ASTM E243-97
(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
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: E 243 – 97
Standard Practice for
Electromagnetic (Eddy-Current) Examination of Copper and
Copper-Alloy Tubes
This standard is issued under the fixed designation E 243; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number 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.
1. Scope Condenser Tubes and Ferrule Stock
2 B 395 Specification for U-Bend Seamless Copper and Cop-
1.1 This practice covers the procedures that shall be
per Alloy Heat Exchanger and Condenser Tubes
followed in eddy-current examination of copper and copper-
B 543 Specification for Welded Copper and Copper-Alloy
alloy tubes for detecting discontinuities of a severity likely to
Heat Exchanger Tube
cause failure of the tube. These procedures are applicable for
E 543 Practice for Evaluating Agencies that Perform Non-
tubes with outside diameters to 3 ⁄8 in. (79.4 mm), inclusive,
destructive Testing
and wall thicknesses from 0.017 in. (0.432 mm) to 0.120 in.
E 1316 Terminology for Nondestructive Examinations
(3.04 mm), inclusive, or as otherwise stated in ASTM product
2.2 Other Documents:
specifications; or by other users of this practice. These proce-
SNT-TC-1A Recommended Practice for Nondestructive
dures may be used for tubes beyond the size range recom-
Testing Personnel Qualification and Certification
mended, upon contractual agreement between the purchaser
ANSI/ASNT CP-189 ASNT Standard for Qualification and
and the manufacturer.
Certification of Nondestructive Testing Personnel
1.2 The procedures described in this practice are based on
MIL-STD-410 Nondestructive Testing Personnel Qualifica-
methods making use of encircling annular test coil systems.
tion and Certification
1.3 The values stated in inch-pound units are to be regarded
as the standard.
3. Terminology
NOTE 1—This practice may be used as a guideline for the examination,
3.1 Definitions of Terms Specific to this Standard
by means of internal probe test coil systems, of installations using tubular
3.1.1 The following terms are defined in relation to this
products where the outer surface of the tube is not accessible. For such
standard.
applications, the technical differences associated with the use of internal
3.1.1.1 artificial discontinuity calibration standard—a stan-
probe coils should be recognized and accommodated. The effect of foreign
dard consisting of a selected tube with defined artificial
materials on the tube surface and signals due to tube supports are typical
of the factors that must be considered.
discontinuities, used when adjusting the system controls to
obtain some predetermined system output signal level. This
1.4 This standard does not purport to address all of the
standard may be used for periodic checking of the instrument
safety concerns, if any, associated with its use. It is the
during a test.
responsibility of the user of this standard to establish appro-
3.1.1.2 percent maximum unbalance calibration
priate safety and health practices and determine the applica-
standard—a method of calibration that can be used with
bility of regulatory limitations prior to use.
speed-insensitive instruments (see 3.1.1.4). The acceptance
2. Referenced Documents level of the test is established at the operating test frequency as
an accurately calibrated fraction of the maximum unbalance
2.1 ASTM Standards:
signal resulting from the end effect of a tube. Any low-noise
B 111 Specification for Copper and Copper-Alloy Seamless
tube from the production run having a squared end may be used
This practice is under the jurisdiction of ASTM Committee E-7 on Nonde-
structive Testing and is the direct responsibility of Subcommittee E07.07 on
Annual Book of ASTM Standards, Vol 02.01.
Electromagnetic Methods.
Annual Book of ASTM Standards, Vol 03.03.
Current edition approved May 10, 1997. Published February 1998. Originally
Available from American Society for Nondestructive Testing, 1711 Arlingate
published as E 243 – 67 T. Last previous edition E 243 – 90.
Plaza, PO Box 28518, Columbus, Ohio 43228-0518.
For ASME Boiler and Pressure Vessel Code applications see related Practice
Available from Standardization Documents Order Desk, Building 4 Section D,
SE-243 in the Code.
700 Robbins Avenue, Philadelphia, PA 19111-5904, Attn: NPODS
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E243–97
as this standard. This standard may be used for periodic 5.4 Discontinuities such as scratches or seams that are
checking of the instrument during a test. continuous and uniform for the full length of the tube may not
always be detected.
3.1.1.3 electrical center—the center established by the elec-
tromagnetic field distribution within the test coil. A constant-
intensity signal, irrespective of the circumferential position of 6. Basis of Application
a discontinuity, is indicative of electrical centering. The elec-
6.1 Personnel Qualification—Nondestructive testing (NDT)
trical center may be different from the physical center of the
personnel shall be qualified in accordance with a nationally
test coil.
recognized NDT personnel qualification practice or standard
3.1.1.4 speed-sensitive equipment—test equipment that pro-
such as ANSI/ASNT CP-189, SNT-TC-1A, MIL-STD-410 or a
duces a variation in signal response with variations in the test
similar document. The practice or standard used and its
speed. Speed-insensitive equipment provides a constant signal
applicable revision shall be specified in the purchase specifi-
response with changing test speeds.
cation or contractual agreement between the using parties.
3.1.1.5 off-line testing—eddy-current tests conducted on
6.2 Qualification of Nondestructive Testing Agencies—If
equipment that includes the test coil and means to propel
specified in the purchase specification or contractual agree-
individual tubes under test through the coil at appropriate
ment, NDT agencies shall be evaluated and qualified as
speeds and conditions.
described in Practice E 543. The applicable edition of Practice
3.1.1.6 on-line testing—eddy-current tests conducted on
E 543 shall be identified in the purchase specification or
equipment that includes the test coil and means to propel tubes
contractual agreement between the using parties.
under test through the coil at appropriate speeds and conditions
as an integral part of a continuous tube manufacturing se-
7. Apparatus
quence.
7.1 Electronic Apparatus—The electronic apparatus shall
3.2 Definitions of Terms—Refer to Terminology E 1316 for
be capable of energizing the test coil with alternating currents
definitions of terms that are applicable to nondestructive
of suitable frequencies (for example, 1 kHz to 125 kHz), and
examinations in general.
shall be capable of sensing the changes in the electromagnetic
response of the coils. Electrical signals produced in this
4. Summary of Practice
manner are processed so as to actuate an audio or visual
4.1 Testing is usually performed by passing the tube length-
signaling device or mechanical marker which produces a
wise through a coil energized with alternating current at one or
record.
more frequencies. The electrical impedance of the coil is
7.2 Test Coils—Test coils shall be capable of inducing
modified by the proximity of the tube, the tube dimensions,
current in the tube and sensing changes in the electrical
electrical conductivity and magnetic permeability of the tube
characteristics of the tube. The test coil diameter should be
material, and metallurgical or mechanical discontinuities in the
selected to yield the largest practical fill-factor.
tube. During passage of the tube, the changes in electromag-
7.3 Driving Mechanism—A mechanical means of passing
netic response caused by these variables in the tube produce
the tube through the test coil with minimum vibration of the
electrical signals which are processed so as to actuate an audio
test coil or the tube. The device shall maintain the tube
or visual signaling device or mechanical marker which pro-
substantially concentric with the electrical center of the test
duces a record.
coil. A uniform speed (65.0 % speed variation maximum)
shall be maintained.
5. Significance and Use
7.4 End Effect Suppression Device—A means capable of
suppressing the signals produced at the ends of the tube.
5.1 Eddy-current testing is a nondestructive method of
Individual ASTM product specifications shall specify when an
locating discontinuities in a product. Signals can be produced
end effect suppression device is mandatory.
by discontinuities located either on the external or internal
surface of the tube or by discontinuities totally contained
NOTE 2—Signals close to the ends of the tube may carry on beyond the
within the walls. Since the density of eddy currents decreases
limits of end suppression. Refer to 9.5.
nearly exponentially as the distance from the external surface
8. Reference Standards
increases, the response to deep-seated defects decreases.
5.2 Some indications obtained by this method may not be
8.1 Artificial Discontinuity Reference Standard:
relevant to product quality; for example, a reject signal may be 8.1.1 The tube used when adjusting the sensitivity setting of
caused by minute dents or tool chatter marks that are not
the apparatus shall be selected from a typical production run
detrimental to the end use of the product. Irrelevant indications and shall be representative of the purchaser’s order. The tubes
can mask unacceptable discontinuities. Relevant indications
shall be passed through the test coil with the instrument
are those which result from nonacceptable discontinuities. Any sensitivity high enough to determine the nominal background
indication above the reject level that is believed to be irrelevant
noise inherent in the tubes. The reference standard shall be
shall be regarded as unacceptable until it is demonstrated by selected from tubes exhibiting low background noise. For
re-examination or other means to be irrelevant (see 10.3.2).
on-line eddy-current testing, the reference standard is created
5.3 Eddy-current testing systems are generally not sensitive in a tube portion existent in the continuous manufacturing
to discontinuities adjacent to the ends of the tube (end effect). sequence or in other forms as allowed by the product specifi-
On-line eddy-current testing would not be subject to end effect. cation.
E243–97
8.1.2 The artificial discontinuities shall be spaced to provide
signal resolution adequate for interpretation. The artificial
discontinuities shall be prepared in accordance with one of the
following options:
(a) A round bottom transverse notch on the outside of the
tube in each of three successive transverse planes at 0, 120, and
240° (Fig. 1).
(b) A hole 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. 4 Reference Standard with Four Notches in Line
FIG. 2 Reference Standard with Three Holes
(c) One round bottom transverse notch on the outside of
NOTE 1—A = Space to provide signal resolution adequate for interpre-
the tube at 0° and another at 180°, and one hole drilled radially
tation.
through the wall at 90° and another at 270°. Only one notch or
FIG. 5 Reference Standard with Four Holes in Line
hole shall be made in each transverse plane (Fig. 3).
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 3—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
guide the drill, care being taken to avoid distortion of the tube
while drilling. The drilled hole diameter shall be in accordance
NOTE 1—A = Space to provide signal resolution adequate for interpre-
with the ASTM product specification or Appendix X1 if the
tation.
product specification does not specify and shall not vary by
FIG. 3 Reference Standard with Two Notches and Two Holes
more than +0.001, −0.000 in. ( +0.026 mm) of the hole diam-
eter specified (see Table X1.2) (Note 3).
(d) Four round bottom transverse notches on the outside of
8.1.2.3 Other Artificial Discontinuities—Discontinuities of
the tube, all on the same element of the tube (Fig. 4).
other contours may be used in the reference standard by mutual
(e) Four holes drilled radially through the tube wall, all the
agreement between supplier and purchaser.
same element of the tube (Fig. 5).
8.2 Percent Maximum Unbalance Reference Standard—
8.1.2.1 Round Bottom Transverse Notch—The notch shall
This method of standardization shall be used only with
be made using a suitable jig with a 0.250-in. (6.35-mm)
speed-insensitive equipment, and equipment specifically de-
diameter No. 4 cut, straight, round file. The outside surface of
signed or adapted to accommodate the use of this calibration
the tube shall be stroked in a substantially straight line
method. Maximum unbalance of differential coils is obtained
perpendicular to the axis of the tube. The notch depth shall be
by placing the squared end of a tube in only one of the
in accordance with the ASTM product specification or Appen-
differential coils and using an accurately calibrated attenuator
dix X1 if the product specification does not specify and shall
to obtain the (100 %) maximum unbalance signal. A percentage
of the maximum unbalance signal shall define the test accep-
tance level at a specific operating frequency and this percent-
age shall be obtained from the ASTM product specification.
8.3 Other Reference Standards—Other reference standards
may be used by mutual agreement between supplier and
purchaser.
Tables X1.1 and X1.2 are extracted from Specifications B 111, B 395, and
FIG. 1 Reference Standard with Three Notches B 543.
E243–97
NOTE 4—Artificial discontinuities and the percent of maximum unbal-
(photo relay, mechanical switches, or proximity devices are
ance are not intended to be representative of natural discontinuities or
commonly used) to permit testing only when the length of
produce a direct relationship between instrument response and disconti-
tubing exhibiting uniform signals is within the test coil. The
nuity severity; they are intended only for establishing sensitivity l
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