1、Designation: E1211/E1211M 12E1211/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
2、the case of revision, 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 detecting and locating the steady stat
3、e source of gas and liquid leaking out ofa pressurized system. The method employs surface-mounted acoustic emission sensors (for non-contact sensors see Test MethodE1002), or sensors attached to the system via acoustic waveguides (for additional information, see Terminology E1316), and maybe used fo
4、r continuous in-service monitoring and hydrotest monitoring of piping and pressure vessel systems. High sensitivitiesmay be achieved, although the values obtainable depend on sensor spacing, background noise level, system pressure, and type ofleak.1.2 UnitsThe values stated in either SI units or inc
5、h-pound units are to be regarded as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standards.1.3 This standard does not purport to add
6、ress all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.4 This international standard was developed in accordanc
7、e with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standa
8、rds:2E543 Specification for Agencies Performing Nondestructive TestingE650 Guide for Mounting Piezoelectric Acoustic Emission SensorsE750 Practice for Characterizing Acoustic Emission InstrumentationE976 Guide for Determining the Reproducibility of Acoustic Emission Sensor ResponseE1002 Practice for
9、 Leaks Using UltrasonicsE1316 Terminology for Nondestructive ExaminationsE2374 Guide for Acoustic Emission System Performance Verification2.2 ASNT Documents:3SNT-TC-1A Recommended Practice for Nondestructive Testing Personnel Qualification and CertificationANSI/ASNT CP-189 Standard for Qualification
10、 and Certification of Nondestructive Testing Personnel2.3 AIA Document:NAS 410 Certification and Qualification of Nondestructive Testing Personnel42.4 ISO Standard:5ISO 9712 Non-Destructive Testing: Qualification and Certification of NDT Personnel1 This practice is under the jurisdiction ofASTM Comm
11、ittee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.04 on Acoustic EmissionMethod.Current edition approved June 15, 2012June 1, 2017. Published August 2012June 2017. Originally approved in 1987. Last previous edition approved in 20072012 asE1211 - 07.E1211 - 12.
12、DOI: 10.1520/E1211_E1211M-12.10.1520/E1211_E1211M-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Availa
13、ble from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.4 Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http:/www.aia-aerospace.org.
14、5 Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, http:/www.iso.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indicatio
15、n of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be consid
16、ered the official document.*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 States13. Summary of Practice3.1 This practice requires the use of contact sensors, amplifier electro
17、nics, and equipment to measure their output signal levels.The sensors may be mounted before or during the examination period and are normally left in place once mounted rather than beingmoved from point to point.3.2 Detection of a steady-state leak is based on detection of the continuous, broadband
18、signal generated by the leak flow. Signaldetection is accomplished through measurement of some input signal level, such as its root-mean-square (RMS) amplitude oraverage signal level.3.3 The simplest leak test procedure involves only detection of leaks, treating each sensor channel individually.Amor
19、e complexexamination requires processing the signal levels from two or more sensors together to allow computation of the approximate leaklocation, based on the principle that the leak signal amplitude decreases as a function of distance from the source.4. Significance and Use4.1 Leakage of gas or li
20、quid from a pressurized system, whether through a crack, orifice, seal break, or other opening, mayinvolve turbulent or cavitational flow, which generates acoustic energy in both the external atmosphere and the system pressureboundary. Acoustic energy transmitted through the pressure boundary can be
21、 detected at a distance by using a suitable acousticemission sensor.4.2 With proper selection of frequency passband, sensitivity to leak signals can be maximized by eliminating background noise.At low frequencies, generally below 100 kHz, it is possible for a leak to excite mechanical resonances wit
22、hin the structure thatmay enhance the acoustic signals used to detect leakage.4.3 This practice is not intended to provide a quantitative measure of leak rates.5. Basis of Application5.1 The following items are subject to contractual agreement between parties using or referencing this practice.5.2 P
23、ersonnel Qualification5.2.1 If specified in the contractual agreement, personnel performing examinations to this practice shall be qualified inaccordance with a nationally or internationally recognized NDT personnel qualification practice or standard such as ANSI/ASNT CP-189, SNT-TC-1A, NAS 410, ISO
24、 9712, or a similar document and certified by the employer or certifying agency, asapplicable. The practice or standard used and its applicable revision shall be identified in the contractual agreement between theusing parties.5.3 Qualification of Nondestructive AgenciesIf specified in the contractu
25、al agreement, NDT agencies shall be qualified andevaluated as described in Practice E543. The applicable edition of Practice E543 shall be specified in the contractual agreement.5.4 Timing of ExaminationThe timing of examination shall be in accordance with 7.1.7 unless otherwise specified.5.5 Extent
26、 of ExaminationThe extent of examination shall be in accordance with 7.1.4 and 10.1.1.1 unless otherwise specified.5.6 Reporting Criteria/Acceptance CriteriaReporting criteria for the examination results shall be in accordance with 10.2.2and Section 11 unless otherwise specified. Since acceptance cr
27、iteria are not specified in this practice, they shall be specified in thecontractual agreement.5.7 Reexamination of Repaired/Reworked ItemsReexamination of repaired/reworked items is not addressed in this practiceand if required shall be specified in the contractual agreement.6. Interferences6.1 Ext
28、ernal or internal noise sources can affect the sensitivity of an acoustic emission leak detection system. Examples ofinterfering noise sources are:6.1.1 Turbulent flow or cavitation of the internal fluid,6.1.2 Noise from grinding or machining on the system,6.1.3 Airborne acoustic noise, in the frequ
29、ency range of the measuring system,6.1.4 Metal impacts against, or loose parts frequently striking the pressure boundary, and6.1.5 Electrical noise pick-up by the sensor channels.6.2 Stability or constancy of background noise can also affect the maximum allowable sensitivity, since fluctuation inbac
30、kground noise determines the smallest change in level that can be detected.6.3 The acoustic emission sensors must have stable characteristics over time and as a function of both the monitoring structureand the instrumentation system examination parameters, such as temperature.6.4 Improper sensor mou
31、nting, electronic signal conditioner noise, or improper amplifier gain levels can decrease sensitivity.E1211/E1211M 1727. Basic Information7.1 The following items must be considered in preparation and planning for monitoring:7.1.1 Known existing leaks and their distance from the areas to be monitore
32、d 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 be examined, together with assembly, or layout drawings, or both, givingsufficient detail to establish dimensions, changes of shape likely to affect flow cha
33、racteristics, positions of welds, and the locationof components such as valves or flanges, and attachments to the vessel or pipe such as pipe hangers where leaks are most likelyto arise. Regions with restricted accessibility due to walls, the existence or location of cladding, insulation, or below s
34、urfacecomponents must be specified.7.1.3 When location of the peak is of primary interest, quantitative information regarding the leakage rates of interest andwhenever possible the type of leak is necessary.7.1.4 Extent of monitoring, for example, entire volume of pressure boundary, weld areas only,
35、 etc.7.1.5 Material specifications and type of surface covering (for example paint or other coating) to allow the acoustic propagationcharacteristics of the structure to be evaluated.7.1.6 Proposed program of pressure application or process-pressure schedule, specifying the pressurization schedule t
36、ogetherwith a layout or sketch of the pressure-application system and specifying the type of fluid used during the examination, forexample, gas, water, or oil.7.1.7 Time of monitoring, that is, the point(s) in the manufacturing process, or service life at which the system will bemonitored, or both.7
37、.1.8 Frequency range to be used in the monitoring equipment.7.1.9 Environmental conditions during examination that may affect instrumentation and interpretation of results; for example,temperature, moisture, radioactivity, vibration, pressure, and electromagnetic interference.7.1.10 Limitations or r
38、estrictions on the sensor mounting procedure, if applicable, including restrictions on couplant materials.7.1.11 The location of sensors or waveguides and preparation for their installation to provide adequate coverage of the areasspecified in 7.1.3. Where particular sections are to be examined with
39、 particular sensors, the coverage of the vessel or system bysensor subgroups shall be specified. The sensor locations must be given as soon as possible, to allow positioning difficulties to beidentified.7.1.12 The communications procedure between the acoustic emission staff and the control staff, th
40、e time intervals at whichpressure readings are to be taken, and the procedure for giving warning of unexpected variations in the pressure system.7.1.13 Requirements for permanent records, if applicable.7.1.14 Content and format of examination report, if required.7.1.15 Acoustic Emission Examiner qua
41、lifications and certification, if required.8. Apparatus8.1 SensorsThe acoustic emission sensors are generally piezoelectric devices and should be mounted in accordance withPractice E650 to ensure proper signal coupling. The frequency range of the sensors may be as high as 1 MHz, and either widebando
42、r resonant sensors may be employed. The higher frequencies can be used to achieve greater discrimination against airborne ormechanical background noise.8.2 AmplifiersAmplifiers/preamplifiers should have sufficient gain or dynamic range, or both, to allow the signal processingequipment to detect the
43、level of acoustic background noise on the pressurized system. The sensor/amplifier bandwidth should beselected to minimize background noise.8.3 Signal ProcessorThe signal processor measures the RMS level, the acoustic emission signal power, the average signallevel, or any other similar parameters of
44、 the continuous signal.Aleak location processor to compute the source location from signallevels and attenuation data may be included. Alarm setpoints may also be included as a processor function.8.4 Leak Signal Simulator:8.4.1 A device for simulating leaks should be included to evaluate the effecti
45、veness of the monitoring system. The followingcould be considered: a sensor on the pressure boundary driven from a random-noise generator, a small water jet, or a gas jet.8.4.2 When leak location processing is to be performed, leak simulation should be carried out initially over a sufficiently large
46、number of diverse points to verify proper operation of the location algorithm.9. System Performance Verification9.1 System performance verification consists of two stages. The first stage concerns periodic calibration and verification of theequipment under laboratory conditions. This procedure is be
47、yond the scope of this practice (see Practice E750) but the results mustbe made available to the system owners if requested. The second stage concerns in-situ verification to check the sensitivities ofall channels and the satisfactory operation of the detection equipment. For every verification oper
48、ation, a written procedure shallbe prepared.E1211/E1211M 1739.2 In-situ sensitivity check of all sensors should be performed by placing a leak signal simulator (see Guide E976) at a specifieddistance from each sensor and recording the resulting output level from the amplifier, as referred to the amp
49、lifier input terminal.Amplifier gains may also be adjusted as appropriate to correct for sensitivity variations.9.3 Periodic system verification checks shall be made prior to the examination and during long examinations (days) or if anyenvironmental changes occur. The relative verification check is accomplished by driving various sensors or activating various leaksimulation devices such as water or gas jets (see Guide E2374) and measuring the outputs of the receiving sensors. The ratio ofthe outputs of two receiving sensors for a given injection point should remain con
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