ASTM E309-95(2001)
(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
SCOPE
1.1 This practice covers a procedure for applying the eddy-current method to detect discontinuities in ferromagnetic pipe and tubing (Note 1) 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.
Note 1—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 contractural 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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: E 309 – 95 (Reapproved 2001)
Standard Practice for
Eddy-Current Examination of Steel Tubular Products Using
Magnetic Saturation
This standard is issued under the fixed designation E 309; 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 specification has been approved for use by agencies of the Department of Defense.
1. Scope Certification of Nondestructive Testing Personnel
2 2.3 Military Standard:
1.1 This practice covers a procedure for applying the
MIL-STD-410E Nondestructive Testing Personnel Qualifi-
eddy-current method to detect discontinuities in ferromagnetic
cation and Certification
pipe and tubing (Note 1) where the article being examined is
rendered substantially non-magnetic by the application of a
3. Terminology
concentrated,strongmagneticfieldintheregionadjacenttothe
3.1 General—Standard terminology relating to electromag-
examining coil.
netic examination may be found in Terminology E 1316,
NOTE 1—For convenience, the term tube or tubular product will
Section C, “Electromagnetic Testing.”
hereafter be used to refer to both pipe and tubing.
4. Summary of Practice
1.2 The procedure is specifically applicable to eddy-current
examination methods using an encircling-coil assembly. How- 4.1 The examination is conducted using one of two general
ever, eddy-current techniques that employ either fixed or
techniques shown in Fig. 1.
rotating probe-coil assemblies may be used to either enhance 4.1.1 Onetechniqueemploysoneormoreexciterandsensor
discontinuity sensitivity on the large diameter tubular products
coils that encircle the tube and through which the tubular
or to maximize the response received from a particular type of product to be examined is passed. Some circuit configurations
discontinuity.
employ one or more coils that concurrently function as both
1.3 This practice is intended for use on tubular products exciters and sensors. Alternating current passes through the
having outside diameters from approximately ⁄4 to 10 in. (6.35
exciting coil which, by reason of its proximity, induces
to254.0mm).Thesetechniqueshavebeenusedforsmallerand corresponding currents (eddy currents) to flow in the tubular
larger sizes however, and may be specified upon contractual product. The sensor coil detects the resultant electromagnetic
agreement between the purchaser and the supplier.
flux related to these currents.The presence of discontinuities in
the tubular product will alter the normal flow of currents and
2. Referenced Documents
this change is detected by the sensor. The encircling-coil
2.1 ASTM Standards:
technique is capable of examining the entire circumference of
E 543 Practice for Agencies Performing Nondestructive
a tubular product.
Testing
4.1.2 Another technique employs a probe coil with one or
E 1316 Terminology for Nondestructive Examinations
more sensors that are in close proximity to the surface of the
2.2 Other Documents:
tubular product to be examined. Since the probe is generally
SNT-TC-1A Recommended Practice for Personnel Qualifi-
small and does not encircle the article being examined, it
cation and Certification in Nondestructive Testing
examines only a limited area in the vicinity of the probe. This
ANSI/ASNT CP-189 ASNT Standard for Qualification and
technique is frequently used for examination of welded tubular
productsinwhichonlytheweldisexaminedbyscanningalong
the weld zone.
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
4.1.3 The magnetic permeability of ferromagnetic materials
structive Testing, and is the direct responsibility of Subcommittee E07.07 on
severely limits the depth of penetration of induced eddy
Electromagnetic Methods.
currents. Furthermore, the permeability variations inherent in
Current edition approved October 10, 1995. Published December 1995. Origi-
nally published as E 309 – 66 T. Last previous edition E 309 – 93a.
ferromagnetic tubular products often cause anomalous test
For ASME Boiler and Pressure Vessel Code applications see related Recom-
mended Practice SE 309 in Section V of that Code.
Annual Book of ASTM Standards, Vol 03.03.
4 5
Available from American Society for Nondestructive Testing, 1711 Arlingate Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
Plaza, P.O. Box 28518, Columbus, OH 43228-0518. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
E 309 – 95 (2001)
(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
results. A useful solution to this problem involves the applica- gical variations that occur as a result of processing, thus all
tion of a strong external magnetic field in the region of the received indications are not necessarily indicative of defective
examining coil or probe. This technique, known as magnetic
tubing.
saturation, is applied to a magnetic material, such as a steel
tube, to suppress the magnetic characteristics of permeability,
5. Significance and Use
hysteresis, etc., so that the material under examination is
5.1 The purpose of this practice is to outline a procedure for
effectively rendered nonmagnetic. When achieved, this condi-
the detection and location of discontinuities such as pits, voids,
tion allows an eddy-current system to measure and detect
inclusions, cracks, or abrupt dimensional variations in ferro-
electrical resistivity and geometrical variations (including de-
magnetic tubing using the electromagnetic (eddy-current)
fects) independent of concurrent variations in magnetic prop-
method. Furthermore, the relative severity of a discontinuity
erties.
may be indicated, and a rejection level may be set with respect
4.1.4 Changes in electromagnetic response caused by the
to the magnitude of the indication.
presence of discontinuities are detected by the sensor, ampli-
5.2 The response from natural discontinuities can be signifi-
fied, and modified in order to actuate audio or visual indicating
cantly different than that from artificial discontinuities such as
devices, or both, a mechanical marker, or a signal-recording
drilled holes or notches. For this reason, sufficient work should
device, or a combination of these. Signals can be caused by
be done to establish the sensitivity level and set-up required to
outer surface, inner surface, or subsurface discontinuities if the
eddy-current frequency provides sufficient depth of penetration detect natural discontinuities of consequence to the end use of
(see 11.1). The eddy-current method is sensitive to metallur- the product.
E 309 – 95 (2001)
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 E 543. The
applicable edition of Practice E 543 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, and other circuitry, as well as speed of examination.
7.1
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