ASTM E243-97(2004)e1
(Practice)Standard Practice for Electromagnetic (Eddy-Current) Examination of Copper and Copper-Alloy Tubes
Standard Practice for Electromagnetic (Eddy-Current) Examination of Copper and Copper-Alloy Tubes
SIGNIFICANCE AND USE
Eddy-current examination is a nondestructive method of locating discontinuities in a product. Signals can be produced by discontinuities located either on the external or internal surface of the tube or by discontinuities totally contained within the walls. Since the density of eddy currents decreases nearly exponentially as the distance from the external surface increases, the response to deep-seated defects decreases.
Some indications obtained by this method may not be relevant to product quality; for example, a reject signal may be caused by minute dents or tool chatter marks that are not detrimental to the end use of the product. Irrelevant indications can mask unacceptable discontinuities. Relevant indications are those which result from nonacceptable discontinuities. Any indication above the reject level that is believed to be irrelevant shall be regarded as unacceptable until it is demonstrated by re-examination or other means to be irrelevant (see 10.3.2).
Eddy-current examination systems are generally not sensitive to discontinuities adjacent to the ends of the tube (end effect). On-line eddy-current examining would not be subject to end effect.
Discontinuities such as scratches or seams that are continuous and uniform for the full length of the tube may not always be detected.
SCOPE
1.1 This practice covers the procedures that shall be followed in eddy-current examination of copper and copper-alloy tubes for detecting discontinuities of a severity likely to cause failure of the tube. These procedures are applicable for tubes with outside diameters to 31/8 in. (79.4 mm), inclusive, and wall thicknesses from 0.017 in. (0.432 mm) to 0.120 in. (3.04 mm), inclusive, or as otherwise stated in ASTM product specifications; or by other users of this practice. These procedures may be used for tubes beyond the size range recommended, upon contractual agreement between the purchaser and the manufacturer.
1.2 The procedures described in this practice are based on methods making use of encircling annular test coil systems.
1.3 The values stated in inch-pound units are to be regarded as the standard. Note 1-This practice may be used as a guideline for the examination, by means of internal probe test coil systems, of installations using tubular products where the outer surface of the tube is not accessible. For such applications, the technical differences associated with the use of internal probe coils should be recognized and accommodated. The effect of foreign materials on the tube surface and signals due to tube supports are typical of the factors that must be considered.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E243–97 (Reapproved 2004)
Standard Practice for
Electromagnetic (Eddy-Current) Examination of Copper and
Copper-Alloy Tubes
This standard is issued under the fixed designation E243; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—Editorial changes were made throughout the standard in January 2004.
1. Scope 2. Referenced Documents
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1.1 This practice covers the procedures that shall be 2.1 ASTM Standards:
followed in eddy-current examination of copper and copper- B111 Specification for Copper and Copper-Alloy Seamless
alloy tubes for detecting discontinuities of a severity likely to Condenser Tubes and Ferrule Stock
cause failure of the tube. These procedures are applicable for B395 Specification for U-Bend Seamless Copper and Cop-
tubes with outside diameters to 3 ⁄8 in. [79.4 mm], inclusive, per Alloy Heat Exchanger and Condenser Tubes
and wall thicknesses from 0.017 in. [0.432 mm] to 0.120 in. B543 Specification for Welded Copper and Copper-Alloy
[3.04 mm], inclusive, or as otherwise stated inASTM product Heat Exchanger Tube
specifications; or by other users of this practice. These proce- E543 Practice for Evaluating Agencies that Perform Non-
dures may be used for tubes beyond the size range recom- destructive Testing
mended, upon contractual agreement between the purchaser E1316 Terminology for Nondestructive Examinations
and the manufacturer. 2.2 Other Documents:
1.2 The procedures described in this practice are based on SNT-TC-1A Recommended Practice for Nondestructive
methods making use of encircling annular examination coil Testing Personnel Qualification and Certification
systems. ANSI/ASNTCP-189 ASNT Standard for Qualification and
1.3 The values stated in inch-pound units are to be regarded Certification of Nondestructive Testing Personnel
as the standard. NAS-410 NAS Certification and Qualification of Nonde-
structive Personnel (Quality Assurance Committee)
NOTE 1—This practice may be used as a guideline for the examination,
bymeansofinternalprobeexaminationcoilsystems,ofinstallationsusing
3. Terminology
tubular products where the outer surface of the tube is not accessible. For
3.1 Definitions of Terms Specific to this Standard
such applications, the technical differences associated with the use of
internal probe coils should be recognized and accommodated. The effect 3.1.1 The following terms are defined in relation to this
of foreign materials on the tube surface and signals due to tube supports
standard.
are typical of the factors that must be considered.
3.1.1.1 artificial discontinuity reference standard—a stan-
1.4 This standard does not purport to address all of the dard consisting of a selected tube with defined artificial
safety concerns, if any, associated with its use. It is the discontinuities, used when adjusting the system controls to
responsibility of the user of this standard to establish appro- obtain some predetermined system output signal level. This
priate safety and health practices and determine the applica- standard may be used for periodic checking of the instrument
bility of regulatory limitations prior to use. during an examination.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
structive Testing and is the direct responsibility of Subcommittee E07.07 on Standards volume information, refer to the standard’s Document Summary page on
Electromagnetic Methods. the ASTM website.
Current edition approved January 1, 2004. Published February 2004. Originally AvailablefromTheAmericanSocietyforNondestructiveTesting(ASNT),P.O.
approved in 1967. Last previous edition approved in 1997 as E243-97. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518.
2 5
For ASME Boiler and Pressure Vessel Code applications see related Practice Available from Aerospace Industries Association of America, Inc., 1250 Eye
SE-243 in the Code. St., NW, Washington, DC 20005.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E243–97 (2004)
3.1.1.2 percent maximum unbalance standardization indicationabovetherejectlevelthatisbelievedtobeirrelevant
standard—a method of standardization that can be used with shall be regarded as unacceptable until it is demonstrated by
speed-insensitive instruments (see 3.1.1.4). The acceptance re-examination or other means to be irrelevant (see 10.3.2).
level of the examination is established at the operating exami- 5.3 Eddy-current examination systems are generally not
nation frequency as an accurate fraction of the maximum sensitivetodiscontinuitiesadjacenttotheendsofthetube(end
unbalance signal resulting from the end effect of a tube. Any effect). On-line eddy-current examining would not be subject
low-noise tube from the production run having a squared end to end effect.
may be used as this standard. This standard may be used for 5.4 Discontinuities such as scratches or seams that are
periodic checking of the instrument during an examination. continuous and uniform for the full length of the tube may not
3.1.1.3 electrical center—thecenterestablishedbytheelec- always be detected.
tromagnetic field distribution within the examination coil. A
6. Basis of Application
constant-intensity signal, irrespective of the circumferential
position of a discontinuity, is indicative of electrical centering. 6.1 Personnel Qualification—Nondestructivetesting(NDT)
The electrical center may be different from the physical center personnel shall be qualified in accordance with a nationally
of the examination coil. recognized NDT personnel qualification practice or standard
3.1.1.4 speed-sensitive equipment—examination equipment
such as ANSI/ASNT CP-189, SNT-TC-1A, MIL-STD-410,
that produces a variation in signal response with variations in NAS-410,orasimilardocument.Thepracticeorstandardused
theexaminationspeed.Speed-insensitiveequipmentprovidesa
and its applicable revision shall be specified in the purchase
constant signal response with changing examination speeds. specification or contractual agreement between the using
3.1.1.5 off-line examining—eddy-current examinations con- parties.
ducted on equipment that includes the examination coil and
NOTE 2—MIL-STD-410 is canceled and has been replaced with NAS-
means to propel individual tubes under examination through
410,however,itmaybeusedwithagreementbetweencontractingparties.
the coil at appropriate speeds and conditions.
6.2 Qualification of Nondestructive Testing Agencies—If
3.1.1.6 on-line examining—eddy-current examinations con-
specified in the purchase specification or contractual agree-
ducted on equipment that includes the examination coil and
ment, NDT agencies shall be evaluated and qualified as
means to propel tubes under examination through the coil at
described in Practice E543. The applicable edition of Practice
appropriate speeds and conditions as an integral part of a
E543 shall be identified in the purchase specification or
continuous tube manufacturing sequence.
contractual agreement between the using parties.
3.2 Definitions of Terms—Refer to Terminology E1316 for
definitions of terms that are applicable to nondestructive
7. Apparatus
examinations in general.
7.1 Electronic Apparatus—The electronic apparatus shall
be capable of energizing the examination coil with alternating
4. Summary of Practice
currents of suitable frequencies (for example, 1 kHz to 125
4.1 Examining is usually performed by passing the tube
kHz), and shall be capable of sensing the changes in the
lengthwise through a coil energized with alternating current at
electromagnetic response of the coils. Electrical signals pro-
one or more frequencies. The electrical impedance of the coil
duced in this manner are processed so as to actuate an audio or
is modified by the proximity of the tube, the tube dimensions,
visual signaling device or mechanical marker which produces
electrical conductivity and magnetic permeability of the tube
a record.
material,andmetallurgicalormechanicaldiscontinuitiesinthe
7.2 Examination Coils—Examination coils shall be capable
tube. During passage of the tube, the changes in electromag-
of inducing current in the tube and sensing changes in the
netic response caused by these variables in the tube produce
electrical characteristics of the tube. The examination coil
electrical signals which are processed so as to actuate an audio
diameter should be selected to yield the largest practical
or visual signaling device or mechanical marker which pro-
fill-factor.
duces a record.
7.3 Driving Mechanism—A mechanical means of passing
5. Significance and Use the tube through the examination coil with minimum vibration
of the examination coil or the tube. The device shall maintain
5.1 Eddy-currentexaminationisanondestructivemethodof
the tube substantially concentric with the electrical center of
locating discontinuities in a product. Signals can be produced
theexaminationcoil.Auniformspeed(65.0%speedvariation
by discontinuities located either on the external or internal
maximum) shall be maintained.
surface of the tube or by discontinuities totally contained
7.4 End Effect Suppression Device—A means capable of
within the walls. Since the density of eddy currents decreases
suppressing the signals produced at the ends of the tube.
nearly exponentially as the distance from the external surface
IndividualASTM product specifications shall specify when an
increases, the response to deep-seated defects decreases.
end effect suppression device is mandatory.
5.2 Some indications obtained by this method may not be
relevanttoproductquality;forexample,arejectsignalmaybe
NOTE 3—Signals close to the ends of the tube may carry on beyond the
caused by minute dents or tool chatter marks that are not
limits of end suppression. Refer to 9.5.
detrimentaltotheenduseoftheproduct.Irrelevantindications
8. Reference Standards
can mask unacceptable discontinuities. Relevant indications
arethosewhichresultfromnonacceptablediscontinuities.Any 8.1 Artificial Discontinuity Reference Standard:
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E243–97 (2004)
8.1.1 Thetubeusedwhenadjustingthesensitivitysettingof (d) Fourroundbottomtransversenotchesontheoutsideof
the apparatus shall be selected from a typical production run the tube, all on the same element of the tube (Fig. 4).
and shall be representative of the purchaser’s order. The tubes
shall be passed through the examination coil with the instru-
ment sensitivity high enough to determine the nominal back-
groundnoiseinherentinthetubes.Thereferencestandardshall
be selected from tubes exhibiting low background noise. For
on-line eddy-current examining, the reference standard is
created in a tube portion existent in the continuous manufac-
turing sequence or in other forms as allowed by the product
specification.
8.1.2 Theartificialdiscontinuitiesshallbespacedtoprovide
NOTE 1—A= Space to provide signal resolution adequate for interpre-
signal resolution adequate for interpretation. The artificial
tation.
discontinuities shall be prepared in accordance with one of the
FIG. 4 Reference Standard with Four Notches in Line
following options:
(a) Around bottom transverse notch on the outside of the
(e) Fourholesdrilledradiallythroughthetubewall,allthe
tubeineachofthreesuccessivetransverseplanesat0,120,and
same element of the tube (Fig. 5).
240° (Fig. 1).
(b) Ahole drilled radially through the tube wall in each of
three successive transverse planes at 0, 120, and 240° (Fig. 2).
NOTE 1—A= Space to provide signal resolution adequate for interpre-
tation.
FIG. 2 Reference Standard with Three Holes
FIG. 5 Reference Standard with Four Holes in Line
(c) One round bottom transverse notch on the outside of
8.1.2.1 Round Bottom Transverse Notch—The notch shall
thetubeat0°andanotherat180°,andoneholedrilledradially
be made using a suitable jig with a 0.250-in. [6.35-mm]
through the wall at 90° and another at 270°. Only one notch or
diameter No. 4 cut, straight, round file. The outside surface of
hole shall be made in each transverse plane (Fig. 3).
the tube shall be stroked in a substantially straight line
perpendicular to the axis of the tube. The notch depth shall be
in accordance with theASTM product specification orAppen-
dix X1 if the product specification does not specify and shall
not vary from the notch depth by more than 60.0005 in.
[60.013 mm] when measured at the center of the notch (see
Table X1.1).
NOTE 4—Tables X1.1 and X1.2 should not be used for acceptance or
rejection of materials.
8.1.2.2 Drilled Holes—The hole shall be drilled radially
through the wall using a suitable drill jig that has a bushing to
NOTE 1—A= Space to provide signal resolution adequate for interpre-
tation. guide the drill, care being taken to avoid distortion of the tube
FIG. 3 Reference Standard with Two Notches and Two Holes
whiledrilling.Thedrilledholediametershallbeinaccordance
with the ASTM product specification or Appendix X1 if the
product specification does not specify and shall not vary by
more than+0.001,−0.000 in. [+0.026 mm] of the hole diam-
eter specified (see Table X1.2) (Note 4).
8.1.2.3 Other Artificial Discontinuities—Discontinuities of
othercontoursmaybeusedinthereferencestandardbymutual
agreement between supplier and purchaser.
Tables X1.1 and X1.2 are extracted from Specifications B111, B395, and
FIG. 1 Reference Standard with Three Notches B543.
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E243–97 (2004)
8.2 Percent Maximum Unbalance Reference Standard— 9.5 Determine the length of tubing requiring suppression of
This method of standardization shall be used only with end effect signals by selecting a tube of low background noise
speed-insensitive equipment, and equipment specifically de- and making a series of reference holes or notches at 0.5-in.
signed or adapted to accommodate the use of this calibration [12.7-mm] intervals near the end of this special tube. Pass the
method. Maximum unbalance of differential coils is obtained tube through the examination coil at the production examina-
by placing the squared end of a tube in only one of the tion speed with the artificial discontinuities end first, and then
differential coils and using an accurately calibrated attenuator with the artificial discontinuities end last. Determine
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