1、Designation: E2775 11Standard Practice forGuided Wave Testing of Above Ground Steel PipeworkUsing Piezoelectric Effect Transduction1This standard is issued under the fixed designation E2775; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides a procedure for the use of guidedwave testing (GWT), also previously known
3、as long rangeultrasonic testing (LRUT) or guided wave ultrasonic testing(GWUT).1.2 GWT utilizes ultrasonic guided waves, sent in the axialdirection of the pipe, to non-destructively test pipes for defectsor other features by detecting changes in the cross-sectionand/or stiffness of the pipe.1.3 GWT
4、is a screening tool. The method does not providea direct measurement of wall thickness or the exact dimensionsof defects/defected area; an estimate of the defect severityhowever can be provided.1.4 This practice is intended for use with tubular carbonsteel or low-alloy steel products having Nominal
5、Pipe size(NPS) 2 to 48 corresponding to 60.3 to 1219.2 mm (2.375 to 48in.) outer diameter, and wall thickness between 3.81 and 25.4mm (0.15 and 1 in.).1.5 This practice covers GWT using piezoelectric transduc-tion technology.1.6 This practice only applies to GWT of basic pipeconfiguration. This incl
6、udes pipes that are straight, constructedof a single pipe size and schedules, fully accessible at the testlocation, jointed by girth welds, supported by simple contactsupports and free of internal, or external coatings, or both; thepipe may be insulated or painted.1.7 This practice provides a genera
7、l procedure for perform-ing the examination and identifying various aspects of particu-lar importance to ensure valid results, but actual interpretationof the data is excluded.1.8 This practice does not establish an acceptance criterion.Specific acceptance criteria shall be specified in the contract
8、ualagreement by the responsible system user or engineering entity.1.9 UnitsThe values stated in SI units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.10 This standard doe
9、s 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.2. Referenced Documents2.1 ASTM Stan
10、dards:2E543 Specification for Agencies Performing Nondestruc-tive TestingE1065 Guide for Evaluating Characteristics of UltrasonicSearch UnitsE1316 Terminology for Nondestructive ExaminationsE1324 Guide for Measuring Some Electronic Characteris-tics of Ultrasonic Examination Instruments3. Terminology
11、3.1 Definitions of Terms Specific to This Standard:3.1.1 circumferential extentthe length of a pipe feature inthe circumferential direction, usually given as a percentage ofthe pipe circumference.3.1.2 coherent noiseindications caused by real disconti-nuities causing a background noise, which expone
12、ntially de-cays with distance.3.1.3 Cross-Sectional Area Change (CSC)the CSC iscalculated assuming that a reflection is purely caused by achange in cross-section. It is given as a percentage of the totalcross-section. However it is commonly used to report therelative amplitude of any signal regardle
13、ss of its source.3.1.4 Distance Amplitude Correction (DAC) curvea ref-erence curve plotted using reference reflections (for example,weld reflections) at different distances from the test position.This curve corrects for attenuation and amplitude drops whenestimating the cross-section change from a r
14、eflection at acertain distance.3.1.5 Estimated Cross Sectional Loss (ECL)this is some-times used instead of Cross-Sectional Area Change, where thefeature is related to a defect.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility
15、of Subcommittee E07.10 onSpecialized NDT Methods.Current edition approved July 15, 2011. Published July 2011. DOI:10.1520/E2775-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
16、tion, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6 flexural wavewave propagation mode that producesbending motion in the pipe.3.1.7 Guided Wave (GW)stress waves
17、 whose characteris-tics are constrained by the system material, geometry andconfiguration in which the waves are propagating.3.1.8 Guided Wave Testing (GWT)non-destructive testmethod that utilizes guided waves.3.1.9 longitudinal wavewave propagation mode that pro-duces compressional motion in the pi
18、pe.3.1.10 incoherent noiserandom indications caused byelectrical and ambient signal pollution, giving rise to a constantaverage noise floor. The terms “ambient noise” and “randomnoise” are also used.3.1.11 pipe feature pipe components including but notlimited to weld, support, flange, bend and flaw
19、(defect) causereflections of a guided wave due to a change in geometry.3.1.12 reflection amplitudethe amplitude of the reflectionsignal typically reported as CSC.3.1.13 reflector orientationthe circumferential position ofthe feature on the pipe. This is reported as the clock position ordegrees with
20、regards to the orientation of the transducer ring.3.1.14 Signal to Noise Ratio (SNR)Ratio of the amplitudeof any signal of interest to the amplitude of the averagebackground noise which includes both coherent and non-coherent types of noise as defined in Fig. 1.3.1.15 torsional wavewave propagation
21、mode that pro-duces twisting motion in the pipe.3.1.16 transducer ringa ring array of transducers that isattached around the circumference of the pipe to generate GW.It is also commonly known as the Ring.3.1.17 wave modea particular form of propagating wavemotion generated into a pipe, such as flexu
22、ral, torsional orlongitudinal.4. Summary of Practice4.1 GWT evaluates the condition of metal pipes to primarilyestablish the severity classification of defects by applying GWat a typical test frequency of up to 150 kHz, which travelsalong the pipe. Reflections are generated by the change incross-sec
23、tional area and/or local stiffness of the pipe.4.2 A transducer ring attached around the pipe screens thepipe in both directions simultaneously. It can evaluate longlengths of pipe, and is especially useful when access to the pipeis limited.4.3 This examination locates areas of thickness reduction(s
24、)and provides a severity classification as to the extent of thatdamage. The results are used to assess the condition of thepipe, to determine where damaged areas are located and theirFIG. 1 Typical GWT Results Collected in Normal Environment (Top) and in High Ambient Noise Environment (Bottom). (Bot
25、h results aredisplayed in the logarithmic amplitude scale.)E2775 112circumferential position on the pipe. The information can beused to program and prioritize additional inspection work andrepairs.4.4 Reflections produced by pipe features that are notassociated with areas containing possible defects
26、 are consid-ered as relevant signals. These features can be used for settingGW system DAC levels and identifying the relative positionand distance of discontinuities and areas containing possibledefects. Examples of these features are: circumferential welds,elbows, welded supports, vents, drainage,
27、insulation lugs andother welded attachments.4.5 Other sources of reflection may include changes insurface impedance of the pipe. These reflections are normallynot relevant, but should be analyzed and classified in aninterpretation process. Examples of these changes are presenceof pipe supports and c
28、lamps. In the advanced applicationswhich are not covered by this practice, these changes may alsoinclude various types of external/internal coatings, entrance ofthe pipe to ground or concrete wall.4.6 Inspection of the pipe section immediately connecting tobranch connections, bends or flanges are co
29、nsidered advanceapplications which are not covered by this practice.4.7 False echoes are produced by phenomena such asreverberations, incomplete control of direction, distortion atelbows and others. These signals should be analyzed andclassified as false echoes in the interpretation process.5. Signi
30、ficance and Use5.1 The purpose of this practice is to outline a procedure forusing GWT to locate areas in metal pipes in which wall losshas occurred due to corrosion or erosion.5.2 GWT does not provide a direct measurement of wallthickness, but is sensitive to a combination of the CSC andcircumferen
31、tial extent and axial extent of any metal loss. Basedon this information, a classification of the severity can beassigned.5.3 The GWT method provides a screening tool to quicklyidentify any discontinuity along the pipe. Where a possibledefect is found, follow-up inspection of suspected areas withult
32、rasonic testing or other NDT methods is normally requiredto obtain detailed thickness information, nature and extent ofdamage.5.4 GWT also provides some information on the axiallength of a discontinuity, provided that the axial length islonger than roughly a quarter of the wavelength.5.5 The identif
33、ication and severity assessment of any pos-sible defects is qualitative only. An interpretation process todifferentiate between relevant and non-relevant signals isnecessary.5.6 This practice only covers the application specified in thescope. The GWT method has the capability and can be used forappl
34、ications where the pipe is insulated, buried, in roadcrossings and where access is limited.5.7 GWT shall be performed by qualified and certifiedpersonnel, as specified in the contract or purchase order.Qualifications shall include training specific to the use of theequipment employed, interpretation
35、 of the test results andguided wave technology.5.8 A documented program which includes training, exami-nation and experience for the GWT personnel certificationshall be maintained by the supplying party.6. Basis of Application6.1 The following items are subject to contractual agree-ment between the
36、parties using or referencing this practice.6.2 Personnel QualificationsUnless otherwise specifiedin the contractual agreement, personnel performing examina-tions to this practice shall be qualified in accordance with oneof the following:6.2.1 Personnel performing examinations to this practiceshall b
37、e qualified in accordance with SNT-TC-1A and certifiedby the employer or certifying agency, as applicable. Otherequivalent qualification documents may be used when speci-fied in the contract or purchase order. The applicable revisionshall be the latest unless otherwise specified in the contractualag
38、reement between parties.6.2.2 Personnel qualification accredited by the GWT manu-facturers.6.3 This practice or standard used and its applicable revisionshall be identified in the contractual agreement between theusing parties.6.4 Qualifications of Non-destructive Testing AgenciesUnless otherwise sp
39、ecified in the contractual agreement, NDTagencies shall be qualified and evaluated as described in E543,the applicable edition of E543 shall be specified in thecontractual agreement.6.5 Procedure and TechniquesThe procedures and tech-niques to be utilized shall be specified in the contractualagreeme
40、nt. It should include the scope of the inspection, that is,the overall NDT examination intended to identify and estimatethe size of any indications detected by the examination, orsimply locate and provide a relative severity classification.6.6 Surface PreparationThe pre-examination site prepa-ration
41、 criteria shall be in accordance with 8.3 unless otherwisespecified.6.7 Required Interval of ExaminationThe required inter-val or the system time in service of the examination shall bespecified in the contractual agreement.6.8 Extent of the ExaminationThe extent of the examina-tion shall be in accor
42、dance with 6.5 above unless otherwisespecified. The extent should include but is not limited to:6.8.1 The sizes and length(s) of pipes to be inspected.6.8.2 Limitations of the method in the areas of application.6.8.3 Drawings of pipe circuits, pipe nomenclature andidentification of examination locat
43、ions.6.8.4 Pipe access method(s).6.8.5 Safety requirements.6.9 Reporting CriteriaThe test results of the examinationshall be documented in accordance with the contractual agree-ment. This may include requirements for permanent records ofthe collected data and test reports. The report documentationsh
44、ould include:6.9.1 Equipment inspector and test results reviewed by (ifapplicable).6.9.2 Date and time of the examination performed.6.9.3 Equipment used.6.9.4 Test procedure/specification used.E2775 1136.9.5 Acceptance criteria.6.9.6 Inspection location.6.9.7 Identification of areas inspected.6.9.8
45、Identification of the inspection range.6.9.9 Any other information deemed necessary to reproduceor duplicate test results.6.10 Re-examination of Repairs/Rework ItemsExamination of repaired/reworked items is not addressed inthis practice and if required shall be specified in the contractualagreement.
46、7. Apparatus7.1 The GWT apparatus shall include the following:7.1.1 Transducer Ring TransmitterA transduction systemusing piezoelectric effect for the generation of guided wavemodes with axial propagation on cylindrical pipes.7.1.2 Transducer Ring ReceiverA system for the detec-tion of the signal re
47、flected by the geometric features on thepipe, which can be the same as the transmitter or an analogoustransduction system.7.1.3 InstrumentationThe GWT instrumentation shall becapable of generating, receiving and amplifying electricalpulses within the frequency range used by GWT. Additionally,it shal
48、l be capable of communicating with a computer so thatcollected data can be processed and recorded.7.1.4 Processing SystemThis is a software interface forprocessing and analyzing the signal, capable of distinguishingat least one guided wave mode for the specific detectionsystem.8. Examination Procedu
49、re8.1 It is important to ensure that the proposed inspectionfalls within the capabilities of the technology and equipmentand that the using party or parties understand the capabilitiesand limitations as it applies to their inspection.8.2 Pre-examination Preparation:8.2.1 All test equipment shall have current and valid cali-bration certificates.8.2.2 Follow the equipment manufacturers recommenda-tions with regard to equipment pre-test verification and checklist. As a minimum this check list should include but is notlimited to:8.2.2.1 Electronics fully o
