109.5 Accumulation technique (B.3) 109.5.1 General. 109.5.2 Accumulation technique procedure (B.3) .109.6 Sniffing test (B.4

20、) . 129.7 Bombing technique (B.5) 129.8 Vacuum chamber technique (B.6) . 149.9 Carrier gas technique (B.7) . 1410 Test report 16Annex A (informative) Accumulation technique: calibrated leak connected to enclosure of unknown volume .17Bibliography .19 ISO 2017 All rights reserved iiiContents PageBS E

21、N ISO 20485:2018ISO 20485:2017(E)ForewordISO (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 inter

22、ested 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

23、 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 docume

24、nts 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 some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible

25、 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 declarations received (see www.iso.org/patents).Any trade name used in this document is information given for th

26、e convenience of users and does not constitute an endorsement.For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in t

27、he Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.This document was prepared by Technical Committee ISO/TC 135, Non-destructive testing, Subcommittee SC 6, Leak testing.iv ISO 2017 All rights reservedBS EN ISO 20485:2018Non-destructive testing - Leak testing -

28、 Tracer gas method (ISO 20485:2017)1 ScopeThis document describes the techniques to be applied for the detection of a leak, using a tracer gas and a tracer gas specific leak detector.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their con

29、tent constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 20484, Non-destructive testing Leak testing Vocabulary3 Terms and definitionsFor the purp

30、oses of this document, the terms and definitions given in ISO 20484 apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: ISO Online browsing platform: available at https:/www.iso.org/obp IEC Electropedia: available at http:/www.electropedia.org/4

31、 Principles of detectionA partial pressure difference of tracer gas is created across the boundary of the object to be tested. The tracer gas, having passed through the leak, is revealed by its physical or chemical properties. Chemical detection is generally based on reactions that cause a local col

32、our change (the object surface shall therefore be visible).Detection based on physical properties usually involves a sensor, for example: a mass spectrometer, tuned for the specific tracer gas used (generally helium-4); an alkali ion diode, for halogen gas, and electron-capture equipment (i.e. for S

33、F6); a Pirani gauge, for tracer gas with thermal conductivity different from that of the ambient atmosphere; a photometer, with band-pass filter in the frequency range of the tracer gas absorption or emission.These types of detection generally give an electrical signal which varies with the tracer g

34、as partial pressure.The reference conditions should be selected and agreed between a leak tester and a customer. The reference conditions should be clearly stated and claimed by a leak tester in the test report (see Clause 10).INTERNATIONAL STANDARD ISO 20485:2017(E) ISO 2017 All rights reserved 1BS

35、 EN ISO 20485:2018ISO 20485:2017(E)5 Generation and detection of tracer gas flow5.1 Tracer gas flows into the object (Group A techniques)A pressure difference across the wall is obtained either by evacuation of the object, e.g. through a connection or by placing it in a pressurized chamber. Usually

36、the test object is evacuated. Tracer gas is then applied to the external surface using a probe jet or by enclosing the object (totally or partially) in a hood or chamber filled with the tracer gas. Tracer gas leakage into the test object is detected by a sensor within or connected to the internal vo

37、lume.5.2 Tracer gas flows out of the object (Group B techniques)The object is filled with a tracer gas. A pressure difference across the wall is obtained either by pressurization of the object, e.g. through a connection or by placing it in a vacuum chamber. The tracer gas is collected on the outside

38、 surface by a sampling probe, a carrier gas flow or by accumulation into a hood or chamber. Tracer gas can also be detected by chemical reactions.A special technique (bombing) may also be used. This involves the pressurization of a sealed object to force the tracer gas into its internal cavities, if

39、 a leak exists. The object is then placed in a vacuum chamber and escaping tracer gas is detected (this procedure is generally used only with helium-4). This method is applicable to specimens with small free internal volumes (in the order of a few cubic centimetres).6 ApparatusThe test apparatus may

40、 include part or all of the following:6.1 Leak detector or chemical reagents able to detect the selected tracer gas.6.2 Calibrated leaks, calibrated for discharge into vacuum and/or against atmospheric pressure; refer to ISO 20486.6.3 Pressure and temperature gauges.6.4 Tracer gas or certified gas m

41、ixture.6.5 Auxiliary vacuum systems.6.6 Hood, vacuum or pressurizing chamber, jet or sampling probe.6.7 Purging dry gas, liquid nitrogen (for cold trap), if necessary.6.8 Equipment for tracer gas treatment-recovery.6.9 Equipment for test area ventilation.6.10 Data recording equipment.7 Object prepar

42、ationThe object to be tested shall be adequately cleaned, degreased and dried. Openings and apertures which are not involved in the test shall be closed with test seals, e.g. plugs, welding, suitable material and gaskets. Whenever possible, testing should be carried out before plating, painting or t

43、he application of ultrasonic couplant. If the object needs to be evacuated, the presence of porous or plastic 2 ISO 2017 All rights reservedBS EN ISO 20485:2018ISO 20485:2017(E)materials should be avoided. This helps to avoid spurious indications (virtual leaks), and shortens the clean-up time.The c

44、onnections between the object, the pumping system, the leak detector (LD) and the calibrated leaks used shall be suitable and checked for tightness.8 Group A techniques, tracer gas flows into the object.8.1 GeneralThese techniques are applicable to an object that can be evacuated or withstand an ext

45、ernal test pressure. The tracer gas is applied on the outer surface of the object and the LD is connected to the internal volume. If the LD is of mass spectrometer type (MSLD), the pumping system of the MSLD itself can be used to directly evacuate small items under test.Larger objects need an auxili

46、ary pumping system parallel to the LD. In this case, the loss of sensitivity shall be considered, as only part of the tracer gas will enter the LD.Three techniques may be used refer to EN 1779: Vacuum technique (Total) (A.1)The object, placed in an enclosure (a bag or a chamber), is evacuated and co

47、nnected to the detector. The enclosure is then filled with the tracer gas or a gas mixture containing the tracer gas. This technique allows the evaluation of the leakage rate but does not permit precise location of the leaks.When the purpose of the leak testing is the determination of the acceptabil

48、ity of the test object against a specified leakage rate, only the “total“ technique shall be used. In this case, the tracer gas concentration, pressure and temperature shall be measured and the homogeneity of the gas mixture shall be ensured. Further the enclosure shall be gas-tight and, preferably,

49、 rigid. Vacuum technique (Partial) (A.2)The object to be tested is evacuated and connected to the detector. Suspect areas are then covered by a suitable gas-tight enclosure filled with tracer gas. Vacuum technique (Local) (A.3)The object to be tested is evacuated and connected to the detector. Suspect areas on the external surface of the object are sprayed with tracer gas. Leaks can be localized using this technique but it is not possible to measure the total leakage rate.8.2 Initial system set-up procedure8.2.1 The LD shall be adjusted in