ASTM E309-95
(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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 309 – 95 An American National Standard
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 2.3 Military Standard:
MIL-STD-410E Nondestructive Testing Personnel Qualifi-
1.1 This practice covers a procedure for applying the
cation and Certification
eddy-current method to detect discontinuities in ferromagnetic
pipe and tubing (Note 1) where the article being examined is
3. Terminology
rendered substantially non-magnetic by the application of a
3.1 General—Standard terminology relating to electromag-
concentrated, strong magnetic field in the region adjacent to the
netic examination may be found in Terminology E 1316,
examining coil.
Section C, “Electromagnetic Testing.”
NOTE 1—For convenience, the term tube or tubular product will
hereafter be used to refer to both pipe and tubing.
4. Summary of Practice
1.2 The procedure is specifically applicable to eddy-current
4.1 The examination is conducted using one of two general
examination methods using an encircling-coil assembly. How- techniques shown in Fig. 1.
ever, eddy-current techniques that employ either fixed or
4.1.1 One technique employs one or more exciter and sensor
rotating probe-coil assemblies may be used to either enhance coils that encircle the tube and through which the tubular
discontinuity sensitivity on the large diameter tubular products
product to be examined is passed. Some circuit configurations
or to maximize the response received from a particular type of employ one or more coils that concurrently function as both
discontinuity.
exciters and sensors. Alternating current passes through the
1.3 This practice is intended for use on tubular products exciting coil which, by reason of its proximity, induces
having outside diameters from approximately ⁄4 to 10 in. (6.35
corresponding currents (eddy currents) to flow in the tubular
to 254.0 mm). These techniques have been used for smaller and product. The sensor coil detects the resultant electromagnetic
larger sizes however, and may be specified upon contractural
flux related to these currents. The presence of discontinuities in
agreement between the purchaser and the supplier. the tubular product will alter the normal flow of currents and
this change is detected by the sensor. The encircling-coil
2. Referenced Documents
technique is capable of examining the entire circumference of
2.1 ASTM Standards:
a tubular product.
E 543 Practice for Evaluating Agencies that Perform Non-
4.1.2 Another technique employs a probe coil with one or
destructive Testing
more sensors that are in close proximity to the surface of the
E 1316 Terminology for Nondestructive Examinations
tubular product to be examined. Since the probe is generally
2.2 Other Documents:
small and does not encircle the article being examined, it
SNT-TC-1A Recommended Practice for Personnel Qualifi-
examines only a limited area in the vicinity of the probe. This
cation and Certification in Nondestructive Testing
technique is frequently used for examination of welded tubular
ANSI/ASNT CP-189 ASNT Standard for Qualification and
products in which only the weld is examined by scanning along
Certification of Nondestructive Testing Personnel
the weld zone.
4.1.3 The magnetic permeability of ferromagnetic materials
severely limits the depth of penetration of induced eddy
This practice is under the jurisdiction of ASTM Committee E-7 on Nonde-
currents. Furthermore, the permeability variations inherent in
structive Testing, and is the direct responsibility of Subcommittee E07.07 on
ferromagnetic tubular products often cause anomalous test
Electromagnetic Methods.
results. A useful solution to this problem involves the applica-
Current edition approved Oct. 10, 1995. Published December 1995. Originally
published as E 309 – 66 T. Last previous edition E 309 – 93a.
tion of a strong external magnetic field in the region of the
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 Standardization Documents Order Desk, Bldg. 4 Section D, 700 Available from American Society for Nondestructive Testing, 1711 Arlingate
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. Plaza, P.O. Box 28518, Columbus, OH 43228-0518.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 309
(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
examining coil or probe. This technique, known as magnetic the detection and location of discontinuities such as pits, voids,
saturation, is applied to a magnetic material, such as a steel inclusions, cracks, or abrupt dimensional variations in ferro-
tube, to suppress the magnetic characteristics of permeability, magnetic tubing using the electromagnetic (eddy-current)
hysteresis, etc., so that the material under examination is method. Furthermore, the relative severity of a discontinuity
effectively rendered nonmagnetic. When achieved, this condi- may be indicated, and a rejection level may be set with respect
tion allows an eddy-current system to measure and detect to the magnitude of the indication.
electrical resistivity and geometrical variations (including de- 5.2 The response from natural discontinuities can be signifi-
fects) independent of concurrent variations in magnetic prop- cantly different than that from artificial discontinuities such as
erties. drilled holes or notches. For this reason, sufficient work should
4.1.4 Changes in electromagnetic response caused by the be done to establish the sensitivity level and set-up required to
presence of discontinuities are detected by the sensor, ampli- detect natural discontinuities of consequence to the end use of
fied, and modified in order to actuate audio or visual indicating the product.
devices, or both, a mechanical marker, or a signal-recording 5.3 Eddy-current testing systems are generally not sensitive
device, or a combination of these. Signals can be caused by to discontinuities adjacent to the ends of the tube. The extent of
outer surface, inner surface, or subsurface discontinuities if the the end effect region can be determined in accordance with 8.6.
eddy-current frequency provides sufficient depth of penetration
6. Basis of Application
(see 11.1). The eddy-current method is sensitive to metallur-
6.1 The following acceptance criteria may be specified in
gical variations that occur as a result of processing, thus all
the purchase specification, contractual agreement, or else-
received indications are not necessarily indicative of defective
where, and may require agreement between the purchaser and
tubing.
the supplier:
5. Significance and Use
6.1.1 Time of examination or point(s) in the manufacturing
5.1 The purpose of this practice is to outline a procedure for process at which the material will be examined,
E 309
6.1.2 Maximum time interval between equipment calibra-
tion checks,
6.1.3 Methods for detemining the extent of end effect,
6.1.4 Size and type of product,
6.1.5 Type, method of manufacture, dimensions, location,
and number of artificial discontinuities to be placed on the
calibration standard,
6.1.6 Methods of verifying dimensions and allowable toler-
ances of artificial discontinuities,
6.1.7 Extent of examination, and
6.1.8 Disposition of material with indications.
6.1.9 Operator Qualification and Certification—If required,
NDT personnel shall be qualified in accordance with a nation-
ally recognized NDT personnel qualification practice or stan-
(a) Longitudinal Notch (Milled or EDM) ID, OD, or both.
dard such as ANSI/ASNT-CP-189, SNT-TC-1A, MIL-STD-
(b) Transverse Notch (Milled, Filed, or EDM) ID, OD, or both.
(c) Drilled Hole (Radially Through One Wall).
410, or a similar document. The practice or standard used and
FIG. 2 Various Types of Artificial Discontinuities
its applicable revision shall be documented in the contractual
agreement between the using parties.
6.1.10 Qualification of Nondestructive Agencies—If speci-
dimensions (width, length, and depth), and configuration of the
fied in the contractual agreement, NDT agencies shall be
notches affect the response of the eddy-current system. Notch
qualified and evaluated in accordance with Practice E 543. The
depth is usually specified as a percentage of nominal wall
applicable edition of Practice E 543 shall be specified in the
thickness of the tubular product being examined. Notches may
contractual agreement.
be placed on the outer, inner, or both surfaces of the reference
(calibration) standard. Outer surface notches provide an indi-
7. Apparatus
cation of system response to discontinuities originating on the
7.1 Electronic Apparatus—The electronic apparatus shall
outer tube surface; whereas inner surface notches provide an
be capable of energizing the coils or probes with alternating
indication of system response to discontinuities originating on
currents of a selected frequency and shall be capable of sensing
the inner tube surface.
the changes in the electromagnetic response of the sensors.
NOTE 2—Longitudinal notch standards are normally used when testing
Equipment may include appropriate signal processing circuits
with a rotating-probe system.
such as a phase discriminator, filter circuits, etc., as required
7.6.2 Holes—Drilled holes may be used. They are usually
for the particular application.
drilled completely through the wall. Care should be taken
7.2 Encircling-Coil Assembly—The encircling-coil assem-
bly shall consist of one or more electrical coils that encircle the during drilling to avoid distortion of the tube and hole.
7.6.3 The configuration, orientation, and dimensions (diam-
article being examined.
7.3 Probe-Coil Assembly—The probe-coil assembly nor- eter of holes and the width, length, and depth of notches) of the
artificial discontinuities to be used for establishing acceptance
mally contains an exciting coil and a sensor, although in some
cases the exciter and sensor are one and the same. limits should be subject to agreement between the purchaser
and the supplier.
7.4 Magnetic Saturation System—The magne
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.