ASTM E2261/E2261M-17(2021)
(Practice)Standard Practice for Examination of Welds Using the Alternating Current Field Measurement Technique
Standard Practice for Examination of Welds Using the Alternating Current Field Measurement Technique
SIGNIFICANCE AND USE
5.1 The purpose of the alternating current field measurement method is to evaluate welds for surface breaking discontinuities such as fabrication and fatigue cracks. The examination results may then be used by qualified organizations to assess weld service life or other engineering characteristics (beyond the scope of this practice). This practice is not intended for the examination of welds for non-surface breaking discontinuities.
SCOPE
1.1 This practice describes procedures to be followed during alternating current field measurement examination of welds for baseline and service-induced surface breaking discontinuities.
1.2 This practice is intended for use on welds in any metallic material.
1.3 This practice does not establish weld acceptance criteria.
1.4 Units—The values stated in either inch-pound units or SI units are to be regarded separately as standard. The values stated in each system might not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2261/E2261M − 17 (Reapproved 2021)
Standard Practice for
Examination of Welds Using the Alternating Current Field
Measurement Technique
ThisstandardisissuedunderthefixeddesignationE2261/E2261M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2.2 ASNT Standard:
SNT-TC-1APersonnel Qualification and Certification in
1.1 Thispracticedescribesprocedurestobefollowedduring
Nondestructive Testing
alternatingcurrentfieldmeasurementexaminationofweldsfor
ANSI/ASNT-CP-189Standard for Qualification and Certifi-
baseline and service-induced surface breaking discontinuities.
cation of Nondestructive Testing Personnel
1.2 This practice is intended for use on welds in any
2.3 ISO Standard:
metallic material.
ISO 9712Nondestructive Testing—Qualification and Certi-
fication of Nondestructive Testing Personnel
1.3 This practice does not establish weld acceptance crite-
ria.
3. Terminology
1.4 Units—The values stated in either inch-pound units or
3.1 Definitions—For definitions of terms relating to this
SI units are to be regarded separately as standard. The values
practice refer to Terminology E1316, Section A, Common
statedineachsystemmightnotbeexactequivalents;therefore,
NDT terms, and Section C, Electromagnetic testing. The
each system shall be used independently of the other. Combin-
followingdefinitionsarespecifictothealternatingcurrentfield
ingvaluesfromthetwosystemsmayresultinnonconformance
measurement technique:
with the standard.
3.2 Definitions:
1.5 This standard does not purport to address all of the
3.2.1 exciter—a device that generates a time varying elec-
safety concerns, if any, associated with its use. It is the
tromagnetic field, usually a coil energized with alternating
responsibility of the user of this standard to establish appro-
current (AC); also known as a transmitter.
priate safety, health, and environmental practices and deter-
3.2.2 detector—one or more coils or elements used to sense
mine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accor- or measure a magnetic field; also known as a receiver.
dance with internationally recognized principles on standard-
3.2.3 uniform field—as applied to nondestructive testing
ization established in the Decision on Principles for the
with magnetic fields, the area of uniform magnetic field over
Development of International Standards, Guides and Recom-
the surface of the material under examination produced by a
mendations issued by the World Trade Organization Technical
parallel induced alternating current, which has been passed
Barriers to Trade (TBT) Committee.
through the weld and is observable beyond the direct coupling
of the exciting coil.
2. Referenced Documents
3.2.4 graduated field—as applied to nondestructive testing
2.1 ASTM Standards:
with magnetic fields, a magnetic field having a controlled
E543Specification forAgencies Performing Nondestructive
gradient in its intensity.
Testing
3.3 Definitions of Terms Specific to This Standard:
E1316Terminology for Nondestructive Examinations
3.3.1 alternating current field measurement system—the
electronic instrumentation, software, probes, and all associated
components and cables required for performing weld exami-
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
nation using the alternating current field measurement tech-
structive Testing and is the direct responsibility of Subcommittee E07.07 on
Electromagnetic Method.
nique.
Current edition approved Nov. 1, 2021. Published November 2021. Originally
approved in 2003. Last previous edition approved in 2017 as E2261/E2261M–17.
DOI: 10.1520/E2261_E2261M-17R21. Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 4th Floor, New York, NY 10036, http://www.ansi.org.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Available from International Organization for Standardization (ISO), ISO
Standards volume information, refer to the standard’s Document Summary page on Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
the ASTM website. Geneva, Switzerland, http://www.iso.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2261/E2261M − 17 (2021)
3.3.2 operational reference standard—a reference standard
with specified artificial slots, used to confirm the operation of
the system.
3.3.3 Bx—the x component of the magnetic field, parallel to
the weld toe, the magnitude of which is proportional to the
current density set up by the electric field.
3.3.4 Bz—the z component of the magnetic field normal to
the inspected base metal/heat affected zone surface, the mag-
nitude of which is proportional to the lateral deflection of the
induced currents in the plane of that surface.
3.3.5 X-Y Plot—an X-Ygraph with two orthogonal compo-
nents of magnetic field plotted against each other.
3.3.6 time base plots—these plot the relationship between
Bx or Bz values with time.
3.3.7 surface plot—for use with array probes. This type of
plot has one component of the magnetic field plotted over an
area, typically as a color contour plot or 3-D wire frame plot.
3.3.8 data sample rate—the rate at which data is digitized
for display and recording, in data points per second.
3.3.9 configuration data—standardization data and instru-
mentation settings for a particular probe stored in a computer
file.
FIG. 1 Example Bx and Bz Traces as a Probe Passes Over a
Crack
3.3.10 twin fields—magnetic fields generated in two or-
(The orientation of the traces may differ depending upon the
thogonal directions by use of two exciters
instrumentation.)
NOTE 1—Different equipment manufacturers may use slightly different
terminology. Reference should be made to the equipment manufacturer’s non-ferritic metals) requires scans with the induced magnetic
documentation for clarification.
field perpendicular to the direction of the weld.
4.2 Configuration data is loaded at the start of the exami-
4. Summary of Practice
nation. System sensitivity and operation is verified using an
4.1 In a basic alternating current field measurement system,
operation reference standard. System operation is checked and
a small probe is moved along the toe of a weld. The probe recorded prior to and at regular intervals during the examina-
containsanexcitercoil,whichinducesanACmagneticfieldin
tion. Note that when a unidirectional input current is used, any
the material surface aligned to the direction of the weld. This, decay in strength of the input field with probe lift-off or thin
in turn, causes alternating current to flow across the weld. The
coatingisrelativelysmallsothatvariationsofoutputsignal(as
depth of penetration of this current varies with material type may be associated with a discontinuity) are reduced. If a thick
and frequency but is typically 0.004 in. [0.1 mm] deep in
coating is present, then the discontinuity size estimation must
magnetic materials and 0.08 to 0.3 in. [2 to 7 mm] deep in compensate for the coating thickness. The coating thickness
non-ferrous materials. Any surface breaking discontinuities
requiring compensation is probe dependent. This can be
within a short distance of either side of the scan line at this
accomplished using discontinuity-sizing tables in the system
location will interrupt or disturb the flow of the alternating
software and an operator-entered coating thickness or auto-
current. The maximum distance from the scan line to a target
matically if the equipment measures the coating thickness or
discontinuity, potentially detectable at a specified probability
stand-off distance during the scanning process. Using the
of detection, is determined by the probe assembly size, but is
wrongcoatingthicknesswouldhaveanegativeeffectondepth
typically 0.4 in [10 mm]. Measurement of the absolute quan-
sizing accuracy if the coating thickness discrepancy is too
tities of the two major components of the surface magnetic
large. Data is recorded in a manner that allows archiving and
fields (Bx and Bz) determines the severity of the disturbance
subsequent recall for each weld location. Evaluation of exami-
(see Fig. 1) and thus the severity of the discontinuity. Discon-
nation results may be conducted at the time of examination or
tinuity sizes, such as crack length and depth, can be estimated at a later date. The examiner generates an examination report
from key points selected from the Bx and Bz traces along with
detailing complete results of the examination.
the standardization data and instrument settings from each
5. Significance and Use
individual probe. This discontinuity sizing can be performed
automatically using system software. Discontinuities essen- 5.1 The purpose of the alternating current field measure-
tially perpendicular to the weld may be detected (in ferritic ment method is to evaluate welds for surface breaking discon-
metals only) by the flux leakage effect. However confirmation tinuities such as fabrication and fatigue cracks. The examina-
ofsuchtransversediscontinuities(anddetectionofthesamein tion results may then be used by qualified organizations to
E2261/E2261M − 17 (2021)
assess weld service life or other engineering characteristics 7.1.13 Disposition of examination records and reference
(beyond the scope of this practice). This practice is not standards.
intendedfortheexaminationofweldsfornon-surfacebreaking 7.1.14 Format and outline contents of the examination
discontinuities. report.
6. Basis of Application 8. Interferences
6.1 Personnel Qualification: 8.1 This section describes items and conditions, which may
compromise the alternating current field measurement tech-
6.1.1 If specified in the contractual agreement, personnel
nique.
performing examinations to this practice shall be qualified in
accordance with a nationally or internationally recognized
8.2 Material Properties:
NDT personnel qualification practice or standard such as
8.2.1 Although there are permeability differences in a fer-
ANSI/ASNT-CP-189, SNT-TC-1A, ISO 9712, or a similar
romagnetic material between weld metal, heat affected zone
document and certified by the employer or certifying agent, as
and parent plate, the probe is normally scanned along a weld
applicable. The practice or standard used and its applicable
toe and so passes along a line of relatively constant permeabil-
revision shall be identified in the contractual agreement be-
ity. If a probe is scanned across a weld then the permeability
tween the using parties.
changes may produce indications, which could be similar to
thosefromadiscontinuity.Differentiationbetweenatransverse
6.2 Qualification of Nondestructive Evaluation Agencies—if
discontinuity signal and the weld signal can be achieved by
specified in the contractual agreement, NDT agencies shall be
takingfurtherscansparalleltotheindication,orusinganarray
qualified and evaluated as described in Practice E543, with
probe.Thesignalfromadiscontinuitywilldieawayquickly.If
reference to sections on electromagnetic examination. The
there is no significant change in indication amplitude at 0.8 in.
applicable edition of Practice E543 shall be specified in the
[20 mm] distance from the weld then the indication is likely
contractual agreement.
due to the permeability changes in the weld.
7. Job Scope and Requirements
8.3 Magnetic State:
8.3.1 Demagnetization—It must be ensured that the surface
7.1 The following items may require agreement by the
being examined is in the non-magnetized state. Therefore the
examining party and their client and should be specified in the
procedure followed with any previous magnetic technique
purchase document or elsewhere:
deployed must include demagnetization of the surface. This is
7.1.1 Location and type of welded component to be
becauseareasofremnantmagnetization,particularlywherethe
examined, design specifications, degradation history, previous
leg of a magnetic particle examination yoke was sited, can
nondestructive examination results, maintenance history, pro-
produce loops in the X-Y plot, which may sometimes be
cess conditions, and specific types of discontinuities that are
confused with a discontinuity indication.
required to be detected, if known.
8.3.2 Grinding marks—magnetic permeability can also be
7.1.2 The maximum window of opportunity for work.
affected by surface treatments such as grinding. These can
(Detection of small discontinuities may require a slower probe
cause localized areas of altered permeability across the line of
scan speed, or cleaning of surface, or both, which will affect
scan direction. The extent and pressure of any grinding marks
productivity.)
should always be reported by the probe operator, since these
7.1.3 Size, material grade and type, and configuration of
can give rise to strong indications in both Bx and Bz, which
weldstobeexamined.Ifrequiredbytypeofequipmentchosen,
may be confused with a discontinuity indication. If a discon-
thickness of coating and variation of coating thickness.
tinuityissuspectedinaregionofgrinding,furtherscansshould
7.1.4 A weld numbering or identification system.
betakenparallelbutawayfromtheweldtoeandperpendicular
7.1.5 Extent of examination, for example: complete or
across the region of grinding. The indication from a linear
partial coverage, which welds and to what length, whether
discontinuity will die away quickly away from the location of
straight sections only and the minimum surface curvature.
the discontinuity so that the scan away from the weld toe will
7.1.6 Meansofaccesstowelds,andareaswhereaccessmay
be flatter. If there is no significant change in indication
be restricted.
amplitude at 0.80 in. [20 mm] distance from the weld then the
7.1.7 Type of alternating current field measurement instru-
indication is likely due to the effect of the grinding. The
ment and probe; and description of operations referece stan-
indication from a region of grinding will be the same for the
dard used, including such details as dimensions and material.
perpendicular scan.
7.1.8 Required operator qualifications and certification.
8.4 Residual stress, with accompanying permeability
7.1.9 Required weld cleanliness.
variations, may be
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.