ASTM E1002-2011 3750 Standard Practice for Leaks Using Ultrasonics《使用超声波检漏的标准操作规程》.pdf

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1、Designation: E1002 11Standard Practice forLeaks Using Ultrasonics1This standard is issued under the fixed designation E1002; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicat

2、es the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 Practice A, PressurizationThis practice covers proce-dures for calibration of ultrasonic instruments, location, andestimated measurements of gas leakage to atmosphe

3、re by theairborne ultrasonic technique.21.2 In general practice this should be limited to leaksdetected by two classifications of instruments, Class I andClass II. Class I instruments should have a minimum detectableleak rate of 6.7 3 107mol/s (1.5 3 102std. cm3/s at 0C) ormore for the pressure meth

4、od of gas leakage to atmosphere.Class II instruments should have a minimal detectable leak rateof 6.7 3 106mol/s (1.5 3 101std. cm3/s at 0C) or more forthe pressure method of gas leakage to atmosphere. Refer toGuide E432 for additional information.1.3 Practice B, Ultrasonic TransmitterFor object und

5、ertest not capable of being pressurized but capable of havingultrasonic tone placed/injected into the test area to act as anultrasonic leak trace source.1.3.1 This practice is limited to leaks producing leakage of6.7 3 106mol/s (1.5 3 101std. cm3/s at 0C) or greater.1.4 The values stated in SI units

6、 are to be regarded as thestandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regula

7、tory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E432 Guide for Selection of a Leak Testing MethodE543 Specification for Agencies Performing Nondestruc-tive TestingE1316 Terminology for Nondestructive Examinations2.2 Other Documents:SNT-TC-1A Recommended Practice for Personne

8、l Qualifi-cation and Certification in Nondestructive Testing4ANSI/ASNT CP-189 ASNT Standard for Qualification andCertification of Nondestructive Testing Personnel4NAS-410 Certification and Qualification of NondestructivePersonnel53. Terminology3.1 DefinitionsFor definitions of terms used in this pra

9、c-tice, see Terminology E1316, Section E.4. Summary of Practice4.1 Practice AThis practice sets minimum requirementsfor an ultrasonic detector (Classifications I and II). It providesfor sensitivity validation of the detector and gives proceduresfor pressurizing the test object, locating leaks, and e

10、stimatingthe leakage rates.4.2 Practice BThis practice sets minimum requirementsfor an ultrasonic detector used in conjunction with an ultra-sonic transmitter. It gives procedures for locating leaks usingan electronically generated ultrasonic leak tracer source.5. Basis of Application5.1 The followi

11、ng items are subject to 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 national or internationally recognize

12、d NDTpersonnel qualification practice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, or a similar documentand certified by the employer or certifying agency, as appli-cable. The practice or standard used and its applicable revisionshall be identified in the contractual agreement between t

13、heusing parties.5.3 Qualification of Nondestructive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated as described in Practice E543. The applicablerevision of Practice E543 shall be in the contractual agreement.1This practice is under the jurisdiction of

14、ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.08 on LeakTesting Method.Current edition approved July 1, 2011. Published July 2011. Originally approvedin 1986. Last previous edition approved in 2005 as E1002 - 05. DOI: 10.1520/E1002-11.2This techni

15、que is sometimes called “ultrasonic translation.”3For referenced ASTM standards, visit the ASTM website, 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.4Available f

16、romAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.5Available from Aerospace Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, VA22209-3928, http:/www.aia-aerospace.org.1Copyright

17、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Significance and Use6.1 Practice AThis practice is useful for locating andestimating the size of pressurized gas leaks, either as a qualitycontrol test or as a field inspection procedure. It is

18、 also valuableas a pretest before other more time consuming and moresensitive leak tests are employed. It should not be usedexclusively to locate highly toxic or explosive gas leaks.6.2 Practice BThis practice is useful for locating leaks insystems that are not under pressure or vacuum as either aqu

19、ality control or a field inspection procedure. It is not usefulfor estimating the size of a leak. It is also valuable as a pretestbefore leak tests using pressurized gas methods and moresensitive leak tests are employed.7. Interferences7.1 The areas to be tested must be free of oil, grease, paint,an

20、d other contaminants that might mask a leak.7.2 Under certain conditions background noise detected bythe instrument can prevent the detection of relevant leakage.This background noise can result from equipment vibration andair movement due, for example, to wind, or air-cooled motors,aircraft engines

21、, pneumatic systems, etc.7.3 Use of earphones is required in areas where the back-ground noise might interfere with hearing the audible output ofa speaker.8. Apparatus8.1 Ultrasonic Leak Detection System:8.1.1 The system shall consist of an instrument, probes,focusing probe accessory and earphones.

22、(A speaker may ormay not be utilized.)8.1.2 The system shall provide for detection of acousticenergy in the ultrasonic range from 20 000 to 100 000 Hz andshall translate this energy into an audible signal that can beheard by use of earphones or speaker, or both.8.1.3 The detected energy shall be ind

23、icated on a signallevel indicator.8.2 Minimum Instrument RequirementsThe instrumentshall meet the following requirements:8.2.1 The detected ultrasonic energy shall be indicated on asignal level indicator with a change above normal backgroundfluctuations.8.2.2 The audible response shall consist of th

24、e down-converted heterodyned ultrasonic signal. This audio signal willbe representative of the amplitude or frequency characteristics,or both, of the original ultrasonic signal. Heterodyned signalscould allow the operator to discriminate audible backgroundinterference as in 7.2.8.2.3 The instrument

25、shall be equipped with a sensitivitycontrol or gain adjustment, or both, to achieve the conditions of9.3.3.8.2.4 The internal power supply shall be regulated toprovide repeatability of the sensitivity set point to within 65%of full scale over the full range of battery condition.8.2.5 The instrument

26、may include additional features whichcould enhance leak detection such as frequency controls ormeter/display response selection, or both.8.3 Other ApparatusPressure gages, valves, and piping asrequired.8.4 Ultrasonic Transmission8.4.1 The system shall consist of an apparatus described in8.1-8.3 with

27、 the addition of an ultrasonic transmitter.8.4.2 The transmitter shall produce an ultrasound peakedbetween the frequencies of 38 to 42 kHz.8.4.3 The output of the transmitter transducer shall be inexcess of 100 dB at 1 ft.8.4.4 The intensity of the output may be adjustable.8.4.5 The heterodyned sign

28、al received by the ultrasonic leakdetection system from the ultrasonic transmitter must be easilyidentified and recognized as the ultrasonic tracer source.8.4.6 The internal power supply shall be regulated and besufficient to produce the required output (see 8.4.3).8.4.7 The transmitter may include

29、additional features thatcould enhance the leak detection process such as a warble tonetransmission and amplitude adjustments.9. Calibration9.1 Calibration/Sensitivity ValidationThe ultrasonic in-strument should be calibrated or have the sensitivity validatedbefore each initial use.9.2 Calibration/Se

30、nsitivity Validation EquipmentUse thefollowing equipment for calibration of the test system:NOTE 1This equipment serves a dual function; either to calibrate theultrasonic instrument for leakage rate approximation as in 11.3,ortoverify the sensitivity for detection and location as in 11.1.9.2.1 Leak

31、Standard, with a preset flow rate of 6.7 3 105mol/s (1.5 std. cm3/s at 0C) 65 % for both Class I and ClassII instruments. The orifice size shall be approximately 0.2 mm0.008 in.9.2.2 Regulator, for the nitrogen supply with output pres-sure and flow gages. The tank pressure gage is optional.9.3 Air P

32、robe Sensitivity Validation:9.3.1 For Class I instruments, locate the detection probe adistance of 10.0 m (60.1 m) from the calibrated leak standardspecified in 9.2.1. For Class II instruments, place the detectionprobe a distance of 5.0 m (60.1 m) from the calibrated leakspecified in 9.2.1.9.3.2 Che

33、ck to see that the detector probe and leak sourceare aligned to obtain the peak response (see Fig. 1).9.3.3 A signal level indication above normal backgroundfluctuations should be observed.9.3.4 Place a sound absorbing barrier in front of the micro-phone, blocking out the calibrated leak source; the

34、 meterreading should zero with a corresponding absence of an audiblesignal.9.4 Recalibration:9.4.1 Recheck or validate the sensitivity of the equipment atthe beginning of each shift or designated work period interval.This test must be performed at the same sensing frequency asthe initial test.9.4.2

35、Recheck the equipment when abnormalities are ob-served in its operation.9.5 Ultrasonic Transmitter Sensitivity Validation, shouldhave the generated amplitude validated before each initial use.This could be done by placing the ultrasonic transmitter a fixeddistance from the detection instrument to ob

36、tain a reading or bytaking a NIST-traceable reading with a sound pressure levelE1002 112detector. Another method would be to place the ultrasonictransmitter in a container with a known leak that is equivalentto the leaks that are to be detected. To eliminate vessel orcontainer vibrations from influe

37、ncing the readings, the interiorshould be lined with closed cell foam, or rubber, or both. Theorifice size shall be equivalent to the leaks that are to bedetected.10. General Considerations10.1 Openings:10.1.1 Seal all openings using plugs, covers or other suit-able materials that can be readily and

38、 completely removed afterthe completion of the test.10.1.2 Provide a gas inlet by attaching a valve to one of thetest covers on all items to be pressurized.10.2 Check of Test Parts:10.2.1 Examine the part and test equipment before pressureis applied to ensure that it is tight and all appurtenances t

39、hatshould not be subjected to the test pressure have been discon-nected or isolated by valves or other suitable means.10.2.2 Check safe pressure rating to be sure it will not beexceeded during test.10.3 Temperature of Vessel and Testing Medium:10.3.1 The temperature of the pressurizing gas must not

40、beat a level that would be injurious to the part or its components.10.3.2 The test gas is dry nitrogen. (Compressed air cancontain oil or water droplets which can seal leaks.)10.4 Pressure:10.4.1 Unless otherwise specified the gage pressure shall beat least 70 kPa 10 psig. Normal safety precautions

41、should beobserved when pressurizing the part under test with the gas toavoid test part ruptures.10.4.2 Gradually increase the pressure in the part to finaltest pressure.10.5 Ultrasonic Transmitter MethodInspect test object tobe sure it is free of debris and liquids at the test sites.11. Detection an

42、d Location of Pressurized Gas Leaks11.1 Detection:11.1.1 Set the sensitivity at maximum.11.1.2 Begin to scan by pointing the probe towards the testarea. The procedure is to go from “high sensitivity” to “lowsensitivity,” reducing the sensitivity as the leak is approached.11.1.3 Note the fluctuations

43、 in meter readings and thevolume from the earphones or speaker.11.1.4 If there is too much ultrasound in the area, reduce thesensitivity and continue to scan.11.1.5 If it is difficult to isolate the leak due to competingultrasound, place the focusing probe accessory over the scan-ning probe. This in

44、creases the directional response character-istics of the probe.11.1.6 Listen for a “rushing” sound while observing themeter.11.1.7 Follow the ultrasound to the loudest point. The meterwill show a higher reading as the leak is approached.11.2 Ultrasonic Transmitter MethodProvide for access oftransmit

45、ter placement in the test object or provide an inlet pipeconduit fitting to couple with the transmitter allowing it toFIG. 1 Calibrated Leak Standard/Sensitivity Validation EquipmentE1002 113adequately saturate the test object with ultrasound in such away as to shield stray ultrasonic leakage into t

46、he ultrasonic leakdetection side.11.2.1 All potential interferences shall be cleared away fromthe test areas either by cleaning or by blowing the areas drywith compressed gas.11.2.2 Transmitter PlacementThe transmitters shall beplaced to adequately cover the test object with a uniformultrasound.11.2

47、.3 Listen for the distinct heterodyned ultrasound pro-duced by the ultrasonic transmitter. This may be a whistle orwarbling tone.11.3 Location:11.3.1 In order to focus on the leak, keep reducing thesensitivity until a leak is located.11.3.2 To Confirm a LeakPosition the scanning probewith or without

48、 the rubber focusing extension close to thesuspect leak site and move it, slightly back and forth, up anddown. If the leak is at this location, the sound and meterreadings will both increase and decrease in intensity. Thissource discrimination technique will eliminate false leak iden-tification due

49、to reflected leak signals from other sites near thesuspect leak site.12. Report12.1 The following information should be recorded at thetime of the measurements and included in the report:12.1.1 Date tested.12.1.2 Test conditions such as temperature and pressure.12.1.3 Location of leak.12.1.4 Name and model of apparatus used.12.1.5 Calibration.12.1.6 Signature of tester.13. Keywords13.1 leak detectionultrasonic; leak testing; leakage rate;ultrasonic detectorASTM International takes no position respecting the validity of any patent rights asserted i