ASTM E1211E1211M-17 Standard Practice for Leak Detection and Location Using Surface-Mounted Acoustic Emission Sensors.pdf

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1、Designation: E1211/E1211M 17Standard Practice forLeak Detection and Location Using Surface-MountedAcoustic Emission Sensors1This standard is issued under the fixed designation E1211/E1211M; the number immediately following the designation indicates the yearof original adoption or, in the case of rev

2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice describes a passive method for detectingand locating the steady state source of gas

3、and liquid leakingout of a pressurized system. The method employs surface-mounted acoustic emission sensors (for non-contact sensorssee Test Method E1002), or sensors attached to the system viaacoustic waveguides (for additional information, see Terminol-ogy E1316), and may be used for continuous in

4、-servicemonitoring and hydrotest monitoring of piping and pressurevessel systems. High sensitivities may be achieved, althoughthe values obtainable depend on sensor spacing, backgroundnoise level, system pressure, and type of leak.1.2 UnitsThe values stated in either SI units or inch-pound units are

5、 to be regarded as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standards.1.3 This standard does not purport to address all of thesafe

6、ty concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internati

7、onally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E543 Spec

8、ification for Agencies Performing NondestructiveTestingE650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE750 Practice for Characterizing Acoustic Emission Instru-mentationE976 Guide for Determining the Reproducibility ofAcousticEmission Sensor ResponseE1002 Practice for Leaks Using Ultr

9、asonicsE1316 Terminology for Nondestructive ExaminationsE2374 Guide for Acoustic Emission System PerformanceVerification2.2 ASNT Documents:3SNT-TC-1A Recommended Practice for NondestructiveTesting Personnel Qualification and CertificationANSI/ASNT CP-189 Standard for Qualification and Certifi-cation

10、 of Nondestructive Testing Personnel2.3 AIA Document:NAS 410 Certification and Qualification of NondestructiveTesting Personnel42.4 ISO Standard:5ISO 9712 Non-Destructive Testing: Qualification and Certi-fication of NDT Personnel3. Summary of Practice3.1 This practice requires the use of contact sen

11、sors, ampli-fier electronics, and equipment to measure their output signallevels. The sensors may be mounted before or during theexamination period and are normally left in place oncemounted rather than being moved from point to point.3.2 Detection of a steady-state leak is based on detection ofthe

12、continuous, broadband signal generated by the leak flow.Signal detection is accomplished through measurement ofsome input signal level, such as its root-mean-square (RMS)amplitude or average signal level.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is

13、 the direct responsibility of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved June 1, 2017. Published June 2017. Originallyapproved in 1987. Last previous edition approved in 2012 as E1211 - 12. DOI:10.1520/E1211_E1211M-17.2For referenced ASTM standards, visit the ASTM websit

14、e, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH

15、 43228-0518, http:/www.asnt.org.4Available from Aerospace Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, VA22209-3928, http:/www.aia-aerospace.org.5Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de

16、Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in acc

17、ordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.3 The simplest leak test pro

18、cedure involves only detectionof leaks, treating each sensor channel individually. A morecomplex examination requires processing the signal levelsfrom two or more sensors together to allow computation of theapproximate leak location, based on the principle that the leaksignal amplitude decreases as

19、a function of distance from thesource.4. Significance and Use4.1 Leakage of gas or liquid from a pressurized system,whether through a crack, orifice, seal break, or other opening,may involve turbulent or cavitational flow, which generatesacoustic energy in both the external atmosphere and the system

20、pressure boundary. Acoustic energy transmitted through thepressure boundary can be detected at a distance by using asuitable acoustic emission sensor.4.2 With proper selection of frequency passband, sensitivityto leak signals can be maximized by eliminating backgroundnoise. At low frequencies, gener

21、ally below 100 kHz, it ispossible for a leak to excite mechanical resonances within thestructure that may enhance the acoustic signals used to detectleakage.4.3 This practice is not intended to provide a quantitativemeasure of leak rates.5. Basis of Application5.1 The following items are subject to

22、contractual agree-ment between parties using or referencing this practice.5.2 Personnel Qualification5.2.1 If specified in the contractual agreement, personnelperforming examinations to this practice shall be qualified inaccordance with a nationally or internationally recognizedNDT personnel qualifi

23、cation practice or standard such asANSI/ASNT CP-189, SNT-TC-1A, NAS 410, ISO 9712, or asimilar document and certified by the employer or certifyingagency, as applicable. The practice or standard used and itsapplicable revision shall be identified in the contractual agree-ment between the using parti

24、es.5.3 Qualification of Nondestructive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated as described in Practice E543. The applicableedition of Practice E543 shall be specified in the contractualagreement.5.4 Timing of ExaminationThe timing of examinatio

25、nshall be in accordance with 7.1.7 unless otherwise specified.5.5 Extent of ExaminationThe extent of examination shallbe in accordance with 7.1.4 and 10.1.1.1 unless otherwisespecified.5.6 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in accordance wi

26、th10.2.2 and Section 11 unless otherwise specified. Since accep-tance criteria are not specified in this practice, they shall bespecified in the contractual agreement.5.7 Reexamination of Repaired/Reworked ItemsReexamination of repaired/reworked items is not addressed inthis practice and if required

27、 shall be specified in the contractualagreement.6. Interferences6.1 External or internal noise sources can affect the sensi-tivity of an acoustic emission leak detection system. Examplesof interfering noise sources are:6.1.1 Turbulent flow or cavitation of the internal fluid,6.1.2 Noise from grindin

28、g or machining on the system,6.1.3 Airborne acoustic noise, in the frequency range of themeasuring system,6.1.4 Metal impacts against, or loose parts frequently strik-ing the pressure boundary, and6.1.5 Electrical noise pick-up by the sensor channels.6.2 Stability or constancy of background noise ca

29、n alsoaffect the maximum allowable sensitivity, since fluctuation inbackground noise determines the smallest change in level thatcan be detected.6.3 The acoustic emission sensors must have stable charac-teristics over time and as a function of both the monitoringstructure and the instrumentation sys

30、tem examinationparameters, such as temperature.6.4 Improper sensor mounting, electronic signal conditionernoise, or improper amplifier gain levels can decrease sensitiv-ity.7. Basic Information7.1 The following items must be considered in preparationand planning for monitoring:7.1.1 Known existing l

31、eaks and their distance from the areasto be monitored should be noted so that their influence on thecapabilities of the method can be evaluated.7.1.2 Type of vessel, pipeline, or installation to beexamined, together with assembly, or layout drawings, or both,giving sufficient detail to establish dim

32、ensions, changes ofshape likely to affect flow characteristics, positions of welds,and the location of components such as valves or flanges, andattachments to the vessel or pipe such as pipe hangers whereleaks are most likely to arise. Regions with restricted accessi-bility due to walls, the existen

33、ce or location of cladding,insulation, or below surface components must be specified.7.1.3 When location of the peak is of primary interest,quantitative information regarding the leakage rates of interestand whenever possible the type of leak is necessary.7.1.4 Extent of monitoring, for example, ent

34、ire volume ofpressure boundary, weld areas only, etc.7.1.5 Material specifications and type of surface covering(for example paint or other coating) to allow the acousticpropagation characteristics of the structure to be evaluated.7.1.6 Proposed program of pressure application or process-pressure sch

35、edule, specifying the pressurization schedule to-gether with a layout or sketch of the pressure-applicationsystem and specifying the type of fluid used during theexamination, for example, gas, water, or oil.7.1.7 Time of monitoring, that is, the point(s) in the manu-facturing process, or service lif

36、e at which the system will bemonitored, or both.7.1.8 Frequency range to be used in the monitoring equip-ment.E1211/E1211M 1727.1.9 Environmental conditions during examination thatmay affect instrumentation and interpretation of results; forexample, temperature, moisture, radioactivity, vibration,pr

37、essure, and electromagnetic interference.7.1.10 Limitations or restrictions on the sensor mountingprocedure, if applicable, including restrictions on couplantmaterials.7.1.11 The location of sensors or waveguides and prepara-tion for their installation to provide adequate coverage of theareas specif

38、ied in 7.1.3. Where particular sections are to beexamined with particular sensors, the coverage of the vessel orsystem by sensor subgroups shall be specified. The sensorlocations must be given as soon as possible, to allow position-ing difficulties to be identified.7.1.12 The communications procedur

39、e between the acousticemission staff and the control staff, the time intervals at whichpressure readings are to be taken, and the procedure for givingwarning of unexpected variations in the pressure system.7.1.13 Requirements for permanent records, if applicable.7.1.14 Content and format of examinat

40、ion report, if re-quired.7.1.15 Acoustic Emission Examiner qualifications andcertification, if required.8. Apparatus8.1 SensorsThe acoustic emission sensors are generallypiezoelectric devices and should be mounted in accordancewith Practice E650 to ensure proper signal coupling. Thefrequency range o

41、f the sensors may be as high as 1 MHz, andeither wideband or resonant sensors may be employed. Thehigher frequencies can be used to achieve greater discrimina-tion against airborne or mechanical background noise.8.2 AmplifiersAmplifiers/preamplifiers should have suffi-cient gain or dynamic range, or

42、 both, to allow the signalprocessing equipment to detect the level of acoustic back-ground noise on the pressurized system. The sensor/amplifierbandwidth should be selected to minimize background noise.8.3 Signal ProcessorThe signal processor measures theRMS level, the acoustic emission signal power

43、, the averagesignal level, or any other similar parameters of the continuoussignal. A leak location processor to compute the sourcelocation from signal levels and attenuation data may beincluded. Alarm setpoints may also be included as a processorfunction.8.4 Leak Signal Simulator:8.4.1 A device for

44、 simulating leaks should be included toevaluate the effectiveness of the monitoring system. Thefollowing could be considered: a sensor on the pressureboundary driven from a random-noise generator, a small waterjet, or a gas jet.8.4.2 When leak location processing is to be performed,leak simulation s

45、hould be carried out initially over a suffi-ciently large number of diverse points to verify proper opera-tion of the location algorithm.9. System Performance Verification9.1 System performance verification consists of two stages.The first stage concerns periodic calibration and verification ofthe e

46、quipment under laboratory conditions. This procedure isbeyond the scope of this practice (see Practice E750) but theresults must be made available to the system owners ifrequested. The second stage concerns in-situ verification tocheck the sensitivities of all channels and the satisfactoryoperation

47、of the detection equipment. For every verificationoperation, a written procedure shall be prepared.9.2 In-situ sensitivity check of all sensors should be per-formed by placing a leak signal simulator (see Guide E976)ata specified distance from each sensor and recording theresulting output level from

48、 the amplifier, as referred to theamplifier input terminal. Amplifier gains may also be adjustedas appropriate to correct for sensitivity variations.9.3 Periodic system verification checks shall be made priorto the examination and during long examinations (days) or ifany environmental changes occur.

49、 The relative verificationcheck is accomplished by driving various sensors or activatingvarious leak simulation devices such as water or gas jets (seeGuide E2374) and measuring the outputs of the receivingsensors. The ratio of the outputs of two receiving sensors for agiven injection point should remain constant over time. Anychange in the ratio indicates a deviation in performance. In thisway, all sensors on a system may be compared to one or severalreference signals and proper adjustments made (see GuideE976).9.4 When leak location calculations are to be performed, theac