1、Designation: E 2191 02Standard Test Method 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
2、 of 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 test method provides guidelines for acoustic emis-sion (AE) examination of filament-wo
3、und composite pressurevessels, for example, the type used for fuel tanks in vehicleswhich use natural gas fuel.1.2 This test method requires pressurization to a level equalto or greater than what is encountered in normal use. The tankspressurization history must be known in order to use this testmet
4、hod. Pressurization medium may be gas or liquid.1.3 This test method is limited to vessels designed for lessthan 10 000 psi (689 bar) maximum allowable working pres-sure and water volume less than 2.5 ft3(0.07 m3).1.4 AE measurements are used to detect emission sources.Other nondestructive examinati
5、on (NDE) methods may beused to evaluate the significance of AE sources. Procedures forother NDE methods are beyond the scope of this test method.1.5 This test method applies to examination of new andin-service filament-wound composite pressure vessels.1.6 This test method applies to examinations con
6、ducted atambient temperatures above 70F (21C). This test methodmay be used at ambient temperatures below 70F if provisionhas been made 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 forinfo
7、rmation only.1.8 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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. S
8、pecific precau-tionary statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:E 543 Practice for Agencies Performing NondestructiveTesting2E 650 Guide for Mounting Piezoelectric Acoustic EmissionSensors2E 976 Guide for Determining the Reproducibility of Acous-tic Emission Sensor
9、 Response2E 1316 Terminology for Nondestructive Examinations22.2 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 o
10、f 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 Personnel6SNT-TC-1A, Recommended Practice for Nondestru
11、ctiveTesting Personnel Qualification and Certification63. Terminology3.1 DefinitionsSee Terminology E 1316 for general ter-minology applicable to this test method.3.2 Definitions of Terms Specific to This Standard:3.2.1 AE test pressure, n110 % of the greatest pressurewhich the test article contains
12、 during previous service. Usually125 % of the filling pressure is an acceptable AE test pressure.(Normally, gas is heated when compressed during the fillingprocess; hence, tanks are filled to more than rated servicepressure). After filling, pressure should settle to rated servicepressure as gas temp
13、erature within the tank becomes equal toambient temperature.1This test method is under the jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved March 10, 2002. Published May 2002.2Annua
14、l Book of ASTM Standards, Vol 03.03.3Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.4Available from Compressed Gas Association, 1725 Jefferson Davis Hwy, Suite1004, Arlington, VA 222024102.5Available from DODSSP, Bldg 4, Section D, 700 Robbins Ave.
15、, Philadelphia,PA 191115098.6Available from American Society for Nondestructive Testing, P.O. Box 28518,1711 Arlington Lane, Columbus, OH 432280518.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2 detectability distance, nthe ma
16、ximum 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 Test Method4.1 AE sensors are mounted on a vessel and emission ismonitored while the vessel is pressurized to the “A
17、E testpressure”.4.2 This test method provides guidelines for the detection ofAE from structural flaws in the composite overwrap in gas-filled, filament-wound composite pressure vessels. Damagemechanisms which produce AE include: resin cracking, fiberdebonding, fiber pullout, fiber breakage, delamina
18、tion andbond failure. Flaws in liner portions of a vessel may not bedetected.4.3 This test method and others found in ASTM, ASME,ASNT, SPI relate Acoustic Emission to applied load on thecomposite material. At relatively low load (safe operatingconditions) the acoustic emission from the composite mat
19、erialis low. At higher loads (unsafe operating conditions) the slopeof the AE versus load curve changes drastically. In some casesthis phenomenon can be identified and quantified by a singleAE parameter (that is, AE counts).4.4 Structurally insignificant flaws or processes (for ex-ample, leaks) may
20、produce emission.4.5 This test method is convenient for periodic examinationof vessels in-service.4.6 Gas-filled filament-wound pressure vessels which ex-hibit unacceptable levels of AE should be examined by othermethods; for example, visual, ultrasound, dye penetrant, etc.,and may be repaired and r
21、e-examined in accordance withgovernment regulations and manufacturers guidelines. Repairand repair examination procedures are outside the scope of thistest method.4.7 Any number of pressure vessels may be examinedsimultaneously as long as the appropriate number of sensorsand instrumentation channels
22、 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 examination is listed as an alternative to theminimum three-year visual examination wh
23、ich 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 flow rates thatdo not produce background noise from flow of the pressurizingmedium.
24、Acoustic emission data are recorded throughout apressurization range (that is, 50 % to 100 % of AE testpressure).5.1.2 Fast-fill pressurization can be used if hold periods areprovided. Acoustic emission data are recorded only during thehold periods.5.1.3 Background noise above the threshold will con
25、tami-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 interference (RFI) from nearby broadcasting
26、facilities and from other sources; leaks at pipe or hoseconnections and airborne particles, insects, rain and snow. Thistest method should not be used if background noise cannot beeliminated or controlled.6. Basis of Application6.1 Personnel QualificationNDE personnel shall bequalified in accordance
27、 with a nationally recognized practice orstandard such as ANSI/ASNT-CP-189, SNT-TC-1A, or asimilar document. The practice or standard used and itsapplicable revisions shall be specified in any contractualagreement between the using parties.6.2 Qualification of Nondestructive Test AgenciesIf speci-fi
28、ed in the contractual agreement, NDT agencies shall bequalified and evaluated as described in Practice E 543. Theapplicable edition of Practice E 543 shall be specified in thecontractual agreement.6.3 Extent of ExaminationThe extent of examination shallbe in accordance with 4.2 unless otherwise spec
29、ified.6.4 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in accordance withSection 11 unless otherwise specified. Acceptance criteria shallbe specified in the contractual agreement.6.5 Personnel Training/Test RequirementsNDE personnel(examiner) shall b
30、e familiar with CGA Pamphlet C6 and shallhave attended a training course and passed a written test whichcover the following topics.6.5.1 Basic technology of acoustic emission.6.5.2 Failure mechanisms of reinforced plastics.6.5.3 Acoustic emission instrumentation.6.5.4 Instrumentation check out.6.5.5
31、 Vessel filling requirements.6.5.6 Data collection and interpretation.6.5.7 Test report.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 surf
32、ace. Adhesives that have acceptable acousticproperties and traditional couplants 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 t
33、he vesselwall will be determined by accessibility. Ideally they should beplaced 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. Sen
34、sor spacings aregoverned by the attenuation of the material. If attenuationcharacteristics are not available from previous examinations ofsimilar vessels follow the directions found below.E21910227.5.1 Attenuation CharacterizationTypical signal propa-gation losses shall be determined in accordance w
35、ith thefollowing procedure. This procedure provides a relative mea-sure of the attenuation 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-ta
36、tive region of the vessel with clear access along the cylin-drical section. Mount an 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) interva
37、ls alonglines angled 45 and 90, respectively, to the principal directionof the surface 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 b
38、e retained aspart 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 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 dist
39、ance from the sensor at which thepencil lead break can no longer be detected is known as thedetectability distance; this distance shall be recorded.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
40、 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 preamplifier, must not resu
41、lt 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 are computerized in
42、struments withindependent channels that filter, measure and convert analoginformation into digital form for display and permanent stor-age. A signal processor must have sufficient speed and capacityto independently process data from all sensors simultaneously.The signal processor should provide capa
43、bility 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 replay or for archives.7.12 Hard-copy capability should be available f
44、rom 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 Standardization9.1 Annual calibration and verification of pressure trans-ducer (if applicable),
45、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
46、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 basis or at any time there is concern about signalprocessor performance. An AE electronic waveform generatorFIG. 1 Esse
47、ntial Features of the ApparatusE2191023should be used in making evaluations. Each signal processorchannel must respond with peak amplitude reading within 62dB of the electronic waveform generator output.9.3 Routine performance checking of each sensor should beconducted on a monthly basis or at any t
48、ime there is concernabout the sensor performance. Peak amplitude response andelectronic noise level should be recorded. Sensors can bestimulated by a pencil lead break or electronic waveformgenerator with a pulser. Sensors which are found to have peakamplitudes or electronic noise more than 3 dB gre
49、ater or lessthan the average of the group of sensors to be used during theexamination should be replaced.9.4 A system performance check must be conducted imme-diately before and immediately after each examination. Aperformance check uses a mechanical device to induce stresswaves into the vessel wall at a specified distance from eachsensor. The induced stress waves simulate emission from aflaw. Performance checks verify performance of each systemchannel including couplant).9.4.1 The preferred technique for conducting a performancecheck is a pencil lead break.
