1、Designation: E 2096 05Standard Practice forIn Situ Examination of Ferromagnetic Heat-Exchanger TubesUsing Remote Field Testing1This standard is issued under the fixed designation E 2096; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, 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 describes procedures to be followed duringremote field examination of installed ferroma
3、gnetic heat-exchanger tubing for baseline and service-induced discontinui-ties.1.2 This practice is intended for use on ferromagnetic tubeswith outside diameters from 0.500 to 2.000 in. 12.70 to 50.80mm, with wall thicknesses in the range from 0.028 to 0.134 in.0.71 to 3.40 mm.1.3 This practice does
4、 not establish tube acceptance criteria;the tube acceptance criteria must be specified by the usingparties.1.4 The values stated in either inch-pound units or SI unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall
5、be used independently of the other. Combiningvalues from the two systems may result in nonconformancewith the standard.1.5 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 practice to establish appro-pri
6、ate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 543 Practice for Agencies Performing NondestructiveTestingE 1316 Terminology for Nondestructive Examinations2.2 Other Documents:ASNT SNT-TC-1A Recommen
7、ded Practice for Nonde-structive Testing Personnel Qualification and Certifica-tion3Can CGSB-48.9712-95 Qualification of NondestructiveTesting Personnel, Natural Resources Canada43. Terminology3.1 GeneralDefinitions of terms used in this practice canbe found in Terminology E 1316, Section A, “Common
8、 NDTTerms,” and Section C, “Electromagnetic Testing.”3.2 Definitions:3.2.1 detector, none or more coils or elements used tosense or measure magnetic field; also known as a receiver.3.2.2 exciter, na device that generates a time-varyingelectromagnetic field, usually a coil energized with alternatingc
9、urrent (ac); also known as a transmitter.3.2.3 nominal tube, na tube or tube section meeting thetubing manufacturers specifications, with relevant propertiestypical of a tube being examined, used for reference ininterpretation and evaluation.3.2.4 remote field, nas applied to nondestructive testing,
10、the electromagnetic field which has been transmitted throughthe test object and is observable beyond the direct couplingfield of the exciter.3.2.5 remote field testing, na nondestructive test methodthat measures changes in the remote field to detect andcharacterize discontinuities.3.2.6 using partie
11、s, nthe supplier and purchaser.3.2.6.1 DiscussionThe party carrying out the examinationis referred to as the “supplier,” and the party requesting theexamination is referred to as the “purchaser,” as required inForm and Style for ASTM Standards, April 2004. In commonusage outside this practice, these
12、 parties are often referred to asthe “operator” and “customer,” respectively.3.3 Definitions of Terms Specific to This Standard:1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.07 onElectromagnetic Methods.
13、Current edition approved January 1, 2005. Published January 2005. Originallyapproved in 2000. Last previous edition approved in 2000 as E 2096 - 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar
14、ds volume information, refer to the standards Document Summary page onthe ASTM website.3Available from TheAmerican Society for Nondestructive Testing (ASNT), P.O.Box 28518, 1711 Arlingate Lane, Columbus, OH 43228-0518.4Available from CGSB Sales Centre; Place du Portage, Phase 3, 6B1; 11 LaurierStree
15、t, Hull QC, Canada K1A 1G6.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.3.1 flaw characterization standard, na standard used inaddition to the RFT system reference standard, with artificial orservice-induced flaws, used for flaw
16、 characterization.3.3.2 nominal point, na point on the phase-amplitudediagram representing data from nominal tube.3.3.3 phase-amplitude diagram, na two-dimensional rep-resentation of detector output voltage, with angle representingphase with respect to a reference signal, and radius represent-ing am
17、plitude (Fig. 1a and 1b).3.3.3.1 DiscussionIn this practice, care has been taken touse the term “phase angle” (and “phase”) to refer to an angularequivalent of time displacement, as defined in TerminologyE 1316. When an angle is not necessarily representative oftime, the general term “angle of an in
18、dication on the phase-amplitude diagram” is used.3.3.4 RFT system, nthe electronic instrumentation,probes, and all associated components and cables required forperforming RFT.3.3.5 RFT system reference standard, na reference stan-dard with specified artificial flaws, used to set up and standard-ize
19、a remote field system and to indicate flaw detectionsensitivity.3.3.6 sample ratethe rate at which data is digitized fordisplay and recording, in data points per second.3.3.7 strip chart, na diagram that plots coordinates ex-tracted from points on a phase-amplitude diagram versus timeor axial positi
20、on (Fig. 1c).3.3.8 zero point, na point on the phase-amplitude diagramrepresenting zero detector output voltage.3.3.8.1 DiscussionData on the phase-amplitude diagramare plotted with respect to the zero point. The zero point isseparate from the nominal point unless the detector is config-ured for zer
21、o output in nominal tube. The angle of a flawindication is measured about the nominal point.3.4 Acronyms:Acronyms:3.4.1 RFT, nremote field testing4. Summary of Practice4.1 The RFT data is collected by passing a probe througheach tube. The electromagnetic field transmitted from theexciter to the dete
22、ctor is affected by discontinuities; by thedimensions and electromagnetic properties of the tube; and byobjects in and around the tube that are ferromagnetic orconductive. System sensitivity is verified using the RFT systemFIG. 1 A and B: Typical Phase-Amplitude Diagrams Used in RFT; C: Generic Stri
23、p Chart With FlawE2096052reference standard. System sensitivity and settings are checkedand recorded prior to and at regular intervals during theexamination. Data and system settings are recorded in amanner that allows archiving and later recall of all data andsystem settings for each tube. Interpre
24、tation and evaluation arecarried out using one or more flaw characterization standards.The supplier generates a final report detailing the results of theexamination.5. Significance and Use5.1 The purpose of RFT is to evaluate the condition of thetubing. The evaluation results may be used to assess t
25、helikelihood of tube failure during service, a task which is notcovered by this practice.5.2 Principle of Probe OperationIn a basic RFT probe,the electromagnetic field emitted by an exciter travels outwardsthrough the tube wall, axially along the outside of tube, andback through the tube wall to a d
26、etector5(Fig. 2a).5.2.1 Flaw indications are created when (1) in thin-walledareas, the field arrives at the detector with less attenuation andless time delay, (2) discontinuities interrupt the lines ofmagnetic flux, which are aligned mainly axially, or (3) discon-tinuities interrupt the eddy current
27、s, which flow mainly cir-cumferentially. A discontinuity at any point on the through-transmission path can create a perturbation; thus RFT hasapproximately equal sensitivity to flaws on the inner and outerwalls of the tube.55.3 Warning Against Errors in Interpretation. Characteriz-ing flaws by RFT m
28、ay involve measuring changes fromnominal (or baseline), especially for absolute coil data. Thechoice of a nominal value is important and often requiresjudgment. Practitioners should exercise care to use for nominalreference a section of tube that is free of damage (see definitionof “nominal tube” in
29、 3.2.3). In particular, bends used asnominal reference must be free of damage, and tube supportplates used as nominal reference should be free of metal loss inthe plate and in adjacent tube material. If necessary, a comple-mentary technique (as described in 11.12) may be used toverify the condition
30、of areas used as nominal reference.5Schmidt, T. R., “The Remote Field Eddy Current Inspection Technique,”Materials Evaluation, Vol. 42, No. 2, Feb. 1984, pp. 225-230.NOTE 1Arrows indicate flow of electromagnetic energy from exciter to detector. Energy flow is perpendicular to lines of magnetic flux.
31、FIG. 2 RFT ProbesE20960535.4 Probe ConfigurationThe detector is typically placedtwo to three tube diameters from the exciter, in a locationwhere the remote field dominates the direct-coupling field.5Other probe configurations or designs may be used to optimizeflaw detection, as described in 9.3.5.5
32、Comparison with Conventional Eddy-Current TestingConventional eddy-current test coils are typically configured tosense the field from the tube wall in the immediate vicinity ofthe emitting element, whereas RFT probes are typically de-signed to detect changes in the remote field.6. Basis of Applicati
33、on6.1 Personnel Qualification:6.1.1 Personnel performing examinations to this practiceshall be qualified as specified in the contractual agreement.6.1.2 Recommendations for qualification as an RFT systemoperator (Level I) are as follows:6.1.2.1 Forty hours of RFT (Level I) classroom training.6.1.2.2
34、 Written and practical examinations similar to thosedescribed by ASNT SNT-TC-1A or Can CGSB 48.9712-95.6.1.2.3 Two hundred and fifty hours of field experienceunder the supervision of a qualified RFT Level II, 50 % ofwhich should involve RFT instrumentation setup and opera-tion.6.1.3 Recommendations
35、for qualification as an RFT dataanalyst (Level II) are as follows:6.1.3.1 Forty hours of RFT (Level II) classroom training.6.1.3.2 Written and practical examinations similar to thosedescribed by ASNT SNT-TC-1A or Can CGSB 48.9712-95.6.1.3.3 Fifteen hundred hours of field experience under thesupervis
36、ion of a qualified RFT Level II or higher, 25 % ofwhich should involve RFT data analysis.NOTE 1At the time of approval of this practice, no nationally orinternationally recognized guideline for personnel qualification in RFTwas available.NOTE 2Eddy-current training provides some useful background to
37、RFT training. Previous Level II eddy-current certification may counttowards 50 % of training and experience hours for RFT Level I, providedthat the remaining experience hours are entirely involved in RFTinstrumentation setup and operation.6.2 Qualification of Nondestructive Testing AgenciesIfspecifi
38、ed in the contractual agreement, NDT agencies shall bequalified and evaluated as described in Practice E 543, withreference to sections on electromagnetic testing. The appli-cable edition of Practice E 543 shall be specified in thecontractual agreement.7. Job Scope and Requirements7.1 The following
39、items may require agreement between theusing parties and should be specified in the purchase documentor elsewhere:7.1.1 Location and type of tube component to be examined,design specifications, degradation history, previous nonde-structive examination results, maintenance history, processconditions,
40、 and specific types of flaws that are required to bedetected, if known.7.1.2 The maximum window of opportunity for work.(Detection of small flaws may require a slower probe pullspeed, which will affect productivity.)7.1.3 Size, material grade and type, and configuration oftubes to be examined.7.1.4
41、A tube numbering or identification system.7.1.5 Extent of examination, for example: complete orpartial coverage, which tubes and to what length, whetherstraight sections only, and the minimum radius of bends thatcan be examined.7.1.6 Means of access to tubes, and areas where access maybe restricted.
42、7.1.7 Type of RFT instrument and probe; and description ofreference standards used, including such details as dimensionsand material.7.1.8 Required operator qualifications and certification.7.1.9 Required tube cleanliness.7.1.10 Environmental conditions, equipment, and prepara-tions that are the res
43、ponsibility of the purchaser; commonsources of noise that may interfere with the examination.NOTE 3Nearby welding activities may be a major source of interfer-ence.7.1.11 Complementary methods or techniques (includingpossible tube removal) that may be used to obtain additionalinformation.7.1.12 Acce
44、ptance criteria to be used in evaluating flawindications.7.1.13 Disposition of examination records and referencestandards.7.1.14 Format and outline contents of the examinationreport.8. Interferences8.1 This section describes items and conditions which maycompromise RFT.8.2 Material Properties:8.2.1
45、Variations in the material properties of ferromagnetictubes are a potential source of inaccuracy. Impurities, segrega-tion, manufacturing process, grain size, stress history, presentstress patterns, temperature history, present temperature, mag-netic history, and other factors will affect the electr
46、omagneticresponse measured during RFT. The conductivity and perme-ability of tubes with the same grade of material are oftenmeasurably different. It is common to find that some of thetubes to be examined are newer tubes with different materialproperties.8.2.2 Permeability variations may occur at loc
47、ations wherethere was uneven temperature or stress during tube manufac-ture, near welds, at bends, where there were uneven heattransfer conditions during service, at areas where there is coldworking (such as that created by an integral finning process),and in other locations. Indications from permea
48、bility variationsmay be mistaken for, or obscure flaw indications. Effects maybe less severe in tubes that were stress-relieved during manu-facture.8.2.3 Residual stress, with accompanying permeabilityvariations, may be present when discontinuities are machinedinto a reference standard, or during th
49、e integral finning process.E20960548.2.4 RFT is affected by residual magnetism in the tubing,including residual magnetism created during a previous exami-nation using another magnetic method. Tubes with significantresidual magnetism should be demagnetized prior to RFT.8.3 Ferromagnetic and Conductive Objects:8.3.1 Objects near the tube that are ferromagnetic or con-ductive may reduce the sensitivity and accuracy of flawcharacterization in their immediate vicinity. Such objects mayin some cases be mistaken for flaws. Knowledge of themechanical layout of
