ASTM E309-95(2006)
(Practice)Standard Practice for Eddy-Current Examination of Steel Tubular Products Using Magnetic Saturation
Standard Practice for Eddy-Current Examination of Steel Tubular Products Using Magnetic Saturation
SIGNIFICANCE AND USE
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 using 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 the magnitude of the indication.
The response from natural discontinuities can be significantly 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 set-up required to detect natural discontinuities of consequence to the end use of the product.
Eddy-current examination systems are generally not sensitive to discontinuities adjacent to the ends of the tube. The extent of the end effect region can be determined in accordance with 8.6.
SCOPE
1.1 This practice covers a procedure for applying the eddy-current method to detect discontinuities in ferromagnetic pipe and tubing (Note 0) where the article being examined is rendered substantially non-magnetic by the application of a concentrated, strong magnetic field in the region adjacent to the examining coil. For 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 examination methods using an encircling-coil assembly. However, eddy-current techniques that employ either fixed or rotating probe-coil assemblies may be used to either enhance discontinuity sensitivity on the large diameter tubular products or to maximize the response received from a particular type of discontinuity.
1.3 This practice is intended for use on tubular products having outside diameters from approximately 1/4 to 10 in. (6.35 to 254.0 mm). These techniques have been used for smaller and larger sizes however, and may be specified upon contractual agreement between the purchaser and the supplier.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: E309 – 95 (Reapproved 2006)
Standard Practice for
Eddy-Current Examination of Steel Tubular Products Using
Magnetic Saturation
This standard is issued under the fixed designation E309; 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.
This specification has been approved for use by agencies of the Department of Defense.
1. Scope cation and Certification in Nondestructive Testing
2 ANSI/ASNT CP-189 ASNT Standard for Qualification and
1.1 This practice covers a procedure for applying the
Certification of Nondestructive Testing Personnel
eddy-current method to detect discontinuities in ferromagnetic
2.3 Military Standard:
pipe and tubing (Note 1) where the article being examined is
MIL-STD-410E Nondestructive Testing Personnel Qualifi-
rendered substantially non-magnetic by the application of a
cation and Certification
concentrated,strongmagneticfieldintheregionadjacenttothe
examining coil.
3. Terminology
NOTE 1—For convenience, the term tube or tubular product will
3.1 General—Standard terminology relating to electromag-
hereafter be used to refer to both pipe and tubing.
netic examination may be found in Terminology E1316,
1.2 The procedure is specifically applicable to eddy-current
Section C, “Electromagnetic Testing.”
examination methods using an encircling-coil assembly. How-
4. Summary of Practice
ever, eddy-current techniques that employ either fixed or
rotating probe-coil assemblies may be used to either enhance 4.1 The examination is conducted using one of two general
discontinuity sensitivity on the large diameter tubular products
techniques shown in Fig. 1.
or to maximize the response received from a particular type of 4.1.1 Onetechniqueemploysoneormoreexciterandsensor
discontinuity.
coils that encircle the tube and through which the tubular
1.3 This practice is intended for use on tubular products product to be examined is passed. Some circuit configurations
having outside diameters from approximately ⁄4 to 10 in. (6.35
employ one or more coils that concurrently function as both
to254.0mm).Thesetechniqueshavebeenusedforsmallerand exciters and sensors. Alternating current passes through the
larger sizes however, and may be specified upon contractual exciting coil which, by reason of its proximity, induces
agreement between the purchaser and the supplier.
corresponding currents (eddy currents) to flow in the tubular
product. The sensor coil detects the resultant electromagnetic
2. Referenced Documents
flux related to these currents.The presence of discontinuities in
2.1 ASTM Standards:
the tubular product will alter the normal flow of currents and
E543 Specification for Agencies Performing Nondestruc-
this change is detected by the sensor. The encircling-coil
tive Testing
technique is capable of examining the entire circumference of
E1316 Terminology for Nondestructive Examinations
a tubular product.
2.2 Other Documents:
4.1.2 Another technique employs a probe coil with one or
SNT-TC-1A Recommended Practice for Personnel Qualifi-
more sensors that are in close proximity to the surface of the
tubular product to be examined. Since the probe is generally
small and does not encircle the article being examined, it
1 examines only a limited area in the vicinity of the probe. This
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
structive Testing and is the direct responsibility of Subcommittee E07.07 on technique is frequently used for examination of welded tubular
Electromagnetic Method.
productsinwhichonlytheweldisexaminedbyscanningalong
Current edition approved July 1, 2006. Published July 2006. Originally approved
the weld zone.
in 1966. Last previous edition approved in 2001 as E309 - 95(2001). DOI:
10.1520/E0309-95R06.
For ASME Boiler and Pressure Vessel Code applications see related Recom-
mended Practice SE 309 in Section V of that Code.
3 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518.
Standards volume information, refer to the standard’s Document Summary page on AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700
the ASTM website. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
E309 – 95 (2006)
(a)Encircling Coil.
(b) Probe Coil—longitudinal scanning of weld seam only.
(c)Probe Coil—scanning along a spiral path.
FIG. 1 Encircling-Coil and Probe-Coil Techniques for Electromagnetic Testing of Tubular Products
4.1.3 The magnetic permeability of ferromagnetic materials eddy-current frequency provides sufficient depth of penetration
severely limits the depth of penetration of induced eddy (see 11.1). The eddy-current method is sensitive to metallur-
currents. Furthermore, the permeability variations inherent in
gical variations that occur as a result of processing, thus all
ferromagnetic tubular products often cause anomalous test
received indications are not necessarily indicative of defective
results. A useful solution to this problem involves the applica-
tubing.
tion of a strong external magnetic field in the region of the
examining coil or probe. This technique, known as magnetic
5. Significance and Use
saturation, is applied to a magnetic material, such as a steel
5.1 The purpose of this practice is to outline a procedure for
tube, to suppress the magnetic characteristics of permeability,
the detection and location of discontinuities such as pits, voids,
hysteresis, etc., so that the material under examination is
inclusions, cracks, or abrupt dimensional variations in ferro-
effectively rendered nonmagnetic. When achieved, this condi-
magnetic tubing using the electromagnetic (eddy-current)
tion allows an eddy-current system to measure and detect
method. Furthermore, the relative severity of a discontinuity
electrical resistivity and geometrical variations (including de-
may be indicated, and a rejection level may be set with respect
fects) independent of concurrent variations in magnetic prop-
to the magnitude of the indication.
erties.
5.2 The response from natural discontinuities can be signifi-
4.1.4 Changes in electromagnetic response caused by the
cantly different than that from artificial discontinuities such as
presence of discontinuities are detected by the sensor, ampli-
drilled holes or notches. For this reason, sufficient work should
fied, and modified in order to actuate audio or visual indicating
devices, or both, a mechanical marker, or a signal-recording be done to establish the sensitivity level and set-up required to
detect natural discontinuities of consequence to the end use of
device, or a combination of these. Signals can be caused by
outer surface, inner surface, or subsurface discontinuities if the the product.
E309 – 95 (2006)
5.3 Eddy-current examination systems are generally not 7.6 Reference Standard—The standard used to adjust the
sensitive to discontinuities adjacent to the ends of the tube.The sensitivity of the apparatus shall be free of interfering discon-
extent of the end effect region can be determined in accordance tinuities and shall be of the same nominal alloy, temper, and
with 8.6. dimensions as the tubes to be examined on a production basis.
It shall be of sufficient length to permit the spacing of artificial
6. Basis of Application
discontinuities to provide good signal resolution and be me-
6.1 The following acceptance criteria may be specified in
chanically stable while in the examining position in the
the purchase specification, contractual agreement, or else-
apparatus. Artificial discontinuities placed in the tube shall be
where, and may require agreement between the purchaser and
one or more of the following types. (See Fig. 2.)
the supplier:
7.6.1 Notches—Notches may be produced by Electric Dis-
6.1.1 Time of examination or point(s) in the manufacturing
charge Machining (EDM), milling, or other means. Longitudi-
process at which the material will be examined,
nal, transverse, or both may be used (Note 2). Orientation,
6.1.2 Maximum time interval between equipment calibra-
dimensions (width, length, and depth), and configuration of the
tion checks,
notches affect the response of the eddy-current system. Notch
6.1.3 Methods for determining the extent of end effect,
depth is usually specified as a percentage of nominal wall
6.1.4 Size and type of product, thickness of the tubular product being examined. Notches may
6.1.5 Type, method of manufacture, dimensions, location,
be placed on the outer, inner, or both surfaces of the reference
and number of artificial discontinuities to be placed on the standard. Outer surface notches provide an indication of
reference standard,
system response to discontinuities originating on the outer tube
6.1.6 Methods of verifying dimensions and allowable toler- surface; whereas inner surface notches provide an indication of
ances of artificial discontinuities,
system response to discontinuities originating on the inner tube
6.1.7 Extent of examination, and surface.
6.1.8 Disposition of material with indications.
NOTE 2—Longitudinal notch standards are normally used when testing
6.1.9 Operator Qualification and Certification—If required,
with a rotating-probe system.
NDT personnel shall be qualified in accordance with a nation-
7.6.2 Holes—Drilled holes may be used. They are usually
ally recognized NDT personnel qualification practice or stan-
drilled completely through the wall. Care should be taken
dard such as ANSI/ASNT-CP-189, SNT-TC-1A, MIL-STD-
during drilling to avoid distortion of the tube and hole.
410, or a similar document. The practice or standard used and
7.6.3 The configuration, orientation, and dimensions (diam-
its applicable revision shall be documented in the contractual
eter of holes and the width, length, and depth of notches) of the
agreement between the using parties.
artificial discontinuities to be used for establishing acceptance
6.1.10 Qualification of Nondestructive Agencies—If speci-
limits should be subject to agreement between the purchaser
fied in the contractual agreement, NDT agencies shall be
and the supplier.
qualified and evaluated in accordance with Practice E543. The
applicable edition of Practice E543 shall be specified in the
8. Adjustment and Standardization of Apparatus
contractual agreement.
8.1 Select the apparatus, examining frequency, coil or probe
7. Apparatus
configuration, magnetic saturation system, phase discrimina-
tion,
...
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