1、BS EN ISO 18081:2016Non-destructive testing Acoustic emission testing (AT) Leak detection by meansof acoustic emission (ISO18081:2016)BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN ISO 18081:2016 BRITISH STANDARDNational forewordThis British Standard is the UK
2、 implementation of EN ISO18081:2016.The UK participation in its preparation was entrusted to TechnicalCommittee WEE/46, Non-destructive testing.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necess
3、aryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016. Published by BSI StandardsLimited 2016ISBN 978 0 580 86904 4ICS 19.100Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was publi
4、shed under the authority of theStandards Policy and Strategy Committee on 30 June 2016.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 18081 June 2016 ICS 19.100 English Version Non-destructive testing - Acoustic emission testing (AT) - L
5、eak detection by means of acoustic emission (ISO 18081:2016) Essais non destructifs - Contrle par mission acoustique - Dtection de fuites par mission acoustique (ISO 18081:2016) Zerstrungsfreie Prfung - Schallemissionsprfung - Dichtheitsprfung mittels Schallemission (ISO 18081:2016) This European St
6、andard was approved by CEN on 22 April 2016. 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
7、 such national 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
8、 own language and 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, German
9、y, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR N
10、ORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 18081:2016 EBS EN ISO 18081:2016EN ISO 18081:2016 (E) 3 European foreword This document (EN ISO 18081:
11、2016) has been prepared by Technical Committee CEN/TC 138 “Non-destructive testing” the secretariat of which is held by AFNOR, in collaboration with Technical Committee ISO/TC 135 “Non-destructive testing”. This European Standard shall be given the status of a national standard, either by publicatio
12、n of an identical text or by endorsement, at the latest by December 2016, and conflicting national standards shall be withdrawn at the latest by December 2016. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC sha
13、ll not be held responsible for identifying any or all such patent rights. 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, Den
14、mark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement n
15、otice The text of ISO 18081:2016 has been approved by CEN as EN ISO 18081:2016 without any modification. BS EN ISO 18081:2016ISO 18081:2016(E)Foreword v1 Scope . 12 Normative references 13 Terms and definitions . 14 Personnel qualification . 25 Principle of acoustic emission method . 25.1 The AE phe
16、nomenon 25.2 Influence of different media and different phases . 35.3 Influence of pressure differences 45.4 Influence of geometry of the leak path 45.5 Influence of wave propagation 46 Applications . 57 Instrumentation 57.1 General requirements . 57.2 Sensors . 57.2.1 Typical frequency ranges (band
17、 widths) 57.2.2 Mounting method 67.2.3 Temperature range, wave guide . 67.2.4 Intrinsic safety . 67.2.5 Immersed sensors 67.2.6 Integral electronics (amplifier, RMS converter, ASL converter, band pass). 67.3 Portable and non-portable AT instruments . 67.4 Single and multichannel AT equipment 67.4.1
18、Single-channel systems 67.4.2 Multi-channel systems 67.5 Measuring features (RMS, ASL vs. hit or continuous AE vs. burst AE) . 77.6 Verification using artificial leak noise sources 78 Test steps for leak detection . 78.1 Sensor application . 78.2 Measured features 88.3 Background noise . 88.3.1 Envi
19、ronmental noise 88.3.2 Process noise . 88.4 Data acquisition . 89 Location procedures . 99.1 General considerations 99.2 Single sensor location based on AE wave attenuation 99.3 Multi-sensor location based on t values (linear, planar) . 99.3.1 Threshold level and peak level timing method 99.3.2 Cros
20、s correlation method 109.4 Wave type and wave mode based location 1110 Data presentation .1110.1 Numerical data presentation (level-meter) 1110.2 Parametric dependent function (e.g. pressure) .1110.3 Frequency spectrum . 1211 Data interpretation .1211.1 Leak validation . 1211.1.1 On-site (during tes
21、t) and off-site (post analysis) 1211.1.2 Correlation with pressure . 1211.1.3 Rejection of false indications 12 ISO 2016 All rights reserved iiiContents PageBS EN ISO 18081:2016ISO 18081:2016(E)11.2 Leakage rate estimation . 1311.3 Demands on follow-up actions . 1312 Quality management documents .13
22、12.1 Test procedure 1312.2 Test instruction 1313 Test documentation and reporting 1413.1 Test documentation . 1413.2 Test report 15Annex A (normative) Examples of leak detection 16Bibliography .28iv ISO 2016 All rights reservedBS EN ISO 18081:2016ISO 18081:2016(E)ForewordISO (the International Organ
23、ization 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 interested in a subject for which a technical committee has been establish
24、ed 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 of electrotechnical standardization.
25、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 documents should be noted. This document was drafted in accordance with the
26、 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 for identifying any or all such patent rights. Details of any patent
27、 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 the convenience of users and does not constitute an endorsement.For an
28、explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationISO 18081 was prepared by the Europ
29、ean Committee for Standardization (CEN) Technical Committee CEN/TC 138, Non-destructive testing, in collaboration with ISO Technical Committee TC 135, Non-destructive testing, Subcommittee SC 9, Acoustic emission testing, in accordance with the agreement on technical cooperation between ISO and CEN
30、(Vienna Agreement). ISO 2016 All rights reserved vBS EN ISO 18081:2016BS EN ISO 18081:2016Non-destructive testing Acoustic emission testing (AT) Leak detection by means of acoustic emission1 ScopeThis International Standard specifies the general principles required for leak detection by acoustic emi
31、ssion testing (AT). It is addressed to the application of the methodology on structures and components, where a leak flow as a result of pressure differences appears and generates acoustic emission (AE).It describes phenomena of the AE generation and influence of the nature of fluids, shape of the g
32、ap, wave propagation and environment.The different application methods, instrumentation and presentation of AE results is discussed. Also included are guidelines for the preparation of application documents which describe specific requirements for the application of the AE method.Different applicati
33、on examples are given.Unless otherwise specified in the referencing documents, the minimum requirements of this International Standard are applicable.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its applicat
34、ion. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 9712, Non-destructive testing Qualification and certification of NDT personnelISO/IEC 17025, General requirements for the competence
35、 of testing and calibration laboratoriesEN 1330-1, Non-destructive testing Terminology Part 1: General termsEN 1330-2, Non-destructive testing Terminology Part 2: Terms common to the non-destructive testing methodsEN 1330-9, Non-destructive testing Terminology Part 9: Terms used in acoustic emission
36、 testingEN 13477-1, Non-destructive testing Acoustic emission Equipment characterisation Part 1: Equipment descriptionEN 13477-2, Non-destructive testing Acoustic emission Equipment characterisation Part 2: Verification of operating characteristicsEN 13554, Non-destructive testing Acoustic emission
37、testing General principlesEN 60529, Degrees of protection provided by enclosures (IP Code)3 Terms and definitionsFor the purposes of this document, the terms and definitions given in EN 1330-1, EN 1330-2 and EN 1330-9 and the following apply.NOTE The definitions of leak, leakage rate, leak tight are
38、 those defined in EN 1330-8.INTERNATIONAL STANDARD ISO 18081:2016(E) ISO 2016 All rights reserved 1BS EN ISO 18081:2016ISO 18081:2016(E)4 Personnel qualificationIt is assumed that acoustic emission testing is performed by qualified and capable personnel. In order to prove this qualification, it is r
39、ecommended to certify the personnel in accordance with ISO 9712.5 Principle of acoustic emission method5.1 The AE phenomenonSee Figure 1.Key1 fluid2 AE sensorFigure 1 Schematic principle of acoustic emission and its detectionThe continuous acoustic emission in the case of a leak, in a frequency rang
40、e, looks like an apparent increase in background noise, depending on pressure.2 ISO 2016 All rights reservedBS EN ISO 18081:2016ISO 18081:2016(E)Table 1 Influence of the different parameters on the AE activityParameter Higher activity Lower activity5.2Test mediagasliquidtwo phaseViscosity low highTy
41、pe of flow turbulent laminarFluid velocity high low5.3 Pressure difference high low5.4Shape of leak crack like holeLength of leak path long shortSurface of leak path rough smooth5.2 Influence of different media and different phasesThe detectability of the leak depends on the fluid type and its physi
42、cal properties. These will contribute to the dynamic behaviour of the leak flow (laminar, turbulent) (see Table 1).In contrast to turbulent flow, the laminar flow does not in general, produce detectable acoustic emission signals.Acoustic signals in conjunction with a leakage are generated by the fol
43、lowing: turbulent flow of the escaping gas or liquid; fluid friction in the leak path; cavitations, during two-phase flow (gas coming out of solution) through a leaking orifice; the pressure surge generated when a leakage flow starts or stops; backwash of particles against the surface of equipment b
44、eing monitored; gaseous or liquid jet (verification source); pulsating bubbles; explosion of bubbles; shock-bubbles on the walls; vaporization of the liquid (flashing).The frequency content of cavitation may comprise from several kHz to several MHz.Cavitation results in a burst emission whose energy
45、 is at least one order of magnitude higher than that caused by turbulence.The relative content in gas or air strongly influences the early stage of cavitation.The acoustic waves generated by leaks can propagate by the walls of the system as well as through any fluids inside.Acoustic waves are genera
46、ted by vibration at ultrasonic frequencies of the molecules of the fluid. The vibrations are produced by turbulence and occur in the transition between a laminar and a turbulent flow within the leak path and as these molecules escape from an orifice.The acoustic waves produced by the above mentioned
47、 factors are used for leak detection and location. ISO 2016 All rights reserved 3BS EN ISO 18081:2016ISO 18081:2016(E)5.3 Influence of pressure differencesThe pressure difference is the primary factor affecting leak rate. However, the presence of leak paths may depend on a threshold value of fluid t
48、emperature or pressure. Pressure dependent leaks and temperature dependent leaks have been observed, but in extremely limited number. Pressure-dependent or temperature-dependent leaks denote a condition where no leakage exists until threshold pressure or temperature is reached. At this point, the le
49、akage appears suddenly and may be detectable. When the pressure or temperature is reversed, the leakage follows the prescribed course to the critical point at which leakage drops to zero. Temperature and pressure are not normally applied in the course of leak testing for the purpose of locating such leaks. Instead, they are used to force existing discontinuities to open, so as to start or increase the leakage rate to point of detection.An example of this effect is the reversible leakages at seals below
