1、Designation: E2928/E2928M 13Standard Practice forExamination of Drillstring Threads Using the AlternatingCurrent Field Measurement Technique1This standard is issued under the fixed designation E2928/E2928M; the number immediately following the designation indicates the yearof original adoption or, i
2、n 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 describes procedures to be followed duringalternating current field
3、measurement examination of drill-string threads on tubulars used for oil and gas exploration andproduction for detection and, if required, sizing of service-induced surface breaking discontinuities transverse to the pipe.1.2 This practice is intended for use on threads in anymetallic material.1.3 Th
4、is practice does not establish acceptance criteria.Typical industry practice is to reject these connections ondetection of a confirmed crack.1.4 While the alternating current field measurement tech-nique is capable of detecting discontinuities in theseconnections, supplemental surface NDT methods su
5、ch asmagnetic particle testing for ferrous metals and penetranttesting for non-ferrous metals may detect more discontinuities.1.5 UnitsThe values stated in either inch-pound units orSI units are to be regarded separately as standard. The valuesstated in each system might not be exact equivalents; th
6、erefore,each system shall be used independently of the other. Combin-ing values from the two systems may result in nonconformancewith the standard.1.6 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 sta
7、ndard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E543 Specification for Agencies Performing NondestructiveTestingE1316 Terminology for Nondestructive ExaminationsE2216 Guide
8、for Evaluating Disposal Options for Concretefrom Nuclear Facility Decommissioning2.2 ASNT Standards3SNT-TC-1A Personnel Qualification and Certification inNondestructive TestingANSI/ASNT-CP-189 Standard for Qualification and Certifi-cation of Nondestructive Testing Personnel3. Terminology3.1 For defi
9、nitions of terms relating to this practice refer toTerminology E1316, Section A, Common NDT terms, andSection C, Electromagnetic testing. The following definitionsare specific to the alternating current field measurement tech-nique:3.2 Definitions:3.2.1 detectorone or more coils or elements used to
10、senseor measure a magnetic field; also known as a receiver.3.2.2 excitera device that generates a time varying elec-tromagnetic field, usually a coil energized with alternatingcurrent (AC); also known as a transmitter.3.2.3 uniform fieldas applied to nondestructive testingwith magnetic fields, the a
11、rea of uniform magnetic field overthe surface of the material under examination produced by aparallel induced alternating current, which has been passedthrough the testpiece and is observable beyond the directcoupling of the exciting coil.3.3 Definitions of Terms Specific to This Standard:3.3.1 alte
12、rnating current field measurement systemtheelectronic instrumentation, software, probes, and all associatedcomponents and cables required for performing an examinationusing the alternating current field measurement technique.3.3.2 boxthe female thread in a drillstring connection.3.3.3 Bxthe x compon
13、ent of the magnetic field, parallel tothe thread root, the magnitude of which is proportional to thecurrent density set up by the electric field.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.07 onElectro
14、magnetic Method.Current edition approved June 1, 2013. Published June 2013. DOI: 10.1520/E2928_E2928M13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standard
15、s Document Summary page onthe ASTM website.3Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United Stat
16、es13.3.4 Bzthe z component of the magnetic field normal tothe examined pipe surface, the magnitude of which is propor-tional to the lateral deflection of the induced currents in theplane of that surface.3.3.5 configuration datastandardization data and instru-mentation settings for a particular probe
17、 stored in a computerfile.3.3.6 data sample ratethe rate at which data is digitizedfor display and recording, in data points per second.3.3.7 longitudinalfollowing from the above definition, alongitudinal discontinuity is parallel to the pipe axis andtherefore perpendicular to the scan direction.3.3
18、.8 operational standardization blocka reference stan-dard with specified artificial notches, used to confirm theoperation of the system.3.3.9 pinthe male thread in a drillstring connection.3.3.10 satellite signalsBx and Bz signals observed whenthe probe passes a discontinuity in an adjacent thread r
19、oot.3.3.11 surface plotfor use with array probes. This type ofplot has one component of the magnetic field plotted over anarea, typically as a color contour plot or 3-D wire frame plot.3.3.12 time base plotsthese plot the relationship betweenBx or Bz values with time.3.3.13 transverseas is normal in
20、 drilling, the terms trans-verse and longitudinal are defined in reference to the pipe axis.Therefore, a transverse discontinuity is parallel to the threadand hence to the scan direction. This is different to the situationfor weld inspection, covered in Guide E2216.3.3.14 X-Y Plotan X-Y graph with t
21、wo orthogonal com-ponents of magnetic field plotted against each other.NOTE 1Different equipment manufacturers may use slightly differentterminology. Reference should be made to the equipment manufacturersdocumentation for clarification.4. Summary of Practices4.1 In a basic alternating current field
22、 measurement system,a small probe is moved around the thread root. The probecontains an exciter coil, which induces anAC magnetic field inthe material surface aligned to the direction of the thread root.This, in turn, causes alternating current to flow across thethreads. The depth of penetration of
23、this current varies withmaterial type and frequency but is typically 0.004 in. 0.1 mmdeep in magnetic materials and 0.08 to 0.3 in. 2 to 7 mm deepin non-ferrous materials. Any surface breaking discontinuitieswithin a short distance of either side of the scan line at thislocation will interrupt or di
24、sturb the flow of the alternatingcurrent. Measurement of the absolute quantities of the twomajor components of the surface magnetic fields (Bx and Bz)determines the severity of the disturbance (see Fig. 1) and thusthe severity of the discontinuity. Discontinuity sizes, such ascrack length and depth,
25、 can be estimated from the values ofthese quantities or the physical locations of key points, or both,selected from the Bx and Bz traces along with the standardiza-tion data and instrument settings from each individual probe.This discontinuity sizing can be performed automatically usingsystem softwa
26、re. Discontinuities essentially perpendicular tothe thread may be detected (in ferritic metals only) by the fluxleakage effect.4.2 Configuration data is loaded at the start of the exami-nation. System sensitivity and operation is verified using anoperation standardization block. System operation is
27、checkedand recorded prior to and at regular intervals during theexamination. This can be accomplished using discontinuity-sizing tables in the system software. Data is recorded in amanner that allows archiving and subsequent recall for eachthread. Evaluation of examination results may be conducted a
28、tthe time of examination or at a later date. The examinergenerates an examination report detailing complete results ofthe examination.5. Significance and Use5.1 The purpose of the alternating current field measure-ment method is to evaluate threads for surface breakingdiscontinuities such as fatigue
29、 cracks running along the threadroot. The examination results may then be used to determinethe fate of the tool. This may involve re-examination by analternative technique, immediate scrapping of the tool, orreworking to remove discontinuities (beyond the scope of thispractice). This practice is not
30、 intended for the examination ofthreads for non-surface breaking discontinuities.6. Basis of Application6.1 Personnel Qualificationif specified in the contractualagreement, personnel performing examinations to this practiceshall be qualified in accordance with a nationally or interna-tionally recogn
31、ized NDT personnel qualification practice orstandard such as ANSI/ASNT-CP-189 or SNT-TC-1A or asimilar document and certified by the employer or certifyingagent, as applicable. The practice or standard used and itsFIG. 1 Example Bx and Bz Traces as a Probe Passes Over aCrack (The orientation of the
32、traces may differ depending uponthe instrumentation.)E2928/E2928M 132applicable revision shall be identified in the contractual agree-ment between the using parties6.2 Qualification of Nondestructive Evaluation Agenciesifspecified in the contractual agreement, NDT agencies shall bequalified and eval
33、uated as described in Specification E543,with reference to sections on electromagnetic examination. Theapplicable edition of Specification E543 shall be specified inthe contractual agreement.7. Job Scope and Requirements7.1 The following items may require agreement by theexamining party and their cl
34、ient and should be specified in thepurchase document or elsewhere:7.1.1 Location and type of threaded component to beexamined, design specifications, degradation history, previousnondestructive examination results, maintenance history, pro-cess conditions, and specific types of discontinuities that
35、arerequired to be detected, if known.7.1.2 The maximum recommended probe scan speed is tobe stated by the manufacturer. However, detection of smallerdiscontinuities requires a slower probe scan speed or cleaningof surface, or both.7.1.3 Size, material grade and type, and configuration ofthreads to b
36、e examined.7.1.4 A thread numbering or identification system.7.1.5 Extent of examination, for example: complete orpartial coverage, which threads and to what extent.7.1.6 Type of alternating current field measurement instru-ment and probe; and description of operations standardizationblock used, inc
37、luding such details as dimensions and material.7.1.7 Required thread cleanliness.7.1.8 Environmental conditions, equipment and prepara-tions that are the responsibility of the client; common sourcesof noise that may interfere with the examination, such as motordrive for rotary table.7.1.9 Complement
38、ary methods or techniques may be usedto obtain additional information.7.1.10 Acceptance criteria to be used in evaluating discon-tinuities.7.1.11 Disposition of examination records and referencestandards.7.1.12 Format and outline contents of the examinationreport.8. Interferences8.1 This section des
39、cribes items and conditions, which maycompromise the alternating current field measurement tech-nique.8.2 Material Properties:8.2.1 Although there are unlikely to be permeability differ-ences in a ferromagnetic material between different parts of athread, if a probe is scanned across a permeability
40、change suchas an area of residual magnetism, this may produce indicationswhich could be similar to those from a discontinuity. Differ-entiation between a discontinuity signal and a permeabilitychange signal can be achieved by comparing scans fromneighboring threads. The signal from a discontinuity w
41、ill dieaway quickly. If there is no significant change in indicationamplitude two or more threads away along the pipe axis thenthe indication is likely due to the permeability changes in thecomponent.8.3 Magnetic State:8.3.1 DemagnetizationIt must be ensured that the surfacebeing examined is in a lo
42、w magnetization state, or that anymagnetization is uniform over the surface. Therefore theprocedure followed with any previous magnetic techniquedeployed must include demagnetization of the surface, orensuring that connections are magnetically saturated. This isbecause areas of remnant magnetization
43、, particularly where theleg of a magnetic particle examination yoke was sited, canproduce loops in the X-Y plot, which may sometimes beconfused with a discontinuity indication.8.4 Thread Geometry:8.4.1 When a probe scans away from the shoulder of a pinconnection, the Bx indication value will decreas
44、e with littlechange in the Bz value. In the representative plot of Fig. 2, thisappears as a drop in the X-Y plot. The Bx indication value willalso decrease as a probe approaches the open end of a thread(pin or box).8.5 Crack Geometry Effects:8.5.1 Since the effect of a discontinuity on the signals c
45、an bedetected some distance away, “satellite” signals are observedas the probe passes one thread (or two threads) away from asufficiently-large discontinuity. The satellite signals will besmaller than the main discontinuity signal, and symmetricallyspaced one thread revolution either side. Care shou
46、ld be takennot to classify these signals as additional discontinuities.8.5.2 A large discontinuity may jump across a thread crownfrom one root to the neighboring one. This causes a sudden risein Bx signal where the discontinuity leaves the root, and aFIG. 2 Example X-Y Plot Produced by Plotting the
47、Bx (vertical)and Bz (horizontal) Together (The orientation of the plot may dif-fer depending upon the instrumentation.)E2928/E2928M 133sudden decrease in Bx signal at the same place in theneighboring thread where the discontinuity enters the root.8.5.3 Line Contactwhen contacts occur across a discon
48、ti-nuity then minor loops occur within the main X-Y plot loopproduced by the discontinuity. This can be differentiated fromadjacent multiple discontinuities when there will be a numberof separate loops, each returning to the background level.8.5.4 Longitudinal Discontinuitiesin the unlikely eventtha
49、t a discontinuity exists parallel to the pipe axis then the Bxmay rise instead of fall and the Bz signal will remain the sameas for a short transverse discontinuity. The X-Y plot will thengo upwards instead of down in the representative plot of Fig. 2.The extent of this flux leakage signal above the surface isrelated to the opening of the discontinuity, so it may not beseen for tightly closed discontinuities.8.6 Instrumentation:8.6.1 The operator should be aware of indicators of noise,saturation or signal distortion particular to the instrument beingus
