1、Designation:E237309E2373/E2373M14 Standard Practice for Use of the Ultrasonic Time of Flight Diffraction (TOFD) Technique 1 ThisstandardisissuedunderthexeddesignationE2373;E2373/E2373M;thenumberimmediatelyfollowingthedesignationindicates the year of original adoption or, in the case of revision, the
2、 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. Scope Scope* 1.1 This practice establishes the requirements for developing ultrasonic examination procedures using t
3、he ultrasonic technique known as Time-of-Flight Diffraction (TOFD). 1.2 ConsistentwithASTMPolicy,TOFDmayberegardedasanultrasonictestmethodwherebythequalitiesandcharacteristics of the item tested are evaluated, measured and in some cases identied. Measurements may be subject to precision and bias tha
4、t may be determined statistically or as a function of some parameter(s) such as wavelength. This practice may be used for applicationsthatwouldbequalitativeandproperlyaddressedasexaminationsaswellasquantitativeandmoreproperlyaddressed as tests. 1.3 The values stated in either SI units or inch-pound
5、units are to be regarded as standard. Inch-pound units are provided for information.separately as standard. The values stated 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-conforma
6、nce with the standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior
7、 to use. 2. Referenced Documents 2.1 ASTM Standards: 2 E164Practice for Contact Ultrasonic Testing of Weldments E543Specication for Agencies Performing Nondestructive Testing E1065Practice for Evaluating Characteristics of Ultrasonic Search Units E1316Terminology for Nondestructive Examinations E132
8、4Guide for Measuring Some Electronic Characteristics of Ultrasonic Testing Instruments E1961Practice for Mechanized Ultrasonic Testing of Girth Welds Using Zonal Discrimination with Focused Search Units 2.2 ASNT Documents: 3 SNT-TC-1ARecommended Practice for Nondestructive Testing Personnel Qualicat
9、ion and Certication ANSI/ASNT CP-189Standard for Qualication and Certication of Nondestructive Testing Personnel 2.3 Aerospace Industries Association Document: 4 NAS-410Certication and Qualication of Nondestructive Testing Personnel 2.4 ISO Standard: 5 ISO 9712Non-destructive TestingQualication and
10、Certication of NDT Personnel 2.5 Other Documents: BS 7706 (1993)Guide to Calibration and Setting-up of the Ultrasonic Time-of-Flight Diffraction (TOFD) Technique for Detection, Location and Sizing of Flaws, British Standards Institute, 1993 5 1 ThispracticeisunderthejurisdictionofASTMCommitteeE07onN
11、ondestructiveTestingandisthedirectresponsibilityofSubcommitteeE07.06onUltrasonicMethod. Current edition approved June 1, 2009June 1, 2014. Published July 2009June 2014. Originally approved in 2004. Last previous edition approved in 20042009 as E2373-04.E2373-09. DOI: 10.1520/E2373-09.10.1520/E2373_E
12、2373M-14. 2 ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatserviceastm.org.ForAnnualBookofASTMStandards volume information, refer to the standards Document Summary page on the ASTM website. 3 Available from American Society for Nondestructive Testing (ASNT)
13、, P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org. 4 Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http:/www.aia-aerospace.org. 5 Available from BSI Management Systems, 12110 Sunset Hil
14、ls Road, Suite 140, Reston VA 20190.International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http:/www.iso.org. This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes
15、 have been made to the previous version. Because it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version of the standard as published by ASTM is to be considered the offici
16、al document. *ASummary of Changes section appears at the end of this standard Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States 1Code Case 2235ASME Boiler and Pressure Vessel Code 6 EN583-6 Non-destructiveTesting:UltrasonicExamination.T
17、ime-of-ightDiffractionTechniqueasaMethodforDetectionand Sizing of Discontinuities 3. Terminology 3.1 DenitionsRelated terminology is dened in Terminology E1316. 3.2 Denitions of Terms Specic to This Standard: 3.2.1 B-scan displaya sectional view of the plotted inspection data formed by the stacking
18、ofA-scans. (Some users refer to stacked A-scans from non-parallel scans as D-scans and reserve those used with parallel scans as B-scans.) 3.2.2 back-wall echoa specular reection from the back-wall of the component being examined (usually assumed to be a plate). 3.2.3 lateral waveacompressionwavetha
19、ttravelsbythemostdirectroutefromthetransmittingprobetothereceivingprobe in a TOFD conguration. 3.2.4 parallel scanascanwherebytheprobepairmotionisparalleltotheultrasonicbeamaxis.AlsocalledaB-scanbysome users. 3.2.5 PCSabbreviation for probe center spacing. Refers to the distance between the marked e
20、xit points of a pair of TOFD probes for a specic application. 3.2.6 non-parallel or longitudinal scana scan whereby the probe pair motion is perpendicular to the ultrasonic beam axis. 3.2.7 RF waveformsthe non-rectied A-scan. 4. Signicance and Use 4.1 This practice provides general principles for th
21、e application of the Time-of-Flight Diffraction Technique as a tool for detection and sizing of discontinuities. 4.2 TOFD is a nondestructive ultrasonic examination technique that is not based on amplitude response. However, sufficient sensitivity is required to identify indications for evaluation.
22、4.3 Techniques used are typically applied to welded joints in carbon steel but the principles may be applicable to other applications including other materials with suitable validation procedures agreeable to the contracting parties. 4.4 In addition to a stand-alone ultrasonic detection techniqueTOF
23、D may be used in conjunction with weld examinations such as those described in Practices E164 and E1961 where it may be used to improve sizing estimates of aws detected by the manual or mechanized pulse-echo techniques and help discriminate between aws and geometric reectors. 4.5 The technique has p
24、roven effective on thicknesses from 9 to 300 mm (0.3750.375 to 12 in.).in. TOFD has been used on thicknesses outside of this range but special considerations are necessary.Techniques developed outside of this range of thickness shall be demonstrated as capable of meeting the required detection and s
25、izing requirements of the specication used. 5. Basis ofApplication 5.1 The following items are subject to contractual agreement between the parties using or referencing this standard. 5.2 Personnel Qualication 5.2.1 If specied in the contractual agreement, personnel performing examinations to this s
26、tandard shall be qualied in accordance with a nationally or internationally recognized NDTpersonnel qualication practice or standard such asANSI/ASNT- CP-189,SNT-TC-1A,ISO9712,NAS-410,orasimilardocumentandcertiedbytheemployerorcertifyingagency,asapplicable. Thepracticeorstandardusedanditsapplicabler
27、evisionshallbeidentiedinthecontractualagreementbetweentheusingparties. 5.3 Qualication of Nondestructive AgenciesIf specied in the contractual agreement, NDT agencies shall be qualied and evaluated as described in E543. The applicable edition of E543 shall be specied in the contractual agreement. 5.
28、4 Procedures and TechniquesThe procedures and techniques to be used shall be as specied in the contractual agreement. 5.5 Surface PreparationThe pre-examination surface preparation criteria shall be in accordance with 6.3 unless otherwise specied. 5.6 Timing of ExaminationThe timing of examination s
29、hall be in accordance with 6.3 unless otherwise specied. 5.7 Extent of ExaminationThe extent of examination shall be in accordance with 6.3 unless otherwise specied. 5.8 Reporting Criteria/Acceptance CriteriaReporting criteria for the examination results shall be in accordance with Section 8 unless
30、otherwise specied. Since acceptance criteria (for example, for reference radiographs) are not specied in this practice, they shall be specied in the contractual agreement. 6 Available from the American Society of Mechanical Engineers, ASME International, 22 Law Drive, Box 2900, Faireld, NJ 07007-290
31、0. E2373/E2373M14 25.9 Re-examination of Repaired/Reworked ItemsReexamination of repaired/reworked items is not addressed in this standard and if required shall be specied in the contractual agreement. 6. Procedures 6.1 Introduction: 6.1.1 TOFD is an ultrasonic examination technique that can provide
32、 improved detection and sizing capabilities of discontinuities compared to standard ultrasonic pulse-echo techniques. It uses forward scattered tip diffraction and reection of transmittedultrasonicpulses.ThisdocumentdescribestherequirementsforTOFDequipmentandproceduresonatplatesurfaces. Guidance for
33、 more complex geometries is provided in the Appendix. General guidance on TOFD can also be found in British Standards BS 7706. EN 5836. Acceptance criteria typical and performance demonstration requirements that may be used with TOFD techniques are found in ASME Code Case 2235 7 . 6.1.2 Because phas
34、e inversions of signals play an important role in the evaluation of TOFD results, all procedures developed using this practice shall require that the equipment presentation use and store RF waveforms. 6.1.3 Whether motorized or manually-operated, probe motion must be encoded for position and probes
35、held in a xture that maintains correct PCS during scanning. Time based sampling of data collection is not acceptable. 6.1.4 Fig. 1 illustrates the typical probe conguration for a TOFD examination. The gure uses a weld for convenience of references; however, TOFD need not be restricted to just weld e
36、xaminations. 6.1.5 Thelateralwaveandback-wallechosignalsprovideconvenientreferences.Formostapplicationsmodeconvertedsignals from aws are not used and therefore aw indications are usually recognized as occurring between the lateral wave and back-wall echo signals. Although it is more often the case t
37、o use refracted compression mode in the examination piece, some applications may produce better results when the incident angle is greater than the rst critical angle, thereby providing a refracted transverse shearmodeintheexaminationpiece.Whenusingarefractedcompressionmodeintheexaminationpiecethedi
38、rectshearandhead wavesalsoaregenerated;however,duetotheirloweracousticvelocities,shearwavesarrivelaterintimethantheback-wallsignal. 6.1.6 Fig. 2 is a sketch of a typical presentation for a non-parallel scan of a butt weld in a plate with an imbedded aw. The right side of Fig. 2 illustrates a wavefor
39、m extracted from a B-scan display showing the lateral wave, upper tip diffracted, lower tip diffracted and the back-wall echo signals.The left side of Fig. 2 indicates the probe placement with respect to the weld (upper left) and relative motion of the probes (a non-parallel scan is indicated). 6.1.
40、7 Fig. 3 illustrates an actual TOFD scan with ve indications (identied on the left) and an extracted A-scan from one of the indications. 6.2 Written ProcedureA documented examination strategy or scan plan shall be provided showing probe placement, movement,andcomponentcoveragethatprovidesastandardiz
41、edandrepeatablemethodologyforcomponentacceptance.Thescan plan shall also include ultrasonic beam angle(s) used, beam directions with respect to some reference such as a weld centerline, and volume examined. 6.3 Examination Materials and Surface Preparation: 7 Reference toASME CC2235 is made only as
42、an example of an existing code where the mutually agreed upon acceptance criteria allowsTOFD to be applied.This does not suggest that application of ASME CC2235 would be appropriate in all cases. It should be recognized that the high sensitivity of the TOFD technique could result in indications from
43、 reectors in plate materials that meet all plate ultrasonic specication requirements. Such indications should not be considered unacceptable unless they fail to meet the acceptance criteria agreed upon in 8.1. FIG. 1TOFD Conguration and Signal Origins E2373/E2373M14 36.3.1 TOFDtechniquecanbeappliedt
44、obothmetalsandnonmetals.Bestresultsarehadonne-grainedisotropicmaterialswith lowattenuationincludingsomenergrainedausteniticalloysandaluminum.Withsuitablevalidationprocedures,agreeabletothe contractingparties,coarser-grainedandanisotropicmaterialsmayalsobeexaminedusingTOFD.Theseusuallyrequireaddition
45、al modications to frequencies and digital signal processing. 6.3.2 The scanning area shall be clear of weld spatter and other conditions which may interfere with the movement of the probes, the coupling liquid, or the transmission of acoustic energy into the material. Any surface condition such as g
46、eometry, coating, and so forth, impeding the ultrasonic examination shall be noted for corrective action prior to scanning. 6.3.3 TheTOFDtechniquemaybeusedwithimmersion,contactorgaptechniques.Singleelementorphasedarraypiezoelectric probes may be used. EMAT or other non-standard probes may also be us
47、ed with suitable validation procedures agreeable to the contracting parties. 6.3.4 Theacousticcouplingshallbeobtainedbyusingamediumsuitableforthepurposeandcompatiblewiththematerialbeing examined.Water,couplinggelsorpastes,greasesandoilsaretypicallyused.Wateradditivessuchasenvironmentally-safewetting
48、 agentandcorrosioninhibitorsmaybeusedtoenhanceacousticcouplingandprotecttheexaminationpiece.Forexaminationwhere ambient temperatures are below 0C (32F)32F methyl alcohol or similar media may be used. For examination at elevated temperatures the examination surface or probes may require cool-down or
49、specially designed high-temperature couplants. The coupling medium selected shall provide uniform and reliable examination in the temperature range of intended use. Couplant and scanning conditions, including temperature, used for standardization shall be the same as that used in the examination. FIG. 2Schematic Representation of TOFD Scan (Left) and Data Display (Right) FIG. 3Sample Display (Real Data) of a Nonparallel Scan of a Weld with Flaws Identied E2373/E2373M14 46.3.5 Examination should
