1、Designation: E426 12E426 16Standard Practice forElectromagnetic (Eddy-Current) (Eddy Current) Examinationof Seamless and Welded Tubular Products, Titanium,Austenitic Stainless Steel and Similar Alloys1This standard is issued under the fixed designation E426; the number immediately following the desi
2、gnation indicates the year oforiginal adoption or, in the case of revision, 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.This standard has been approved for use by
3、 agencies of the U.S. Department of Defense.1. Scope*1.1 This practice2 covers procedures for eddy-current eddy current examination of seamless and welded tubular products madeof relatively low conductivity materials such as titanium, stainless steel, and similar alloys, such as nickel alloys. Auste
4、niticchromium-nickel stainless steels, which are generally considered to be nonmagnetic, are specifically covered as distinguished fromthe martensitic and ferritic straight chromium stainless steels which are magnetic.1.2 This practice is intended as a guide for eddy-current eddy current examination
5、 of both seamless and welded tubular productsusing either an encircling coil or a probe-coil technique. Coils and probes are available that can be used inside the tubular product;however, their use is not specifically covered in this document. This type of examination is usually employed only to exa
6、minetubing which has been installed such as in a heat exchanger.1.3 This practice covers the examination of tubular products ranging in diameter from 0.125 to 5 in. (3.2 to 127.0 mm) and wallthicknesses from 0.005 to 0.250 in. (0.127 to 6.4 mm).1.4 For examination of aluminum alloy tubular products,
7、 see standard Practice E215.1.5 UnitsThe values stated in inch-pound units are to be regarded as standard. The values given in parentheses aremathematical conversions to SI units that are provided for information only and are not considered standard.1.6 This standard does not purport to address all
8、of the safety problems, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E215 Practice for Standa
9、rdizing Equipment for Electromagnetic Testing of Seamless Aluminum-Alloy TubeE543 Specification for Agencies Performing Nondestructive TestingE1316 Terminology for Nondestructive Examinations2.2 Other Documents:SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestru
10、ctive Testing4ANSI/ASNT CP-189 ASNT Standard for Qualification and Certification of Nondestructive Testing Personnel4NAS-410 NAS Certification and Qualification of Nondestructive Personnel (Quality Assurance Committee)5ISO 9712 Non-Destructive TestingCertification and Qualification of NDT Personnel6
11、1 This practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on ElectromagneticMethod.Current edition approved Aug. 1, 2012Dec. 1, 2016. Published September 2012December 2016. Originally approved in 1971. Last previ
12、ous edition approved in 20072012as E426 98 (2007).E426 12. DOI: 10.1520/E0426-12.10.1520/E0426-16.2 For ASME Boiler and Pressure Vessel Code applications see related Practice SE-426 in Section II of that Code.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Custome
13、r Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.5 A
14、vailable from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http:/www.aia-aerospace.org.6 Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Ve
15、rnier, Geneva,Switzerland, http:/www.iso.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately,
16、 ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive,
17、 PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Standard terminology relating to electromagnetic testing may be found in Terminology E1316, Section C, ElectromagneticTesting.4. Summary of Practice4.1 The examination is conducted using one of two general techniques sho
18、wn in Fig. 1. One of these techniques employs oneor more exciter and sensor coils which encircle the pipe or tube and through which the tubular product to be examined is passed.Some circuit configurations employ separate exciter and sensor coils; whereas other configurations employ one or more coils
19、 thatconcurrently function as both exciters and sensors. Alternating current passes through the exciting coil which by reason of itsproximity induces current in the tubular product. The sensor coil detects the resultant electromagnetic flux related to these currents.The presence of discontinuities i
20、n the tubular product will affect the normal flow of currents and this change is detected by thesensor. The encircling coil technique is capable of examining the entire 360-deg expanse of the tubular product.4.2 Another technique employs a probe coil with one or more exciters and sensors which is br
21、ought in close proximity of thesurface of the tubular product to be examined. Since the probe is generally small and does not encircle the article being examined,it examines only a limited area in the vicinity of the probe. If it is desired to examine the entire volume of the tubular product,it is c
22、ommon practice to either rotate the tubular product or the probe. In the case of welded tubular products frequently only theweld is examined by scanning along the weld zone. In the case where the tubular products are joined by welding and the probeis rotated, the probe is orbited about the central a
23、xis of the tube such that a circumferential examination of the tube and/or weldmay be made. The depth of penetration of the interrogating magnetic fields into the tubular product may be smaller for this typeof probe coil compared to the encircling coil.5. Significance and Use5.1 Eddy-current Eddy cu
24、rrent testing is a nondestructive method of locating discontinuities in a product. Changes inelectromagnetic response caused by the presence of discontinuities are detected by the sensor, amplified and modified in order toFIG. 1 Sketch Showing Encircling-Coil and Probe-Coil Techniques for Electromag
25、netic Examination of Tubular ProductsE426 162actuate audio or visual indicating devices, or both, or a mechanical marker. Signals can be caused by outer surface, inner surface,or subsurface discontinuities. The eddy-current eddy current examination is sensitive to many factors that occur as a result
26、 ofprocessing (such as variations in conductivity, chemical composition, permeability, and geometry) as well as other factors notrelated to the tubing. Thus, all received indications are not necessarily indicative of defective tubing.6. Basis of Application6.1 If specified in the contractual agreeme
27、nt, personnel performing examinations to this practice shall be qualified in accordancewith a nationally recognized NDT personnel qualification practice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A,NAS-410, ASNT-ACCP, ISO 9712, or a similar document and certified by the certifying agency, as appl
28、icable. The practice orstandard used and its applicable revision shall be identified in the contractual agreement between the using parties.NOTE 1MIL-STD-410 is canceled and has been replaced with NAS-410, however, it may be used with agreement between contracting parties.6.2 If specified in the con
29、tractual agreement, NDT agencies shall be qualified and evaluated in accordance with SpecificationE543. The applicable edition of Specification E543 shall be specified in the contractual agreement.7. Apparatus7.1 Electronic ApparatusThe electronic apparatus shall be capable of energizing the examina
30、tion coils or probes withalternating currents of suitable frequencies and shall be capable of sensing the changes in the electromagnetic response of thesensors. Equipment may include a detector, phase discriminator, filter circuits, modulation circuits, magnetic-saturation devices,recorders, and sig
31、naling devices as required for the particular application.7.2 Examination CoilsExamination coils shall be capable of inducing current in the tube and sensing changes in the electricalcharacteristics of the tube.NOTE 2Fill factor effect is an important consideration since coupling variations can affe
32、ct the examination significantly.7.3 Probe CoilsProbe coils shall be capable of inducing current in the tube and sensing changes in the electrical characteristicsof the tube (Note 3). Probes generally consist of an exciting coil and sensing coil or Hall element mounted in a common holder.A Hall elem
33、ent is a semiconductor that by reason of the Hall effect is capable of responding in a manner directly proportional tomagnetic-flux density. However, when used with an exciting coil, it should be remembered that eddy-current eddy current flow isinfluenced by the excitation frequency.NOTE 3Lift-off e
34、ffect is an important consideration since coupling variations can affect the examination significantly.7.4 Driving MechanismA mechanical device capable of passing the tube through the examination coil or past the probe. Itshall operate at a uniform speed with minimum vibration of coil, probe, or tub
35、e and maintain the article being examined in properregister or concentricity with the probe or examination coil. Where required, the mechanism shall be capable of uniformly rotatingthe tube or probe.7.5 Reference StandardThe standard used to adjust the sensitivity setting of the apparatus shall be s
36、ound and of the samenominal alloy, temper, and nominal dimensions as the lot of tubes or pipes to be examined on a production basis. It shall be ofsufficient length to permit the required spacing of the artificial discontinuities (at least 4 ft, and preferably longer). Artificialdiscontinuities made
37、 in the tube or pipe shall be centered as nearly as possible on one inside or outside diameter surface of thetube and shall preferably be of one of the following types:7.5.1 HolesHoles that are usually drilled completely through the wall may be used. Care should be taken during drilling toavoid dist
38、ortion of the tube (or pipe) and hole.7.5.2 NotchesNotches may be produced by electric discharge machining (EDM), milling, or other means. Longitudinal ortransverse notches or both may be used (Note 4). Orientation, dimensions (width, length, and depth), and configuration of thenotches affect the re
39、sponse of the eddy-current eddy current system. Notch depth is usually specified as a percentage of nominalwall thickness of the tubular product being examined. Notches may be placed on the outer, inner, or both surfaces of the reference(calibration) standard. Outer surface notches provide an indica
40、tion of system response to discontinuities originating on the outertube surface, whereas inner surface notches provide an indication of system response to discontinuities originating on the inner tubesurface (Note 5).NOTE 4Longitudinal notch standards are normally used when examining with rotating p
41、robe systems.NOTE 5The density of eddy currents decreases nearly exponentially with increasing distance from the surface nearest the coil, and the sensitivity tosubsurface discontinuities decreases with the change in depth allowing the use of phase analysis techniques.7.5.3 The configuration, orient
42、ation, and dimensions (diameter of holes and the width, length, and depth of notches) of theartificial discontinuities to be used for establishing acceptance limits should be subject to agreement between supplier andpurchaser.8. Adjustment and Standardization of Apparatus Sensitivity8.1 Select the a
43、pparatus, examination frequency, coil or probe, or both, design, phase discrimination, and other circuitry as wellas speed of examining which shall demonstrate the system capability for detecting the discontinuities of interest.E426 1638.2 Fabricate the applicable reference standard in accordance wi
44、th the agreement between the purchaser and tubing supplier.8.3 Adjust the apparatus to obtain an optimum signal-to-noise ratio with the minimum sensitivity required to detect the artificialdiscontinuities in the reference standard. Do this under conditions (such as examining speed) identical to thos
45、e to be used inproduction examination of the tubular products.8.4 Determine the end effect by using a special reference tube or pipe containing a series of notches or holes near one or bothof the ends and passing this reference standard through the system at production examination speeds. If notches
46、 or holes are placednear only one of the ends, pass the tube through the system backwards and forwards.9. Procedure9.1 Standardize the apparatus at the start of the examination run using the reference standard. The recommended maximuminterval between re-standardization is four hours although more or
47、 less frequent re-standardization may be done by agreementbetween using parties, or whenever improper functioning of the equipment is suspected. If improper functioning is found,re-standardize the apparatus and re-examine all tubes or pipes examined during the period since the last successful standa
48、rdization.9.2 Pass the lot of tubes or pipes to be examined through the examination coil or past the probe coil of the apparatus adjustedto the sensitivity as described in Section 8. Set aside tubes or pipes with discontinuities indicated by the apparatus. It isrecommended that tubes with discontinu
49、ity indications be re-examined in accordance with the purchase specification.9.3 Tubes or pipes may be examined in the final drawn, annealed, heat treated, as-welded, or other step in processing. The pointin processing at which examination is made should be agreed upon by the supplier and the purchaser. The tubes should be freeof any substance that may interfere with the examination.10. Supplemental Information Regarding Eddy-Current Eddy Current Examination of High Alloy Steels and SimilarAlloys10.1 In the eddy-current eddy current examination of austenitic c
