1、Designation: E 1930 07Standard Practice forExamination of Liquid-Filled Atmospheric and Low-PressureMetal Storage Tanks Using Acoustic Emission1This standard is issued under the fixed designation E 1930; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case 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 practice covers guidelines for acoustic emission(AE) examinations of new and in
3、-service aboveground storagetanks of the type used for storage of liquids.1.2 This practice will detect acoustic emission in areas ofsensor coverage that are stressed during the course of theexamination. For flat-bottom tanks these areas will generallyinclude the sidewalls (and roof if pressure is a
4、pplied above theliquid level). The examination may not detect flaws on thebottom of flat-bottom tanks unless sensors are located on thebottom.1.3 This practice may require that the tank experience a loadthat is greater than that encountered in normal use. The normalcontents of the tank can usually b
5、e used for applying this load.1.4 This practice is not valid for tanks that will be operatedat a pressure greater than the examination pressure.1.5 It is not necessary to drain or clean the tank beforeperforming this examination.1.6 This practice applies to tanks made of carbon steel,stainless steel
6、, aluminum and other metals.1.7 This practice may also detect defects in tank linings (forexample, high-bulk, phenolics and other brittle materials).1.8 AE measurements are used to detect and localize emis-sion sources. Other NDT methods may be used to confirm thenature and significance of the AE in
7、dications (s). Proceduresfor other NDT techniques are beyond the scope of this practice.1.9 Examination liquid must be above its freezing tempera-ture and below its boiling temperature.1.10 Superimposed internal or external pressures must notexceed design pressure.1.11 Leaks may be found during the
8、course of this exami-nation but their detection is not the intention of this practice.1.12 The values stated in inch-pound units are to be re-garded as the standard. The SI units given in parentheses arefor information only.1.13 This standard does not purport to address all of thesafety concerns, if
9、 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 statements are given in Section 8.2. Referenced Documents2.1 ASTM
10、 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 Terminology for Nondestructive ExaminationsE 2374 Guide for Acoust
11、ic Emission System PerformanceVerification2.2 ANSI/ASNT Standard:Recommended Practice ASNT SNT-TC-1A for Qualifica-tion and Certification of Nondestructive Testing Person-nel3ANSI/ASNT CP-189 Standard for Qualification and Certi-fication of NDT Personnel32.3 ASME Standard:Section V, Article 12, Boil
12、er metal storage tanks; above groundstorage tanksFIG. 3 In Service Tank Fill ScheduleE1930078ANNEX(Mandatory Information)A1. SPECIFICATIONS FOR APPARATUSA1.1 Instrumentation SpecificationsA1.1.1 AE sensors shall be resonant in a 100 to 200 kHzfrequency band.A1.1.2 Sensors shall have a peak sensitivi
13、ty greater than -77dB (referred to 1 volt per microbar, determined by face-to-faceultrasonic examination) within the frequency range 100 to 200kHz. Sensitivity within the 100 - 200 kHz range shall not varymore than 3 dB within the temperature range of intended use.A1.1.3 Sensors shall be shielded ag
14、ainst electromagneticinterference through proper design practice or differential(anti-coincidence) element design, or both.A1.1.4 Sensors shall be electrically isolated from conduc-tive surfaces.A1.1.5 Sensors shall have omni-directional response, withvariations not exceeding 2 dB from the peak resp
15、onse.A1.2 Sensor-Preamplifier CableA1.2.1 Cable connecting sensor to preamplifier shall notattenuate the sensor peak voltage in the 100 to 200 kHzfrequency range more than 3 dB (6 ft (1.83 m) is a typicallength). Integral preamplifier sensors meet this requirement.They have inherently short, interna
16、l, signal cables.A1.2.2 Sensor-preamplifier cable shall be shielded againstelectromagnetic interference. Standard low-noise coaxial cableis generally adequate.A1.3 CouplantA1.3.1 Commercially available couplants for ultrasonicflaw detection may be used. Silicone-based stopcock greasehas been found t
17、o be particularly suitable. Quick-settingadhesives may be used, provided the reduced couplant sensi-tivity is accounted for by closer sensor spacing. Couplantselection should be made to minimize changes in couplingsensitivity during an examination. Consideration should begiven to the time duration o
18、f the examination and to the surfacetemperature of the tank.A1.4 PreamplifierA1.4.1 Preamplifier shall have noise level no greater than 5microvolts rms (referred to a shorted input) within the 100 to200 kHz frequency range.A1.4.2 Preamplifier gain shall vary no more than 6 1dBwithin the 100 to 200 k
19、Hz frequency band and temperaturerange of use.A1.4.3 Preamplifier shall be shielded from electromagneticinterference.A1.4.4 Preamplifiers of differential design shall have aminimum of 40 dB common-mode rejection.A1.4.5 Preamplifier shall include a bandpass filter with aminimum of 18 dB/octave signal
20、 attenuation below the 100kHz and 18 dB/octave above 200 kHz. Note that the crystalresonant characteristics provide additional filtering as does theband pass filter in the signal conditioner.A1.4.6 It is preferred that the preamplifier be mountedinside the sensor housing.A1.5 Power-Signal CableA1.5.
21、1 Cable and connectors that provide power to pream-plifiers, and that conduct amplified signals to the main proces-sor, shall be shielded against electromagnetic interference.Signal loss shall be less than 3 dB over the length of the cable.(When standard coaxial cable is used, 1000 ft is the maximum
22、recommended cable length to avoid excessive signal attenua-tion).A1.6 Power SupplyA1.6.1 A stable, grounded, power supply that meets signalprocessor manufacturers specification shall be used.A1.7 Signal ProcessorA1.7.1 Electronic circuitry gain shall be stable within 61dB in the temperature range 40
23、 to 100F (4.4 to 37.8C).A1.7.2 Threshold shall be accurate within 6 1 dB.A1.7.3 Signal strength shall be measured on a per channelbasis and shall have a resolution of 1 % of the value obtainedfrom a one millisecond duration, 150 kHz sine burst having anamplitude 25 dB above the data analysis thresho
24、ld. Usabledynamic range shall be a minimum of 35 dB.A1.7.4 Peak amplitude shall have a usable dynamic range ofa minimum of 60 dB with 1 dB resolution over the frequencyband of 100 kHz to 200 kHz, and the temperature range of 40to 100F (4 to 52C). Not more than 62 dB variation in peakdetection accura
25、cy shall be allowed over the stated temperaturerange. Amplitude values shall be stated in dB, and must bereferenced to a fixed gain output of the system (sensor orpreamplifier).A1.7.5 Hit duration shall be accurate to 610 s and ismeasured from the first threshold crossing to the last thresholdcrossi
26、ng of the signal or envelope of the rectified linear voltagetime signal. It shall not include the hit definition time thatdefines the end of an event.A1.7.6 Arrival TimeHit arrival time shall be recordedglobally, for each channel accurate to within one millisecondwhen a zone location technique is us
27、ed.A1.7.7 Rearm TimeThe rearm time of each channel of thesystem shall be no greater than 200 s.A1.7.8 Hit Definition TimeThe hit definition time shall be400 s.E1930079APPENDIXES(Nonmandatory Information)X1. SENSOR LOCATION GUIDELINESX1.1 GeneralAcommon approach is used to select sensorlocations rega
28、rdless of the size or shape of the tanks examined.The first step is to determine the maximum distance betweensensors using the techniques described in 10.8.5. Once themaximum spacing has been determined, sensors can be spacedaccordingly in rings around the circumference of the tank shell.The first r
29、ing will generally start at or near the bottom of theshell. Additional rings will be added up the sidewall. Thevertical distance between rings should also be determined onthe basis of 10.8.5. The following guidelines should also beconsidered:X1.1.1 Sensor positions in alternate rings should be stag-
30、gered. A staggered arrangement provides maximum coverageof the shell plate sections and is particularly helpful inminimizing the number ofAE channels necessary to cover verylarge tanks.X1.1.2 When possible, additional sensors should be placednear large diameter openings such as manways. When rein-fo
31、rcing pads are present and a zone location technique is used,it is advisable to tee at least two sensors together, placing oneon the pad and one on the opposite side of the manway on thetank shell.X1.1.3 For vented storage tanks which cannot fill up into theroof and are not otherwise pressurized abo
32、ve the liquid, it maynot be necessary to place sensors on the roof. AE will notdetect defects in locations which are not stressed during thecourse of the examination. Flat roofs on non-pressurizedstorage tanks normally will not be stressed during AEexamination.X2. EXAMPLE INSTRUMENT SETTINGS AND REJ
33、ECTION CRITERIAX2.1 Acceptance Criteria:X2.1.1 Signal strengths (that is, of signals fromAE sources)shall not increase with increasing load.X2.1.2 Activity shall not increase with increasing load.X2.1.3 Evaluation Threshold shall be 50 dB (where 0 dBequals one microvolt at the preamplifier input).X2
34、.1.4 Any flaw which is detected must be preciselylocated; and, flaw dimensions must be determined usingsecondary NDT method (for example, ultrasonic inspection).X2.1.5 Flaws that are large enough to be “fracture criticalflaws”, or that are large enough to grow to fracture critical sizebefore another
35、 re-examination is performed, shall cause a tankto be repaired or removed from service.X2.1.5.1 “Fracture critical” flaw dimensions are based uponfracture mechanics analysis of a vessel using strength proper-ties which correspond to materials of construction.X2.2 Material of ConstructionThis example
36、 is based ontanks made from carbon steel.X2.3 Instrumentation, Characteristics and Settings:Sensor sensitivity -77 dB ref. 1 volt/microbar at approxi-mately 150 kHzCouplant silicone greasePreamplifier gain 40 dBPreamplifier filter 100 to 300 kHz bandpassPower/signal cable length less than 500 ft (15
37、2 m)Signal processor threshold 40 dB (0 dB=1v,preamplifier input)Signal processor filter 100 to 300 kHz bandpassHit definition time 400 sBackground noise less than 27 dB (0 dB=1v,atthepreamplifier input)Functional check amplitude greater than 80 dB (0 dB = 1v, preamp input)X3. EXAMINATION REPORTE193
38、00710ASTM 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 that determination of the validity of any such patent rights, and the riskof infringement of such rights
39、, 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 reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional st
40、andardsand 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 feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Co
41、mmittee 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 reprints (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).FIG. X3.1 Sample Examination ReportE19300711
