ASTM E1312-09(2013)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: E1312 − 09 (Reapproved 2013)
Standard Practice for
Electromagnetic (Eddy Current) Examination of
Ferromagnetic Cylindrical Bar Product Above the Curie
Temperature
This standard is issued under the fixed designation E1312; 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 (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Changes were made editorially in July 2013.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice covers procedures for eddy current exami-
E543 Specification for Agencies Performing Nondestructive
nation of hot ferromagnetic bars above the Curie temperature
Testing
where the product is essentially nonmagnetic, but below
E1316 Terminology for Nondestructive Examinations
2100 °F (1149 °C).
2.2 Other Documents:
1.2 This practice is intended for use on bar products having
SNT-TC-1A Recommended Practice for Personnel Qualifi-
diameters of ⁄2 in. (12.7 mm) to 8 in. (203 mm) at linear
cation and Certification in Nondestructive Testing
throughput speeds up to 1200 ft/min (366 m/min). Larger or
ANSI/ASNT-CP-189 Standard for Qualification and Certifi-
smaller diameters may be examined by agreement between the
cation of NDT Personnel
using parties.
2.3 AIA Standard:
NAS 410 Certification and Qualification of Nondestructive
1.3 Thepurposeofthispracticeistoprovideaprocedurefor
Testing Personnel
in-line eddy current examination of bars during processing for
the detection of major or gross surface discontinuities.
3. Terminology
1.3.1 The types of discontinuities capable of being detected
3.1 Standard terminology relating to electromagnetic testing
are commonly referred to as: slivers, laps, seams, roll-ins
may be found in Terminology E1316, Section C: Electromag-
(scale, dross, and so forth), and mechanical damage such as
netic Testing.
scratches, scores, or indentations.
4. Summary of Practice
1.4 This practice does not establish acceptance criteria.
They must be specified by agreement between the using
4.1 Principle—The major advantage of examining ferro-
parties.
magnetic bar product above the Curie temperature with eddy
currents is the enhanced signal-to-noise ratio obtained without
1.5 The values stated in inch-pound units are to be regarded
the need for magnetic saturation.
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only 4.2 Sensors—This examination may be performed with
various types or designs of encircling coils or with probe coils
and are not considered standard.
that are fixed or rotating.
1.6 This practice does not purport to address all of the
4.2.1 One or more exciter or sensor coils is used to encircle
safety concerns, if any, associated with its use. It is the
the bar through which the product to be examined is passed.
responsibility of the user of this practice to establish appro-
When the hot bar is in close proximity to the sensing and
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- the ASTM website.
structive Testing and is the direct responsibility of Subcommittee E07.07 on AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
Electromagnetic Method. 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
Current edition approved July 15, 2013. Published August 2013. Originally Available fromAerospace IndustriesAssociation ofAmerica, Inc. (AIA), 1000
approved in 1989. Last previous edition approved in 2009 as E1312 – 09. DOI: WilsonBlvd.,Suite1700,Arlington,VA22209-3928,http://www.aia-aerospace.org.
10.1520/E1312-09R13E01.
*A Summary of Changes section appears at the end of this standard
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E1312 − 09 (2013)
exciting coils, eddy currents are induced in the hot product by 6. Basis of Application
an alternating current. The sensing coil detects the electromag-
6.1 Personnel Qualification—If specified in the contractual
netic flux related to these currents. Changes or disruptions in
agreement, personnel performing examinations to this practice
the normal flux pattern indicate the presence of discontinuities.
shall be qualified in accordance with a nationally recognized
This technique is capable of examining the entire circumfer-
nondestructive testing (NDT) personnel qualification practice
ence without contacting the product.
or standard such as ANSI/ASNT-CP-189, SNT-TC-1A, NAS-
4.2.2 The surface can also be examined with probe coils
410, or a similar document and certified by the employer or
having one or more exciters and sensors which are spaced in
certifying agency, as applicable. The practice or standard used
close proximity to the product surface. The probe is usually
and its applicable revision shall be identified in the contractual
small and does not encircle the product, making it necessary to
agreement between the using parties.
rotateeithertheprobesortheproducttoobtain100%coverage
6.2 Qualification of Nondestructive Testing Agencies—If
of the circumference. This is essentially a contact technique
specified in the contractual agreement, NDT agencies shall be
because the coil is fixtured in a device that rides on the
qualified and evaluated as described in Practice E543. The
circumferencetomaintainafixeddistancebetweenthecoiland
applicable edition of Practice E543 shall be specified in the
product surface.
contractual agreement.
4.2.3 Discontinuities cause either a change in phase or
6.3 Acceptance Criteria—Since acceptance criteria are not
signal amplitude when detected by the sensing coil. These
specified in this practice, they shall be specified in the
signals are amplified and processed to activate marking or
contractual agreement.
recording devices, or both. Relative severity of the imperfec-
tion can be indicated by the signal amplitude generated by the
7. Apparatus
flux change or the degree of change in phase.
7.1 Electronic Apparatus, should be capable of energizing
4.2.4 Caution must be exercised in establishing reference
the test coils or probes with alternating current at selectable
standards because flux changes caused by natural discontinui-
frequencies from 400 Hz to 100 kHz. Either manual or
ties might differ significantly from those generated by artificial
remotely operated switches can be used for frequency selec-
discontinuities.
tion. The equipment should include a detector display (CRT,
meters), phase discriminator, filters, modulators, recorders, and
5. Significance and Use
alarming/marking devices required for particular applications.
5.1 The purpose of this practice is to describe a procedure
7.2 Sensors, whether probe or encircling coils, should op-
for in-line-eddy-current examination of hot cylindrical bars in
erate through a frequency range from 400 Hz to 100 kHz.
the range of diameters listed in 1.2 for large and repetitive
7.2.1 The sensor windings must be cooled (such as water
discontinuities that may form during processing.
jackets) to control the sensor operating temperature and pre-
5.2 The discontinuities in bar product capable of being vent thermal damage to the sensors.
detected by the electromagnetic method are listed in 1.3.1. The 7.2.2 Magneticorelectrostaticshieldsmightbenecessaryto
method is capable of detecting surface and some subsurface suppress extraneous electrical transient noise. Electrostatic
discontinuities that are typically in the order of 0.030 in. (0.75 shields usually float above ground at the sensor and are
mm) and deeper, but some shallower discontinuities might also connected to a cable and then to the preamplifier shield.
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be found. 7.2.3 Constant spacing, ranging from ⁄16 in. (1.6 mm) to ⁄4
in. (6.4 mm) between the sensors and product surface is
5.3 Discontinuities that are narrow and deep, but short in
obtained with positioning mechanisms usually equipped with
length,arereadilydetectablebybothprobeandencirclingcoils
product guiding devices to prevent mechanical damage to the
because they cause abrupt flux changes. Surface and subsur-
sensors.
face discontinuities (if the electromagnetic frequency provides
7.3 Transport Mechanism—A conveyor or other type of
sufficient effective depth of penetration) can be detecte
...