ASTM E1316-24

Standard Terminology for <?Pub Dtl?>Nondestructive Examinations

SIGNIFICANCE AND USE
3.1 The terms found in this standard are intended to be used uniformly and consistently in all nondestructive testing standards. The purpose of this standard is to promote a clear understanding and interpretation of the NDT standards in which they are used.
SCOPE
1.1 This standard covers the terminology used in the standards prepared by the E07 Committee on Nondestructive Testing. These nondestructive testing (NDT) methods include: acoustic emission, electromagnetic testing, gamma- and X-radiology, leak testing, liquid penetrant testing, magnetic particle testing, neutron radiology and gauging, ultrasonic testing, and other technical methods.  
1.2 Committee E07 recognizes that the terms examination, testing, and inspection are commonly used as synonyms in nondestructive testing. For uniformity and consistency in E07 nondestructive testing standards, Committee E07 encourages the use of the terms examination or inspection and their derivatives when describing the application of nondestructive test methods. In a specific standard, either examination or inspection shall be used consistently throughout the document. Similarly, E07 encourages the use of the term test and its derivatives when referring to the body of knowledge of a nondestructive testing method. There are, however, appropriate exceptions when the term test and its derivatives may be used to describe the application of a nondestructive test, such as measurements which produce a numeric result (for example, when using the leak testing method to perform a leak test on a component, or an ultrasonic measurement of velocity). Additionally, the term test should be used when referring to the NDT method, that is, Radiologic Testing (RT), Ultrasonic Testing (UT), and so forth. (Example: Radiologic Testing (RT) is often used to examine material to detect internal discontinuities.)
Note 1: The following sentences clarify this policy and illustrate its use:
(a) Nondestructive testing methods are used extensively for the examination or inspection of materials and components.
(b) The E07 Committee on Nondestructive Testing has prepared many documents to promote uniform usage of the nondestructive testing methods that are applied to examine or inspect materials and components.  
(c) Radiologic Testing (RT) is often used to inspect material to detect internal discontinuities.
(d) Magnetic Particle Testing (MT), Liquid Penetrant Testing (PT), and Visual Testing (VT) are often used to examine the surface of a component.
(e) The Bubble Leak Testing (BLT) method is sometimes used to leak test a pressure containing component to detect leaks.
(f) A guide for Nondestructive Testing of additively manufactured materials will describe several methods but a practice will focus on a single inspection method.  
1.3 Section A defines terms that are common to multiple NDT methods, whereas the subsequent sections define terms pertaining to specific NDT methods.  
1.4 As shown on the chart below, when a nondestructive examination or inspection produces an indication, the indication is subject to interpretation as false, nonrelevant, or relevant. If it has been interpreted as relevant, the necessary subsequent evaluation will result in the decision to accept or reject the material. With the exception of accept and reject, which retain the meaning found in most dictionaries, all the words used in the chart are defined in Section A.    
1.5 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

• Status: Published
• Publication Date: 31-Jan-2024
• ICS: 01.040.19 - Testing (Vocabularies)
• ICS: 19.100 - Non-destructive testing
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.92 - Editorial Review

Relations

• Replaces: ASTM E1316-23b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Referred By: ASTM E1781/E1781M-20 - Standard Practice for Secondary Calibration of Acoustic Emission Sensors
• Effective Date: 01-Feb-2024
• Referred By: ASTM E2907/E2907M-13(2019) - Standard Practice for Examination of Paper Machine Rolls Using Acoustic Emission from Crack Face Rubbing
• Effective Date: 01-Feb-2024
• Referred By: ASTM E1934-99a(2024) - Standard Guide for Examining Electrical and Mechanical Equipment with Infrared Thermography
• Effective Date: 01-Feb-2024
• Referred By: ASTM E2445/E2445M-20 - Standard Practice for Performance Evaluation and Long-Term Stability of Computed Radiography Systems
• Effective Date: 01-Feb-2024
• Referred By: ASTM E2001-18 - Standard Guide for Resonant Ultrasound Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts
• Effective Date: 01-Feb-2024
• Referred By: ASTM E1135-19(2024) - Standard Test Method for Comparing the Brightness of Fluorescent Penetrants
• Effective Date: 01-Feb-2024
• Referred By: ASTM E2104-22 - Standard Practice for Radiographic Examination of Advanced Aero and Turbine Materials and Components
• Effective Date: 01-Feb-2024
• Referred By: ASTM E1213-14(2022) - Standard Practice for Minimum Resolvable Temperature Difference for Thermal Imaging Systems
• Effective Date: 01-Feb-2024
• Referred By: ASTM E1815-18(2023) - Standard Test Method for Classification of Film Systems for Industrial Radiography
• Effective Date: 01-Feb-2024
• Referred By: ASTM E2002-22 - Standard Practice for Determining Image Unsharpness and Basic Spatial Resolution in Radiography and Radioscopy
• Effective Date: 01-Feb-2024
• Referred By: ASTM E2491-23 - Standard Guide for Evaluating Performance Characteristics of Phased-Array Ultrasonic Testing Instruments and Systems
• Effective Date: 01-Feb-2024
• Referred By: ASTM E2373/E2373M-19 - Standard Practice for Use of the Ultrasonic Time of Flight Diffraction (TOFD) Technique
• Effective Date: 01-Feb-2024
• Referred By: ASTM E1311-14(2022) - Standard Practice for Minimum Detectable Temperature Difference for Thermal Imaging Systems
• Effective Date: 01-Feb-2024
• Referred By: ASTM E1417/E1417M-21e1 - Standard Practice for Liquid Penetrant Testing
• Effective Date: 01-Feb-2024

Overview

ASTM E1316-24, Standard Terminology for Nondestructive Examinations, is a key terminology standard developed by ASTM International’s Committee E07 on Nondestructive Testing. This standard provides uniform and consistent definitions for terms commonly used in nondestructive testing (NDT), covering a wide range of NDT methods. By fostering consistent terminology across various standards and industries, ASTM E1316-24 ensures clear communication, proper interpretation, and effective application of NDT methods in sectors that rely on material integrity and safety.

Key Topics

• Uniform Terminology
  • Defines terms for all major NDT methods, including acoustic emission, electromagnetic testing, gamma- and X-radiology, leak testing, liquid penetrant, magnetic particle, neutron radiology, ultrasonic, and more.
• Scope of Application
  • Applies to standards prepared by ASTM Committee E07 and is designed for international use.
• Consistent Use of Terms
  • Clarifies the preferred use of terms such as "examination," "inspection," and "testing" to reduce ambiguity across NDT documentation.
• Section Structure
  • Organized into sections:
    • Section A: Common NDT terms used across multiple methods.
    • Sections B-L: Terms specific to each NDT method.
• Interpretation of Indications
  • Establishes distinction between false, nonrelevant, and relevant indications, guiding actions for material acceptance or rejection.
• Support for International Standards
  • Developed in line with WTO principles to support global harmonization in nondestructive examination terminology.

Applications

ASTM E1316-24 is broadly applicable across industries and use cases where nondestructive testing plays a critical role in ensuring quality and safety:

• Industry Sectors: Oil & gas, aerospace, automotive, construction, power generation, manufacturing, and infrastructure rely on standardized NDT terminology for compliance, inspection, and quality assurance processes.
• Document Consistency: Facilitates the clear drafting of technical documents, inspection procedures, and training materials by providing definitive descriptions of NDT terms.
• Training and Certification: Serves as the foundational reference for NDT personnel certification programs and professional development, ensuring all practitioners use terminology consistently.
• Cross-Disciplinary Communication: Improves collaboration among stakeholders (engineers, inspectors, regulators, and manufacturers) by eliminating confusion over NDT language.
• Regulatory Compliance: Supports regulatory frameworks and codes that mandate the use of consistent NDT standards in procurement, fabrication, and maintenance documentation.
• Adoption in New Technologies: As additive manufacturing and advanced materials become more widespread, the standard ensures that emerging NDT practices use terminology in line with established methods.

Related Standards

ASTM E1316-24 is referenced and complemented by several other important NDT standards and guides, such as:

• ASTM E94: Guide for Radiographic Examination Using Industrial Radiographic Film.
• ASTM E1106: Test Method for Primary Calibration of Acoustic Emission Sensors.
• ASTM E1781: Practice for Secondary Calibration of Acoustic Emission Sensors.
• International Standards: Aligns with globally recognized principles for standardization, driving compatibility with ISO and other national/international NDT standards.

Keywords: ASTM E1316-24, nondestructive testing terminology, NDT standards, NDT methods, material inspection, consistent terminology, industrial standards, inspection, examination, international standards compliance

By enabling the universal and precise use of NDT vocabulary, ASTM E1316-24 strengthens quality assurance and risk management across industries that depend on nondestructive testing.

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: E1316 − 24
Standard Terminology for
Nondestructive Examinations
This standard is issued under the fixed designation E1316; 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.
INDEX OF TERMS
Section
A: Common NDT Terms
B: Acoustic Emission (AE) Terms
C: Electromagnetic Testing (ET) Terms
D: Gamma- and X-Radiologic Testing (RT) Terms
E: Leak Testing (LT) Terms
F: Liquid Penetrant Testing (PT) Terms
G: Magnetic Particle Testing (MT) Terms
H: Neutron Radiologic Testing (NRT) Terms
I: Ultrasonic Testing (UT) Terms
J: Infrared Testing (IRT) Terms
K: Optical Holographic Testing (HT) Terms
L: Visual Testing (VT) Terms
1. Scope* component, or an ultrasonic measurement of velocity).
Additionally, the term test should be used when referring to the
1.1 This standard covers the terminology used in the stan-
NDT method, that is, Radiologic Testing (RT), Ultrasonic
dards prepared by the E07 Committee on Nondestructive
Testing (UT), and so forth. (Example: Radiologic Testing (RT)
Testing. These nondestructive testing (NDT) methods include:
is often used to examine material to detect internal disconti-
acoustic emission, electromagnetic testing, gamma- and
nuities.)
X-radiology, leak testing, liquid penetrant testing, magnetic
particle testing, neutron radiology and gauging, ultrasonic
NOTE 1—The following sentences clarify this policy and illustrate its
testing, and other technical methods. use:
(a) Nondestructive testing methods are used extensively for the exami-
1.2 Committee E07 recognizes that the terms examination,
nation or inspection of materials and components.
testing, and inspection are commonly used as synonyms in
(b) The E07 Committee on Nondestructive Testing has prepared many
documents to promote uniform usage of the nondestructive testing
nondestructive testing. For uniformity and consistency in E07
methods that are applied to examine or inspect materials and components.
nondestructive testing standards, Committee E07 encourages
(c) Radiologic Testing (RT) is often used to inspect material to detect
the use of the terms examination or inspection and their
internal discontinuities.
derivatives when describing the application of nondestructive
(d) Magnetic Particle Testing (MT), Liquid Penetrant Testing (PT), and
test methods. In a specific standard, either examination or
Visual Testing (VT) are often used to examine the surface of a component.
(e) The Bubble Leak Testing (BLT) method is sometimes used to leak
inspection shall be used consistently throughout the document.
test a pressure containing component to detect leaks.
Similarly, E07 encourages the use of the term test and its
(f) A guide for Nondestructive Testing of additively manufactured
derivatives when referring to the body of knowledge of a
materials will describe several methods but a practice will focus on a
nondestructive testing method. There are, however, appropriate
single inspection method.
exceptions when the term test and its derivatives may be used
1.3 Section A defines terms that are common to multiple
to describe the application of a nondestructive test, such as
NDT methods, whereas the subsequent sections define terms
measurements which produce a numeric result (for example,
pertaining to specific NDT methods.
when using the leak testing method to perform a leak test on a
1.4 As shown on the chart below, when a nondestructive
examination or inspection produces an indication, the indica-
tion is subject to interpretation as false, nonrelevant, or
This terminology is under the jurisdiction of ASTM Committee E07 on
Nondestructive Testing and is the direct responsibility of Subcommittee E07.92 on
relevant. If it has been interpreted as relevant, the necessary
Editorial Review.
subsequent evaluation will result in the decision to accept or
Current edition approved Feb. 1, 2024. Published February 2024. Originally
reject the material. With the exception of accept and reject,
approved in 1989. Last previous edition approved in 2023 as E1316 – 23b. DOI:
10.1520/E1316-24. which retain the meaning found in most dictionaries, all the
*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
E1316 − 24
words used in the chart are defined in Section A. E94 Guide for Radiographic Examination Using Industrial
Radiographic Film
E1106 Test Method for Primary Calibration of Acoustic
Emission Sensors
E1781 Practice for Secondary Calibration of Acoustic Emis-
sion Sensors
NOTE 2—This standard defines the terminology used in the standards
prepared by Committee E07 on Nondestructive Testing and published in
the Annual Book of ASTM Standards, Volumes 03.03 and 03.04.
3. Significance and Use
3.1 The terms found in this standard are intended to be used
uniformly and consistently in all nondestructive testing stan-
dards. The purpose of this standard is to promote a clear
1.5 This international standard was developed in accor-
understanding and interpretation of the NDT standards in
dance with internationally recognized principles on standard-
which they are used.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Terminology
mendations issued by the World Trade Organization Technical
4.1 Definitions—The definitions provided below have been
Barriers to Trade (TBT) Committee.
broken up into sections; each section is arranged in alphabeti-
2. Referenced Documents
cal order.
2.1 ASTM Standards:
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Section A: Common NDT Terms
The terms defined in Section A are the direct responsibility of Subcommittee E07.92, Editorial Review.
acceptable quality level, n—the maximum percent defective storage and transmission protocol that defines the organiza-
or the maximum number of units defective per hundred units tion of NDT image data and associated metadata in a
that, for the purpose of sampling test, can be considered standard electronic format.
satisfactory as a process average.
DISCUSSION—DICONDE is based on and inherits from the univer-
sally adopted medical standard, DICOM, which facilitates the interop-
calibration, instrument, v—the comparison of an instrument
erability of imaging equipment through data storage and network
with, or the adjustment of an instrument to, a known
communication protocols.
reference(s) often traceable to the National Institute of
discontinuity, n—a lack of continuity or cohesion; an inten-
Standards and Technology (NIST). (See also standardizat-
tional or unintentional interruption in the physical structure
ion, instrument.)
or configuration of a material or component.
cognizant engineering organization, n—the company, gov-
evaluation, n—determination of whether a relevant indication
ernment agency or other authority responsible for the design,
is cause to accept or to reject a material or component.
or end use, of the material or component for which nonde-
structive testing is required. examination, n—a procedure for determining a property (or
DISCUSSION—In addition to design personnel, the cognizant engineer- properties) or other conditions or characteristics of a material
ing organization could include personnel from engineering, material
or component by direct or indirect means.
and process engineering, stress analysis, nondestructive testing, quality
DISCUSSION—Examples include utilization of X-rays or ultrasonic
assurance and others, as appropriate.
waves for the purpose of determining (directly or by calculation) flaw
content, density, or (for ultrasound) modulus; or detection of flaws by
defect, n—one or more flaws whose aggregate size, shape,
induction of eddy currents, observing thermal behavior, AE response,
orientation, location, or properties do not meet specified
or utilization of magnetic particles or liquid penetrants.
acceptance criteria and are rejectable.
false indication, n—an NDT indication that is interpreted to be
Digital Imaging and Communication for Nondestructive caused by a condition other than a discontinuity or imper-
Evaluation (DICONDE), n—a vendor-neutral digital data fection.
E1316 − 24
flaw, n—an imperfection or discontinuity that may be detect- nonrelevant indication, n—an NDT indication that is caused
able by nondestructive testing and is not necessarily reject- by a condition or type of discontinuity that is not rejectable.
able. False indications are non-relevant.
flaw characterization, n—the process of quantifying the size, reference standard, n—a material or object for which all
shape, orientation, location, growth, or other properties, of a
relevant chemical and physical characteristics are known and
flaw based on NDT response. measurable, used as a comparison for, or standardization of,
equipment or instruments used for nondestructive testing.
imperfection, n—a departure of a quality characteristic from
(See also standardization, instrument.)
its intended condition.
relevant indication, n—an NDT indication that is caused by a
indication, n—the response or evidence from a nondestructive
condition or type of discontinuity that requires evaluation.
examination.
DISCUSSION—An indication is determined by interpretation to be
standard, n—(1) a physical reference used as a basis for
relevant, non-relevant, or false.
comparison or calibration; (2) a concept that has been
established by authority, custom, or agreement to serve as a
inspection, n—see examination.
model or rule in the measurement of quality or the estab-
interpretation, n—the determination of whether indications
lishment of a practice or procedure.
are relevant, nonrelevant, or false.
standardization, instrument, n—the adjustment of an NDT
Nondestructive Evaluation, n—see Nondestructive Testing.
instrument using an appropriate reference standard, to obtain
Nondestructive Examination, n—see Nondestructive Testing.
or establish a known and reproducible response. (This is
Nondestructive Inspection, n—see Nondestructive Testing.
usually done prior to an examination, but can be carried out
Nondestructive Testing (NDT), n—the development and ap-
anytime there is concern about the examination or instru-
plication of technical methods to examine materials or
ment response.) (See also calibration, instrument.)
components in ways that do not impair future usefulness and
serviceability in order to detect, locate, measure and evaluate test, n—see preferred terms examination or inspection.
flaws; to assess integrity, properties and composition; and to
measure geometrical characteristics.
Section B: Acoustic Emission (AE) Terms
The terms defined in Section B are the direct responsibility of Subcommittee E07.04 on Acoustic Emission Method.
acoustic emission (AE), n—the class of phenomena whereby acoustic emission signal amplitude, n—see signal amplitude,
transient stress/displacement waves are generated by the acoustic emission.
rapid release of energy from localized sources within a
acoustic emission signal (emission signal), n—see signal,
material, or the transient waves so generated.
acoustic emission.
DISCUSSION—Acoustic emission is the recommended term for general
acoustic emission signature (signature), n—see signature,
use. Other terms that have been used in AE literature include: (1) stress
acoustic emission.
wave emission, (2) microseismic activity, and (3) emission or acoustic
acoustic emission transducer, n—see sensor, acoustic emis-
emission with other qualifying modifiers.
sion.
acoustic emission channel, n—see channel, acoustic emission.
acoustic emission waveguide, n—see waveguide, acoustic
acoustic emission count (emission count) (N), n—see count,
emission.
acoustic emission.
acousto-ultrasonics (AU), n—a nondestructive examination
acoustic emission count rate, n—see count rate, acoustic
method that uses induced stress waves to detect and assess
˙
emission (emission rate or count rate) (N).
diffuse defect states, damage conditions, and variations of
acoustic emission event, n—see event, acoustic emission.
mechanical properties of a test structure. The AU method
acoustic emission event energy, n—see energy, acoustic event.
combines aspects of acoustic emission (AE) signal analysis
acoustic emission mechanism or acoustic emission source
with ultrasonic materials characterization techniques.
mechanism, n—a dynamic process or combination of pro-
cesses occurring within a material, generating acoustic
active source, n—one which exhibits increasing cumulative
emission events. AE source mechanisms can be subdivided
AE activity with increasing or constant stimulus.
into several categories: material and mechanical, macro-
adaptive location, n—source location by iterative use of
scopic and microscopic, and primary and secondary.
simulated sources in combination with computed location.
DISCUSSION—Examples of macroscopic material AE source mecha-
nisms in metals are incremental crack advancements, plastic deforma-
AE activity, n—the presence of acoustic emission during a test.
tion development and fracture of inclusions. Friction and impacts are
examples of mechanical AE. A crack advancement can be considered a
AE amplitude, n—see dB .
AE
primary AE mechanism while a resulting crack surface friction can be
considered as a secondary AE mechanism.
AE rms, n—the rectified, time averaged AE signal, measured
acoustic emission sensor, n—see sensor, acoustic emission. on a linear scale and reported in volts.
E1316 − 24
AE signal duration, n—the time between AE signal start and couplant, n—a material used at the structure-to-sensor inter-
AE signal end. face to improve the transmission of acoustic energy across
the interface during acoustic emission monitoring.
AE signal end, n—the recognized termination of an AE signal,
usually defined as the last crossing of the threshold by that critically active source, n—one which exhibits an increasing
signal. rate of change of cumulative AE activity with increasing or
constant stimulus.
AE signal generator, n—a device which can repeatedly induce
a specified transient signal into an AE instrument. critically intense source, n—one in which the AE source
intensity consistently increases with increasing stimulus or
AE signal rise time, n—the time between AE signal start and
with time under constant stimulus.
the peak amplitude of that AE signal.
cumulative (acoustic emission) amplitude distribution F(V),
AE signal start, n—the beginning of an AE signal as recog-
n—see distribution, amplitude, cumulative.
nized by the system processor, usually defined by an
cumulative (acoustic emission) threshold crossing distribution
amplitude excursion exceeding threshold.
F (V), n—see distribution, threshold crossing, cumulative.
t
AE source intensity, n—average energy, counts or amplitude dB , n—a logarithmic measure of acoustic emission signal
AE
per hit.
amplitude, referenced to 1 μV at the sensor, before amplifi-
cation.
array, n—a group of two or more AE sensors positioned on a
Signal peak amplitude dB 5 dB 5 20 log A /A
~ ! ~ !
AE ~ 1μV at sensor! 10 1 0
structure for the purposes of detecting and locating sources.
(1)
The sources would normally be within the array.
where:
arrival time interval (Δt ), n—see interval, arrival time.
ij
attenuation, n—the gradual loss of acoustic emission wave A = 1 μV at the sensor (before amplification), and
A = peak voltage of the measured acoustic emission signal
energy as a function of distance through absorption,
(also before amplification).
scattering, diffraction and geometric spreading.
DISCUSSION—Attenuation can be measured as the decrease in AE
Acoustic Emission Reference Scale:
amplitude or other AE signal parameter per unit distance.
dB Value Voltage at Sensor
AE
0 1 μV
average signal level, n—the rectified, time averaged AE
20 10 μV
logarithmic signal, measured on the AE amplitude logarith-
40 100 μV
60 1 mV
mic scale and reported in dB units (where 0 dB refers to
ae ae
80 10 mV
1 μV at the preamplifier input).
100 100 mV
broadband or wideband AE sensor, n—an AE sensor which,
DISCUSSION—In the case of sensors with integral preamplifiers, the A
when calibrated in accordance with Test Method E1106 or
reference is before internal amplification.
Practice E1781, exhibits a displacement or velocity response
dead time, n—any interval during data acquisition when the
over several hundred kHz with a coefficient of variation of
instrument or system is unable to accept new data for any
the response in V/m or V/m/s that does not exceed 50 %.
reason.
burst emission, n—see emission, burst.
differential (acoustic emission) amplitude distribution F(V),
channel, acoustic emission, n—an assembly of a sensor,
n—see distribution, differential (acoustic emission) am-
preamplifier or impedance matching transformer, filters
plitude f(V).
secondary amplifier or other instrumentation as needed,
differential (acoustic emission) threshold crossing distribution
connecting cables, and detector or processor.
f (V), n—see distribution, differential (acoustic emission)
t
DISCUSSION—A channel for examining fiberglass reinforced plastic
threshold crossing.
(FRP) may utilize more than one sensor with associated electronics.
Channels may be processed independently or in predetermined groups distribution, amplitude, cumulative (acoustic emission)
having similar sensitivity and frequency characteristics.
F(V), n—the number of acoustic emission events with
signals that exceed an arbitrary amplitude as a function of
continuous emission, n—see emission, continuous.
amplitude V.
count, acoustic emission (emission count) (N), n—the num-
ber of times the acoustic emission signal exceeds a preset
distribution, threshold crossing, cumulative (acoustic emis-
threshold during any selected portion of a test.
sion) F (V), n—the number of times the acoustic emission
t
signal exceeds an arbitrary threshold as a function of the
count, event (N ), n—the number obtained by counting each
e
threshold voltage (V).
discerned acoustic emission event once.
distribution, differential (acoustic emission) amplitude f(V),
count rate, acoustic emission (emission rate or count rate)
n—the number of acoustic emission events with signal
˙
(N), n—the time rate at which emission counts occur.
amplitudes between amplitudes of V and V + ΔV as a
count, ring-down, n—see count, acoustic emission, the pre- function of the amplitude V. f(V) is the absolute value of the
ferred term. derivative of the cumulative amplitude distribution F(V).
E1316 − 24
distribution, differential (acoustic emission) threshold For analysis purposes, dependence of measured data on the
crossing f (V), n—the number of times the acoustic emission system examination threshold must be taken into consider-
t
signal waveform has a peak between thresholds V and V + Δ ation.
V as a function of the threshold V. f (V) is the absolute value
t
event, acoustic emission (emission event), n—an occurrence
of the derivative of the cumulative threshold crossing
of a local material change or mechanical action resulting in
distribution F (V).
t
acoustic emission.
distribution, logarithmic (acoustic emission) amplitude
event count (Ne), n—see count, event.
g(V), n—the number of acoustic emission events with signal
˙
event count rate (Ne), n—see rate, event count.
amplitudes between V and αV (where α is a constant
examination area (examination region), n—that portion of a
multiplier) as a function of the amplitude. This is a variant of
structure, or test article, being examined using acoustic
the differential amplitude distribution, appropriate for loga-
emission technology.
rithmically windowed data.
Felicity effect, n—the presence of detectable acoustic emission
dynamic range, n—the difference, in decibels, between the
at a fixed predetermined sensitivity level at stress levels
overload level and the minimum signal level (usually fixed
below those previously applied.
by one or more of the noise levels, low-level distortion,
interference, or resolution level) in a system or sensor. Felicity ratio, n—the ratio of the stress at which acoustic
emission is detected, to the previously applied maximum
effective velocity, n—velocity calculated on the basis of arrival
stress.
times and propagation distances determined by artificial AE
DISCUSSION—The fixed sensitivity level will usually be the same as
generation; used for computed location.
was used for the previous loading or examination.
emission, burst, n—a qualitative description of an individual
first hit location, n—a zone location method defined by which
emission event resulting in a discrete signal.
a channel among a group of channels first detects the signal.
DISCUSSION—Fig. 1 shows an oscilloscope trace of burst emission
floating threshold, n—any threshold with amplitude estab-
signals on a background of continuous emission signal.
lished by a time average measure of the input signal.
emission, continuous, n—a qualitative description of emission
hit, n—the detection and measurement of an AE signal on a
producing a sustained signal as a result of time overlapping
channel.
or successive emission events from one or several sources,
or both.
instrumentation dead time, n—see dead time, instrumenta-
DISCUSSION—Fig. 2 and Fig. 3 show oscilloscope traces of continuous
tion.
emission signals at two different sweep rates.
intense source, n—one in which the AE source intensity of an
energy, acoustic emission event, n—the total elastic energy
active source consistently exceeds, by a specified amount,
released by an emission event. the average AE source intensity of active sources.
energy, acoustic emission signal, n—the energy contained in interval, arrival time (Δt ), n—the time interval between the
ij
an acoustic emission signal, which is evaluated as the
detected arrivals of an acoustic emission wave at the ith and
integral of the volt-squared function over time. jth sensors of a sensor array.
evaluation threshold, n—a threshold value used for analysis
Kaiser effect, n—the absence of detectable acoustic emission
of the examination data. Data may be recorded with a system at a fixed sensitivity level, until previously applied stress
examination threshold lower than the evaluation threshold. levels are exceeded.
FIG. 1 Burst Emission Signal on a Continuous Emission Signal Background (Sweep Rate—5 ms/cm)
E1316 − 24
FIG. 2 Continuous Emission Signal (Sweep Rate—5 ms/cm)
FIG. 3 Continuous Emission Signal (Sweep Rate—0.1 ms/cm)
DISCUSSION—Whether or not the effect is observed is material (a) linear location, n—one-dimensional source location requiring two
specific. The effect usually is not observed in materials containing or more channels.
developing flaws. (b) planar location, n—two-dimensional source location requiring
three or more channels.
location accuracy, n—a value determined by comparison of
(c) 3D location, n—three-dimensional source location requiring five or
the actual position of an AE source (or simulated AE source)
more channels.
to the computed location. (d) adaptive location, n—source location by iterative use of simulated
sources in combination with computed location.
location, cluster, n—a location technique based upon a speci-
fied amount of AE activity located within a specified length location, continuous AE signal, n—a method of location
based on continuous AE signals, as opposed to hit or
or area, for example: 5 events within 12 linear inches or 12
difference in arrival time location methods.
square inches.
DISCUSSION—This type of location is commonly used in leak location
location, computed, n—a source location method based on
due to the presence of continuous emission. Some common types of
algorithmic analysis of the difference in arrival times among
continuous signal location methods include signal attenuation and
sensors. correlation analysis methods.
DISCUSSION—Several approaches to computed location are used, (a) signal attenuation-based source location, n—a source location
including linear location, planar location, three-dimensional location, method that relies on the attenuation versus distance phenomenon of
and adaptive location. AE signals. By monitoring the AE signal magnitudes of the continuous
E1316 − 24
signal at various points along the object, the source can be determined
signal amplitude, acoustic emission, n—the peak voltage of
based on the highest magnitude or by interpolation or extrapolation of
the largest excursion attained by the signal waveform from
multiple readings.
an emission event.
(b) correlation-based source location, n—a source location method
that compares the changing AE signal levels (usually waveform-based
signal overload level—that level above which operation
amplitude analysis) at two or more points surrounding the source and
ceases to be satisfactory as a result of signal distortion,
determines the time displacement of these signals. The time displace-
overheating, or damage.
ment data can be used with conventional hit-based location techniques
to arrive at a solution for the source site.
signal overload point, n—the maximum input signal ampli-
tude at which the ratio of output to input is observed to
location, source, n—any of several methods of evaluating AE
remain within a prescribed linear operating range.
data to determine the position on the structure from which
the AE originated. Several approaches to source location are
signal strength, n—the measured area of the rectified AE
used, including zone location, computed location, and con-
signal with units proportional to volt-sec.
tinuous location.
DISCUSSION—The proportionality constant is specified by the AE
location, zone, n—any of several techniques for determining instrument manufacturer.
the general region of an acoustic emission source (for
signature, acoustic emission (signature), n—a characteristic
example, total AE counts, energy, hits, and so forth).
set of reproducible attributes of acoustic emission signals
DISCUSSION—Several approaches to zone location are used, including
associated with a specific test article as observed with a
independent channel zone location, first hit zone location, and arrival
particular instrumentation system under specified test con-
sequence zone location.
ditions.
(a) independent channel zone location, n—a zone location technique
that compares the gross amount of activity from each channel.
stimulation, n—the application of a stimulus such as force,
(b) first-hit zone location, n—a zone location technique that
pressure, heat, and so forth, to a test article to cause
compares only activity from the channel first detecting the AE event.
(c) arrival sequence zone location, n—a zone location technique
activation of acoustic emission sources.
that compares the order of arrival among sensors.
system examination threshold, n—the electronic instrument
logarithmic (acoustic emission) amplitude distribution g(V),
threshold (see evaluation threshold) which data will be
n—see distribution, logarithmic (acoustic emission) am-
detected.
plitude.
overload recovery time, n—an interval of nonlinear operation transducers, acoustic emission, n—see sensor, acoustic emis-
of an instrument caused by a signal with amplitude in excess
sion.
of the instrument’s linear operating range.
verification, AE system (performance check, AE system),
n—the process of testing an AE system to assure confor-
performance check, AE system, n—see verification, AE sys-
mance to a specified level of performance or measurement
tem.
accuracy. (This is usually carried out prior to, during, or
processing capacity, n—the number of hits that can be
after, or combinations thereof, an AE examination with the
processed at the processing speed before the system must
AE system connected to the examination object, using a
interrupt data collection to clear buffers or otherwise prepare
simulated or artificial acoustic emission source.)
for accepting additional data.
voltage threshold, n—a voltage level on an electronic com-
processing speed, n—the sustained rate (hits/s), as a function
parator such that signals with amplitudes larger than this
of the parameter set and number of active channels, at which
level will be recognized. The voltage threshold may be user
AE signals can be continuously processed by a system
adjustable, fixed, or automatic floating.
without interruption for data transport.
waveguide, acoustic emission, n—a device that couples elastic
˙
rate, event count (Ne), n—the time rate of the event count.
energy from a structure or other test object to a remotely
rearm delay time, n—see time, rearm delay.
mounted sensor during AE monitoring. An example of an
resonant or narrowband AE sensor, n—an AE sensor which,
acoustic emission waveguide would be a solid wire of rod
when calibrated in accordance with Test Method E1106 or
that is coupled at one end to a monitored structure, and to a
Practice E1781, exhibits a displacement or velocity response
sensor at the other end.
with one or more dominant frequency peaks such that it does
wideband-based (modal) AE techniques, n—AE techniques
not satisfy the definition of a broadband AE sensor.
with wideband AE sensors that subject waveforms of the
ring-down count, n—see count, acoustic emission, the pre-
signals to combined time and frequency analysis to obtain
ferred term.
mode-based arrival times (for source location calculations)
sensor, acoustic emission, n—a detection device, generally
and modal amplitudes for potential source identification.
piezoelectric, that transforms the particle motion produced
Note that mode-based arrival times can also be obtained with
by an elastic wave into an electrical signal.
resonant sensors, but only at certain experimentally deter-
signal, acoustic emission (emission signal), n—an electrical mined frequencies.
signal obtained by detection of one or more acoustic
emission events.
E1316 − 24
Section C: Electromagnetic Testing (ET) Terms
The terms defined in Section C are the direct responsibility of Subcommittee E07.07 on Electromagnetic Methods.
absolute coil, n—a coil (or coils) that respond(s) to the total comparative measurements, n—measurements made in
detected electric or magnetic properties, or both, of a part or which the unbalance in the system is measured using
section of the part without comparison to another section of comparator coils in contrast to differential and absolute
the part or to another part. measurements.
DISCUSSION—See also comparator coils.
absolute measurements, n—measurements made without a
comparative readout, n—the signal output of comparator
direct reference using an absolute coil in contrast to differ-
coils.
ential and comparative measurements.
DISCUSSION—See also comparator coils.
DISCUSSION—See also absolute coil.
comparative system, n—a system that uses coil assemblies
absolute readout, n—the signal output of an absolute coil.
and associated electronics to detect any electric or magnetic
DISCUSSION—See also absolute coil.
condition, or both, that is not common to the specimen and
absolute system, n—a system that uses a coil assembly and
the standard.
associated electronics to measure the total electromagnetic
DISCUSSION—See comparator coils.
properties of a part without direct comparison to another
comparator coils, n—two or more coils electrically connected
section of the part or to another part.
in series opposition but arranged so that there is no mutual
DISCUSSION—See also absolute coil.
induction (coupling) between them such that any electric or
acceptance level, n—a level above or below which specimens
magnetic condition, or both, that is not common to the
are acceptable in contrast to rejection level.
specimen and the standard, will produce an unbalance in the
system and thereby yield an indication.
acceptance limits, n—levels used in electromagnetic sorting
which establish the group into which the material under
conductivity, n—the intrinsic property of a particular material
examination belongs.
to carry electric current; it is commonly expressed in percent
IACS (International Annealed Copper Standard) or MS/m
amplitude distortion, n—same as harmonic distortion.
(MegaSiemens/metre).
amplitude response, n—that property of an examination
system whereby the amplitude of the detected signal is
conformable, adj—refers to an ability of sensors or sensor
measured without regard to phase.
arrays to conform to non-planar surfaces without significant
DISCUSSION—See also harmonic analysis and phase analysis.
effects on the measurement results, or with effects that are
limited to a quantifiable bound.
annular coil clearance, n—the mean radial distance between
adjacent coil assembly and part surface in electromagnetic
coupling, v—two electric circuits are said to be coupled to each
encircling coil examination.
other when they have an impedance in common so that a
current in one causes a voltage in the other.
annular coils, n—see encircling coils.
artificial discontinuity, n—reference discontinuities, such as
cut-off level, n—same as rejection level.
holes, grooves, or notches, that are introduced into a refer-
defect resolution, n—a property of an examination system that
ence standard to provide accurately reproducible sensitivity
enables the separation of indications due to defects in a
levels for electromagnetic test equipment.
sample that are located in proximity to each other.
band pass filter, n—a wave filter having a single transmission
depth of penetration, n—the depth at which the magnetic field
band; neither of the cut-off frequencies being zero or infinity.
strength or intensity of induced eddy currents has decreased
to 37 % of its surface value.
bobbin coil, n—see ID coil.
DISCUSSION—The depth of penetration depends upon the coil size, the
bucking coils, n—same as differential coils.
frequency of the signal, and the conductivity and permeability of the
circumferential coils, n—see encircling coils.
material. It is related to the coil size at low frequencies and is equal to
coil, absolute, n—see absolute coil. the skin depth at high frequencies. Related synonymous terms are
standard depth of penetration and skin depth. (See also skin effect.)
coil, reference, n—see reference coil.
depth of sensitivity, n—depth to which the sensor response to
coil size, n—the dimension of a coil, for example, length or
features or properties of interest exceeds a noise threshold.
diameter.
DISCUSSION—The depth of sensitivity can be larger or smaller than
the depth of penetration since it incorporates a comparison between the
coil spacing, n—the axial distance between two encircling
signal obtained from a feature as well as measurement noise, whereas
coils of a differential system.
the depth of penetration refers to the decrease in field intensity with
distance away from a test coil.
coil, test, n—the section of the probe or coil assembly that
excites or detects, or both, the electromagnetic field in the diamagnetic material—a material whose relative permeabil-
material under examination. ity is less than unity.
E1316 − 24
DISCUSSION—The intrinsic induction Bi is oppositely directed to the
a given set of physical conditions such as a cylindrical
applied magnetizing force H.
specimen in an encircling coil at a specific frequency.
DISCUSSION—This quantity may be different from the permeability of
differential coils, n—two or more coils electrically connected
the particular metal being examined in that it takes into account such
in series opposition such that any electric or magnetic
things as the geometry of the part, the relative position of the encircling
condition, or both, that is not common to the areas of a
coil, and characteristics of the magnetic field.
specimen being electromagnetically examined will produce
electrical center, n—the center established by the electromag-
an unbalance in the system and thereby yield an indication.
netic field distribution within a test coil.
differential measurements, n—measurements made in which
DISCUSSION—A constant intensity signal, irrespective of the circum-
the imbalance in the system is measured using differential
ferential position of a discontinuity, is indicative of electrical centering.
The electrical center may be different from the physical center of the
coils in contrast to absolute and comparative measurements.
test coil.
DISCUSSION—See also differential coils.
electromagnetic testing, n—a nondestructive test method for
differential readout, n—the signal output of differential coils.
materials, including magnetic materials, that uses electro-
DISCUSSION—See also differential coils.
magnetic energy having frequencies less than those of
differential signal, n—an output signal that is proportional to
visible light to yield information regarding the quality of
the rate of change of the input signal.
examined material.
differential system, n—an electromagnetic examination sys-
encircling coils, n—coil(s) or coil assembly that surround(s)
tem that uses coil assemblies and associated electronics to
the part to be examined. Coils of this type are also referred
detect an electric or magnetic condition, or both, that is not
to as annular, circumferential, or feed-through coils.
common to the areas of the specimen being examined.
end effect, n—see edge effect.
DISCUSSION—See also differential coils.
end effect, n—the loss in sensitivity to discontinuities located
drive winding, n—a conductor pattern or coil that produces a
near the extreme ends of the tube as the ends of the tube
magnetic field that couples to the material being examined.
enter or leave the test coil.
DISCUSSION—The drive winding can have various geometries, includ-
ing: (1) a simple linear conductor that is placed adjacent to a
feed-through coils, n—see encircling coils.
one-dimensional array of sensing elements; (2) one or multiple con-
ferromagnetic material, n—a material that, in general, exhib-
ducting loops driven to create a complex field pattern; and (3) multiple
its the phenomena of magnetic hysteresis and saturation, and
conducting loops with a separate loop for each sensing element.
whose permeability is dependent on the magnetizing force.
eddy current, n—an electrical current caused to flow in a
fill factor, n—(a) for encircling coil electromagnetic testing,
conductor by the time or space variation, or both, of an
the ratio of the cross-sectional area of the specimen to the
applied magnetic field.
effective cross-sectional core area of the primary encircling
eddy current testing, n—a nondestructive testing method in coil (outside diameter of coil form, not inside diameter
which is adjacent to specimen); (b) for internal probe
which eddy current flow is induced in the material under
examination. electromagnetic testing, the ratio of the effective cross-
sectional area of the primary internal probe coil to the
DISCUSSION—Changes in the flow caused by variations in the
specimen are reflected into a nearby coil, coils, Hall effect device,
cross-sectional area of the tube interior.
magnetoresistive sensor, or other magnetic field sensor for subsequent
filter, n—a network that passes electromagnetic wave energy
analysis by suitable instrumentation and techniques.
over a described range of frequencies and attenuates energy
edge effect, n—the disturbance of the magnetic field and eddy
at all other frequencies.
currents due to the proximity of an abrupt change in
gate, n—same as rejection level.
specimen geometry (edge).
DISCUSSION—This effect generally results in the masking of discon-
harmonic analysis, n—an analytical technique whereby the
tinuities within the affected region. (This effect is also termed the end
amplitude or phase, or both, of the frequency components of
effect.)
a complex periodic signal is determined.
effective depth of penetration (EDP), n—for (a) thickness,
harmonic distortion, n—nonlinear distortion characterized by
the minimum depth beyond which an examination system
the appearance in the output of harmonics other than the
can no longer reliably detect a further increase in specimen
fundamental component when the input wave is sinusoidal.
thickness, or (b) defects, the limit for reliably detecting
metallurgical or mechanical discontinuities by way of con- IACS, n—the International Annealed Copper Standard; an
international standard of electrical conductivity.
ventional continuous wave (CW) eddy current instrumenta-
tion and sensors.
ID coil, n—a coil or coil assembly used for electromagnetic
DISCUSSION—The EDP point is approximately three times the stan-
testing by insertion into the examination piece as in the case
dard depth of penetration.
of an inside probe for tubing.
effective permeability, n—a hypothetical quantity that de-
DISCUSSION—Coils of this type are also referred to as inside coils,
scribes the magnetic permeability that is experienced under inserted coils, or bobbin coils.
E1316 − 24
impedance, n—the total opposition that a circuit presents to noise, n—any nonrelevant signal that tends to interfere with the
the flow of an alternating current, specifically the complex normal reception or processing of a desired flaw signal.
quotient of voltage divided by current.
DISCUSSION—It should be noted that such noise signals may be
generated by inhomogeneities in the inspected part that are not
impedance analysis, n—an analytical method that consists of
detrimental to the end use of the part.
correlating changes in the amplitude, phase, or quadrature
nonferromagnetic material, n—a material that is not magne-
components, or all of these, of a complex signal voltage to
tizable and hence, essentially not affected by magnetic fields.
the electromagnetic conditions within a specimen.
This would include paramagnetic materials and diamagnetic
impedance plane diagram, n—a graphical representation of
materials.
the locus of points, indicating the variations in the imped-
normal permeability, n—the ratio of the induction (when
ance of a test coil as a function of basic examination
cyclically made to change symmetrically about zero) to the
parameters.
corresponding change in magnetizing force.
incremental permeability, n—the ratio of the change in
off-line testing, n—eddy current tests conducted on equipment
magnetic induction to the corresponding change in magne-
tizing force when the mean induction differs from zero. that includes the test coil and means to propel individual
tubes under examination through the coil at appropriate
initial permeability, n—the slope of the induction curve at
speeds and conditions.
zero magnetizing force as the specimen is being removed
from a demagnetizing condition (slope at origin of BH curve
on-line testing, n—eddy current tests conducted on equipment
before hysteresis is observed). that includes the test coil and means to propel tubes under
examination through the coil at appropriate speeds and
inserted coil, n—see ID coil.
conditions as an integral part of a continuous tube manufac-
inside coil, n—see ID coil.
turing sequence.
insulating shims, n—conformable and substantially non-
conducting or insulating foils that are used to measure effects optimum frequency, n—that frequency which provides the
of small lift-off excursions on sensor response. largest signal-to-noise ratio obtainable for the detection of an
individual material property.
lift-off, n—normal distance from the plane of the sensor coil or
DISCUSSION—A different optimum frequency may be associated with
winding conductors to the surface of the conducting material
each material property.
under examination.
paramagnetic material, n—a material that has a relative
lift-off effect, n—the effect observed in an examination system
permeability slightly greater than unity and that is practically
output due to a change in magnetic coupling between a
independent of the magnetizing force.
specimen and a probe
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1316 − 23b E1316 − 24
Standard Terminology for
Nondestructive Examinations
This standard is issued under the fixed designation E1316; 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.
INDEX OF TERMS
Section
A: Common NDT Terms
B: Acoustic Emission (AE) Terms
C: Electromagnetic Testing (ET) Terms
D: Gamma- and X-Radiologic Testing (RT) Terms
E: Leak Testing (LT) Terms
F: Liquid Penetrant Testing (PT) Terms
G: Magnetic Particle Testing (MT) Terms
H: Neutron Radiologic Testing (NRT) Terms
I: Ultrasonic Testing (UT) Terms
J: Infrared Testing (IRT) Terms
K: Optical Holographic Testing (HT) Terms
L: Visual Testing (VT) Terms
1. Scope*
1.1 This standard covers the terminology used in the standards prepared by the E07 Committee on Nondestructive Testing. These
nondestructive testing (NDT) methods include: acoustic emission, electromagnetic testing, gamma- and X-radiology, leak testing,
liquid penetrant testing, magnetic particle testing, neutron radiology and gauging, ultrasonic testing, and other technical methods.
1.2 Committee E07 recognizes that the terms examination, testing, and inspection are commonly used as synonyms in
nondestructive testing. For uniformity and consistency in E07 nondestructive testing standards, Committee E07 encourages the use
of the terms examination or inspection and their derivatives when describing the application of nondestructive test methods. In a
specific standard, either examination or inspection shall be used consistently throughout the document. Similarly, E07 encourages
the use of the term test and its derivatives when referring to the body of knowledge of a nondestructive testing method. There are,
however, appropriate exceptions when the term test and its derivatives may be used to describe the application of a nondestructive
test, such as measurements which produce a numeric result (for example, when using the leak testing method to perform a leak
test on a component, or an ultrasonic measurement of velocity). Additionally, the term test should be used when referring to the
NDT method, that is, Radiologic Testing (RT), Ultrasonic Testing (UT), and so forth. (Example: Radiologic Testing (RT) is often
used to examine material to detect internal discontinuities.)
NOTE 1—The following sentences clarify this policy and illustrate its use:
(a) Nondestructive testing methods are used extensively for the examination or inspection of materials and components.
(b) The E07 Committee on Nondestructive Testing has prepared many documents to promote uniform usage of the nondestructive testing methods that
are applied to examine or inspect materials and components.
(c) Radiologic Testing (RT) is often used to inspect material to detect internal discontinuities.
(d) Magnetic Particle Testing (MT), Liquid Penetrant Testing (PT), and Visual Testing (VT) are often used to examine the surface of a component.
This terminology is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.92 on Editorial
Review.
Current edition approved Sept. 1, 2023Feb. 1, 2024. Published September 2023February 2024. Originally approved in 1989. Last previous edition approved in 2023 as
E1316 – 23a.E1316 – 23b. DOI: 10.1520/E1316-23B.10.1520/E1316-24.
*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
E1316 − 24
(e) The Bubble Leak Testing (BLT) method is sometimes used to leak test a pressure containing component to detect leaks.
(f) A guide for Nondestructive Testing of additively manufactured materials will describe several methods but a practice will focus on a single
inspection method.
1.3 Section A defines terms that are common to multiple NDT methods, whereas the subsequent sections define terms pertaining
to specific NDT methods.
1.4 As shown on the chart below, when a nondestructive examination or inspection produces an indication, the indication is subject
to interpretation as false, nonrelevant, or relevant. If it has been interpreted as relevant, the necessary subsequent evaluation will
result in the decision to accept or reject the material. With the exception of accept and reject, which retain the meaning found in
most dictionaries, all the words used in the chart are defined in Section A.
1.5 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:
E94 Guide for Radiographic Examination Using Industrial Radiographic Film
E1106 Test Method for Primary Calibration of Acoustic Emission Sensors
E1781 Practice for Secondary Calibration of Acoustic Emission Sensors
NOTE 2—This standard defines the terminology used in the standards prepared by Committee E07 on Nondestructive Testing and published in the Annual
Book of ASTM Standards, Volumes 03.03 and 03.04.
3. Significance and Use
3.1 The terms found in this standard are intended to be used uniformly and consistently in all nondestructive testing standards.
The purpose of this standard is to promote a clear understanding and interpretation of the NDT standards in which they are used.
4. Terminology
4.1 Definitions—The definitions provided below have been broken up into sections; each section is arranged in alphabetical order.
Section A: Common NDT Terms
The terms defined in Section A are the direct responsibility of Subcommittee E07.92, Editorial Review.
acceptable quality level, n—the maximum percent defective or the maximum number of units defective per hundred units that,
for the purpose of sampling test, can be considered satisfactory as a process average.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
E1316 − 24
calibration, instrument, v—the comparison of an instrument with, or the adjustment of an instrument to, a known reference(s)
often traceable to the National Institute of Standards and Technology (NIST). (See also standardization,standardizat-
ion, instrument.)
cognizant engineering organization, n—the company, government agency or other authority responsible for the design, or end
use, of the material or component for which nondestructive testing is required.
DISCUSSION—
In addition to design personnel, the cognizant engineering organization could include personnel from engineering, material and process engineering,
stress analysis, nondestructive testing, quality assurance and others, as appropriate.
defect, n—one or more flaws whose aggregate size, shape, orientation, location, or properties do not meet specified acceptance
criteria and are rejectable.
Digital Imaging and Communication for Nondestructive Evaluation (DICONDE), n—a vendor-neutral digital data storage
and transmission protocol that defines the organization of NDT image data and associated metadata in a standard electronic
format.
DISCUSSION—
DICONDE is based on and inherits from the universally adopted medical standard, DICOM, which facilitates the interoperability of imaging equipment
through data storage and network communication protocols.
discontinuity, n—a lack of continuity or cohesion; an intentional or unintentional interruption in the physical structure or
configuration of a material or component.
evaluation, n—determination of whether a relevant indication is cause to accept or to reject a material or component.
examination, n—a procedure for determining a property (or properties) or other conditions or characteristics of a material or
component by direct or indirect means.
DISCUSSION—
Examples include utilization of X-rays or ultrasonic waves for the purpose of determining (directly or by calculation) flaw content, density, or (for
ultrasound) modulus; or detection of flaws by induction of eddy currents, observing thermal behavior, AE response, or utilization of magnetic particles
or liquid penetrants.
false indication, n—an NDT indication that is interpreted to be caused by a condition other than a discontinuity or imperfection.
flaw, n—an imperfection or discontinuity that may be detectable by nondestructive testing and is not necessarily rejectable.
flaw characterization, n—the process of quantifying the size, shape, orientation, location, growth, or other properties, of a flaw
based on NDT response.
imperfection, n—a departure of a quality characteristic from its intended condition.
indication, n—the response or evidence from a nondestructive examination.
DISCUSSION—
An indication is determined by interpretation to be relevant, non-relevant, or false.
inspection, n—see examination.
interpretation, n—the determination of whether indications are relevant, nonrelevant, or false.
Nondestructive Evaluation,n—see Nondestructive Testing.
E1316 − 24
Nondestructive Examination,n—see Nondestructive Testing.
Nondestructive Inspection,n—see Nondestructive Testing.
Nondestructive Testing (NDT), n—the development and application of technical methods to examine materials or components
in ways that do not impair future usefulness and serviceability in order to detect, locate, measure and evaluate flaws; to assess
integrity, properties and composition; and to measure geometrical characteristics.
nonrelevant indication, n—an NDT indication that is caused by a condition or type of discontinuity that is not rejectable. False
indications are non-relevant.
reference standard, n—a material or object for which all relevant chemical and physical characteristics are known and
measurable, used as a comparison for, or standardization of, equipment or instruments used for nondestructive testing. (See also
standardization, instrument.)
relevant indication, n—an NDT indication that is caused by a condition or type of discontinuity that requires evaluation.
standard, n—(1) a physical reference used as a basis for comparison or calibration; (2) a concept that has been established by
authority, custom, or agreement to serve as a model or rule in the measurement of quality or the establishment of a practice or
procedure.
standardization, instrument, n—the adjustment of an NDT instrument using an appropriate reference standard, to obtain or
establish a known and reproducible response. (This is usually done prior to an examination, but can be carried out anytime there
is concern about the examination or instrument response.) (See also calibration, instrument.)
test, n—see preferred terms examination or inspection.
Section B: Acoustic Emission (AE) Terms
The terms defined in Section B are the direct responsibility of Subcommittee E07.04 on Acoustic Emission Method.
acoustic emission (AE), n—the class of phenomena whereby transient stress/displacement waves are generated by the rapid
release of energy from localized sources within a material, or the transient waves so generated.
DISCUSSION—
Acoustic emission is the recommended term for general use. Other terms that have been used in AE literature include: (1) stress wave emission, (2)
microseismic activity, and (3) emission or acoustic emission with other qualifying modifiers.
acoustic emission channel,n—see channel, acoustic emission.
acoustic emission count (emission count) (N),n—see count, acoustic emission.
acoustic emission count rate,n—see count rate, acoustic emission (emission rate or count rate) (N˙).
acoustic emission event,n—see event, acoustic emission.
acoustic emission event energy,n—see energy, acoustic event.
acoustic emission mechanism or acoustic emission source mechanism, n—a dynamic process or combination of processes
occurring within a material, generating acoustic emission events. AE source mechanisms can be subdivided into several
categories: material and mechanical, macroscopic and microscopic, and primary and secondary.
DISCUSSION—
Examples of macroscopic material AE source mechanisms in metals are incremental crack advancements, plastic deformation development and fracture
of inclusions. Friction and impacts are examples of mechanical AE. A crack advancement can be considered a primary AE mechanism while a resulting
crack surface friction can be considered as a secondary AE mechanism.
E1316 − 24
acoustic emission sensor,n—see sensor, acoustic emission.
acoustic emission signal amplitude,n—see signal amplitude, acoustic emission.
acoustic emission signal (emission signal),n—see signal, acoustic emission.
acoustic emission signature (signature),n—see signature, acoustic emission.
acoustic emission transducer,n—see sensor, acoustic emission.
acoustic emission waveguide,n—see waveguide, acoustic emission.
acousto-ultrasonics (AU),n—a nondestructive examination method that uses induced stress waves to detect and assess diffuse
defect states, damage conditions, and variations of mechanical properties of a test structure. The AU method combines aspects
of acoustic emission (AE) signal analysis with ultrasonic materials characterization techniques.
active source, n—one which exhibits increasing cumulative AE activity with increasing or constant stimulus.
adaptive location, n—source location by iterative use of simulated sources in combination with computed location.
AE activity, n—the presence of acoustic emission during a test.
AE amplitude,n—see dB .
AE
AE rms, n—the rectified, time averaged AE signal, measured on a linear scale and reported in volts.
AE signal duration, n—the time between AE signal start and AE signal end.
AE signal end, n—the recognized termination of an AE signal, usually defined as the last crossing of the threshold by that signal.
AE signal generator, n—a device which can repeatedly induce a specified transient signal into an AE instrument.
AE signal rise time, n—the time between AE signal start and the peak amplitude of that AE signal.
AE signal start, n—the beginning of an AE signal as recognized by the system processor, usually defined by an amplitude
excursion exceeding threshold.
AE source intensity, n—average energy, counts or amplitude per hit.
array, n—a group of two or more AE sensors positioned on a structure for the purposes of detecting and locating sources. The
sources would normally be within the array.
arrival time interval (Δt ), n—see interval, arrival time.
ij
attenuation, n—the gradual loss of acoustic emission wave energy as a function of distance through absorption, scattering,
diffraction and geometric spreading.
DISCUSSION—
Attenuation can be measured as the decrease in AE amplitude or other AE signal parameter per unit distance.
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average signal level, n—the rectified, time averaged AE logarithmic signal, measured on the AE amplitude logarithmic scale
and reported in dB units (where 0 dB refers to 1 μV at the preamplifier input).
ae ae
broadband or wideband AE sensor, n—an AE sensor which, when calibrated in accordance with Test Method E1106 or
Practice E1781, exhibits a displacement or velocity response over several hundred kHz with a coefficient of variation of the
response in V/m or V/m/s that does not exceed 50 %.
burst emission,n—see emission, burst.
channel, acoustic emission, n—an assembly of a sensor, preamplifier or impedance matching transformer, filters secondary
amplifier or other instrumentation as needed, connecting cables, and detector or processor.
DISCUSSION—
A channel for examining fiberglass reinforced plastic (FRP) may utilize more than one sensor with associated electronics. Channels may be processed
independently or in predetermined groups having similar sensitivity and frequency characteristics.
continuous emission,n—see emission, continuous.
count, acoustic emission (emission count) (N), n—the number of times the acoustic emission signal exceeds a preset threshold
during any selected portion of a test.
count, event (N ), n—the number obtained by counting each discerned acoustic emission event once.
e
count rate, acoustic emission (emission rate or count rate) (N˙), n—the time rate at which emission counts occur.
count, ring-down,n—see count, acoustic emission, the preferred term.
couplant, n—a material used at the structure-to-sensor interface to improve the transmission of acoustic energy across the
interface during acoustic emission monitoring.
critically active source, n—one which exhibits an increasing rate of change of cumulative AE activity with increasing or
constant stimulus.
critically intense source, n—one in which the AE source intensity consistently increases with increasing stimulus or with time
under constant stimulus.
cumulative (acoustic emission) amplitude distribution F(V),n—see distribution, amplitude, cumulative.
cumulative (acoustic emission) threshold crossing distribution F (V),n—see distribution, threshold crossing, cumulative.
t
dB , n—a logarithmic measure of acoustic emission signal amplitude, referenced to 1 μV at the sensor, before amplification.
AE
Signal peak amplitude dB 5 dB 5 20 log A /A (1)
~ ! ~ !
AE ~ 1μV at sensor! 10 1 0
where:
A = 1 μV at the sensor (before amplification), and
A = peak voltage of the measured acoustic emission signal (also before amplification).
Acoustic Emission Reference Scale:
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dB Value Voltage at Sensor
AE
0 1 μV
20 10 μV
40 100 μV
60 1 mV
80 10 mV
100 100 mV
DISCUSSION—
In the case of sensors with integral preamplifiers, the A reference is before internal amplification.
dead time, n—any interval during data acquisition when the instrument or system is unable to accept new data for any reason.
differential (acoustic emission) amplitude distribution F(V),n—see distribution, differential (acoustic emission) amplitude
f(V).
differential (acoustic emission) threshold crossing distribution f (V),n—see distribution, differential (acoustic emission)
t
threshold crossing.
distribution, amplitude, cumulative (acoustic emission) F(V), n—the number of acoustic emission events with signals that
exceed an arbitrary amplitude as a function of amplitude V.
distribution, threshold crossing, cumulative (acoustic emission) F (V), n—the number of times the acoustic emission signal
t
exceeds an arbitrary threshold as a function of the threshold voltage (V).
distribution, differential (acoustic emission) amplitude f(V), n—the number of acoustic emission events with signal
amplitudes between amplitudes of V and V + ΔV as a function of the amplitude V. f(V) is the absolute value of the derivative
of the cumulative amplitude distribution F(V).
distribution, differential (acoustic emission) threshold crossing f (V), n—the number of times the acoustic emission signal
t
waveform has a peak between thresholds V and V + Δ V as a function of the threshold V. f (V) is the absolute value of the
t
derivative of the cumulative threshold crossing distribution F (V).
t
distribution, logarithmic (acoustic emission) amplitude g(V), n—the number of acoustic emission events with signal
amplitudes between V and αV (where α is a constant multiplier) as a function of the amplitude. This is a variant of the differential
amplitude distribution, appropriate for logarithmically windowed data.
dynamic range, n—the difference, in decibels, between the overload level and the minimum signal level (usually fixed by one
or more of the noise levels, low-level distortion, interference, or resolution level) in a system or sensor.
effective velocity, n—velocity calculated on the basis of arrival times and propagation distances determined by artificial AE
generation; used for computed location.
emission, burst, n—a qualitative description of an individual emission event resulting in a discrete signal.
DISCUSSION—
Fig. 1 shows an oscilloscope trace of burst emission signals on a background of continuous emission signal.
emission, continuous, n—a qualitative description of emission producing a sustained signal as a result of time overlapping or
successive emission events from one or several sources, or both.
DISCUSSION—
Fig. 2 and Fig. 3 show oscilloscope traces of continuous emission signals at two different sweep rates.
energy, acoustic emission event, n—the total elastic energy released by an emission event.
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FIG. 1 Burst Emission Signal on a Continuous Emission Signal Background (Sweep Rate—5 ms/cm)
FIG. 2 Continuous Emission Signal (Sweep Rate—5 ms/cm)
energy, acoustic emission signal, n—the energy contained in an acoustic emission signal, which is evaluated as the integral of
the volt-squared function over time.
evaluation threshold, n—a threshold value used for analysis of the examination data. Data may be recorded with a system
examination threshold lower than the evaluation threshold. For analysis purposes, dependence of measured data on the system
examination threshold must be taken into consideration.
event, acoustic emission (emission event), n—an occurrence of a local material change or mechanical action resulting in
acoustic emission.
event count (Ne),n—see count, event.
event count rate (N˙e),n—see rate, event count.
examination area (examination region), n—that portion of a structure, or test article, being examined using acoustic emission
technology.
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FIG. 3 Continuous Emission Signal (Sweep Rate—0.1 ms/cm)
Felicity effect, n—the presence of detectable acoustic emission at a fixed predetermined sensitivity level at stress levels below
those previously applied.
Felicity ratio, n—the ratio of the stress at which acoustic emission is detected, to the previously applied maximum stress.
DISCUSSION—
The fixed sensitivity level will usually be the same as was used for the previous loading or examination.
first hit location, n—a zone location method defined by which a channel among a group of channels first detects the signal.
floating threshold, n—any threshold with amplitude established by a time average measure of the input signal.
hit, n—the detection and measurement of an AE signal on a channel.
instrumentation dead time, n—see dead time, instrumentation.
intense source, n—one in which the AE source intensity of an active source consistently exceeds, by a specified amount, the
average AE source intensity of active sources.
interval, arrival time (Δt ), n—the time interval between the detected arrivals of an acoustic emission wave at the ith and jth
ij
sensors of a sensor array.
Kaiser effect, n—the absence of detectable acoustic emission at a fixed sensitivity level, until previously applied stress levels
are exceeded.
DISCUSSION—
Whether or not the effect is observed is material specific. The effect usually is not observed in materials containing developing flaws.
location accuracy, n—a value determined by comparison of the actual position of an AE source (or simulated AE source) to
the computed location.
location, cluster, n—a location technique based upon a specified amount of AE activity located within a specified length or area,
for example: 5 events within 12 linear inches or 12 square inches.
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location, computed, n—a source location method based on algorithmic analysis of the difference in arrival times among sensors.
DISCUSSION—
Several approaches to computed location are used, including linear location, planar location, three-dimensional location, and adaptive location.
(a) linear location, n—one-dimensional source location requiring two or more channels.
(b) planar location, n—two-dimensional source location requiring three or more channels.
(c) 3D location, n—three-dimensional source location requiring five or more channels.
(d) adaptive location, n—source location by iterative use of simulated sources in combination with computed location.
location, continuous AE signal, n—a method of location based on continuous AE signals, as opposed to hit or difference in
arrival time location methods.
DISCUSSION—
This type of location is commonly used in leak location due to the presence of continuous emission. Some common types of continuous signal location
methods include signal attenuation and correlation analysis methods.
(a) signal attenuation-based source location, n—a source location method that relies on the attenuation versus distance phenomenon of AE signals.
By monitoring the AE signal magnitudes of the continuous signal at various points along the object, the source can be determined based on the highest
magnitude or by interpolation or extrapolation of multiple readings.
(b) correlation-based source location, n—a source location method that compares the changing AE signal levels (usually waveform-based amplitude
analysis) at two or more points surrounding the source and determines the time displacement of these signals. The time displacement data can be used
with conventional hit-based location techniques to arrive at a solution for the source site.
location, source, n—any of several methods of evaluating AE data to determine the position on the structure from which the
AE originated. Several approaches to source location are used, including zone location, computed location, and continuous
location.
location, zone, n—any of several techniques for determining the general region of an acoustic emission source (for example,
total AE counts, energy, hits, and so forth).
DISCUSSION—
Several approaches to zone location are used, including independent channel zone location, first hit zone location, and arrival sequence zone location.
(a) independent channel zone location, n—a zone location technique that compares the gross amount of activity from each channel.
(b) first-hit zone location, n—a zone location technique that compares only activity from the channel first detecting the AE event.
(c) arrival sequence zone location, n—a zone location technique that compares the order of arrival among sensors.
logarithmic (acoustic emission) amplitude distribution g(V),n—see distribution, logarithmic (acoustic emission) amplitude.
overload recovery time, n—an interval of nonlinear operation of an instrument caused by a signal with amplitude in excess of
the instrument’s linear operating range.
performance check, AE system,n—see verification, AE system.
processing capacity, n—the number of hits that can be processed at the processing speed before the system must interrupt data
collection to clear buffers or otherwise prepare for accepting additional data.
processing speed, n—the sustained rate (hits/s), as a function of the parameter set and number of active channels, at which AE
signals can be continuously processed by a system without interruption for data transport.
rate, event count (N˙e), n—the time rate of the event count.
rearm delay time,n—see time, rearm delay.
resonant or narrowband AE sensor, n—an AE sensor which, when calibrated in accordance with Test Method E1106 or
Practice E1781, exhibits a displacement or velocity response with one or more dominant frequency peaks such that it does not
satisfy the definition of a broadband AE sensor.
ring-down count,n—see count, acoustic emission, the preferred term.
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sensor, acoustic emission, n—a detection device, generally piezoelectric, that transforms the particle motion produced by an
elastic wave into an electrical signal.
signal, acoustic emission (emission signal), n—an electrical signal obtained by detection of one or more acoustic emission
events.
signal amplitude, acoustic emission, n—the peak voltage of the largest excursion attained by the signal waveform from an
emission event.
signal overload level—that level above which operation ceases to be satisfactory as a result of signal distortion, overheating,
or damage.
signal overload point, n—the maximum input signal amplitude at which the ratio of output to input is observed to remain within
a prescribed linear operating range.
signal strength, n—the measured area of the rectified AE signal with units proportional to volt-sec.
DISCUSSION—
The proportionality constant is specified by the AE instrument manufacturer.
signature, acoustic emission (signature), n—a characteristic set of reproducible attributes of acoustic emission signals
associated with a specific test article as observed with a particular instrumentation system under specified test conditions.
stimulation, n—the application of a stimulus such as force, pressure, heat, and so forth, to a test article to cause activation of
acoustic emission sources.
system examination threshold, n—the electronic instrument threshold (see evaluation threshold) which data will be detected.
transducers, acoustic emission,n—see sensor, acoustic emission.
verification, AE system (performance check, AE system), n—the process of testing an AE system to assure conformance to
a specified level of performance or measurement accuracy. (This is usually carried out prior to, during, or after, or combinations
thereof, an AE examination with the AE system connected to the examination object, using a simulated or artificial acoustic
emission source.)
voltage threshold, n—a voltage level on an electronic comparator such that signals with amplitudes larger than this level will
be recognized. The voltage threshold may be user adjustable, fixed, or automatic floating.
waveguide, acoustic emission, n—a device that couples elastic energy from a structure or other test object to a remotely
mounted sensor during AE monitoring. An example of an acoustic emission waveguide would be a solid wire of rod that is
coupled at one end to a monitored structure, and to a sensor at the other end.
wideband-based (modal) AE techniques, n—AE techniques with wideband AE sensors that subject waveforms of the signals
to combined time and frequency analysis to obtain mode-based arrival times (for source location calculations) and modal
amplitudes for potential source identification. Note that mode-based arrival times can also be obtained with resonant sensors,
but only at certain experimentally determined frequencies.
Section C: Electromagnetic Testing (ET) Terms
The terms defined in Section C are the direct responsibility of Subcommittee E07.07 on Electromagnetic Methods.
absolute coil, n—a coil (or coils) that respond(s) to the total detected electric or magnetic properties, or both, of a part or section
of the part without comparison to another section of the part or to another part.
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absolute measurements, n—measurements made without a direct reference using an absolute coil in contrast to differential and
comparative measurements.
DISCUSSION—
See also absolute coil.
absolute readout, n—the signal output of an absolute coil.
DISCUSSION—
See also absolute coil.
absolute system, n—a system that uses a coil assembly and associated electronics to measure the total electromagnetic
properties of a part without direct comparison to another section of the part or to another part.
DISCUSSION—
See also absolute coil.
acceptance level, n—a level above or below which specimens are acceptable in contrast to rejection level.
acceptance limits, n—levels used in electromagnetic sorting which establish the group into which the material under
examination belongs.
amplitude distortion,n—same as harmonic distortion.
amplitude response, n—that property of an examination system whereby the amplitude of the detected signal is measured
without regard to phase.
DISCUSSION—
See also harmonic analysis and phase analysis.
annular coil clearance, n—the mean radial distance between adjacent coil assembly and part surface in electromagnetic
encircling coil examination.
annular coils,n—see encircling coils.
artificial discontinuity, n—reference discontinuities, such as holes, grooves, or notches, that are introduced into a reference
standard to provide accurately reproducible sensitivity levels for electromagnetic test equipment.
band pass filter, n—a wave filter having a single transmission band; neither of the cut-off frequencies being zero or infinity.
bobbin coil,n—see ID coil.
bucking coils,n—same as differential coils.
circumferential coils,n—see encircling coils.
coil, absolute,n—see absolute coil.
coil, reference,n—see reference coil.
coil size, n—the dimension of a coil, for example, length or diameter.
coil spacing, n—the axial distance between two encircling coils of a differential system.
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coil, test, n—the section of the probe or coil assembly that excites or detects, or both, the electromagnetic field in the material
under examination.
comparative measurements, n—measurements made in which the unbalance in the system is measured using comparator coils
in contrast to differential and absolute measurements.
DISCUSSION—
See also comparator coils.
comparative readout, n—the signal output of comparator coils.
DISCUSSION—
See also comparator coils.
comparative system, n—a system that uses coil assemblies and associated electronics to detect any electric or magnetic
condition, or both, that is not common to the specimen and the standard.
DISCUSSION—
See comparator coils.
comparator coils, n—two or more coils electrically connected in series opposition but arranged so that there is no mutual
induction (coupling) between them such that any electric or magnetic condition, or both, that is not common to the specimen
and the standard, will produce an unbalance in the system and thereby yield an indication.
conductivity, n—the intrinsic property of a particular material to carry electric current; it is commonly expressed in percent
IACS (International Annealed Copper Standard) or MS/m (MegaSiemens/metre).
conformable, adj—refers to an ability of sensors or sensor arrays to conform to non-planar surfaces without significant effects
on the measurement results, or with effects that are limited to a quantifiable bound.
coupling, v—two electric circuits are said to be coupled to each other when they have an impedance in common so that a current
in one causes a voltage in the other.
cut-off level,n—same as rejection level.
defect resolution, n—a property of an examination system that enables the separation of indications due to defects in a sample
that are located in proximity to each other.
depth of penetration, n—the depth at which the magnetic field strength or intensity of induced eddy currents has decreased to
37 % of its surface value.
DISCUSSION—
The depth of penetration depends upon the coil size, the frequency of the signal, and the conductivity and permeability of the material. It is related
to the coil size at low frequencies and is equal to the skin depth at high frequencies. Related synonymous terms are standard depth of penetration and
skin depth. (See also skin effect.)
depth of sensitivity, n—depth to which the sensor response to features or properties of interest exceeds a noise threshold.
DISCUSSION—
The depth of sensitivity can be larger or smaller than the depth of penetration since it incorporates a comparison between the signal obtained from a
feature as well as measurement noise, whereas the depth of penetration refers to the decrease in field intensity with distance away from a test coil.
diamagnetic material—a material whose relative permeability is less than unity.
DISCUSSION—
The intrinsic induction Bi is oppositely directed to the applied magnetizing force H.
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differential coils, n—two or more coils electrically connected in series opposition such that any electric or magnetic condition,
or both, that is not common to the areas of a specimen being electromagnetically examined will produce an unbalance in the
system and thereby yield an indication.
differential measurements, n—measurements made in which the imbalance in the system is measured using differential coils
in contrast to absolute and comparative measurements.
DISCUSSION—
See also differential coils.
differential readout, n—the signal output of differential coils.
DISCUSSION—
See also differential coils.
differential signal, n—an output signal that is proportional to the rate of change of the input signal.
differential system, n—an electromagnetic examination system that uses coil assemblies and associated electronics to detect an
electric or magnetic condition, or both, that is not common to the areas of the specimen being examined.
DISCUSSION—
See also differential coils.
drive winding, n—a conductor pattern or coil that produces a magnetic field that couples to the material being examined.
DISCUSSION—
The drive winding can have various geometries, including: (1) a simple linear conductor that is placed adjacent to a one-dimensional array of sensing
elements; (2) one or multiple conducting loops driven to create a complex field pattern; and (3) multiple conducting loops with a separate loop for
each sensing element.
eddy current, n—an electrical current caused to flow in a conductor by the time or space variation, or both, of an applied
magnetic field.
eddy current testing, n—a nondestructive testing method in which eddy current flow is induced in the material under
examination.
DISCUSSION—
Changes in the flow caused by variations in the specimen are reflected into a nearby coil, coils, Hall effect device, magnetoresistive sensor, or other
magnetic field sensor for subsequent analysis by suitable instrumentation and techniques.
edge effect, n—the disturbance of the magnetic field and eddy currents due to the proximity of an abrupt change in specimen
geometry (edge).
DISCUSSION—
This effect generally results in the masking of discontinuities within the affected region. (This effect is also termed the end effect.)
effective depth of penetration (EDP), n—for (a) thickness, the minimum depth beyond which an examination system can no
longer reliably detect a further increase in specimen thickness, or (b) defects, the limit for reliably detecting metallurgical or
mechanical discontinuities by way of conventional continuous wave (CW) eddy current instrumentation and sensors.
DISCUSSION—
The EDP point is approximately three times the standard depth of penetration.
effective permeability, n—a hypothetical quantity that describes the magnetic permeability that is experienced under a given
set of physical conditions such as a cylindrical specimen in an encircling coil at a specific frequency.
DISCUSSION—
This quantity may be different from the permeability of the particular metal being examined in that it takes into account such things as the geometry
of the part, the relative position of the encircling coil, and characteristics of the magnetic field.
electrical center, n—the center established by the electromagnetic field distribution within a test coil.
E1316 − 24
DISCUSSION—
A constant intensity signal, irrespective of the circumferential position of a discontinuity, is indicative of electrical centering. The electrical center may
be different from the physical center of the test coil.
electromagnetic testing, n—a nondestructive test method for materials, including magnetic materials, that uses electromagnetic
energy having frequencies less than those of visible light to yield information regarding the quality of examined material.
encircling coils, n—coil(s) or coil assembly that surround(s) the part to be examined. Coils of this type are also referred to as
annular, circumferential, or feed-through coils.
end effect,n—see edge effect.
end effect, n—the loss in sensitivity to discontinuities located near the extreme ends of the tube as the ends of the tube enter
or leave the test coil.
feed-through coils,n—see encircling coils.
ferromagnetic material, n—a material that, in general, exhibits the phenomena of magnetic hysteresis and saturation, and
whose permeability is dependent on the magnetizing force.
fill factor, n—(a) for encircling coil electromagnetic testing, the ratio of the cross-sectional area of the specimen to the effective
cross-sectional core area of the primary encircling coil (outside diameter of coil form, not inside diameter which is adjacent to
specimen); (b) for internal probe electromagnetic testing, the ratio of the effective cross-sectional area of the primary internal
probe coil to the cross-sectional area of the tube interior.
filter, n—a network that passes electromagnetic wave energy over a described range of frequencies and attenuates energy at all
other frequencies.
gate,n—same as rejection level.
harmonic analysis, n—an analytical technique whereby the amplitude or phase, or both, of the frequency components of a
complex periodic signal is determined.
harmonic distortion, n—nonlinear distortion characterized by the appearance in the output of harmonics other than the
fundamental component when the input wave is sinusoidal.
IACS, n—the International Annealed Copper Standard; an international standard of electrical conductivity.
ID coil, n—a coil or coil assembly used for electromagnetic testing by insertion into the examination piece as in the case of an
inside probe for tubing.
DISCUSSION—
Coils of this type are also referred to as inside coils, inserted coils, or bobbin coils.
impedance, n—the total opposition that a circuit presents to the flow of an alternating current, specifically the complex quotient
of voltage divided by current.
impedance analysis, n—an analytical method that consists of correlating changes in the amplitude, phase, or quadrature
components, or all of these, of a complex signal voltage to the electromagnetic conditions within a specimen.
impedance plane diagram, n—a graphical representation of the locus of points, indicating the variations in the impedance of
a test coil as a function of basic examination parameters.
E1316 − 24
incremental permeability, n—the ratio of the change in magnetic induction to the corresponding change in magnetizing force
when the mean induction differs from zero.
initial permeability, n—the slope of the induction curve at zero magnetizing force as the specimen is being removed from a
demagnetizing condition (slope at origin of BH curve before hysteresis is observed).
inserted coil,n—see ID coil.
inside coil,n—see ID coil.
insulating shims, n—conformable and substantially non-conducting or insulating foils that are used to measure effects of small
lift-off excursions on sensor response.
lift-off, n—normal distance from the plane of the sensor coil or winding conductors to the surface of the conducting material
under examination.
lift-off effect, n—the effect observed in an examination system output due to a change in magnetic coupling between a specimen
and a probe coil whenever the distance between them is varied.
magnetic history, n—magnetic condition of a ferromagnetic part under examination based on previous exposures to magnetic
fields.
magnetic leakage flux, n—the excursion of magnetic lines of force from the surface of a specimen.
magnetic saturation, n—that degree of magnetization where a further increase in magnetizing force produces no significant
increase in magnetic flux density (permeability) in a specimen.
model for sensor response, n—a relation between the response of the sensor (for example, impedance magnitude and phase or
real and imaginary parts) and properties of interest (for example, electrical conductivity, magnetic permeability, lift-off, and
material thickness) for at least one sensing element and at least one drive winding.
DISCUSSION—
These model responses may be obtained from database tables and may be analysis-based or empirical.
modulation analysis, n—an analytical method used in electromagnetic testing that sep
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