1、Designation: E2191/E2191M 10Standard Practice forExamination of Gas-Filled Filament-Wound CompositePressure Vessels Using Acoustic Emission1This standard is issued under the fixed designation E2191/E2191M; 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. Scope1.1 This practice provides guidelines for acoustic emission(AE) examination of filament
3、-wound composite 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 thispracti
4、ce. Pressurization medium may be gas or liquid.1.3 This practice is limited to vessels designed for less than690 bar 10,000 psi maximum allowable working pressure andwater volume less than 1 m3or 1000 L 35.4 ft3.1.4 AE measurements are used to detect emission sources.Other nondestructive examination
5、 (NDE) methods may 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 condu
6、cted atambient temperatures above 20C 70F. This practice may beused at ambient temperatures below 20C 70F if provisionhas been made to fill to the tanks rated pressure at 20C70F.1.7 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalues sta
7、ted in each system may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the standard.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its u
8、se. 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 statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2E543 Specificat
9、ion for Agencies Performing Nondestruc-tive TestingE650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE976 Guide for Determining the Reproducibility of Acous-tic Emission Sensor ResponseE1316 Terminology for Nondestructive ExaminationsE2374 Guide for Acoustic Emission System PerformanceVe
10、rification2.2 Natural Gas Vehicle Standard:American National Standard for Basic Requirements forCompressed Natural Gas Vehicle (NGV) FuelContainers ANSI/AGA/NGV232.3 Compressed Gas Association Standard:Pamphlet C-6.4, Methods for Visual Inspection of AGANGV2 Containers42.4 U.S. Department of Transpo
11、rtation 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 Personnel6SNT-TC-1A, Recommended Practice for NondestructiveTesting Personnel Qualification and Certificat
12、ion63. Terminology3.1 DefinitionsSee Terminology E1316 for general termi-nology applicable to this practice.3.2 Definitions of Terms Specific to This Standard:1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E0
13、7.04 onAcoustic Emission Method.Current edition approved June 1, 2010. Published July 2010. Originally approvedin 2002. Last previous edition approved in 2008 as E2191 - 08. DOI: 10.1520/E2191_E2191M-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Ser
14、vice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to 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
15、Association (CGA), 4221 Walney Rd., 5thFloor, Chantilly, VA 20151-2923, http:/.5Available 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),
16、P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.1 AE test pressure, n110 % of the greatest pressurethat the examination article contains during previo
17、us 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 filling, pressure shouldsettle to rated service pressure as gas temperatu
18、re 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 usingappropriate pressurization medium.4. Summary of Practice4.1 AE sensors a
19、re 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-filled,filament-wound composite pressure vessels. Damage mecha-nisms wh
20、ich 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 relate Acoustic Emission to applied load on the compositematerial. At
21、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 thisphenomenon can be identified and quantified by a single AEparameter (that
22、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 vessels which ex-hibit unacceptable levels of AE should be examined by othe
23、rmethods; 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 scope of thispractice.4.7 Any number of pressure vessels may be examinedsi
24、multaneously 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 whichaddress in-service inspection of NGV fuel containers (see2.2-2.4). AE e
25、xamination 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”examination of the container.5.1.1 Slow-fill pressurization must proceed at
26、 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 pressurization can be used if hold periods areprovided. Acoustic emission data a
27、re 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 Background noise above the threshold will contami-nate the AE data and render th
28、em 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 interference (RFI) from nearby broadcastingfacilities and from other sources;
29、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 elasticwave propagation, sensor coupling and signal processor set-tings.5.3 It i
30、s 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 Personnel QualificationIf specified in the contractualagreement, person
31、nel 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 document and certified by the employer or certifyingagency, as applicable. Th
32、e 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 agencies shall bequalified and evaluated as described in Practice E543.
33、Theapplicable edition of Practice E543 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/Acceptance CriteriaReporting cri-teria for the examination results shall be in acc
34、ordance 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 whichcover the following topics.6.6.1 Basic technology of acoustic emission.6.6.
35、2 Failure mechanisms of reinforced plastics.6.6.3 Acoustic emission instrumentation.6.6.4 Instrumentation verification.6.6.5 Vessel filling requirements.6.6.6 Data collection and interpretation.6.6.7 Examination report generation.E2191/E2191M 1027. Apparatus7.1 Essential features of the apparatus re
36、quired 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 couplants are acceptable.7.3 Sensors may be held in place with elastic
37、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 beplaced 180 apart at opposite ends of the container on theshoulders.7.
38、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 attenuationcharacteristics are not available from previous examinations ofsimi
39、lar 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 attenuation but may not be representative of agenuine AE source. It sho
40、uld 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 AE sensor and mark off 15-cm 6-in.intervals from the center of th
41、e sensor along a line parallel tothe principal direction of the surface fiber. Select additionalpoints on the surface of the vessel at 15-cm 6-in. intervalsalong lines angled 45 and 90, respectively, to the principaldirection of the surface fiber. Break pencil leads (see GuideE976) and record peak a
42、mplitude.All lead breaks shall be doneat an angle of approximately 30 to the surface with a 2.5-mm0.1-in. lead extension. The attenuation data shall be retainedas part of the test report.7.5.2 Record the distances from the center of the sensor tothe points where hits are no longer detected. Repeat t
43、hisprocedure 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 as thedetectability distance; this distance shall be recorded.NO
44、TE 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 sensors are used to detect stress waves produced byflaws. Sensors must
45、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 preamplifier, must not result in asignal loss of greater than 3 dB (typi
46、cally2m6ftisacceptable).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 150 m 500 ft is acceptable).7.9 Signal processors are computerized instruments withindependent channels that filter, meas
47、ure and convert analoginformation into digital form for display and permanent stor-age.Asignal processor must have sufficient speed and capacityto independently process data from all sensors simultaneously.The signal processor should provide capability to filter data forreplay.FIG. 1 Essential Featu
48、res of the ApparatusE2191/E2191M 1037.10 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 replay or for archives.7.12 Hard-copy capability should be availab
49、le 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 calibration 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 toeq
