ASTM E3052-21

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of the standard as published by ASTM is to be considered the official document.
Designation: E3052 − 16 E3052 − 21
Standard Practice for
Examination of Carbon Steel Welds Using An Eddy Current
Array
This standard is issued under the fixed designation E3052; 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.
1. Scope Scope*
1.1 This practice covers the use of an eddy current array sensors (ECA) or an eddy current sensor for nondestructive examination
of carbon steel welds. It includes the detection and sizing of surface-breaking cracks in such joints, accommodating for
nonmagnetic and nonconductive coating up to 5 mm thick (typical) between the sensor and the joint. The practice covers a variety
of cracking defects, such as fatigue cracks and other types of planar discontinuities, at various locations in the weld (heat-affected
zone, toe area, and weld cap, for example). It covers the length and depth sizing of such surface-breaking discontinuities. This
practice can be used for flush-ground and not flush-ground welds. For specific ferrous alloys or specific welded parts, the user may
need a more specific procedure.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
E543 Specification for Agencies Performing Nondestructive Testing
E1316 Terminology for Nondestructive Examinations
E2261 Practice for Examination of Welds Using the Alternating Current Field Measurement Technique
E2884 Guide for Eddy Current Testing of Electrically Conducting Materials Using Conformable Sensor Arrays
E2905 Practice for Examination of Mill and Kiln Girth Gear Teeth—Electromagnetic Methods
2.2 ASNT Documents
SNT-TC-1A Recommended Practice for Personnel Qualification and Certification In Nondestructive Testing
ANSI/ASNT-CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel
This test method practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on
Electromagnetic Method.
Current edition approved Feb. 1, 2016Nov. 1, 2021. Published February 2016November 2021. Originally approved in 2016. Last previous edition approved in 2016 as
E3052 – 16. DOI: 10.1520/E3052-16.10.1520/E3052-21.
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 the ASTM website.
Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.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
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2.3 Other Standards:ISO Standard:
ISO 9712 Nondestructive Testing—Qualification and Certification of Nondestructive Testing Personnel
NAS–410 Certification and Qualification of Nondestructive Testing Personnel
2.4 AIA Standard:
NAS–410 Certification and Qualification of Nondestructive Testing Personnel
3. Terminology
3.1 Definitions: For definitions of terms relating to this practice, refer to Terminology E1316, Guide E2884, and Practice E2905.
The following definitions are specific to the examination of carbon steel welds using an eddy current array:
3.1.1 air reference measurement, n—the measured response of the sensor and instrumentation to a nonmagnetic and electrically
insulating reference material such as air.
3.1.1.1 Discussion—
the instrument shall process this measurement as a reference response for signal adjustment. This measurement is typically used
as part of the standardization process and to verify operation of the instrument. Measurements on conductive materials after
standardization with an air reference measurement should provide absolute electrical properties properties, such as electrical
conductivity, and lift-off values.
3.1.2 encoder—encoder, n—a spatial sensing device (based on mechanical, optical, or electromagnetic principles, for example)
allowing that allows for accurate monitoring of a sensor’s position during data collection, collection and is typically used to
construct spatially referenced data presentations.
3.1.3 examined part reference measurement—measurement, n—the measured response of the sensor and instrumentation to the
magnetic a region of the part to be examined.examined for which no discontinuities are present.
3.1.3.1 Discussion—
the instrument shall be capable of measuring and recording the response of the sensor on the part to be examined, and compensate
for specific material properties.This measurement is typically used to compensate for differences in material properties between
the examined material and a reference material used to develop a correlation between the eddy current sensor reponse and a
characteristic of a discontinuity, such as a crack depth.
3.1.4 known material reference measurement—measurement, n—the measured response of the sensor and instrumentation to a
given material with known, homogeneous properties electrical conductivity and magnetic permeability (such as aluminum
6061-T6, for example).example) for which no discontinuities are present.
3.1.4.1 Discussion—
the instrument shall process this as a reference response for signal adjustment and standardization to provide values that are similar
for all of the sense elements.This measurement is typically used as part of the standardization process and to verify operation of
the instrument.
4. Significance and Use
4.1 Eddy Current ArrayArrays for Crack Detection and Sizing in Carbon Steel Welds—Eddy current array allows for a fast sensor
arrays permit rapid examination of carbon steel welds for surface-breaking cracks located on the surface closest to the sensor.
sensor array. As described in Guide E2884, these sensor arrays can have multiple drive-sense pairs for each element of the array
or a large single drive winding construct with multiple individual sense elements. However, not all ECA probe designs allow for
accurate depth sizing of such discontinuities over a significant range (several millimeters, for example). To achieve proper crack
depth sizing, the system shall exhibit certain characteristics, such as: 1)(1) a lift-off signal that allows monitoring thatthe lift-off
over an adequate range of values, the range of values of interest for the examination, 2)(2) suitable phase separation between the
lift-off signal and the defect signal, signal (this depends upon the instrument used and can be viewed as a phase separation in an
impedance plane display), 3)(3) the capability to make use of the lift-off monitoringvalues for crack depth determination, 4)(4) the
capability to take into account material properties variations for crack depth determination along and across the weld and,weld,
and 5)(5) a uniform sensitivity acrossfor the sensing elements of the array in order to provide an effective single-pass examination,
as it which is expected when using an array sensor.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
Switzerland, http://www.iso.org.
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4.2 Array Sensors and Single Sensing Element Sensors—Depending on the weld geometry, it may be possible to use either a sensor
array or a sensor with a single sensing element. The sensor array would providegenerally provides a better spatial representation
of the weld properties and an improved probability of detection. detection for discontinuities. The size of the array, as well as the
size and number of individual sensing elements within the array depend on the weld geometry and other factors such as target
discontinuities. When a single-sensing element sensor is used, it shall produce signals that exhibit the characteristics listed in
subsection 4.1 and the maximum distance from the scan line to a target discontinuity, potentially detectable at a specified
probability of detection, is typically 5 mm. Imaging of the weld region can be obtained with a single element sensor if raster
scanning is performed.
4.3 Conformable Sensors—Examining welds that are not ground flush typically requires a conformable array sensor, minimally
along one axis. A conformable sensor is key to allowallowing the individual sensing elements to follow the profile of the weld cap,
and to provide a uniform response over the region of interest during the examination when the array is oriented transverse to the
weld and scanned along the length of the weld.
4.4 Crack Depth Range—The crack depth sizing range over which the array sensor can provide accurate measurement depends
on the sensor geometry, such as individual sensing element size and configuration. For example, larger sensing elements may
provide the ability to size deeper cracks, but offer limited detection capability for shallow cracks. Appropriate array sensor
selection and operating frequency is critical to ensure adequate performance for a given application. Typical operating frequencies
range between 10 kHz and 500 kHz.
4.5 Coating Thickness Range—The coating thickness range over which the array sensor can reliably detect and size cracks
depends on the individual sensing element size and overall probe geometry, among other parameters. For any coated weld
examination, a verification that the coating thickness is within the probe specification range is critical to ensure adequate results.
4.6 Crack Length Range—The crack length range over which the array sensor performs best depends on the individual sensing
element size and on any data processing performed on the data. The size of the individual sensing element mainly affects the
minimum crack length detectable, while data processing (a high pass filter, for example) may have a critical impact on the
maximum measurable crack length.
4.7 Sensitivity Uniformity—In order to maximize the provide a high probability of detection and allow accurate length and depth
sizing, it is critical that the sensitivity across the sense elements of the array be uniform. The array sensor shall exhibit variations
in sensitivity no greater than 15%.15 %. The sensitivity across the array depends on the size and configuration of single sensing
elements and shall be considered to determine the overall array accuracy. Overlapping individual sensing elements may be required
to achieve the adequate level of sensitivity uniformity (e.g. (for example, this can be achieved with multiple staggered rows of
single sensing elements is typical).or with a linear array oriented at a non-perpendicular angle to the scan direction).
4.8 Sizing and Accuracy—Depending on the material properties and weld surface condition, there is an optimal measurement
performance range for the system. The instrument and sensor array probe, the air reference measurement and known material
reference measurement, along with the operation procedure typically allow depth sizing within 630 % of its true depth. Depth
sizing accuracy is reduced when the system is operated outside its optimal range.
5. Interferences
5.1 Material Properties:
5.1.1 Base Metal—Magnetic permeability and electrical conductivity of the metal can affect the eddy current measurements, and
as such, may have an impact on the crack sizing accuracy. The system must be able to compensate for variations in the magnetic
permeability and electrical conductivity typically found in carbon steels, by using, for example steels. For example, a
standardization technique that measures and compensates for base metal properties. can be use to measure and adjust the sense
element responses to reduce the sensor response variations to the base metal property variations.
5.1.2 Variations Across the Weld—In welded structures, the magnetic permeability and electrical conductivity may vary between
the weld metal, the heat affected zone, and the base metal. Considering the array sensor is moved along the weld axis, each
individual sensing element is usually exposed to relatively constant material properties. However, from one individual sensor sense
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element to another within the array, significant properties variation may exist and the inspection system shall be able to compensate
for those local variations in order to avoid noise and undesired signals in the C-scans.
5.2 Weld Geometric Features—Geometric features in the weld such as bumps and craters can create non-relevant localized signals
that will contribute to increasing the noise level perceived by each sensor. Typically, such geometric features produce signals that
exhibit a phase response that is significantly different from a crack-like discontinuity, and can be easily discriminated. However,
the presence of several, large geometric features may reduce the overall sensitivity of the probe.
5.3 Coating—Non-conductive and non-magneticThe presence of a nonconductive and nonmagnetic coating over the weld must
be compensated for accurate depth sizing. can affect the depth sizing accuracy. If a coating thickness exceeds the specified coating
thickness range of the system, the crack depth sizing accuracy can be significantly reduced.
5.4 Curvature of Examination Surface—The examination of welds located along a curved surface may affect lift-off and coating
thickness evaluation if the individual sensors sense elements are not properly in contact with the surface (normal to the surface).
In general, the radius of curvature of the inspected part should be large compared to the sensor length. Bi-dimensional conformable
arrays may have to be used to ensure appropriate sensor contact with the surface.
5.5 Surface Roughness—Surface roughness will create localized lift-off variations that are likely to be different from one sensing
element to another within the array. To yield accurate depth sizing, the individual lift-off variations must be monitored and these
values used when compensating crack depth measurements.
5.6 Resi
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