ASTM E571-98
(Practice)Standard Practice for Electromagnetic (Eddy-Current) Examination of Nickel and Nickel Alloy Tubular Products
Standard Practice for Electromagnetic (Eddy-Current) Examination of Nickel and Nickel Alloy Tubular Products
SCOPE
1.1 This practice covers the procedures for eddy-current testing of nickel and nickel alloy tubes. These procedures are applicable for tubes with outside diameters up to 2 in. (50.8 mm), incl, and wall thicknesses from 0.035 to 0.120 in. (0.889 to 3.04 mm), incl. These procedures may be used for tubes beyond the size range recommended, by contractual agreement between the purchaser and the producer.
1.2 The procedures described in this practice make use of fixed encircling test coils or probe systems.
1.3 The values stated in inch-pound units are to be regarded as the standard. Note 1-For convenience, the term "tube" or "tubular product" will hereinafter be used to refer to both pipe and tubing.
1.4 This standard does not purport to address all of the safety problems, 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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Standards Content (Sample)
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Designation: E 571 – 98
Standard Practice for
Electromagnetic (Eddy-Current) Examination of Nickel and
Nickel Alloy Tubular Products
This standard is issued under the fixed designation E 571; 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.
1. Scope cation and Certification
NAS-410 Certification and Qualification of Nondestructive
1.1 This practice covers the procedures for eddy-current
Personnel (Quality Assurance Committee)
testing of nickel and nickel alloy tubes. These procedures are
applicable for tubes with outside diameters up to 2 in. (50.8
3. Terminology
mm), incl, and wall thicknesses from 0.035 to 0.120 in. (0.889
3.1 Standard terminology relating to electromagnetic ex-
to 3.04 mm), incl. These procedures may be used for tubes
amination may be found in Terminology E 1316, Section C,
beyond the size range recommended, by contractual agreement
Electromagnetic Testing.
between the purchaser and the producer.
1.2 The procedures described in this practice make use of
4. Summary of Practice
fixed encircling test coils or probe systems.
4.1 Examination is usually performed by the use of one of
1.3 The values stated in inch-pound units are to be regarded
two general techniques:
as the standard.
4.1.1 Encircling Coil Technique—Examination is per-
NOTE 1—For convenience, the term “tube” or “tubular product” will
formed by passing the tube lengthwise through a coil energized
hereinafter be used to refer to both pipe and tubing.
with alternating current at one or more frequencies. See Fig. 1.
1.4 This standard does not purport to address all of the
The electrical impedance of the coil is modified by the
safety concerns, if any, associated with its use. It is the proximity of the tube, the tube dimensions, electrical conduc-
responsibility of the user of this standard to establish appro-
tivity, saturating magnetic field, magnetic permeability, and
priate safety and health practices and determine the applica- metallurgical or mechanical discontinuities in the tube. As the
bility of regulatory limitations prior to use.
tube passes through the coil, the changes in electromagnetic
response caused by these variables in the tube change the coil
2. Referenced Documents
impedance, which activates an audible or visual signaling
2.1 ASTM Standards:
device or a mechanical marker.
E 309 Practice for Eddy-Current Examination of Steel Tu-
4.1.2 Probe Coil Technique—Probe coils are positioned in
bular Products Using Magnetic Saturation
close proximity to the outside diameter or to the inside
E 543 Practice for Agencies Performing Nondestructive
diameter, or to both diameter surfaces, of the tubular product
Testing
being examined as shown in Fig. 1. Since the probe is generally
E 1316 Terminology for Nondestructive Examinations
small and does not encircle the tube, it examines only a limited
2.2 Other Documents:
area in the vicinity of the probe. When required to examine the
SNT-TC-1A Recommended Practice for Personnel Qualifi-
entire volume of the tubular product, it is common practice to
cation and Certification in Nondestructive Testing
rotate either the tubular product or the probe around the tube.
ANSI/ASNT-CP-189 ASNT Standard for Qualification and
Frequently, in the case of welded tubular products, only the
Certification of Nondestructive Testing Personnel
weld is inspected by scanning along the weld zone.
MIL-STD-410E Nondestructive Testing Personnel Qualifi-
4.2 The magnetic permeability of magnetic materials se-
verely limits the depth of penetration of induced eddy currents.
Furthermore, the permeability variations inherent in magnetic
This practice is under the jurisdiction of ASTM Committee E-7 on Nonde-
tubular products can cause spurious test results. A useful
structive Testing and is the direct responsibility of Subcommittee E07.07 on
solution to this problem involves the application of a strong
Electromagnetic Methods.
Current edition approved Dec. 10, 1998. Published February 1999. Originally
published as E 571 – 76. Last previous edition E 571 – 92.
For ASME Boiler and Pressure Vessel Code applications see related Practice
SE-571 in Section II of that Code. Available from Standardization Documents Order Desk, Bldg. 4, Section D,
Annual Book of ASTM Standards, Vol 03.03. 700 Robbins Ave., Philadelphia, PA 19111–5904, Attn: NPODS.
4 6
Available from American Society for Nondestructive Testing, 1711 Arlingate Available from Aerospace Industries Association of America, Inc., 1250 Eye
Plaza, P.O. Box 28518, Columbus, OH 43228–0518. Street, N.W., Washington, DC 20005.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E571–98
decreases correspondingly. Phase changes are also associated
with changes in depth, allowing the use of phase analysis
techniques.
5.2 The response from natural discontinuities can be signifi-
cantly different than that from artificial discontinuities, such as
drilled holes or notches. For this reason, sufficient work should
be done to establish the sensitivity level and setup required to
detect natural discontinuities of consequence to the end use of
the product.
5.3 Some indications obtained by this method may not be
relevant to product quality; for example, an irrelevant indica-
tion may be caused by minute dents or tool chatter marks,
which are not detrimental to the end use of the product.
Irrelevant indications can mask unacceptable discontinuities.
Relevant indications are those which result from discontinui-
ties. Any indication that exceeds the rejection level shall be
treated as a relevant indication until it can be demonstrated that
it is irrelevant.
5.4 Generally, eddy-current testing systems are not sensitive
to discontinuities adjacent to the ends of the tube (end effect).
5.5 Discontinuities such as scratches or seams that are
continuous and uniform over the full length of the tube may not
always be detected with differential encircling coils or probes
scanned along the tube length.
5.6 For material that is magnetic, a strong magnetic field
shall be placed in the region of the examining coil. A magnetic
field may also be used to improve the signal-to-noise ratio in
tubing that exhibits slight residual magnetism.
6. Basis of Application
6.1 The following criteria may be specified in the purchase
FIG. 1 Encircling-Coil and Probe-Coil Techniques for
specification contractual agreement, or elsewhere, and may
Electromagnetic Testing of Tubular Products
require agreement between the purchaser and the supplier.
6.1.1 Acceptance criteria.
6.1.2 Type, dimensions, and number of artificial disconti-
external magnetic field in the region of the examining coil or
nuities to be placed in the reference standard.
probe. This technique, known as magnetic saturation, causes a
6.1.3 Extent of inspection; that is, full circumference of
magnetic material to exhibit sufficiently small magnetic char-
outside or inside diameter, or both, or weld only, if welded.
acteristics of permeability, hysteresis, etc., so that the material
6.1.4 Operator qualifications, if required.
under examination is effectively rendered nonmagnetic. When
6.1.5 Calibration intervals.
achieved, this condition allows an eddy-current system to
6.1.6 If specified in the contractual agreement, personnel
measure and detect electrical resistivity and geometrical varia-
performing examinations to this practice shall be qualified in
tions (including defects) independent of concurrent variations
accordance with a nationally recognized NDT personnel quali-
in magnetic properties.
fication practice or standard such as ANSI/ASNT-CP-189,
NOTE 2—Practice E 309 may be used for strongly magnetic materials.
SNT-TC-1A, MIL-STD-410E, NAS-410, ASNT-ACCP, or a
similar document and certified by the certifying agency as
4.2.1 During the testing of slightly magnetic tubing the
signals resulting from the variation of magnetic permeability applicable. the practice or standard used and its applicable
revision shall be identified in the contractual agreement be-
can mask the signals resulting from small imperfections. A
magnetic saturation technique can be used to reduce this tween the using parties.
interference to an acceptable level.
NOTE 3—MIL-STD-410 is canceled and has been replaced with NAS-
410, however, it may be used with agreement between contracting parties.
5. Significance and Use
6.1.7 If specified in the contractual agreement, NDT agen-
5.1 Eddy-current testing is a nondestructive method of
cies shall be qualified and evaluated in accordance with
locating discontinuities in metallic materials. Signals can be
Practice E 543. The applicable edition of Practice E 543 shall
produced by discontinuities originating on either the external
be specified in the contractual agreement.
or internal surfaces of the tube or by discontinuities totally
7. Apparatus
contained within the wall. Since the density of eddy currents
decreases nearly exponentially with increasing distance from 7.1 Electronic Apparatus—The electronic apparatus shall
the surface nearest the coil, the response to deep-seated defects be capable of energizing the encircling coils or probes with
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E571–98
NOTE 4—Longitudinal notch standards are normally used when testing
alternating current of suitable frequencies and shall be capable
with rotating probe systems.
of sensing changes in impedance of the encircling coils or
probes. Equipment may include any appropriate signal pro-
8.1.2 Hole—The holes shall be drilled radially partially or
cessing circuits such as a phase discriminator, filter circuits,
completely through the tube wall without causing permanent
etc., as required for the particular application.
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