1、Designation:E30995 (Reapproved 2006) Designation: E309 11Standard Practice forEddy-Current Examination of Steel Tubular Products UsingMagnetic Saturation1This standard is issued under the fixed designation E309; the number immediately following the designation indicates the year oforiginal adoption
2、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 specification has been approved for use by agencies of the Department of Defense.1.
3、Scope*1.1 This practice2covers a procedure for applying the eddy-current method to detect discontinuities in ferromagnetic pipe andtubing (Note 1) where the article being examined is rendered substantially non-magnetic by the application of a concentrated,strong magnetic field in the region adjacent
4、 to the examining coil.NOTE 1For convenience, the term tube or tubular product will hereafter be used to refer to both pipe and tubing.1.2 The procedure is specifically applicable to eddy-current examinationtesting methods using an encircling-coil assembly.However, eddy-current techniques that emplo
5、y either fixed or rotating probe-coil assemblies may be used to either enhancediscontinuity sensitivity on the large diameter tubular products or to maximize the response received from a particular type ofdiscontinuity.1.3 This practice is intended for use on tubular products having outside diameter
6、s from approximately14 to 10 in. (6.35 to 254.0mm). These techniques have been used for smaller and larger sizes however, and may be specified upon contractual agreementbetween the purchaser and the supplier.1.4 This practice does not establish acceptance criteria; they must be specified by the usin
7、g party or parties.1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.2. Referenced Documents2.1 ASTM Standards:3E543 Specification fo
8、r Agencies Performing Nondestructive TestingE1316 Terminology for Nondestructive Examinations2.2 Other Documents:SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestructive Testing4ANSI/ASNT CP-189 ASNT Standard for Qualification and Certification of Nondestructive
9、 Testing Personnel42.3 Military Standard:MIL-STD-410E Nondestructive Testing Personnel Qualification and Certification53. Terminology3.1GeneralStandard terminology relating to electromagnetic examination may be found in Terminology3.1 GeneralFor definitions of terms used in this practice, refer to T
10、erminology E1316, Section C, “Electromagnetic Testing.”.1This 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 July 1, 2006. Published July 2006. Originally app
11、roved in 1966. Last previous edition approved in 2001 as E309-95(2001). DOI:10.1520/E0309-95R06.Current edition approved Feb. 15, 2011. Published March 2011. Originally approved in 1966. Last previous edition approved in 2006 as E309 - 95(2006). DOI:10.1520/E0309-11.2For ASME Boiler and Pressure Ves
12、sel Code applications see related Recommended Practice SE 309 in Section V of that Code.3For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summ
13、ary page on the ASTM website.4Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.5Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-
14、5094, Attn: NPODS.19111-5098,http:/dodssp.daps.dla.mil.1This 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
15、accurately, 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 standard.Copyright ASTM International, 100 Barr H
16、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Practice4.1 The examination is conducted using one of two general techniques shown in Fig. 1.4.1.1 One technique employs one or more exciter and sensor coils that encircle the tube and through which the tubular p
17、roductto be examined is passed. Some circuit configurations employ one or more coils that concurrently function as both exciters andsensors. Alternating current passes through the exciting coil which, by reason of its proximity, induces corresponding currents(eddy currents) to flow in the tubular pr
18、oduct. The sensor coil detects the resultant electromagnetic flux related to these currents.The presence of discontinuities in the tubular product will alter the normal flow of currents and this change is detected by thesensor. The encircling-coil technique is capable of examining the entire circumf
19、erence of a tubular product.4.1.2 Another technique employs a probe coil with one or more sensors that are in close proximity to the surface of the tubularproduct to be examined. Since the probe is generally small and does not encircle the article being examined, it examines only alimited area in th
20、e vicinity of the probe. This technique is frequently used for examination of welded tubular products in whichonly the weld is examined by scanning along the weld zone.4.1.3 The magnetic permeability of ferromagnetic materials severely limits the depth of penetration of induced eddy currents.Further
21、more, the permeability variations inherent in ferromagnetic tubular products often cause anomalous test results. A usefulsolution to this problem involves the application of a strong external magnetic field in the region of the examining coil or probe.This technique, known as magnetic saturation, is
22、 applied to a magnetic material, such as a steel tube, to suppress the magneticcharacteristics of permeability, hysteresis, etc., so that the material under examination is effectively rendered nonmagnetic. Whenachieved, this condition allows an eddy-current system to measure and detect electrical re
23、sistivity and geometrical variations(including defects) independent of concurrent variations in magnetic properties.4.1.4 Changes in electromagnetic response caused by the presence of discontinuities are detected by the sensor, amplified, andmodified in order to actuate audio or visual indicating de
24、vices, or both, a mechanical marker, or a signal-recording device, or acombination of these. Signals can be caused by outer surface, inner surface, or subsurface discontinuities if the eddy-current(a) Encircling Coil.(b) Probe Coillongitudinal scanning of weld seam only.(c) Probe Coilscanning along
25、a spiral path.FIG. 1 Encircling-Coil and Probe-Coil Techniques for Electromagnetic Testing of Tubular ProductsE309 112frequency provides sufficient depth of penetration (see 11.15.4). The eddy-current method is sensitive to metallurgical variationsthat occur as a result of processing, thus all recei
26、ved indications are not necessarily indicative of defective tubing.5. Significance and Use5.1 The purpose of this practice is to outline a procedure for the detection and location of discontinuities such as pits, voids,inclusions, cracks, or abrupt dimensional variations in ferromagnetic tubing usin
27、g the electromagnetic (eddy-current) method.Furthermore, the relative severity of a discontinuity may be indicated, and a rejection level may be set with respect to themagnitude of the indication.5.2 The response from natural discontinuities can be significantly different than that from artificial d
28、iscontinuities such as drilledholes or notches. For this reason, sufficient work should be done to establish the sensitivity level and set-up required to detectnatural discontinuities of consequence to the end use of the product.5.3 Eddy-current examinationtesting systems are generally not sensitive
29、 to discontinuities adjacent to the ends of the tube. Theextent of the end effect region can be determined in accordance with 8.6.5.4 Since the density of eddy currents decreases nearly exponentially as the distance from the external surface increases, theresponse to deep-seated discontinuities decr
30、eases and some deep-seated discontinuities may give no detectable repsonse.5.5 Discontinuity orientation also affects the system response and should be taken into consideration when establishing theexamination sensitivity.5.6 In preparing a reference standard for welded tubing, artificial discontinu
31、ities should be placed in both the weld metal andthe parent metal when the responses are expected to be different and if both are to be examined. The apparatus is then adjustedto obtain an optimum signal-to-noise ratio.5.6.1 When examining only the weld area, the discontinuities shall be placed only
32、 in the weld area.5.7 The examination frequency and the type of apparatus being used should be considered when choosing the examining speed.Certain types of equipment are effective only over a given speed range; therefore, the examining speed should fall within this range.5.8 Discontinuities such as
33、 scratches or seams that are continuous and uniform over the full length of the tube may not alwaysbe detected with differential encircling coils or probes scanned along the tube length.6. Basis of Application6.1 The following acceptance criteria may be specified in the purchase specification, contr
34、actual agreement, or elsewhere, andmay require agreement between the purchaser and the supplier:6.1.1 Time of examination or point(s) in the manufacturing process at which the material will be examined,6.1.2 Maximum time interval between equipment calibration checks,6.1.3 Methods for determining the
35、 extent of end effect,6.1.4 Size and type of product,6.1.5 Type, method of manufacture, dimensions, location, and number of artificial discontinuities to be placed on the referencestandard,6.1.6 Methods of verifying dimensions and allowable tolerances of artificial discontinuities,6.1.7 Extent of ex
36、amination, and6.1.8 Disposition of material with indications.6.1.9 Operator Qualification and CertificationIf required, NDT personnel shall be qualified in accordance with a nationallyrecognized NDT personnel qualification practice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A, MIL-STD-410, or asi
37、milar document. The practice or standard used and its applicable revision shall be documented in the contractual agreementbetween the using parties.NOTE 2MIL-STD-410 is canceled and has been replaced with NAS-410; however, it may be used with agreement between contracting parties.6.1.10 Qualificatio
38、n of Nondestructive AgenciesIf specified in the contractual agreement, NDT agencies shall be qualified andevaluated in accordance with Practice E543. The applicable edition of Practice E543 shall be specified in the contractualagreement.7. Apparatus7.1 Electronic ApparatusThe electronic apparatus sh
39、all be capable of energizing the coils or probes with alternating currentsof a selected frequency and shall be capable of sensing the changes in the electromagnetic response of the sensors. Equipment mayinclude appropriate signal processing circuits such as a phase discriminator, filter circuits, et
40、c., as required for the particularapplication.7.2 Encircling-Coil AssemblyThe encircling-coil assembly shall consist of one or more electrical coils that encircle the articlebeing examined.7.3 Probe-Coil AssemblyThe probe-coil assembly normally contains an exciting coil and a sensor, although in som
41、e cases theexciter and sensor are one and the same.7.4 Magnetic Saturation SystemThe magnetic saturation system shall consist of a suitable method of applying a strongmagnetic field to the region of the tube adjacent to the coil or probe-coil assembly so as to render that region of the tube effectiv
42、elynonmagnetic. Typical systems employ either permanent magnets or electromagnets.E309 1137.5 Driving MechanismThe movement of the tube through the coil or past the probe shall be performed at uniform speed andwith minimum vibration of the tube, coil, and probe.7.6 Reference StandardThe standard use
43、d to adjust the sensitivity of the apparatus shall be free of interfering discontinuitiesand shall be of the same nominal alloy, temper, and dimensions as the tubes to be examined on a production basis. It shall be ofsufficient length to permit the spacing of artificial discontinuities to provide go
44、od signal resolution and be mechanically stablewhile in the examining position in the apparatus. Artificial discontinuities placed in the tube shall be one or more of the followingtypes. (See Fig. 2.)7.6.1 NotchesNotches may be produced by Electric Discharge Machining (EDM), milling, or other means.
45、 Longitudinal,transverse, or both may be used (Note 2Note 3). Orientation, dimensions (width, length, and depth), and configuration of thenotches affect the response of the eddy-current system. Notch depth is usually specified as a percentage of nominal wall thicknessof the tubular product being exa
46、mined. Notches may be placed on the outer, inner, or both surfaces of the reference standard. Outersurface notches provide an indication of system response to discontinuities originating on the outer tube surface; whereas innersurface notches provide an indication of system response to discontinuiti
47、es originating on the inner tube surface.NOTE 23Longitudinal notch standards are normally used when testing with a rotating-probe system.7.6.2 HolesDrilled holes may be used. They are usually drilled completely through the wall. Care should be taken duringdrilling to avoid distortion of the tube and
48、 hole.7.6.3 The configuration, orientation, 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 the purchaser andthe supplier.8. Adjustment and Standardiza
49、tion of Apparatus8.1 Select the apparatus, examining frequency, coil or probe configuration, magnetic saturation system, phase discrimination,and other circuitry, as well as speed of examination.8.2 Fabricate applicable reference standards in accordance with the agreement between the purchaser and the tubing supplier.8.3 Adjust the field strength of the magnetic saturation system to obtain an adequate level of magnetization in the tube inaccordance with 8.3.1 and 8.3.2. This is the minimum degree of magnetization required for the successful examination of the ty
