ASTM E2024 E2024M-2011 Standard Practice for Atmospheric Leaks Using a Thermal Conductivity Leak Detector《用导热泄漏探测器测定大气泄漏的标准操作规程》.pdf

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1、Designation: E2024/E2024M 11Standard Practice forAtmospheric Leaks Using a Thermal Conductivity LeakDetector1This standard is issued under the fixed designation E2024/E2024M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year

2、 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 covers procedures for detecting thesources of gas leaking at the rate of 1 3 105Pa m3/s (1 3 104sta

3、ndard cm3/s) or greater. The tests may be conducted on anyobject that can be pressurized with a tracer gas that isdetectable by a thermal conductivity detector. The test sensi-tivity will vary widely depending on the tracer gas used.1.2 UnitsThe values stated in either SI or std-cc/sec unitsare to b

4、e regarded separately 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 standard.1.3 This standard does not purport to address all of th

5、esafety 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.2. Referenced Documents2.1 ASTM Standards:2E543 Specification for Agen

6、cies Performing Nondestruc-tive TestingE1316 Terminology for Nondestructive Examinations2.2 ASNT Documents:3SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification in Nondestructive TestingANSI/ASNT CP-189 Standard for Qualification and Certi-fication of Nondestructive Testing

7、Personnel2.3 AIA Standard:NAS-410 Certification and Qualification of NondestructiveTest Personnel43. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, see Terminology E1316, Section E.4. Summary of Practice4.1 Scanning MethodThis test method sets minimumrequirements for a

8、 thermal conductivity leak detector. Itprovides for calibration of the detector and gives proceduresfor pressurizing the test object, locating leaks and estimatingthe leakage rate.4.2 Accumulation MethodThe accumulation method issometimes the only practical method for accessing complexshaped flanges

9、 or sections of pressurized vessels to be leaktested. It may be achieved by entrapping or enclosing an areaof a test component with a suitable covering and sampling thebuildup of tracer gas concentration with the thermal conduc-tivity leak detector. The acceptance criteria is based on thetracer gas

10、concentration detected by the thermal conductivitydetector after an accumulation time from leakage from theleak(s) into the known sample volume.5. Significance and Use5.1 These test methods are useful for locating and estimat-ing the size of pressurized gas leaks, either as quality controltests or a

11、s field inspection procedures. Also, they are valuableas pretests before other more time consuming and moresensitive leak tests are employed. These test methods aresemi-quantitative techniques used to locate leaks but cannot beused to quantify except for approximation. These test methodsmay be used

12、in an accept-reject test mode.6. Basis of Application6.1 The following items are subject to contractual agree-ment between the parties using or referencing these testmethods:1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of

13、Subcommittee E07.08 on LeakTesting Method.Current edition approved July 1, 2011. Published July 2011. Originally approvedin 1999. Last previous edition approved in 1999 as E2024 - 05. DOI: 10.1520/E2024_E2024M-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cu

14、stomer 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 43228-0518, http:/www.asnt.org.4A

15、vailable from Aerospace Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, VA22209-3928, http:/www.aia-aerospace.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc

16、ken, PA 19428-2959, United States.6.2 Personnel Qualification6.2.1 If specified in the contractual agreement. Personnelperforming examinations to these test methods shall be quali-fied in accordance with a nationally or internationally recog-nized NDT personnel qualification practice or standard suc

17、h asANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, or similar docu-ment and certified by the employer or certifying agency, asapplicable. The practice or standard used and its applicablerevision shall be identified in the contractual agreement.6.3 Qualification of Nondestructive AgenciesIf specifiedin the co

18、ntractual agreement, NDT agencies shall be qualifiedand evaluated as described in Practice E543. The applicableedition of Practice E543 shall be specified in the contractualagreement.6.4 Re-examination of Repaired/Reworked ItemsRe-examination of repaired/reworked items is not addressed inthese test

19、methods, they shall be specified in the contractualagreement7. Interferences7.1 Background GasesThermal conductivity detectors aresensitive to all gases that have a thermal conductivity valuedifferent from air and their sensitivity changes with the degreeof difference. Background gases in the test a

20、rea may signifi-cantly alter the test sensitivity to a particular tracer gas.7.2 Cleanliness of Test SurfaceThe areas to be tested mustbe free of oil, grease, paint, water, and other contaminants thatmight mask a leak or be drawn into the leak detector and clogthe probe.7.3 Pressurizing with Test Ga

21、sIn order to evaluate leak-age accurately, the test gas in all parts of the device or systemmust contain substantially the same concentration of tracer gas.When the device contains air prior to the introduction of testgas, or when an inert gas and a tracer gas are added separately,this may not be tr

22、ue. Devices in which the effective diameterand length are not greatly different, such as tanks, may betested satisfactorily by simply adding tracer gas; however,when long or restricted systems (piping) are to be tested, moreuniform tracer gas distribution will be obtained by firstevacuating to less

23、than 100 Pa (.75 torr), and then filling withthe tracer gas or by employing proper purge technique.7.4 Unknown Tracer Gas ConcentrationWhen perform-ing the calibration of the leak detector, a capillary standard leakgenerally is used that contains 100 % concentration of thetracer gas. Leak testing of

24、ten is done on devices or systems thatdo not contain this same gas concentration as the standard leak.Doing so will cause the test sensitivity (detector response) to beless than that from the standard leak.7.5 Operator Scanning VariationsThe leak detector re-sponse will change when the test operator

25、 varies the scanningparameters because the scanning distance and speed deter-mines the tracer gas concentration that the leak detectormeasured. Any change in scanning parameters from those usedfor calibration may cause a reduction in test sensitivity andinstrument response.7.6 Gas CompatibilitySome

26、gases, such as hydrogen andammonia, may permanently alter the instrument sensitivity andstability. Refer to the instrument manufacturers manual.8. Apparatus8.1 Thermal Conductivity Leak DetectorThis detectorshould have a minimum detectable leak rate of 1 3 105Pam3/s (1 3 104Std cm3/s). To perform te

27、sts as specified inthese test methods, the detector should have the followingminimum features:8.1.1 Thermal conductivity sensor.8.1.2 Device to maintain a stable probe air velocity.8.1.3 Controls to zero detector.8.1.4 Battery status indicator for portable instruments. Theinstrument sensitivity for

28、a portable detector shall not varyprior to a low battery indication.8.2 Standard Leaks of Both Fixed and Variable TypeTheleak rate of the standard leak (CL) used for the systemcalibration shall be equal to the acceptance level (maximumpermissible leakage rate). The leak rate of the standard leakwill

29、 be less than the acceptance level when the system tracerconcentration is less than 100 % for testing. value of thestandard leak to be used is determined by the followingformula:CL 5 LRacc3 %C/100 (1)where:CL = leakage rate of standard leak (Pa m3/s or stdcm3/s),LRacc= acceptance level (maximum perm

30、issible leakagerate), and%C = percentage concentration of tracer gas.8.3 Test Component/System Enclosure, either a rigid struc-ture or heavy plastic cover, to contain partially or totallysurround the test part to accumulate the escaping tracer gas.The enclosure must not restrict flow to the leak det

31、ector.9. Calibration of Leak Detector9.1 The detector shall be turned on and allowed to warm upand zeroed as specified by the manufacturer. The probe(sensor) then shall be moved across the standard leak at adistance of not more than 1 mm 0.04 in. from the standardleak orifice and moved not faster th

32、an 20 mm/s 0.8 in./s, andthe detectors response observed. The standard shall bescanned several times and the average indicated leakage rate isthe test acceptance reading. The scanning speed and distancemay have to be adjusted during calibration to improve thedetector response. These scanning paramet

33、ers established dur-ing calibration shall not be exceeded while scanning the testsystem.9.2 The capsule leak should be stored with the shutoff valve,if present, closed, and the leak should be allowed to stabilizefor approximately 5 min after opening.9.3 Calibration shall be performed prior to, upon

34、comple-tion of, and during testing at intervals not to exceed 1 h. Failureof a calibration check to obtain the same or greater response asthe previous check shall require that an evaluation or retest ofall tested parts or areas examined be performed.9.4 For the accumulation method, the thermal condu

35、ctivitydetector needs to be checked against a known standardconcentration of the tracer gas in air into the test volume duringthe accumulation time. For volumes different from the testE2024/E2024M 112volume, a proportional adjustment shall be made. Stratificationof the tracer gas shall also be taken

36、 into consideration.10. Procedure10.1 Evacuate the device or test system to remove air andpressurize with tracer gas to the specification test pressure.When the test system cannot be evacuated, either the systemmust be purged sufficiently with the tracer gas or the tracer gasconcentration calculated

37、. When testing is performed with atracer gas concentration less than 100 %, then the CL leakagerate shall be determined in accordance with 8.2.10.2 Calibrate the leak detector in accordance with 9.1. Thiscalibration shall be performed in the test area to allow theprobe to sample the background gases

38、.10.3 Probe Areas Suspected of LeakingThe thermal con-ductivity sensor shall be held not more than 1 mm 0.04 in.from the test surface and moved not faster than 20 mm/s 0.8in./s. The gases, scanning rate, and distance shall be equal tothat used in the calibration performed in 9.1. Any detectorrespons

39、e shall be verified by moving the probe away from thearea and then rescanning the area. Any verified response lessthan the instrument response established from sampling theleak standard in accordance with 9.1 is acceptable, and leakagereadings equal to or greater than that instrument response isunac

40、ceptable.10.4 When surface scanning is hindered by adverse atmo-spheric or testing conditions, such as wind, drafts, or wetsurfaces, an enclosure may be used to protect and accumulatethe tracer gas. An exact quantitative measurement under theseconditions usually is not possible.10.5 Check calibratio

41、n as specified in 9.1.11. Keywords11.1 conductivity leak test; leak testing; sensitive leak test;thermal conductivity leak testSUMMARY OF CHANGESCommittee E07 has identified the location of selected changes to this standard since the last issue (E2024 - 05)that may impact the use of this standard. (

42、July 1, 2011)(1) Changed standard from Test Method to Practice.(2) Added combined units statement as 1.2.(3) Changed SI units of mol/s to Pa m3/s in 1.1 and 8.1.(4) Added formula to 8.2 to clarify relationship of CL, LRacc,and %C.(5) Added caution about stratification of tracer gas to 9.4.(6) Added

43、reference to 8.2 formula in 10.1.(7) Deleted Precision and Bias section; and renumbered Key-words section.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised tha

44、t determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reappro

45、ved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you fe

46、el that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual rep

47、rints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).E2024/E2024M 113