1、Designation: E 2191 08Standard Practice forExamination of Gas-Filled Filament-Wound CompositePressure Vessels Using Acoustic Emission1This standard is issued under the fixed designation E 2191; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides guidelines for acoustic emission(AE) examination of filament-wound comp
3、osite pressure ves-sels, for example, the type used for fuel tanks in vehicles whichuse natural gas fuel.1.2 This practice requires pressurization to a level equal toor greater than what is encountered in normal use. The tankspressurization history must be known in order to use thispractice. Pressur
4、ization medium may be gas or liquid.1.3 This practice is limited to vessels designed for less than5000 psi (340 bar) maximum allowable working pressure andwater volume less than 2.5 ft3(0.07 m3).1.4 AE measurements are used to detect emission sources.Other nondestructive examination (NDE) methods ma
5、y beused to gain additional insight into the emission source.Procedures for other NDE methods are beyond the scope ofthis practice.1.5 This practice applies to examination of new and in-service filament-wound composite pressure vessels.1.6 This practice applies to examinations conducted atambient te
6、mperatures above 70F (21C). This practice may beused at ambient temperatures below 70F if provision has beenmade to fill to the tanks rated pressure at 70F.1.7 The values stated in inch-pound units are to be regardedas the standard. SI units which are in parentheses are forinformation only.1.8 This
7、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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary
8、 statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2E 543 Specification for Agencies Performing Nondestruc-tive TestingE 650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE 976 Guide for Determining the Reproducibility of Acous-tic Emission Sensor ResponseE 1316
9、Terminology for Nondestructive ExaminationsE 2374 Guide for Acoustic Emission System PerformanceVerification2.2 Natural Gas Vehicle Standard:American National Standard for Basic Requirements forCompressed Natural Gas Vehicle (NGV) FuelContainers ANSI/AGA/NGV232.3 Compressed Gas Association Standard:
10、Pamphlet C-6.4, Methods for Visual Inspection of AGANGV2 Containers42.4 U.S. Department of Transportation Reference:NHTSA Federal Motor Vehicle Safety Standard No. 304,March 27, 199552.5 ASNT Standards:ANSI/ASNT CP-189, Standard for Qualification and Cer-tification of Nondestructive Testing Personne
11、l6SNT-TC-1A, Recommended Practice for NondestructiveTesting Personnel Qualification and Certification61This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved
12、Feb. 15, 2008. Published March 2008. Originallyapproved in 2002. Last previous edition approved in 2002 as E2191 - 02.2For 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 t
13、o the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from Compressed Gas Association (CGA), 4221 Walney Rd., 5thFloor, Chantilly, VA 20151-2923, http:/.5Avail
14、able from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/www.dodssp.daps.mil.6Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.1Copyr
15、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 DefinitionsSee Terminology E 1316 for general ter-minology applicable to this practice.3.2 Definitions of Terms Specific to This Standard:3.2.1 AE test pressure, n110 % of t
16、he greatest pressurethat the examination article contains during previous service.Usually 125 % of the filling pressure is an acceptable AEexamination pressure. (Normally, gas is heated when com-pressed during the filling process; hence, tanks are filled tomore than rated service pressure). After fi
17、lling, pressure shouldsettle to rated service pressure as gas temperature within thetank becomes equal to ambient temperature.3.2.2 detectability distance, nthe maximum distance froma sensor at which a defined simulated AE source can bedetected by the instrumentation with defined settings and usinga
18、ppropriate pressurization medium.4. Summary of Practice4.1 AE sensors are mounted on a vessel and emission ismonitored while the vessel is pressurized to the “AE exami-nation pressure”.4.2 This practice provides guidelines for the detection ofAEfrom structural flaws in the composite overwrap in gas-
19、filled,filament-wound composite pressure vessels. Damage mecha-nisms which produceAE include: resin cracking, fiber debond-ing, fiber pullout, fiber breakage, delamination and bondfailure. Flaws in liner portions of a vessel may not be detected.4.3 This practice and others found inASTM,ASME,ASNT,SPI
20、 relate Acoustic Emission to applied load on the compositematerial. At relatively low load (safe operating conditions) theacoustic emission from the composite material is low. Athigher loads (unsafe operating conditions) the slope of the AEversus load curve changes drastically. In some cases thisphe
21、nomenon can be identified and quantified by a single AEparameter (that is, AE counts).4.4 Structurally insignificant flaws or processes (for ex-ample, leaks) may produce emission.4.5 This practice is convenient for periodic examination ofvessels in-service.4.6 Gas-filled filament-wound pressure vess
22、els which ex-hibit unacceptable levels of AE should be examined by othermethods; for example, visual, ultrasound, dye penetrant, etc.,and may be repaired and re-examined in accordance withgovernment regulations and manufacturers guidelines. Repairand repair examination procedures are outside the sco
23、pe of thispractice.4.7 Any number of pressure vessels may be examinedsimultaneously as long as the appropriate number of sensorsand instrumentation channels are used.5. Significance and Use5.1 Due to safety considerations, the Compressed GasAssociation (CGA) and others have produced guidelines which
24、address in-service inspection of NGV fuel containers (see2.2-2.4). AE examination is listed as an alternative to theminimum three-year visual examination which generally re-quires that the container be removed from the vehicle to exposethe entire container surface. The AE method allows “in-situ”exam
25、ination of the container.5.1.1 Slow-fill pressurization must proceed at flow rates thatdo not produce background noise from flow of the pressurizingmedium. Acoustic emission data are recorded throughout apressurization range (that is, 50 % to 100 % ofAE examinationpressure).5.1.2 Fast-fill pressuriz
26、ation can be used if hold periods areprovided. Acoustic emission data are recorded only during thehold periods.NOTE 1Fast-fill pressurization is less appropriate for carbon (orgraphite) composites due to the lower sensitivity of carbon fibers to stressrupture compared to other fibers.5.1.3 Backgroun
27、d noise above the threshold will contami-nate the AE data and render them useless. Users must be awareof the following common causes of background noise: high fillrate (measurable flow noise); mechanical contact with thevessel by objects; electromagnetic interference (EMI) andradio frequency interfe
28、rence (RFI) from nearby broadcastingfacilities and from other sources; leaks at pipe or hoseconnections and airborne particles, insects, rain and snow. Thispractice should not be used if background noise cannot beeliminated or controlled.5.2 Sensitivity is influenced by factors that affect elasticwa
29、ve propagation, sensor coupling and signal processor set-tings.5.3 It is possible to measure AE from AE sources thatcannot be verified by other NDE methods.6. Basis of Application6.1 The following items are subject to contractual agree-ment between the parties using or referencing this practice.6.2
30、Personnel QualificationIf specified in the contractualagreement, personnel performing examinations to this practiceshall be qualified in accordance with a nationally or interna-tionally recognized NDT personnel qualification practice orstandard such as ANSI/ASNT-CP-189, SNT-TC-1A, or asimilar docume
31、nt 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 parties.6.3 Qualification of Nondestructive Test AgenciesIf speci-fied in the contractual agreement, NDT a
32、gencies shall bequalified and evaluated as described in Practice E 543. Theapplicable edition of Practice E 543 shall be specified in thecontractual agreement.6.4 Extent of ExaminationThe extent of examination shallbe in accordance with 4.2 unless otherwise specified.6.5 Reporting Criteria/Acceptanc
33、e CriteriaReporting cri-teria for the examination results shall be in accordance withSection 11 unless otherwise specified.6.6 Personnel Training/Test RequirementsNDE personnel(examiner) shall be familiar with CGA Pamphlet C6 and shallhave attended a training course and passed a written test whichco
34、ver the following topics.6.6.1 Basic technology of acoustic emission.6.6.2 Failure mechanisms of reinforced plastics.6.6.3 Acoustic emission instrumentation.6.6.4 Instrumentation verification.6.6.5 Vessel filling requirements.E21910826.6.6 Data collection and interpretation.6.6.7 Examination report
35、generation.7. Apparatus7.1 Essential features of the apparatus required for thisstandard are shown in Fig. 1. Specifications are provided inAnnex A1.7.2 Couplant must be used to acoustically couple sensors tothe vessel surface. Adhesives that have acceptable acousticproperties and traditional coupla
36、nts are acceptable.7.3 Sensors may be held in place with elastic straps,adhesive tape, or other mechanical means.7.4 On small vessels (that is, where 100 % coverage can beachieved with two sensors) the sensor locations on the vesselwall will be determined by accessibility. Ideally they should beplac
37、ed 180 apart at opposite ends of the container on theshoulders.7.5 On larger vessels (that is, where two sensors cannotprovide 100 % coverage) sensors are positioned on the vesselwall so as to provide complete coverage. Sensor spacings aregoverned by the attenuation of the material. If attenuationch
38、aracteristics are not available from previous examinations ofsimilar vessels follow the directions found below.7.5.1 Attenuation CharacterizationTypical signal propa-gation losses shall be determined in accordance with thefollowing procedure. This procedure provides a relative mea-sure of the attenu
39、ation but may not be representative of agenuine AE source. It should be noted that peak amplitudecaused by a mechanical pencil lead break may vary withsurface hardness, resin condition and cure. Select a represen-tative region of the vessel with clear access along the cylin-drical section. Mount an
40、AE sensor and mark off 6-in. intervalsfrom the center of the sensor along a line parallel to theprincipal direction of the surface fiber. Select additional pointson the surface of the vessel at 6-in. (15-cm) intervals alonglines angled 45 and 90, respectively, to the principal directionof the surfac
41、e fiber. Break pencil leads (see Guide E 976) andrecord peak amplitude. All lead breaks shall be done at anangle of approximately 30 to the surface with a 0.1 in. (2.5mm) lead extension. The attenuation data shall be retained aspart of the test report.7.5.2 Record the distances from the center of th
42、e sensor tothe points where hits are no longer detected. Repeat thisprocedure along lines angled 45 and 90 to the direction of theoriginal line. The data shall be retained as part of the testreport. The minimum distance from the sensor at which thepencil lead break can no longer be detected is known
43、 as thedetectability distance; this distance shall be recorded.NOTE 2Detectability distance may be reduced to achieve greatersensitivity to sources at farther distance.7.5.3 Sensor spacing (distance between adjacent sensors)shall not be greater than 1.5 times the detectability distance.7.6 AE sensor
44、s are used to detect stress waves produced byflaws. Sensors must be held in contact with the vessel wall toensure adequate acoustic coupling.7.7 A preamplifier may be enclosed in the sensor housing orin a separate enclosure. If a separate preamplifier is used, cablelength, between sensor and preampl
45、ifier, must not result in asignal loss of greater than 3 dB typically 6 ft (1.8 m) isacceptable.7.8 Power/signal cable length (that is, cable between pream-plifier and signal processor) shall not result in a signal loss ofgreater than 3 dB typically 500 ft (150 m) is acceptable.7.9 Signal processors
46、 are computerized instruments withindependent channels that filter, measure and convert analoginformation into digital form for display and permanent stor-age.Asignal processor must have sufficient speed and capacityFIG. 1 Essential Features of the ApparatusE2191083to independently process data from
47、 all sensors simultaneously.The signal processor should provide capability to filter data forreplay.7.10 A video monitor is used to display processed data invarious formats. Display format may be selected by theexaminer.7.11 A data storage device, such as a magnetic disk, is usedto store data for re
48、play or for archives.7.12 Hard-copy capability should be available from agraphics/line printer or equivalent device.8. Safety Precautions8.1 Ambient temperature should not be below the ductile-brittle transition temperature of the pressure vessel liner.9. Calibration and Verification9.1 Annual calib
49、ration and verification of pressure trans-ducer (if applicable), AE sensors, preamplifiers (if applicable),signal processor (particularly the signal processor time refer-ence), and AE electronic waveform generator should be per-formed. Equipment should be adjusted so that it conforms toequipment manufacturers specifications. Instruments used forcalibrations must have current accuracy certification that istraceable to the National Institute for Standards and Technol-ogy (NIST).9.2 Routine electronic evaluations must be performed on amonthly
