AS 1929—2009
AS 1929—2009
Australian Standard®
Non-destructive testing—Glossary of
terms
This Australian Standard® was prepared by Committee MT-007, Non-destructive Testing of
Metals and Materials. It was approved on behalf of the Council of Standards Australia on
9 June 2009.
This Standard was published on 31 August 2009.
The following are represented on Committee MT-007:
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•
•
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•
•
•
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Australian Aerospace Non-Destructive Testing Committee
Australian Industry Group
Australian Institute for Non-Destructive Testing
Australian Nuclear Science & Technology Organisation
Australian Pipeline Industry Association
Bureau of Steel Manufacturers of Australia
Engineers Australia
Metals Trade Industry Association
National Association of Testing Authorities Australia
New Zealand Non-Destructive Testing Association
NSW WorkCover Authority
Victorian WorkCover Authority
Welding Technology Institute of Australia
This Standard was issued in draft form for comment as DR 07269.
Standards Australia wishes to acknowledge the participation of the expert individuals that
contributed to the development of this Standard through their representation on the
Committee and through the public comment period.
Keeping Standards up-to-date
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systems. To maintain their currency, all Standards are periodically reviewed, and new editions
are published. Between editions, amendments may be issued.
Standards may also be withdrawn. It is important that readers assure themselves they are
using a current Standard, which should include any amendments that may have been
published since the Standard was published.
Detailed information about Australian Standards, drafts, amendments and new projects can
be found by visiting www.standards.org.au
Standards Australia welcomes suggestions for improvements, and encourages readers to
notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at
mail@standards.org.au, or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.
AS 1929—2009
Australian Standard®
Non-destructive testing—Glossary of
terms
Originated as AS B259 Parts 1-5 (1968).
Previous edition AS 1929—1981.
Third edition 2009.
COPYRIGHT
© Standards Australia
All rights are reserved. No part of this work may be reproduced or copied in any form or by
any means, electronic or mechanical, including photocopying, without the written
permission of the publisher.
Published by Standards Australia GPO Box 476, Sydney, NSW 2001, Australia
ISBN 0 7337 9233 2
AS 1929—2009
2
PREFACE
This Standard was prepared by the Australian members of the Joint Standard Australia/New
Zealand Committee MT-007, Non-destructive Testing and Metals and Materials. This
Standard supersedes AS 1929—1981, Non-destructive testing—Glossary of terms.
After consultation with shareholders in both countries, Standards Australia and Standards
New Zealand decided to develop this Standard as an Australian Standard rather than an
Australian/New Zealand Standard.
The objective of this Standard is to provide a list of current terms used in the nondestructive testing industry and to delete terms from the Standard that have become
redundant.
The objective of this edition is to revise the terms used in non-destruction testing and to
introduce terms that relate to condition monitoring, in particular infrared thermography.
During the revision of this Standard, the committee considered only those terms in constant
use in the non-destructive testing industry in Australia, and which relate to non-destructive
testing methods.
During the preparation of this Standard, cognisance was taken of the following Standards:
ISO
5576
5577
Non-destructive testing—Industrial X-ray and gamma ray radiography—
Vocabulary
Non-destructive testing—Ultrasonic inspection—Vocabulary
12706
Non-destructive testing—Terminology—Terms used in penetrant testing
12716
Non-destructive testing—Acoustic emission inspection—Vocabulary
13372
Condition monitoring and diagnostics of machines—Vocabulary
18434
Condition monitoring and diagnostics of machines—Thermography
18434-1 Part 1: General procedures
Terms that specifically relate to a particular field of testing have been placed in the
appropriate section, and cross referencing has been used where terms are related.
3
AS 1929—2009
CONTENTS
Page
FOREWORD.............................................................................................................................. 4
SECTION 1 GENERAL TERMS AND DEFINITIONS .......................................................... 5
SECTION 2 ACOUSTIC EMISSION INSPECTION .............................................................. 8
SECTION 3 ULTRASONIC INSPECTION
3.1 GENERAL ................................................................................................................ 15
3.2 WAVES..................................................................................................................... 16
3.3 ANGLE ..................................................................................................................... 17
3.4 PULSE AND ECHO.................................................................................................. 18
3.5 PROBE ...................................................................................................................... 19
3.6 ULTRASONIC TEST INSTRUMENT...................................................................... 21
3.7 TEST BLOCKS ......................................................................................................... 23
3.8 TEST TECHNIQUES ................................................................................................ 23
3.9 TEST OBJECT .......................................................................................................... 25
3.10 COUPLING ............................................................................................................... 26
3.11 LOCATION............................................................................................................... 26
3.12 EVALUATION METHODS...................................................................................... 26
3.13 DISPLAY METHODS .............................................................................................. 27
SECTION 4 ELECTROMAGNETIC INSPECTION ............................................................. 46
SECTION 5 MAGNETIC PARTICLE INSPECTION ........................................................... 50
SECTION 6 PENETRANT INSPECTION ............................................................................ 55
SECTION 7 RADIOGRAPHIC INSPECTION
7.1 RADIOGRAPHIC INSPECTION.............................................................................. 58
7.2 COMPUTERIZED RADIOGRAPHY ....................................................................... 70
SECTION 8 CONDITION MONITORING
8.1 GENERAL ................................................................................................................ 72
8.2 MACHINE CHARACTERISTICS ............................................................................ 73
8.3 OPERATION AND MAINTENANCE...................................................................... 73
8.4 FAULTS.................................................................................................................... 74
8.5 DATA COLLECTION (ACQUISITION).................................................................. 74
8.6 DATA CHARACTERISTICS ................................................................................... 75
8.7 DATA (SIGNAL) PROCESSING ............................................................................. 75
8.8 ANALYSIS ............................................................................................................... 76
8.9 DIAGNOSTICS......................................................................................................... 77
8.10 PROGNOSTICS ........................................................................................................ 77
SECTION 9 INFRARED THERMOGRAPHY ...................................................................... 78
AS 1929—2009
4
FOREWORD
Many terms that relate to the non-destruction testing industry are known by more than one
name, but, unfortunately, each name is not always used with the same meaning; moreover,
in the case of some defects/methods, the same name may be used by two persons to indicate
two entirely different types of defects/methods. Such variations in meaning have led to
confusion, especially where writing is the only form of communication in the exchange of
ideas.
This Standard concentrates on definitions of those terms that relate to the non-destructive
testing industry.
5
AS 1929—2009
STANDARDS AUSTRALIA
Australian Standard
Non-destructive testing—Glossary of terms
S E C T I O N
1
G E N E RA L T E RM S
DE F I N I T I O N S
A N D
Term
Definition
acceptable quality level
(AQL)
Maximum percent defective or the maximum number of
units defective per hundred units which, for the purpose of
a sampling test, can be considered satisfactory as a process
average.
acceptance criteria
Criteria against which the specimen is examined in order to
determine its acceptability.
acceptance level
Set of prescribed parameters setting the threshold for
acceptance or rejection.
acoustic testing
The method of non-destructive testing which uses acoustic
energy usually within the frequency range 1 MHz to
10 MHz.
artificial discontinuity
Discontinuities such as holes, grooves or notches that are
introduced into a piece by machining or any process.
calibration, instrument
Comparison of an instrument with, or the adjustment of an
instrument to, known reference(s).
defect
One or more flaws whose aggregate size, shape,
orientation, location or properties do not meet specified
acceptance criteria and are rejectable.
detection sensitivity
Capacity of an NDT technique to detect discontinuities
NOTE: The higher the detection sensitivity, the greater its
capability of detecting a small discontinuity (see detection
threshold).
detection threshold
Lowest limit of detection of indications.
discontinuity
Lack of continuity or cohesion by way of an intentional or
unintentional interruption in the physical structure or
configuration of a material or component.
eddy current testing
The method in which eddy current flow is induced and
monitored in the product under test. Changes in current
flow are subsequently analysed.
electromagnetic testing
The method of non-destructive testing which uses
electromagnetic energy having frequencies less than visible
light. It covers eddy current, magnetic field, leakage field
pick-up and direct current conduction tests.
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© Standards Australia
AS 1929—2009
6
Term
Definition
false indication
Representation or signal, in the format allowed by the nondestructive testing method used, which is interpreted to be
caused by a condition other than a discontinuity or
imperfection.
flaw
Imperfection or discontinuity that may be detectable by
NDT and is not necessarily rejectable.
flaw characterization
Process of quantifying the size, shape, orientation,
location, growth or other properties of a flaw, based on
NDT response.
imperfection
Departure of a quality characteristic from its intended
condition.
indication
Representation or signal from a discontinuity in the format
allowed by the NDT method used.
interpretation
Determination of whether indications are relevant, nonrelevant or false.
magnetic particle testing
The method of non-destructive testing which involves the
generation of a magnetic flux within magnetic materials,
used to detect surface or near surface discontinuities.
Testing also involves the application of suitable magnetic
particles to the surface of the material to give an indication
of a discontinuity.
noise
Any undesired signal or response that tends to interfere
with the reception, interpretation or processing of the
desired signal or response.
non-destructive evaluation
See non-destructive testing.
non-destructive examination
See non-destructive testing.
non-destructive inspection
See non-destructive testing.
non-destructive testing
(NDT)
Development and application of technical methods to
examine materials or components in ways that do not
impair their future usefulness and serviceability, in order to
detect, locate, measure and evaluate flaws, to assess
integrity, properties and composition, and to measure
geometrical characteristics.
non-relevant indication
NDT indication that is caused by a condition or type of
discontinuity that is not rejectable.
NOTE: False indications are non-relevant.
penetrant testing
© Standards Australia
The method of non-destructive testing which involves the
application of a penetrant to materials to detect and locate
discontinuities such as laps, folds, cracks, porosity and
fissures which are open to the surface. The method also
involves the removal of excess penetrant, and if necessary,
the application of a developer to produce a visible
indication of a discontinuity.
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7
AS 1929—2009
Term
Definition
radiation testing
The method of non-destructive testing which uses X-rays
or gamma rays in order to produce a graphic record on
sensitized film which indicates comparative soundness of
the material under test.
reference block
Piece of material, with specified metallurgical, geometrical
and dimensional characteristics, used for the calibration
and assessment of equipment.
NOTE: A reference block may contain one or more artificial
discontinuities.
reference test piece
Piece of material containing well-defined discontinuities
used to set or check the sensitivity of the equipment and/or
the process.
relevant indication
NDT indication that is caused by a condition or type of
discontinuity that requires evaluation.
resolution
Ability to distinguish meaningfully between closely
adjacent discontinuities.
sizing
Determination of the dimensions of discontinuities or
indications for evaluation.
viewing
Systematic scanning of the data or evidence produced as a
result of NDT in order to determine the presence or
absence of indications.
viewing conditions
Description of the surrounding environmental conditions
during the process of viewing.
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© Standards Australia
AS 1929—2009
8
SECT ION
2
ACOUST IC
I NSPE C T I ON
EM ISS I ON
Term
Definition
acoustic emission (AE)
Class of phenomena whereby transient elastic waves are
generated by the rapid release of energy from localized
sources within a material, or the transient waves so
generated.
NOTE: Acoustic is the recommended term for general use.
Other terms that have been used in AE literature include:
(a)
Stress wave emission.
(b)
Microseismic activity.
(c)
Emission or acoustic emission with other qualifying
modifiers.
acousto-ultrasonics (AU)
Non-destructive 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 combining aspects of acoustics emission
(AE) signal analysis with ultrasonic materials
characterization techniques.
AE signal duration
Time interval between AE signal start and AE signal end.
AE signal end
Recognized termination of an AE signal, usually defined as
the last crossing of the threshold by that signal.
AE signal generator
Device which can repeatedly induce a specified transient
signal into an AE instrument.
AE signal rise time
Time interval between AE signal start and the peak
amplitude of that AE signal.
AE signal start
Beginning of an AE signal as recognized by the system
processor, usually defined by an amplitude excursion
proceeding threshold.
array
Group of two or more AE sensors positioned on a structure
for the purposes of detecting and locating sources that
would normally be within the array.
attenuation
Decrease in AE amplitude per unit distance normally
expressed in dB per unit length.
average signal level
Rectified time-averaged AE logarithmic signal, measured
on the AE amplitude logarithmic scale and reported in dBAE
units (where 0 dB AE refers to 1 µV at the preamplifier
input).
© Standards Australia
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9
AS 1929—2009
Term
Definition
channel, acoustic emission
Assembly of a sensor, preamplifier or impedance matching
transformer, filters, secondary amplifier or other
instrumentation as needed, connecting cables, and detector
or processor.
NOTE: A channel for examining fibreglass 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.
count, acoustic emission (N)
Number of times the acoustic emission signal exceeds a
preset threshold during any selected portion of a test.
NOTE: Also known as ‘count’, ‘ring-down’, ‘ring-down
count’ or ‘emission count’.
count, event (Ne)
Number obtained by counting each discerned acoustic
emission event once.
count rate, acoustic
Time rate at which emission counts occur.
•
emission ( N )
NOTE: Also known as ‘emission rate’ or ‘count rate’.
couplant
Material used at the structure-to-sensor interface to improve
the transmission of acoustic energy across the interface
during acoustic emission monitoring.
dead time
Instrumentation dead time any interval during data
acquisition when the instrument or system is unable to
accept new data for any reason.
distribution, amplitude,
cumulative (acoustic
emission) (F(V))
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 t(V))
Number of times the acoustic emission signal exceeds an
arbitrary threshold as a function of the threshold voltage V.
distribution, differential
(f(V))
Number of acoustic emission events with signal amplitudes
between amplitudes of V and V + ∆V as a function of the
amplitude V where f(V) is the absolute value of the
derivative of the cumulative amplitude distribution F(V).
NOTE: Also known as ‘differential (acoustic emission)
amplitude distribution’ or ‘(acoustic emission) amplitude’.
distribution, differential
(acoustic emission)
threshold crossing (f t(V))
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Number of times the acoustic emission signal waveform has
a peak between the thresholds V and V + ∆V as a function
of the threshold V where ft (V) is the absolute value of the
derivative of the cumulative threshold crossing distribution.
© Standards Australia
AS 1929—2009
10
Term
Definition
distribution, logarithmic
(g(V))
Number of acoustic emission events with signal amplitudes
between V and αV (where α is a constant multiplier) as a
function of the amplitude.
NOTES:
1
Also known as ‘logarithmic (acoustic emission) amplitude
distribution’.
2
This is a variant of the differential amplitude distribution.
dynamic range
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
Velocity calculated on the basis of arrival times and
propagation distances determined by artificial AE
generation and used for computed location.
emission, burst
Burst emission, qualitative description of the discreet signal
related to an individual emission event occurring within the
material.
NOTE: Use of the term ‘burst emission’ is recommended only
for describing the qualitative appearance of emission signals.
Figure 2.1 shows oscilloscope traces of a continuous emission
at two different sweep rates.
emission, continuous
Continuous emission, qualitative description of the
sustained signal level produced by rapidly occurring
acoustic emission events.
NOTE: Use of the term ‘continuous emission’ is recommended
only for describing the qualitative appearance of emission
signals. Figure 2.2 shows oscilloscope traces of a continuous
emission signal at two different sweep rates.
energy, acoustic emission
event
Total elastic energy released by an emission event.
evaluation threshold
Threshold value used for analysis of the examination data.
NOTE: 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
Local material change giving rise to acoustic emission.
examination area
That portion of a structure being monitored using acoustic
emission.
examination region
That portion of the test evaluated using acoustic emission
technology.
felicity effect
Presence of detectable acoustic emission at a fixed
predetermined sensitivity level at stress levels below those
previously applied.
© Standards Australia
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11
AS 1929—2009
Term
Definition
felicity ratio
Ratio of the stress at which the felicity effect occurs to the
previously applied maximum stress.
NOTE: The fixed sensitivity level will usually be the same as
was used for the previous loading or test.
floating threshold
Any threshold with amplitude established by a time average
measure of the input signal.
hit
Any signal that exceeds the threshold and causes a system
channel to accumulate data.
interval, arrival time (∆tij )
Time interval between the detected arrivals of an acoustic
emission wave at the ith and jth sensors of a sensor array.
kaiser effect
Absence of detectable acoustic emission at a fixed
sensitivity level, until previously applied stress levels are
exceeded.
location cluster
Location method based upon a specified amount of AE
activity located within a specified length or area, e.g.
5 events within 12 linear units (e.g. cm) or 12 square units
(e.g. cm 2 ).
location, computed
Source location method based on algorithmic analysis of
the difference in arrival times among sensors.
NOTES:
1
Also known as ‘adaptive location’.
2
Several approached to computed location are used,
including linear location, three dimensional location and
adaptive location.
linear location
One-dimensional source location requiring two or more
channels.
planar location
Tow-dimensional source location requiring three or more
channels.
3-D location
Three-dimensional source location requiring five or more
channels.
adaptive location
Source location by iterative use of simulated sources in
combination with computed location.
location, continuous AE
signal
Method of location based on continuous AE signals, as
opposed to hit or difference in arrival time location
methods.
NOTE: 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.
signal attenuation-based
source location
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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 us determined based on the
highest magnitude or by interpretation or extrapolation of
multiple readings.
© Standards Australia
AS 1929—2009
12
Term
Definition
correlation-based source
location
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, this time
displacement data being used with conventional hit-based
location techniques to arrive at a solution for the source
site.
location, source
Any of several methods of evaluating AE data to
determined the position on the structure from which it
originated.
NOTE: Several approaches to source location are used,
including zone location, computed, and continuous location.
Any of several techniques for determining the general
region of an acoustic emission source, e.g. total AE counts,
energy, hits, etc.
location, zone
NOTES:
1
Also known as ‘first-hit location’.
2
Several approaches to zone location are used, including
independent channel zone location, first-hit zone location
and arrival sequence zone location.
independent channel zone
location
Zone location technique that compares the gross amount of
activity from each channel.
first-hit zone location
Zone location technique that compares only activity from
the first-hit channel among a group of channels.
arrival sequence zone
location
Zone location technique that compares the order of arrival
among sensors.
location accuracy
Comparison of the actual position of an AE source (or
simulated AE source) to the computed location.
overload recovery time
Interval of nonlinear operation of an instrument caused by a
signal with amplitude in excess of the instrument’s linear
operating range.
processing, capacity
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
Sustained rate in hits per second, 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 )
Time rate of the event count.
sensor, acoustic emission
Detection device, generally piezoelectric, that transforms
the particle motion produced by an elastic wave into an
electrical signal.
NOTE: Also known as ‘acoustic emission transducer’.
© Standards Australia
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13
AS 1929—2009
Term
Definition
signal, acoustic emission
Electrical signal obtained by detection of one ore more
acoustic emission events.
NOTE:Also known as ‘emission signal’.
signal amplitude, acoustic
emission
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
Maximum input signal amplitude at which the ratio of
output to input is observed to remain within a prescribed
linear operating range.
signature, acoustic emission
Characteristics 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.
NOTE: Also known as ‘signature’.
stimulation
Application of a stimulus such as force, pressure, heat, etc,
to a test article to cause activation of acoustic emission
sources.
system examination
threshold
Electronic instrument threshold (see evaluation threshold)
at which data is detected.
transducers, acoustic
emission
Active element in an acoustic emission sensor, usually
piezoelectric.
voltage threshold
Voltage level on en electronic comparator above which
signals will be recognized.
NOTE: The voltage threshold may be user-adjustable, fixed or
automatic floating.
waveguide, acoustic
emission
Device that couples elastic energy from as structure or
other test object to a remotely mounted sensor during AE
monitoring.
NOTE: An example of an acoustic emission waveguide would
be a solid wire or rod that is coupled at one end to a monitored
structure, and to a sensor at the other end.
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© Standards Australia
AS 1929—2009
14
Fi le
0.1562
Vie w D i s pl ay S e t u p
Wavefo r m – T R A 1
Ac q u i sit io n
Hel p
0 0 0:0 0:0 4. 3729 62 0
0.0 938
Re c vd :
5
Procd:
5
0.0312
– 0.0312
– 0.0 938
– 0.1562
–30.0 μ
4 81.μ
Wavefo r m – T R A 1
0. 3125
9 93.μ
1. 51m
2 .0 2 m s e c
0 0 0:0 0:0 4. 3729 62 0
Re c vd :
5
Procd:
5
33.8μ
65.8μ
0.1875
0.0 625
– 0.0 625
– 0.1875
– 0. 3125
–30.0 μ
1.9 4 μ
9 7.7μ s e c
FIGURE 2.1 SAME BURST EMISSION SIGNAL AT TWO
DIFFERENT SWEEP RATES
Fi le
0.0391
Vie w
Set up
Wavefo r m – T R A 1
Ac q u i sit io n
Re s u m e!
St o p! Help
0 0 0:0 0:01. 558638 0
0.0 23 4
Re c vd :
5
Procd:
5
0.0 0 78
– 0.0 0 78
– 0.0 23 4
– 0.0391
0.0391
0.0 0
1.9 2 m
Wavefo r m – T R A 1
3.8 4 m
5.76 m
7.68m s e c
0 0 0:0 0:01. 558638 0
Re c vd :
5
Procd:
5
63.8μ
95.8μ
0.0 23 4
0.0 0 78
– 0.0 0 78
– 0.0 23 4
– 0.0391
– 0.0 0 μ
31.9μ
127μ s e c
FIGURE 2.2 SAME CONTINUOUS EMISSION SIGNAL AT TWO
DIFFERENT SWEEP RATES
© Standards Australia
www.standards.org.au
15
SE C T I ON
3
U L T RA SO N IC
AS 1929—2009
I NSPE CT I O N
3.1 GENERAL
Term
Definition
acoustical absorption
Component of the attenuation resulting from transformation
of ultrasonic energy into other types of energy (e.g.
thermal).
acoustical anisotropy
In relation to piezo-electric materials, the relative
differences of sound strengths generated in different
directions, for a given stimulus.
acoustical impedance
Ratio of sound pressure to sound velocity at a point of a
given material, usually expressed as the product of sound
velocity and density.
acoustic shadow
Shadow zone, region in a body which cannot be reached by
ultrasonic energy travelling in a given direction because of
the geometry of the body or a discontinuity in it, see
Figure 3.6.
attenuation
Sound attenuation, decrease of a sound pressure when a
wave travels through a material, arising from absorption
and scattering.
attenuation co-efficient
Coefficient used to express attenuation per unit of distance
travelled, dependent on material properties, wavelength and
wave mode, usually expressed in dB/m.
beam axis
Line through the points of maximum sound pressure in the
far field extended to the source of sound, see Figures 3.2,
3.10, 3.11, 3.12 and 3.16.
beam edge
Boundary of the ultrasonic beam in the far field where the
sound pressure has fallen in a given fraction of the value on
the beam axis, measured at the same distance from the
probe. See Figure 3.2.
beam profile
Form of the sound beam that is defined by the beam edges.
beam spread
Divergence of the sound beam as the sound travels through
a material.
decibel (dB)
Twenty times the base ten logarithm of the ratio of two
ultrasonic signal amplitudes.
Db = 20 × log 10 (amplitude ratio)
discontinuity
See Section 1 and also see Figures 3.6, 3.10, 3.11, 3.13,
3.14, 3.16, 3.17.1, 3.17.2, 3.17.3, 3.18 and 3.19.
edge effect
Phenomenon resulting from the diffraction of an ultrasonic
wave by the edges of the reflector.
far field
Zone of the ultrasonic beam that extends beyond the last
pressure maximum of the beam axis, see Figure 3.2.
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© Standards Australia
AS 1929—2009
16
Term
Definition
flaw
Defect, discontinuity which is deemed to be recordable, see
Figures 3.6, 3.10, 3.11, 3.13, 3.14, 3.16, 3.17.1, 3.17.2,
3.17.3, 3.18 and 3.19.
interface
Boundary between two materials in acoustic contact, having
different acoustic impedances, see Figure 3.4.
loss of back reflection
Absence or significant reduction in the amplitude of the
indication from the back surface of the part under test.
near field
Fresnel zone, zone of the ultrasonic beam where sound
pressure is not related directly to distance because of
interference, see Figure 3.2.
near field length
Distance from the source of the ultrasonic signal to the near
field point, see Figure 3.3.
near field point
Position in an ultrasonic beam where the sound pressure on
the beam axis reaches a final maximum before far field, see
Figure 3.3.
propagation time
Time of flight, time for the transmitted ultrasonic signal to
reach the receiving points.
reflection coefficient
Ratio of total reflected sound pressure to incident sound
pressure at a reflecting surface.
reflector
Interface at which an ultrasonic beam encounters a change
in acoustic impedance.
scattering
Random reflection caused by grain structure and/or by
small reflectors in the beam path.
sound-field
Three-dimensional pressure pattern produced by
transmitted sound energy, see Figure 3.3.
sound velocity
Velocity of propagation phase or group velocity of an
acoustic wave in a non dispersive material relative to the
propagating direction.
test frequency
Effective ultrasonic wave frequency used to test the object,
usually measured at the receiving point.
ultrasonic beam
Sound beam field within the major part of the ultrasonic
energy is transmitted in a non-dispersive material, see
Figures 3.2 and 3.6.
ultrasonic wave
Any acoustic wave having a frequency higher then the
audible range of the human ear, generally taken as higher
than 20 kHz.
3.2 WAVES
compressional wave
Longitudinal wave, wave mode in which the particle
motion is in the same direction as the propagation of the
wave, see Figure 3.1(a).
continuous wave
Constant flow of ultrasonic waves, as opposed to pulsation.
creeping wave
Wave generated at the first critical angle of incidence and
propagated along the surface as longitudinal wave.
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Term
Definition
mode conversion
Mode transformation, wave conversion, transformation of a
wave mode to another during refraction or reflection.
plate wave
Lamb wave, wave mode which propagates within the
thickness of thin plate and which can be generated only at
particular values of angle of incidence, frequency and plate
thickness.
shear wave
Transverse wave, wave mode in which the particle motion
at each point in a medium is at right angles to the direction
of the propagation of the wave, see Figure 3.1(b).
NOTE: This exists only in solids.
spherical wave
Wave with a spherical wavefront.
surface wave
Rayleigh wave, wave mode which propagates on the
surface of a medium with an effective penetration of
approximately one wavelength.
wavefront
Continuous surface joining all points of a wave that have
the same phase.
wavelength (λ)
Distance travelled by a wave during a complete cycle, see
Figure 3.1.
wave train
Succession of a determined number of ultrasonic waves,
arising from the same source and having the same
character, propagating along the same path.
3.3 ANGLE
angle of incidence
Angle between the incident beam axis and the normal to the
interface, see Figures 3.4 and 3.9.
angle of reflection
Angle between the reflected beam axis and the normal to
the interface, see Figure 3.4.
angle of refraction
Angle between the refracted beam axis and the normal to
the interface, see Figures 3.4, 3.9 and 3.10.
critical angle
Angle of incidence at an interface between two different
materials beyond which the mode of propagation is changed
after refraction.
NOTE: The first critical angle is the angle beyond which the
incident sound is only refracted as shear waves. The second
critical angle is the angle beyond which no more shear waves
are refracted. The Rayleigh angle is the angle at which surface
waves (Rayleigh waves) are generated.
divergence angle
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Angle within the far field between the beam axis and the
beam edge at which the amplitude has fallen to a defined
level, see Figure 3.2.
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3.4 PULSE AND ECHO
Term
Definition
back wall echo (B)
Pulse reflected from a boundary surface which is
perpendicular to the ultrasonic beam axis normally used
for the echo from the opposite surface when testing an
object with parallel surfaces with a normal probe,
see Figures 3.17.1 and 3.17.2.
NOTE: Also known as ‘bottom echo’, ‘back surface echo’
or ‘back reflection’.
delayed echo
Echoes which reach the same receiving point later than
other echoes from the same reflector, due to mode
conversion or different path.
echo
Sound pulse reflected to the probe.
NOTE: Also known as ‘reflexion’.
flaw echo
Indication of an echo from a flaw or discontinuity, see
Figures 3.17.1, 3.17.2 and 3.17.3.
NOTE: Defect echo (F), Discontinuity echo (D).
ghost echo
Echo originating from a transmitted pulse generated in a
previous cycle.
NOTE: Also known as ‘phantom echo’ or ‘wrap-around’.
grass
Spatially random signals arising from the echoes from
grain boundaries and/or microscopic reflectors in a
material.
NOTE: Also known as ‘structural echoes’.
interface echo
Echo from the interface between dissimilar materials.
multiple echo
Repeated reflections of an ultrasonic pulse between two or
more interfaces or discontinuities.
NOTE: Also known as ‘multiple reflection’.
pulse
Electrical or ultrasonic signal of short duration
side wall echo (W)
Indication of an echo from a surface other than the back
wall and test surface, see Figure 3.17.1.
spurious echo
Indication not associated with a discontinuity.
NOTE: Also known as ‘parasitic echo’
surface echo
Indication of an echo from the first boundary of a body to
the probe, usually used in immersion testing techniques or
contact testing techniques using delay material with
probe, see Figure 3.17.2.
transmission pulse indication
(T)
Response of the ultrasonic test instrument display to the
transmitter pulse, usually used in an A-scan display, see
Figures 3.17.1, 3.17.2 and 3.17.3.
transmitter pulse
Electrical pulse for exciting the probe generated by the
transmitter section in the ultrasonic test instrument.
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3.5 PROBE
Term
Definition
angle probe
Probe having an angle of incidence other than normal to
the test surface, see Figures 3.9, 3.10, 3.11, 3.12, 3.13,
3.14, 3.15, 3.16, 3.17.2 and 3.17.3.
NOTE: Also known as ‘angle beam probe’ or ‘angle beam
search unit’.
centre frequency
Arithmetic mean of the frequencies at which the
amplitude is 3 dB below the amplitude at the peak
frequency for a through-transmission test and 6 dB for a
pulse echo test.
convergence distance
Distance between the test surface of the object and
convergence zone for a double transducer probe, see
Figure 3.8.
convergence zone
Convergence point, zone or point at the intersection of the
axes of the transmitting and receiving beams of a double
transducer probe, see Figure 3.8.
delay path
Distance between the transducer and the point of entry
into the test object.
depth of field
Zone in the ultrasonic beam of a focussing probe in which
the sound pressure remains above a level related to the
maximum value, see Figure 3.20.
NOTE: Also known as ‘focal zone’ or ‘focal range’.
double transducer probe
Probe comprising two separate acoustically isolated
transducers in a single housing, one for transmission and
the other for reception of ultrasonic waves, see Figure 3.8.
NOTE: Also known as ‘twin transducer probe dual search
unit’.
effective transducer size
Reduced area of the mechanical size of the transducer,
capable of transforming electrical oscillations into sound
energy or vice-versa, resulting from the magnetoinductive effect (Lorentz effect)
focal length
Distance from the focal point to the source of sound for a
focussing probe, see Figure 3.20.
focal point
Focus point showing the maximum sound pressure at the
greatest distance from the source of sound, see
Figure 3.20.
focussing probe
Probe from which the sound beam is concentrated by
special devices (shaped transducer, lens, electronic
process, etc.) to produce a focussing beam or focal point,
see Figure 3.20.
immersion probe
Compressional wave probe specially designed to be used
in a liquid, see Figure 3.17.2.
nominal angle of probe
Stated nominal value of the refraction angle of a probe for
a given material and temperature.
nominal frequency
Nominal frequency of a probe as stated by manufacturer.
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© Standards Australia
AS 1929—2009
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Term
Definition
nominal transducer size
Physical size of the transducer.
NOTE: Also known as ‘transducer size’ or ‘element size’.
normal probe
Probe from which waves propagate at 90° to the test
surface (beam axis at normal incidence), see Figures 3.2,
3.3, 3.6, 3.7(a) and 3.17.1
NOTE: Also known as ‘straight beam probe’ or ‘straight
beam search unit’.
peak frequency
Frequency at which the maximum amplitude is observed.
peak number
Number of cycles having an amplitude greater than 20%
(−14 dB) of the maximum amplitude in the waveform
duration of the received signals, usually used to express
the waveform duration of the received echo signal, see
Figure 3.5.
NOTE: The reciprocal of this number is called ‘probe
damping factor’.
phased array probe
Probe consisting of several elementary transducers
capable of working independently with different
amplitudes or phases resulting in various beam angles and
focal distances.
probe
Electro-acoustic device usually incorporating one or more
transducers intended for transmission and/or reception of
the ultrasonic waves.
NOTE: Also known as ‘search unit device’.
probe damping factor
Reciprocal of the peak number.
probe index
Intersection point of the sound beam axis with the probe
surface, see Figures 3.9, 3.12, 3.17.3 and 3.19.
NOTE: For an angle probe, this point is usually delineated
on lateral face of the probe.
probe shoe
Shaped piece of material which is interposed between the
probe and the test object for the purpose of improving the
coupling and/or of protecting the probe.
roof-angle
Angle which is half of the angle between the normals to
the transducer faces of a double transducer probe, see
Figure 3.8.
NOTE: Also known as ‘toe-in-semi-angle’.
squint angle
The angle between the geometrical axis of the probe and
the projection of the beam axis on the test surface, see
Figure 3.9.
NOTE: Also known as ‘angle probe’.
surface wave probe
Probe for generating and/or receiving surface waves.
transducer
Active element of the probe causing the conversion of
electrical energy sound energy and vice versa, see
Figures 3.7(a), 3.7(b) and 3.8.
NOTE: Also known as ‘crystal’ or ‘element’.
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Term
Definition
transducer backing
Material coupled to the rear surface of a transducer to
increase damping, see Figures 3.7(a), 3.7(b) and 3.8.
variable angle probe
Probe in which the angle of refraction can be changed.
wear plate
Thin layer of protective material forming an integral part
of the probe and separating the transducer from direct
contact with the test object, see Figure 3.7(a).
NOTE: Also known as ‘diaphragm’.
wedge
Specially shaped component (usually made of plastic
material) which causes an ultrasonic wave to be refracted
into the test object at a defined angle, when placed in
acoustical contact between a transducer and a test object,
see Figure 3.7(b).
NOTE: Also known as ‘refracting prism’.
wheel probe
Probe incorporating one or more transducers mounted
inside a liquid-filled flexible tyre the sound beam being
coupled to the test object through the rolling contact area
of the tyre.
NOTE: Also known as ‘wheel search unit’.
3.6 ULTRASONIC TEST INSTRUMENT
amplitude linearity
Measure of the proportionality of the amplitude of the
signal input to the receiver and the amplitude of the signal
appearing on the display of the ultrasonic test instrument
or an auxiliary display.
dead zone
Zone adjacent to the test surface within which the echoes
of interest are not revealed.
delayed time-base sweep
Time-base sweep triggered with a given delay—fixed or
adjustable—in relation to the transmitter pulse or a
reference echo.
NOTE: Also known as ‘correction of zero point’.
dynamic range
Range of signal amplitudes that can be handled by the
ultrasonic test equipment without overloading or
excessive distortion and without being too small for
detection.
electronic distance-amplitude- Function of a device which electronically changes the
compensation (EDAC)
amplification of echoes from reflectors of equal size but
different distances and results in equal height of the
echoes.
expanded time-base sweep
Increased speed of time-base sweep which enables echoes
from a selected region within the thickness or length of
the test object to be displayed in greater detail in the
screen image
NOTE: Also known as ‘scale expansion’.
flaw (defect) detection
sensitivity
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Characteristics of ultrasonic test equipment defined by the
smallest detectable reflector.
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Term
Definition
gain control
Instrument control normally calibrated in decibels with
which a signal may be adjusted to a convenient height.
NOTE: Also known as ‘dB control’ or ‘gain adjustment’.
gate
Electronic means of selecting a segment of the time base
for monitoring or further processing.
NOTE: Also known as ‘time gate’.
gate level
Defined amplitude level above or below which echo
signals in a gate are selected for further processing.
NOTE: Also known as ‘monitor level’.
pulse (echo) amplitude
Maximum amplitude of a pulse (echo) usually base to
peak when an A-scan display is used.
NOTE: Also known as ‘signal amplitude’.
pulse energy
Total energy within a pulse.
pulse (echo) length
Time interval between the leading and trailing edges of a
pulse (echo) measured at a defined level.
pulse repetition frequency
(prf)
Number of pulses generated per unit of time, usually
expressed in hertz.
NOTE: Also known as ‘pulse repetition rate’.
pulse shape
Form or a pulse in the time domain.
rejection
Reduction of noise indications (grass) by eliminating all
indications below a predetermined amplitude level
(threshold level).
NOTE: Also known as ‘suppression’, ‘reject’ or ‘grass
cutting’.
resolution
Characteristics of the ultrasonic test equipment defined by
the minimum distance between two reflectors providing
two dissociable indications.
NOTE: Distinction is made between the axial resolution
following the direction of propagation and the lateral
resolution following a direction perpendicular to it.
time base
Trace (usually horizontal) on the display unit calibrated in
time or distance of sound path.
NOTE: Also known as ‘sweep’.
time base control
Instrument which is used to adjust the time base to a
preselected distance.
NOTE: Also known as ‘sweep control’.
time base linearity
Proportionality between the indication position on the
time base and input signals supplied by a calibrated time
generator or by multiple echoes from a plate having
known thickness.
time base range
Ultrasonic path length that is displayed on a particular
time-base.
NOTE: Also known as ‘test range’.
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Term
Definition
ultrasonic test equipment
Equipment consisting of ultrasonic test instrument,
probes, cables and all devices connected to the instrument
during testing.
ultrasonic test instrument
Instrument used together with the probe or probes which
transmits, receives, processes and displays ultrasonic
signals for non-destructive signals for non-destructive
testing purposes.
3.7 TEST BLOCKS
calibration block
Piece of material of specified composition, surface finish,
heat treatment and geometric form, by means of which
ultrasonic test equipment can be assessed and calibrated.
NOTE: Also known as standard test block.
flat bottom hole (FBH)
Plane circular disc reflector.
NOTE: Also known as ‘disc flaw’ or ‘disc shaped reflector’.
reference block
Block of similar composition to component/material under
test containing well-defined reflectors, used to adjust the
amplitude and/or time scale of the ultrasonic test
equipment in order to compare detected discontinuity
indications with those arising from the known reflectors,
see Figure 3.21.
reference flaw (defect)
Reflector with known form, size and distance from test
surface in the calibration block or reference block, which
is used for calibration or assessment of flaw detection
sensitivity, see Figure 3.21.
NOTE: Also known as ‘reference reflector’.
side drilled hole (SDH)
Circular cylinder reflector which is created parallel to the
test surface.
NOTE: Also known as ‘side cylindrical hole’.
3.8 TEST TECHNIQUES
angle beam technique
Technique using the ultrasonic beam with an angle probe
of incidence other than normal to the test surface, see
Figure 3.17.3.
automatic scanning
Mechanical displacement of the probe over the test
surface.
contact testing technique
Scanning by means of an ultrasonic probe (or probes) in
direct contact with the test object (with or without
couplant, see Figure 3.17.1.
direct scan technique
Technique in which an ultrasonic beam is directed into a
region of a test object without the intermediate reflection,
see Figure 3.10.
NOTE: Also known as ‘single traverse technique’.
double probe technique
Ultrasonic testing technique involving the use of two
probes both of which can be used as a transmitter and a
receiver.
NOTE: Also known as ‘pitch and catch technique’.
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© Standards Australia
AS 1929—2009
24
Term
Definition
double traverse technique
Technique in which ultrasonic beam is directed into a
region of a test object after having been reflected by one
surface of the test object, see Figure 3.11.
gap testing technique
Technique in which the probe is not in direct contact with
the surface of the test object but it is coupled to it through
a column of liquid, not more than a few wavelengths
thick, see Figure 3.12.
NOTE: Also known as ‘gap scanning’.
immersion technique
Ultrasonic testing technique in which the test object and
probe are immersed in liquid used as a coupling medium
and/or refracting prism, see Figure 3.17.2.
NOTES:
1
Also known as ‘immersion testing’.
2
Immersion can be total or partial. Applications using a
water jet or wheel probe are also included.
indirect scan technique
Technique in which the ultrasonic beam is directed into a
region of a test object by means of using reflection at its
surface (or surfaces).
manual scanning
Manual displacement of the probe over the test surface.
multiple-echo technique
Technique in which repeated echoes from either the back
surface or the discontinuity are used for the evaluation of
amplitude and of path length.
NOTES:
1
In order to evaluate the quality of a material or bonding,
the amplitudes of successively echoes are used.
2
In order to increase the accuracy of a wall thickness
(path length) measurement, a multiple echo of highest
possible number is used.
multiple traverse technique
Technique in which an ultrasonic beam is directed into a
region of a test object after having been reflected several
times from its surfaces, see Figure 3.11.
normal beam technique
Technique using a normal probe.
NOTE: Also known as ‘straight beam technique’.
orbital scanning
Technique used to obtain information about the form of a
previously located reflector, scanning being made around
the reflector, see Figure 3.13.
pulse echo technique
Technique in which ultrasonic pulses are transmitted and
received after reflection in one cycle.
NOTE: Also known as ‘reflection (pulse) technique’.
scanning
Systematic relative displacement between the sound beam
and the test object.
single probe technique
Technique which makes use of only one probe for the
generation and detection of ultrasonic waves.
spiral scanning
Scanning by means of longitudinal displacement and
simultaneous rotation of the tube or probe.
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AS 1929—2009
Term
Definition
swivel scanning
Technique involving rotation of the probe around an axis
through the index point perpendicular to the test surface,
see Figure 3.14.
tandem (scanning) technique
Scanning technique involving the use of two or more
angle probes, usually having the same angle of refraction
facing in the same plane perpendicular to the test surface,
where one probe is used for transmission and the other for
detection of ultrasonic energy, see Figure 3.16.
NOTE: The purpose of the technique is mainly to detect
discontinuities perpendicular to the test surface.
time-of-flight diffraction
technique (TOFD)
Technique in which the correlation between the sound
paths of diffracted waves at various probe positions or
angles of incidence are used mainly for the detection and
sizing of planar discontinuities.
transmission technique
Testing technique in which the quality of a material is
assessed by the intensity of the ultrasonic energy incident
on a detecting probe after it has been transmitted through
that material.
NOTE: This may be performed using continuous waves or
pulses.
tip echo technique
Testing technique in which the apparent size of a
discontinuity not parallel to the test surface is estimated
from the distance of the two highest echoes from both tips
and root edges, and an incident angle of an angle probe.
NOTES:
1
Also known as ‘tip diffraction technique’.
2
This is one of the sizing techniques.
3.9 TEST OBJECT
back wall
Surface opposite the test surface in the pulse-echo normal
probe technique, see Figures 3.17.1 and 3.17.2.
NOTE: Also known as ‘bottom’ or ‘back surface’.
beam index
Point on the test surface on which the axis of an ultrasonic
beam is incident, see Figure 3.12.
echo receiving point
Point on the test surface at which echo of an ultrasonic
beam may be received.
probe orientation
Angle maintained during scanning between a reference
line and the projection of the beam axis on to the test
surface, see Figure 3.15.
scanning direction
Direction of movement of a probe over the test surface,
see Figure 3.15.
test surface
Part of the surface of a test object over which probe (or
probes) is moved, see Figures 3.8, 3.9, 3.10, 3.11, 3.12,
3.16, 3.17.1, 3.17.2, 3.17.3 and 3.18.
NOTE: Also known as ‘scanning surface’.
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© Standards Australia
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26
Term
Definition
test object
Object to be tested; object under test or examination, see
Figures 3.8, 3.9, 3.10, 3.11, 3.12, 3.16, 3.17.1, 3.17.2,
3.17.3, 3.18 and 3.19.
NOTE: Also known as ‘examination object’.
test volume
Volume of the test object which is covered by a test.
NOTE: Also known as ‘examination volume’.
3.10 COUPLING
couplant
Medium interposed between the probe and the test object
to enable the passage of ultrasonic energy between them,
such as water, glycerine, etc, see Figure 3.12.
NOTE: Also known as ‘coupling medium’ or ‘coupling
film’.
coupling losses
Loss of ultrasonic energy across the interface between a
probe and a test object.
couplant path
Distance in the coupling medium between the probe index
and the beam index, see Figure 3.12.
transfer correction
Correction of the gain setting of the ultrasonic test
equipment when transferring the probe from a calibration
or reference block to the test object (including losses due
to coupling reflection and attenuation).
3.11 LOCATION
flaw depth
Shortest distance from the reflector to a test (reference)
surface, see Figure 3.10.
NOTE: Also known as ‘reflector depth’.
projected path length
Projection of the path length on the test object, see
Figure 3.10.
skip distance
Distance measured on the test surface between the beam
index of an angle probe and the point at which the beam
axis impinges the test surface after a single reflection at
the opposite surface, see Figure 3.11.
sound path length
Path length of a sound wave within a test object, see
Figure 3.10.
3.12 EVALUATION METHODS
DAC method
Method for expressing the echo height from a reflector in
relation to DAC curve, see Figure 3.21.
DGS diagram
Series of curves which show the relationship between
distance along a beam and gain in decibels for an infinite
reflector and different sizes of disc shaped reflectors.
NOTE: Also known as ‘AVG diagram’.
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AS 1929—2009
Term
Definition
DGS method
Method using the DGS diagram for expressing the echo
height from a reflector in terms of the flat bottom hole
giving the equivalent echo in terms of the equivalent echo
height from disc shaped reflectors.
NOTE: Also known as ‘AVG method’.
distance-amplitude
correction curve (DAC)
Reference curve constructed on the basis of the peak echo
amplitude responses from identical reference reflectors at
varying distances from the probe, see Figure 3.21.
reference block method
Method for assessment of a discontinuity by comparing
echoes from the discontinuity with echoes from known
reflectors in a reference block.
6 dB drop method
Method for reflector size assessment (length, height
and/or width) wherein the probe is moved from a position
showing maximum echo amplitude until echo has
decreased to its half-value (by 6 dB).
NOTE: Also known as ‘half-amplitude method’.
20 dB drop method
Method of reflector size assessment (length, height and/or
width) wherein the probe is moved from a position
showing maximum echo amplitude until echo has
decreased to its one-tenth-value (by 20 dB)
3.13 DISPLAY METHODS
A-scan display
Display of the ultrasonic signal in which the X-axis
represents the time and Y-axis the amplitude, see
Figures 3.17.1, 3.17.2 and 3.17.3.
NOTE: Also known as ‘A-scan presentation’.
B-scan display
A cross-sectional display of a test object formed by
plotting the beam path lengths for echoes with preset
range of amplitude, in relation to the position of beam
axis as the probe is scanned in one direction only, see
Figure 3.18.
NOTES:
C-scan display
1
Also known as ‘B-scan presentation’.
2
It is generally used to show the depth ad length of a
reflector.
Two-dimensional plane display of a test object formed by
plotting the presence of echoes within a preset range of
amplitude, or of beam path length, in relation to the
position of the scanned probe, see Figure 3.19.
NOTE: Also known as ‘C-scan presentation’.
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© Standards Australia
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1
2
3
( a ) C o m p re s s i o n a l wave
1
2
3
( b ) S h e a r wave
L EG EN D :
1 = Wave l e n g th
2 = D i re c ti o n of pa r ti c l e m oti o n
3 = D i re c ti o n of p ro pag ati o n
FIGURE 3.1 COMPRESSIONAL WAVE AND SHEAR WAVE
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1
4
3
6
5
L EG EN D :
1
2
3
4
5
6
=
=
=
=
=
=
N o r m a l p ro b e
Beam edge
D i ve rg e n c e a n g l e
Beam axis
Fa r f i e l d
Near field
FIGURE 3.2 TERMS RELATING TO ULTRASONIC BEAM
SO U N D PR ES SU R E
1
2
D ISTA N C E
L EG EN D :
1 = N e a r f i e l d p o i nt
2 = N e a r f i e l d l e n g th
FIGURE 3.3 SOUND FIELD OF NORMAL PROBE
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1
2
3
4
L EG EN D :
1
2
3
4
=
=
=
=
A n g l e of i n c i d e n c e
A n g l e of ref l e c ti o n
Inte r fac e
A n g l e of ref rac ti o n
PERC EN TAG E, %
FIGURE 3.4 SOUND WAVES AT INTERFACE
10 0
80
60
40
20
0
20
40
60
80
10 0
3
5
7
9
1
10
2
8
6
4
NOTE: In this example, peak number is ten and cycle number is five.
FIGURE 3.5 TIME DOMAIN RESPONSE, PEAK NUMBER AND CYCLE NUMBER
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4
5
2
3
L EG EN D :
1
2
3
4
5
=
=
=
=
=
Te st o b j e c t
Sound beam
Ac o u sti c s h ad ow
D i s c o nti n u i t y
N o r m a l p ro b e
FIGURE 3.6 ACOUSTIC SHADOW
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1
2
3
4
5
( a ) N o r m a l p ro b e ( fo r c o ntac t te sti n g )
3
4
6
1
2
( b ) A n g l e p ro b e
L EG EN D :
1
2
3
4
5
6
=
=
=
=
=
=
C o n n e c to r
Housing
Tra nsd u c e r bac k i n g
Tra nsd u c e r
We a r p l ate
We d g e
FIGURE 3.7 COMPOSITION OF PROBES
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10
2
3
9
4
8
5
6
7
L EG EN D :
1
2
3
4
5
6
7
8
9
10
=
=
=
=
=
=
=
=
=
=
C o n n e c to r s
Tra nsd u c e r
Housing
Ac o u sti c s e pa rato r
C o nve rg e n c e d i st a n c e
C o nve rg e n c e zo n e
Te st o b j e c t
Te st s u r f a c e
Ro of a n g l e
Tra nsd u c e r b a c k i n g
FIGURE 3.8 COMPOSITION AND BEAM OF DOUBLE TRANSDUCER PROBE
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1
9
2
3
8
5
1
7
6
4
L EG EN D :
1
2
3
4
5
6
7
8
9
=
=
=
=
=
=
=
=
=
A n g l e p ro b e
Pro b e i n d ex
Te st s u r f a c e
Pr i n c i p l e a x i s
S q u i nt a n g l e
Proj e c te d b e a m a x i s
Te st o b j e c t
A n g l e of ref rac ti o n
A n g l e of i n c i d e n c e
FIGURE 3.9 TERMS RELATING TO ANGLE PROBE
© Standards Australia
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35
AS 1929—2009
1
9
2
4
7
3
8
5
6
L EG EN D :
1
2
3
4
5
6
7
8
9
=
=
=
=
=
=
=
=
=
Proj e c te d path l e n g th
Te st s u r f a c e
F l aw d e pth
Te st o b j e c t
D i s c o nti n u i t y / f l aw
S o u n d p ath l e n g th
Beam axis
A n g l e of ref rac ti o n
A n g l e p ro b e
FIGURE 3.10 TERMS RELATING TO DIRECT SCAN TECHNIQUE
1
6
2
5
3
4
L EG EN D :
1
2
3
4
5
6
=
=
=
=
=
=
S k i p d i st a n c e
Te st s u r f a c e
Te st o b j e c t
D i s c o nti n u i t y / f l aw
Beam axis
A n g l e p ro b e
FIGURE 3.11 DOUBLE TRAVERSE TECHNIQUE AND MULTIPLE TRAVERSE
TECHNIQUE
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© Standards Australia
AS 1929—2009
36
1
2
3
8
4
7
6
5
L EG EN D :
1
2
3
4
5
6
7
8
=
=
=
=
=
=
=
=
A n g l e p ro b e
Pro b e i n d ex
C o u p l a nt
Te st o b j e c t
Beam axis
B e a m i n d ex
C o u p l a nt path
Te st s u r fac e
FIGURE 3.12 GAP TESTING TECHNIQUE
1
2
L EG EN D :
1 = D i s c o nti n u i t y / f l aw
2 = A n g l e p ro b e
FIGURE 3.13 ORBITAL SCANNING
© Standards Australia
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37
AS 1929—2009
1
2
L EG EN D :
1 = D i s c o nti n u i t y / f l aw
2 = A n g l e p ro b e
FIGURE 3.14 SWIVEL SCANNING
1
3
2
4
L EG EN D :
1
2
3
4
=
=
=
=
We l d
Pro b e o r i e ntati o n
S c a n n i n g d i re c ti o n
A n g l e p ro b e
FIGURE 3.15 TERMS RELATING TO PROBE DIRECTION
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© Standards Australia
AS 1929—2009
38
A
1
B
1
3
2
6
5
4
L EG EN D :
1
2
3
4
5
6
A
B
=
=
=
=
=
=
=
=
A n g l e p ro b e
Pro b e i n d ex
Te st s u r fac e
D i s c o nti n u i t y / f l aw
Beam axis
Te st o b j e c t
Fo r re c e pti o n
Fo r tra ns m i s s i o n
FIGURE 3.16 TANDEM (SCANNING)TECHNIQUE
© Standards Australia
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39
AS 1929—2009
1
3
5
2
4
T
B
W
F
L EG EN D :
1 =
2 =
3 =
4 =
5 =
T =
F =
W=
B =
D i s c o nti n u i t y / f l aw
B ac k wa l l
Te st o b j e c t
N o r m a l p ro b e
Te st s u r f a c e
Tra ns m i s s i o n p u l s e i n d i c ati o n
F l aw /d efe c t /d i s c o nti n u i t y e c h o
S i d e wa l l e c h o
B ac k wa l l e c h o
FIGURE 3.17.1 A-SCAN DISPLAY—CONTACT TESTING TECHNIQUE
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© Standards Australia
AS 1929—2009
40
1
3
5
2
4
T
S
B
F
L EG EN D :
1
2
3
4
5
T
S
F
B
=
=
=
=
=
=
=
=
=
D i s c o nti n u i t y / f l aw
B ac k wa l l
Te st o b j e c t
Im m e r s i o n p ro b e
Te st s u r f a c e
Tra ns m i s s i o n p u l s e i n d i c ati o n
Sur face echo
F l aw /d efe c t /d i s c o nti n u i t y e c h o
B ac k wa l l e c h o
FIGURE 3.17.2 A-SCAN DISPLAY—IMMERSION TECHNIQUE
© Standards Australia
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41
AS 1929—2009
1
3
2
5
4
T
F
L EG EN D :
1
2
3
4
5
T
F
=
=
=
=
=
=
=
A n g l e p ro b e
Pro b e i n d ex
Te st s u r f a c e
D i s c o nti n u i t y / f l aw
Te st o b j e c t
Tra ns m i s s i o n p u l s e i n d i c ati o n
F l aw /d efe c t /d i s c o nti n u i t y e c h o
FIGURE 3.17.3 A-SCAN DISPLAY—ANGLE BEAM TECHNIQUE
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© Standards Australia
AS 1929—2009
42
Ultrasonic
probe
D efe c t s
(r ef l e c to r s)
Back
s u r fa c e
Ultrasonic
B-scan
d i s p l ay
FIGURE 3.18 B-SCAN DISPLAY
© Standards Australia
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43
AS 1929—2009
1
2
3
4
5
L EG EN D :
1
2
3
4
5
=
=
=
=
=
F l aw a re a i n d i c ati o n
S c re e n p i c tu re re p re s e nti n g to p v i ew
Pro b e s c a n n i n g a l o n g p a r a l l e l l i n e s
Te st o b j e c t
D i s c o nti n u i t y / f l aw a re a s
FIGURE 3.19 C-SCAN DISPLAY
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© Standards Australia
AS 1929—2009
44
1
4
SO U N D PR ES SU R E
2
3
6 dB
5
D ISTA NC E
L EG EN D :
1
2
3
4
5
=
=
=
=
=
Fo c a l l e n g th
A x i a l b e a m p rof i l e
D ef i n e d l eve l
Fo c a l p o i nt
D e pth of f i e l d
FIGURE 3.20 SOUND FIELD OF FOCUSSING PROBE
© Standards Australia
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45
1
AS 1929—2009
1
3
X
Y
2
Z
1
4
X
Y
5
Z
0
1
2
3
4
5
6
7
8
9
10
L EG EN D :
1
2
3
4
5
X
Y
Z
=
=
=
=
=
A n g l e p ro b e
R efe re n c e b l o c k
R efe re n c e ref l e c to r
D i st a n c e a m p l i tu d e c o r re c ti o n c u r ve ( DAC )
50 % DAC
Pro b e p o s i ti o ns
FIGURE 3.21 DAC METHOD
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© Standards Australia
AS 1929—2009
46
S E C T I O N
4
E L E CT RO M A G N E T I C
I NSPE C T I ON
Term
Definition
absolute coil
A coil(s) that respond(s) to all electromagnetic
properties under test.
absolute coil system
A coil assembly which measures changes in current flow
independently of any reference standard.
background noise
Unwanted signals produced as a result of variations in
quality or dimension which are not associated with
defects, or by signals resulting from variations in the
method of inspection such as different inspection speeds
or misalignment of the coil assembly or position in
relation to the product under test.
bridge unbalance method
An alternating current bridge method in which variations
in the product under test are sensed in terms of the
bridge out-of balance signal.
bucking signal
A signal which is adjusted to be equal in frequency and
amplitude but opposite in phase to a signal produced by
the test.
coil
An arrangement of one or more turns of a conductor.
coil assembly
A combination of primary and secondary coils.
comparative coil system
A coil system which measures changes in current flow
between the two separate test pieces.
depth of penetration
For a body of uniform shape, the depth below the
surface at which the current density is one-third of its
value at the surface. (Frequently used in eddy current to
describe the greatest depth at which eddy currents are
sufficiently strong for the detection of discontinuities).
differential coil system
A coil assembly used in eddy current testing in which
two adjacent portions of a test piece are compared.
discrimination
The ability to distinguish between signals, usually
between signals from discontinuities which may differ in
their nature.
drag effect
The effect produced by the relative movement between
the primary coil and the product under test.
eddy current
A local current induced in a conducting body by an
applied alternating or varying magnetic field.
edge-effect
The change in eddy current distribution caused by abrupt
product dimensional change such as the edge of a plane
surface or the end of a rod or tube.
NOTES:
© Standards Australia
1
Also known as ‘end effect’.
2
The resulting distorted magnetic field may prohibit the
detection of discontinuities at or adjacent to these
areas.
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47
AS 1929—2009
Term
Definition
effective coil diameter
The diameter of a theoretical cylindrical coil having the
same electromagnetic effect as the test coil.
encircling coil
A coil assembly which surrounds the product under test.
fill factor
A measure of the special relationship between the coil
and the product under test. It is the square of the ratio of
the product diameter to the diameter of the encircling
coil(s). Alternatively it is the square of the ratio of the
product bore or hole diameter to the diameter of an
internal probe.
gate
A selected transit time range from which signal may be
extracted for further processing.
IACS
The International Annealed Copper Standard, an
international standard of electrical conductivity.
impedance
The ratio of the r.m.s. electromotive force in a circuit to
the r.m.s. current which is produced thereby. (The
impedance, which has resistive and reactive components,
determines the amplitude and phase of the current
relative to a given applied alternating voltage).
impedance analysis
Methods used to analyse changes in the resistance and
reactance to the secondary or search coil which enable
geometrical and/or metallurgical conditions to be
deduced.
impedance diagram
A graph showing the reactive and resistance components
of a coil as functions of, for example, frequency,
conductivity, permeability or dimensions.
internal coil
A coil assembly which is surrounded by the product
under test.
lift-off effect
The change in impedance of a coil which takes place
when it is moved away from the product under test.
magnetic field
The space in the neighbourhood of an electric current or
a permanent magnet, throughout which the forces due to
the current or magnet can be detected.
magnetic field strength
The measured intensity of a magnetic field at a point,
usually expressed in amperes per metre (A/m).
magnetic flux
The surface integral of the magnetic field intensity
normal to the surface. The unit of magnetic flux called
the weber is the flux which, linking to a circuit of one
turn produces in it an electromotive force of one volt as
it is reduced to zero at a uniform rate in one second.
magnetic flux density
The condition which arises when a magnetic flux of one
weber is distributed uniformly over an area of one
square metre where the area is perpendicular to the
direction of magnetic flux. The unit is the tesla.
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© Standards Australia
AS 1929—2009
48
Term
Definition
magnetic saturation (a.c.)
The condition reached in a ferromagnetic material
subjected to an a.c. magnetic field when the incremental
permeability reaches unity during part of each half
cycle.
magnetic saturation (d.c.)
The condition reached in a ferromagnetic subjected to a
d.c. magnetic field when the incremental permeability is
equal to unity.
modulation analysis
A ratio analysis of frequency, strength and variance over
time, signals from the search coil(s), after the separation
of individual interpretation of frequencies or frequency
bands in the modulating envelope of the induction
signal.
monitor
A device used to signal changes in eddy current response
which is outside specified limits for the product under
test. It also signals changes when the test equipment
operates outside prescribed limits.
noise
An unwanted electrical signal in the test equipment
which may interfere with the normal response and
processing of a desired signal.
optimum frequency
That frequency which provides the highest signal-tonoise ratio obtainable for detecting an individual
property such as conductivity, crack or other
discontinuity in the product under test.
NOTE: Each type of discontinuity in a given product may
have its own optimum frequency.
paralysis
The condition of an amplifier that is temporarily
inoperative, e.g. arising from overdriving.
phase analysis
An instrumentation method which uses phase angle
changes to discriminate between geometrical and/or
metallurgical variations in the product under test.
phase angle
The angular equivalent of the time displacement between
corresponding points in two sine waves of the same
frequency.
NOTE: The phase angle is changed by variations in
geometrical and metallurgical condition of the product
under test.
phase shift
A change in the phase relationship between two
alternating quantities of the same frequency.
phase-sensitive system
A system in which the output signals are dependent on
the phase relationship between an input and a reference
voltage.
phasing out
The suppression of drag effects, and other unwanted
signals by adjustment of the setting of the phase of the
reference voltage.
primary coil
The coil which includes alternating magnetic flux in the
product under test.
© Standards Australia
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49
AS 1929—2009
Term
Definition
probe coil
A coil assembly which does not encircle the product
under test.
Q factor
The numerical ratio between the reactance and the
resistance of the winding in a coil at the operating
frequency.
reference standard
A portion of material of the same geometrical and
metallurgical characteristics as the product under test
which may or may not contain natural or artificial
discontinuities.
NOTE: Also known as ‘reference piece’.
resolution
The clarity with which electrical signals may be
separated from each other.
response time
The time delay between the sensing of a discontinuity by
a search coil and its indication.
search coil
Type of eddy current coil or sensor.
secondary coil
The coil which detects the magnetic flux induced by the
primary coil in the product under test.
shielded coil
A coil fitted with a magnetic or non-magnetic shield in
order to limit the distribution of eddy current in the
product under test.
NOTE: The coil assembly may be shielded both
magnetically and electrostatically.
signal-to-noise ratio
The ratio of the amplitude of a signal arising from a
discontinuity to the amplitude of the average background noise signal.
skin effect
The phenomena wherein the depth of penetration of an
alternating electric current into a conductor decreases as
the frequency of the current is increased. At very high
frequencies, the current flow is restricted to an
extremely thin outer layer of the conductor.
suppression
The action taken to ensure that unwanted signal are
prevented or at least reduced.
surface coil
A probe coil shaped to conform to the geometry of the
product under test.
test speed
The relative movement between the coil assembly and
the product under test.
wobulation
An effect which produces variations in output signals
which arise from variations in dimensional clearance
between a coil and the surface of the product under test.
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© Standards Australia
AS 1929—2009
50
SECT ION
5
MAGNET I C
I NSPE C T I ON
PART IC L E
Term
Definition
alternating current
Electric current that reverses flow at a given frequency
to a maximum value in each direction.
alternating current
magnetization
Magnetization by the magnetic field induced when
alternating current is flowing.
background
The general appearance of the test surface of the test
surface on which indications of discontinuities are
sought.
background paint
See contrast aid.
black light
Near ultraviolet radiation (320 nm to 400 nm) used for
exciting fluorescence.
black-light filter
A filter which suppresses visible light and ultraviolet
radiation other than black light.
black-light filter
A filter which suppresses visible light and ultraviolet
radiation other than black light.
burning (arcing)
Local overheating of the component at the electrical
contact area arising from high resistance or from the
generation of an arc.
carrier fluid
The fluid in which magnetic particles are suspended to
facilitate their application.
circular magnetization
Magnetization which establishes a magnetic fluid around
the periphery of a component.
coagulation
The agglomeration of magnetic particles in a fluid,
occasioned by an undesirable contaminant.
coil method
A method of magnetization in which part or the whole of
the component is encircled by a current-carrying coil.
(The use of the term is usually restricted to instances in
which the component does not form part of a continuous
magnetic circuit for the flux generated).
coloured magnetic ink
Fluid containing coloured magnetic particles other than
black.
compass test
A test for demagnetisation carried out by placing the
component in specified positions in relation to a
magnetic compass needle and ascertaining whether the
consequent deflection exceeds a specified maximum.
contact heads
The electrodes between which the magnetizing current
flows.
contact pods
Metal pads, usually of copper braid, placed on electrodes
to give good electrical contact, thereby preventing
damage to the test surface.
continuous method
See sustained magnetization method.
© Standards Australia
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51
AS 1929—2009
Term
Definition
contrast
The difference in reflectivity or coloration between the
test surface and any discontinuities indicated by the
magnetic particle.
contrast aid
Any coating or film applied to a surface to improve
contrast by providing more suitable background.
core
That part of an electromagnetic circuit which is within
the winding.
current flow equipment
Magnetic particle testing equipment supplying
alternating, rectified alternating or direct current for
magnetizing components by the current flow method.
current flow method
A method of magnetizing by passing a current through a
component via electrodes, i.e. prods, contact heads or
clamps. The current may be alternating, rectified
alternating or direct.
current induction equipment
Magnetic particle testing equipment which is designed
for the induced current flow method.
demagnetization
The process whereby a magnetized body has its degree
of magnetism substantially reduced.
demagnetizing coil
A coil carrying alternating current used for
demagnetisation.
demagnetizing factor
A function of the length/diameter ratio of a given
component which can be calculated for components
having the shape of ellipsoids of revolution but has to b
measured experimentally for other shape.
diffuse indications
Indications that are not clearly defined, e.g. indications
of sub-surface discontinuities.
direct current (d.c.)
An electric current flowing in one direction only and
sensibly free from pulsation.
direct current magnetization
Magnetization by a magnetic field induced when direct
current is flowing.
dry powder method
The application of magnetic particles without the use of
a carrier fluid.
effective magnetic permeability A factor depending on the magnetic permeability (µ) and
on a factor N/4π (called the demagnetisation factor)
(µ eff)
where N is the constant of the proportionality.
electrode
A conductor by means of which a current passes into or
out of the component under test.
flash magnetization
Magnetization by a current flow of very brief duration.
fluorescence
Property of emitting light as the result of, and only
during absorption of, radiation from some other energy
source.
fluorescent magnetic ink
A detecting medium consisting, essentially of magnetic
particles in a carrier fluid which fluoresces under black
light.
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© Standards Australia
AS 1929—2009
52
Term
Definition
flux density
The condition which arises when a magnetic flux of one
weber is distributed uniformly over an area of one
square metre where the area is perpendicular to the
direction of magnetic flux. The SI unit is the tesla.
flux indicator
A reference device used for checking the presence
and/or the direction of a magnetic field by placing the
device in contact with the component under test.
flux penetration
The depth to which a magnetic flux is effective in a
component.
furring
Build-up magnetic particle due to excessive
magnetization of the component under test.
induced current flow method
A method of magnetizing in which a current is induced
in a ring component by the influence of a fluctuating
magnetic field which links the component.
longitudinal magnetization
Magnetization in which lines of flux in a component are
essentially parallel to its longitudinal axis.
magnetic circuit
The complete closed path followed by any group of lines
of magnetic flux.
magnetic field
The space in the neighbourhood of an electric current or
of a permanent magnet, throughout which the forces due
to the current or magnet can be detected.
magnetic field distribution
The distribution of field strength in a magnetic field.
magnetic field leakage
The loss of magnetic field strength due to discontinuities
and changes in section in a magnetic circuit.
magnetic field strength
The measured intensity of a magnetic field at a point,
usually expressed in amperes per metre (A/m).
magnetic flow equipment
Magnetic particle testing equipment consisting of an
electromagnet or permanent magnet in series with a
magnetic yoke having an adjustable gap in which the
whole or part of the component is inserted.
magnetic flow method
A method of magnetization in which the component or
portion of it closes the magnetic circuit of an
electromagnet or permanent magnet.
magnetic flux
The surface integral of the magnetic field intensity
normal to the surface. The unit of magnetic flux called
the weber is the flux which, linking a circuit of one turn,
produces in it an electromotive force of one volt as its is
reduced to zero at a uniform rate in one second.
magnetic flux density
The condition which arises when a magnetic flux or one
weber is distributed uniformly over an area of one
square metre where the area is perpendicular to the
direction of magnetic flux. The SI unit is the tesla.
magnetic ink
The detecting medium consisting essentially of magnetic
particles in a carrier fluid.
© Standards Australia
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53
AS 1929—2009
Term
Definition
magnetic leakage field
The magnetic field, external to a component and in
proximity to a discontinuity, which is detectable by
magnetic particles.
magnetic permeability (µ)
The ratio of the magnetic induction to the external
magnetic field causing the induction.
magnetic poles
The points in a magnetic which are the apparent seat of
the external magnetic field.
magnetic powder
Magnetic particles in dry powder form, of suitable shape
and size.
magnetic saturation
The stage at which any increase in the magnetic field
applied to a magnetized component fails to show any
significant increase in the magnetic flux in that
component.
magnetic writing
Unwanted indications arising from random local
magnetization.
magnetization
The process of rendering ferromagnetic materials
capable of attracting or repelling other ferromagnetic
materials.
particle concentration
The apparent volume ratio of magnetic particles to
carrier fluid in magnetic ink.
peak current
The maximum instantaneous value of the direct or
periodic current obtained during excitation. Usually,
with a d.c battery source or with three-phase full wave
rectified a.c it will be approximately that indicated by
the ammeter. With a.c or full wave rectified a.c it will be
√ 2 × the r.m.s current. With half-wave rectified a.c it
will be approximately 2√ 2 × r.m.s current.
NOTE: Ammeters fitted to half-wave equipment are
usually calibrated to take account of the doubling factor
(× 2) and therefore indicate equivalent r.m.s. values.
prods
Hand-held electrode attached to wander cables to
transmit the magnetizing current from the source to the
component under test.
profile pole pieces
Sections of electrically conductive material conforming
to the shape of the part, used to maximize contact
between the part and the magnetising device.
residual magnetism
The magnetism remaining in a component when, after
initial magnetization, the magnetizing force is reduced to
zero.
residual magnetization method
Magnetic particle testing in which the indicating
medium is applied after removal of the magnetizing
force.
settling time
The time allowed for settlement of magnetic particles in
a sample of magnetic ink prior to the assessment of
particle content.
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© Standards Australia
AS 1929—2009
54
Term
Definition
split coil
A single or multi-turn coil constructed with plug
connections to allow it to be opened for positioning over
components having no free ends for normal coil access.
surface field
The magnetic field at the surface of the component
under test.
sustained magnetization method A method of magnetic particle testing in which the
indicating medium is applied during magnetization.
sutherland flask
A flask used for measuring the apparent proportion of
solids separating under gravity from a known volume of
magnetic ink. The ungraduated upper portion, shaped
like an inverted pear, is constricted at the top to receive
a stopper and blended at the bottom into a graduated
tube of small uniform section.
threading bar method
A method of magnetization in which a current-carrying
bar, cable or tube is passed through a bore or aperture in
a component under test.
threading coil method
A method of magnetization in which a current carrying
cable is threaded, one or more times, through a bore or
aperture in a component under test.
yoke
A fixed extension to a magnetic circuit facilitating the
completion of that circuit.
© Standards Australia
www.standards.org.au
55
SEC T I O N
6
P EN E T RA N T
AS 1929—2009
I NSPE CT I O N
Term
Definition
background
Level of fluorescent penetrant or colour contrast
penetrant left on the surface of the component after the
removal of excess penetrant.
bath
Quantity of liquid-penetrant inspection materials
(penetrant, emulsifier, developer) into which parts are
immersed during the test.
bleedout
Egress of penetrant from a discontinuity, usually aided
by developer.
colour contrast penetrant
Penetrant that is a solution of dyes (typically red) in a
liquid base.
developer
Substance which has the property of with-drawing
penetrant from discontinuities to make them more easily
visible.
development time
Time between application of developer and subsequent
examination.
dip rinse
Means of removing excess penetrant in which the test
parts are dipped into a tank of water which may be
agitated.
dry developer
Developer in the form of a fine dry powder used mainly
with fluorescent penetrants.
dual purpose penetrant
Penetrant that gives indications which are capable of
being viewed either under visible lights or UV-A
radiation.
dwell time
The time allowed for penetrant in continuous contact
with the inspection surface to penetrate open features.
electrostatic spraying
Application of electrically charged particles to an
earthed test surface.
emulsification of penetrant
Action of emulsifiers on post emulsifiable penetrants to
render them water-washable.
emulsification time
Period of time an emulsifier is used to render the postemulsifiable penetrant water-washable.
emulsifier
Product which makes the post-emulsifiable penetrant
water-washable.
excess penetrant removal
Means employed to remove excess penetrant from the
test surface, without removing any penetrant from the
discontinuities.
fluorescent intensity
Intensity of light emitted in the visible spectrum by the
penetrant, when excited by radiation in the UV-A range.
fluorescent penetrant
Penetrant that fluoresces under UV-A radiation.
hydrophilic emulsifier
Water-dilutable remover used in penetrant testing.
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© Standards Australia
AS 1929—2009
56
Term
Definition
lipophilic emulsifier
Oil based emulsifier used in penetrant testing.
penetrant testing
Non-destructive test typically comprising a penetrant, a
method of excess removal and a developer to produce a
visible indication of surface-breaking discontinuities.
peelable developer
Liquid developer which, on evaporation, leaves a thin
removable film which retains any indication and can be
used to obtain archivable replicas.
penetration time
Interval comprising penetrant application time plus drain
time, during which the penetrant is in direct contact with
the test surface.
penetrant
Liquid when applied to a component is designed to find
its way into surface discontinuities and to remain there
in detectable amounts during the subsequent removal of
excess penetrant from the surface.
penetrant materials (testing
products)
Cleaners, penetrant, removers and developers used in
penetrant testing.
post cleaning
The removal of penetrant material residues from the test
after the penetrant testing process has been completed.
post emulsifiable penetrant
Penetrant that requires the application of separate
emulsifier to render it water-washable.
precleaning
Removal of contaminants from the test surface.
product family
Compatible group of penetrant, remover and developer.
reference block
Test piece with known discontinuities, either natural or
artificial, used to determine and/or compare the
sensitivity of penetrant processes and to check their
reproducibility.
rinse
Process of removing excess penetrant from the surface
by means of washing or flooding with the relevant
excess penetrant remover, usually water.
sensitivity
Measure of the ability of a penetrant testing process to
detect discontinuities.
sensitivity level (of a penetrant
inspection process)
Grading of sensitivity of a given penetrant testing
process.
solvent based developer;
nonaqueous wet developer
Developer consisting of fine particles in a solution with
a volatile solvent.
solvent-removable penetrant
Penetrant that requires the application of a suitable
solvent to remove the excess surface.
solvent remover
Organic liquid used to remove excess penetrant from the
test surface.
water soluble developer
Product dissolved in water when dry forms an absorbant
coating.
NOTE: Also known as ‘aqueous soluble developer’.
© Standards Australia
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57
AS 1929—2009
Term
Definition
water suspendable developer
Product dispersed in water, which dries to an absorptive
coating.
NOTE: Also known as ‘aqueous suspender developer’.
water tolerance
Portion of water, expressed as a percentage by mass or
volume, which a water-washable penetrant or lipophilic
emulsifier tolerates at a given temperature before its
performance is impaired.
water-washable penetrant
Penetrant which has been formulated to make it directly
water washable.
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© Standards Australia
AS 1929—2009
SECT ION
58
7
RAD I OGR APH IC
I NSP ECT IO N
7.1 RADIOGRAPHIC INSPECTION
Term
Definition
absorbed dose (D)
The quantity of radiation or energy absorbed and is the quotient of
dE by dm, where dE is the energy imparted imparted by ionizing
radiation to the matter in a volume element and dm is the mass of the
matter in that element i.e. D −
dE
dm
The SI unit of absorbed dose is the gray (Gy).
absorption
activity
The reduction in intensity of a beam of radiation during its passage
through matter due to photo-electric absorption and pair production
only (see also attenuation).
The number of radioactive disintegrations of a given source
occurring per unit time.
NOTE: Also known as ‘source strength’.
The SI unit is the becquerel (Bq).
anode
The positive electrode of an X-ray tube carrying the target from
which X-rays are emitted (see Figure 7.7).
attenuation
The reduction in intensity when a beam of ionising radiation passes
through matter.
autoradiography
Production of an image by the photographic recording of natural
radiation.
back scatter
That part of the scattered X-radiation of gamma radiation which is
transmitted at an angle of more than 90 degrees in relation to the
direction of the incident beam.
beam angle
The angle between the central axis of the radiation beam and the
plane of the radiographic film (see Figure 7.1).
beam divergence
The angle of the beam of radiation as it emerges from the X-ray tube
or gamma-ray exposure container (see Figure 7.1).
G a m m a r ay
ex p o s u re c o nta i n e r
Beam
angle
Beam
d i ve rg e n c e
Film
Beam angle
B e a m d i ve rg e n c e
Film
FIGURE 7.1 BEAM DIVERGENCE AND BEAM ANGLE
© Standards Australia
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59
AS 1929—2009
Term
Definition
becquerel (Bq)
The SI unit of activity, equal to one disintegration per second.
NOTE: The becquerel replaces the curie (Ci).
1 curie = 3.7 × 1010 becquerel (Bq).
= 37 gigabecquerel (GBq).
betatron
A source of high energy X-rays in which electrons are accelerated in
a circular orbit by means of magnetic induction.
blocking medium
A material used adjacent to a product during radiography to reduce
the effect on section differences on radiographic exposure.
broad beam
An uncollimated beam containing scattered radiation as well as the
primary beam.
build-up factor
The ratio of the intensity of the total radiation energy reaching a
point to the intensity of the primary radiation reaching the same
point.
cassette
A light-tight container for holding a radiographic film during
exposure.
cathode
The negative electrode of an X-ray tube carrying the filament and
focussing cup (see Figure 7.7).
Characteristic
curve
A curve showing the relation between logarithm to the base 10 of the
relative exposure and the photographic density of a film (see
Figure 7.2). Film A is said to be faster than film B. The gradient of
film B is greater than that of film A and this is indicative if greater
contrast, i.e. it produces a greater density range for the same
difference in exposure.
NOTE: Also known as ‘sensitometric curve’.
characteristics
radiation
X-radiation consisting of discrete wavelengths which are
characteristics of the emitting material (see Figure 7.3).
cine-radiography
The production of a series of radiographs which can be viewed
rapidly in sequence, thus creating an illusion of continuity.
collimation
The production of a near parallel beam of radiation by use of a slit or
aperture in an absorbing material.
constant potential
circuit
A circuit which is arranged to supply a substantially constant
potential across an X-ray tube.
continuous spectrum The plot of the relation between the wave length and relative
intensity of a beam of X-rays (see Figure 7.3).
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© Standards Australia
AS 1929—2009
60
D e ns i t y ra n g e ( B ) = 1.0
D e ns i t y ra n g e ( A ) = 0.5
A
3.5
B
D ENSI T Y
3.0
2.5
0.5
= 1
0.5
1.0
G rad i e nt ( F i l m B ) =
= 2
0.5
G rad i e nt ( F i l m A ) =
2.0
1.5
1.0
0.5
0.5
0.5
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
LO G R EL AT I V E E X P OSU R E
IN T ENSI T Y
FIGURE 7.2 CHARACTERISTICS (SENSITOMETRIC) CURVES
WAV EL ENGT H
FIGURE 7.3 CONTINUOUS SPECTRUM AND CHARACTERICTIC RADIATION
Term
Definition
contrast indicator
A radiographic arrangement whereby variations in densities
in a radiograph can be assessed against known values.
coolidge tube
An X-ray tube in which the source of the bombarding
electrons is a heated filament in the cathode.
coulomb per kilogram
(C/kg)
The SI unit of exposure. It replaces the roentgen (R).
1 R = 2.58 × 10 C/kg
curie
See becquerel.
dark adaptation
The process by which the eye adapts itself to a lower level of
ambient illumination when entering a darkened room.
decay (radioactive)
Decrease of activity due to radioactive disintegration.
decay curve
The activity of a radioactive source, measured in becquerels,
plotted against time.
defect sensitivity
The minimum size of a discontinuity, considered to be a
defect, which can be detected under specified conditions.
densitometer
An instrument for measuring light transmission and/or
reflection density of film, plate or paper.
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61
AS 1929—2009
Term
Definition
density
(photographic)
The degree of blackening of a radiographic film expressed as
the logarithm to base 10 of the opacity of the film, that is,
ratio of intensity of incident light to the intensity of
transmitted or reflected light.
development
The chemical or physical process which converts a latent
image into a visible image.
dichroic fog
For arising from the deposition of a very thin layer of finely
divided silver on an emulsions which, when examined in
white light, appears in two colours, red by transmission and
green by reflection.
diffraction
The phenomenon of the preferential scattering of a beam of
radiation in certain directions arising from the interference
between waves scattered by different elements of volume in
the medium.
diffraction mottle
A mottle superimposed on a radiographic image due to the
diffraction of incident radiation.
discontinuity sensitivity
The capability of radiograph to display the image of a
particular discontinuity.
NOTE: This property is usually expressed quantitatively as the
minimum size of a discontinuity which can be seen under
specified conditions.
dose
A general term denoting the quantity of radiation or energy
absorbed.
NOTE: For the purpose of this Standard the word ‘dose’ when
used alone is a convenient synonym for dose equivalent.
dose equivalent (H)
The product of ‘absorbed dose’ (D), quality factor (Q) and
any other relevant modifying factors (N), i.e. H = DQN. The
SI unit for dose equivalent is the sievert (Sv).
dosimeter
A monitoring device used for measuring or evaluation the
absorbed dose, exposure, or similar radiation quantity.
dose rate
The rate at which radiation is delivered.
NOTE: The term has a slightly different meaning in relation to
health physics.
dose rate meter
An instrument for measuring radiation dose rate.
dual-focus tube
An X-ray tube with a choice of two different size of focal
spot.
dynamic range
The difference between the two extremes of correct exposure
(see also exposure latitude).
NOTE: The dynamic range is set by the minimum acceptable
gradient and by the maximum readable density.
electron radiography
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A method of radiography in which a beam of electrons passes
through a test object and is recorded on film. Alternatively, a
beam of X-rays is incident on the test object and the
electrons emitted from the surface are recorded on film.
© Standards Australia
AS 1929—2009
Term
equalizing filter
equilibrium half-value
layer
62
Definition
A device to equalize the intensity across the primary X-ray
beam.
The greatest thickness of materials required to reduce the
intensity of a polychromatic beam of radiation, passing
through an absorber, by a factor of two
NOTE: Also known as ‘terminal’.
equivalent sensitivity
(IQI)
Is the equated value of sensitivity of the radiograph when
measured by another type of image quality indicator.
exposure container
A device for housing radioisotopes which provides protection
against radiation and permits controlled exposure of
radiation.
exposure chart
A chart on which is plotted one ore more curves which
indicate exposures for specified product thicknesses.
exposure fog
For fog arising from any unwanted exposure of a film, to
ionizing radiation or light, at any time between manufacture
and final fixing.
The exposure latitude relates the ability of a film to
accommodate variations in density occurring as a result of
differences in thickness.
exposure latitude
NOTES:
1
Figure 7.4 refers to the characteristic curve of a film the
dynamic range a of which is set by the minimum acceptable
gradient A and the maximum readable film density B.
2
The useful range of effective exposure for the test object is
assumed to be b, the extremities of which are determined by
the thickest and thinnest sections.
The exposure latitude is given by the ratio—
Dynamic range
a
−
Useful range of effective exp osure b
Expressed logarithmically this is equal to a − b = c
B
3.5
D ENSI T Y
3.0
2.5
2.0
L EG EN D :
1.5
a = D y n a m i c ra n g e
b = Us ef u l ra n g e of
ef fe c ti ve ex p o s u re
c = E x p o s u re l ati tu d e
1.0
A
0.5
c
b
a
0.5
1.0
1.5
2.0
2.5
LO G R EL AT I V E E X P OSU R E
FIGURE 7.4 EXPOSURE LATITUDE
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63
AS 1929—2009
TERM
DEFINITION
filament
The source of electrons in a Coolidge type cathode tube (see
Figure 7.6).
film badge
A film contained within a special holder worn by personnel
in order to assess the radiation to which the wearer has been
exposed.
film base
A flexible transparent or translucent support for the
photographic emulsion.
film clearing time
The time required for the first stage of fixing during which
the unsensitized silver halide is removed as indicated by the
disappearance of the whiteness of the film.
film contrast
The property of a film to record differences in density in
relation to radiation intensity. It depends on the gradient of
the characteristic curve at a given density (see Figure 7.2).
film processing
The operation necessary to transform a latent image into a
permanent visible image.
film speed
A measure of the exposure required to produce a given
density on a photographic emulsion under any given set of
conditions (see Figure 7.3).
film unsharpness
See inherent unsharpness.
filter
A layer of absorptive material interposed in the path of
radiation in order to reduce selectively the intensity of the
lower energy radiation.
fixing
The chemical removal of unexposed silver halides from
emulsion after development.
flash radiography
Radiography for the purpose of examining transient effects,
such as moving objects in which the radiation intensity is
relatively high and the exposure time is relatively short.
fluorescent screen
A suitable mounted layer of material which fluoresces in the
visible region of the spectrum under the action of X-rays or
gamma rays.
fluorography
Photography of a fluoroscopic image.
fluorometallic screen
A support base to which is attached thin lead foil coated with
a fluorescent material.
fluoroscopy
The process by which a single screen containing fluorescent
material is irradiated with X-rays or gamma rays giving a
pattern of visible light corresponding to the intensity of
incident radiation.
focal spot
The area on the surface of the anode of an X-ray tube on
which the electron stream impinges and from which the
primary beam of X-rays is emitted.
fog
A general term used to denote any increase in the density of
a film arising from unwanted chemical reactions during the
manufacture, storage or processing.
full-wave rectification
Rectification which allows current to flow during each half
cycle of an alternating supply.
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© Standards Australia
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64
TERM
DEFINITION
gamma radiation
Electromagnetic radiation emitted in the process of nuclear
transition or particle annihilation.
NOTE: Also known as gamma rays.
gamma radiography
Radiography using a gamma-ray source.
gamma ray source
A quantity of matter emitting gamma-radiation which is
suitable for radiography (see sealed source).
geometric unsharpness
Unsharpness caused by penumbra geometrically related to a
finite source size and source-to-film distance.
gradient (G d)
The slope of a characteristic film curve at a specified density
(see Figure 7.2).
graininess
A visual effect due to the random distribution of groups of
silver grains in the fixed emulsion layer.
gray (Gy)
The SI unit of absorbed dose of ionising radiation, equal to
the joule per kilogram (J/kg).
NOTE: The gray replaces the rad (rad).
1 Gy = 100 rad.
half-life
The time required for the activity of a radio-nuclide to be
halved.
half-value layer (HVL)
The thickness of a specified substance which, when
introduced into the path of a given beam of radiation,
reduces the intensity of radiation by a factor of two (see
Figure 7.5).
NOTE: Half-value layer may be used as an indication of the
quality of the beam or of the opacity of the substance. See also
initial half-value layer and equilibrium half-value layer.
half-wave rectification
Rectification which allows current to flow only during
alternate half cycles of an alternating supply.
hard radiation
Radiation of relatively high penetrating power.
hardener
A substance used to harden the gelatine in the emulsion on a
radiographic film during fixing.
image definition
The sharpness of delineation of image details in a
radiograph. Generally used qualitatively.
image forming radiation
Radiation which is incident on the absorber and continues
unaltered in energy and in direction after passing through the
absorber.
image intensifier
A device used when taking radiographs to render variations
in X-ray intensity directly visible.
NOTE: A higher degree of screen brightness is obtained by
converting the X-ray photons falling on the primary fluorescent
screen into light, this in turn excites an adjacent photoelectric
layer to emit electronic which are accelerated at a potential of
approximately 20 kV to 30 kV and focussed on the final
viewing screen (see Figure 7.6).
© Standards Australia
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65
AS 1929—2009
T R A N S M IS S I O N, %
10 0
Po i nt of
h o m o g e n et y
50
40
20
I n i ti a l H V L
Eq u i l i b r i u m o r
te r m i n a l H V L
SA M PL E T H I C K N ES S
FIGURE 7.5 HALF VALUE LAYER
x or
rays
Te st p i e c e
F l u o re s c e nt s c re e n
Ph oto e l e c tr i c l aye r
V i ew i n g s c re e n
V i ew i n g s c re e n
FIGURE 7.6 IMAGE INTENSIFIER
Term
Definition
image quality indicator
(IQI)
A device used for judging, from the appearance of its image
in a radiograph, the overall quality of that radiograph.
inherent filtration
The filtration of an X-ray beam by any parts of the tune or
tube shield.
inherent unsharpness
(film or intrinsic)
initial half-value layer
www.standards.org.au
Image spread caused by electron or light scatter through
emulsion grains in the radiographic film.
That thickness of material required to reduce the initial
intensity of radiation passing through an absorber by a factor
of two.
© Standards Australia
AS 1929—2009
66
Term
Definition
intensifying factor
The ratio of the exposure time required without intensifying
screens to that when screens are used, other conditions being
the same.
intensifying screen
A layer of material, which when places in close contact with
a photographic emulsion, adds to the radiographic effect of
the incident radiation by reducing exposure time.
ionizing radiation
Radiation which produces ions.
NOTE: Ionizing radiation may be fast moving particles such as
alpha or beta rays or be electromagnetic radiation such as X-ray
or gamma rays.
IQI sensitivity
The sensitivity of a radiograph quantified in terms of the
smallest IQI element seen on the radiograph.
NOTES:
1
IQI sensitivity is usually expressed in terms of a particular
critical dimension of the IQI used.
2
IQI sensitivity should not be confused with discontinuity
sensitivity.
latent image
A change produced in the emulsion of a film, paper or plate
by exposure to radiation and capable of being converted into
a visible image by development.
line focus
An elongated, rectangular focus so angled that the effective
focus size as viewed along the beam axis, is smaller and
approximately square, thereby permitting increased total area
loading of the target for a given effective focus size.
linear accelerator
A straight-line particle accelerator used for the production of
high energy X-rays.
NOTE: Also known as ‘linac’.
masking
The application of material which limits the area of
irradiation to the region undergoing radiographic
examination.
metal intensifying screen
An intensifying screen of metal foil (usually lead) which
emits secondary radiation under the influence of X-rays or
gamma rays.
NOTES:
1
Also known as ‘metal screen’.
2
Metal screens also minimize the amount of scattered radiation
reaching the film from the test object.
microradiography
Radiography of relatively thin sections in such a way that the
resulting image is enlarged, or is capable of being enlarged to
reveal microstructure.
movement unsharpness
Unsharpness caused by uncoordinated relative movement
between radiation source, object and film during an exposure.
neutron radiography
The use of a beam of neutrons to examine an object by
producing a graphical record or image on sensitized film or
on other recording or indicating media.
object-to film distance
The distance from the source side of the test object to the
film surface, i.e. inclusive of object thickness.
© Standards Australia
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67
AS 1929—2009
Term
Definition
panoramic radiography
Radiography using a centrally located source to
simultaneously produce a continuous or overlapping image or
a series of discrete images on radiographic film or paper.
penumbra
Blurring of a radiographic image resulting from the fact that
the radiation is not from a point source.
penetrometer
See image quality indicator.
pressure mark
A mark produced by pressure or a film which after
developing results in areas of either increased or decreased
density.
quality factor (QF)
A factor intended to allow for the effect on biological
response of the microscopic distribution of absorbed energy
when received in small doses. Appropriate values of QF are
given below:
X-rays, λ-rays and electrons…………………………1
Neutrons, protons and singly-charged particles of test
mass greater than one atomic mass unit of unknown
energy………………………………………………..10
Alpha particles and multiple-charged particles (an
particles of unknown charge) of unknown
energy………………………………………………..20
rad
See gray
radioactivity
The property of certain nuclides of—
(a)
spontaneously emitting gamma radiation;
(b)
undergoing spontaneous fission;
(c)
spontaneous emitting X-radiation following orbital
electron capture.
radiograph
A photographic image produced by ionizing radiation on a
film or paper after passing through a material (see also
neutron radiograph).
radiographic contrast
The relative density or brightness between adjacent areas on
an illuminated radiograph or fluorescent screen image.
radiographic exposure
The subjection of a recording medium to radiation for the
purpose of producing a latent image. Radiographic exposure
is commonly expressed in terms of milliampere minutes, and
giga bacquerel minutes.
radiographic film
A photographic film which is usually coated on both sides
with an emulsion designed for use with X-rays and gamma
rays.
radiographic paper
Photographic type paper suitable for production of
radiographs.
radiographic viewer
Equipment incorporating a suitable area of diffuse
illumination for viewing radiographs. The brightness of the
illuminated area being appropriate to the density of the
radiograph.
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© Standards Australia
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68
Term
Definition
radiography
The use of radiant energy in the form of neutrons, protons,
electrons, X-rays or gamma rays for non-destructive testing
of opaque objects, in order to produce graphical records on
sensitized film.
radiology
The science and application of X-rays, gamma rays, and other
penetrating ionizing radiation.
radioisotope
An isotope which undergoes spontaneous disintegration with
the emission of ionizing radiation.
NOTE: Also known as ‘radio nuclide’.
reciprocity failure
The departure from the reciprocity law of any given emulsion
under specified conditions, e.g. when salt screens are used.
reciprocity law
A law which states that, all other conditions remaining
constant, the time of exposure required to produce a given
photographic density is inversely proportional to the intensity
of the radiation.
NOTE: Also known as ‘Bunsen-Roscoe law’.
rectification
Any method by which unidirectional voltage can be obtained
from an alternating supply. See sievert.
rem
See sievert.
reticulation
A net-like structure appearing in an emulsion of a
radiographic film as a result of buckling caused by difference
in temperature between processing baths, or rinsing water.
reversal
A completer or partial reversal of the tones of a radiograph,
generally produced by excessive radiographic exposure.
rod-anode tube
An X-ray in which target is situated near the outer end of a
long tubular anode.
roentgen
See coulomb per kilogram.
safelight
A source of filtered light of colour or waveband chosen to
give insignificant fogging of a particular film type at
intensity levels necessary for handling and processing films
in a dark room.
salt intensifying screen
An intensifying screen consisting of a substance which
fluoresces in the visible or ultraviolet region of the spectrum
under the action of radiation.
scattered radiation
Secondary radiation which is emitted in all directions.
screen unsharpness
Unsharpness caused by the use of intensifying screens or a
fluorescent viewing screen. It may result from the scatter of
light by the crystals of the fluorescent layer and poor contact
between screens and films.
sealed source
A radioactive source bonded or encapsulated to prevent the
escape of the radioactive material under the conditions of use
for which it was designed.
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69
AS 1929—2009
Term
Definition
sensitivity
The limiting amount of detail which can be seen on a
radiograph. It can also be regarded as the smallest
discontinuity which can be detected under given conditions.
sensitometric curve
See characteristic curve.
sievert (Sv)
The SI unit of absorbed radiation dose in biological matter
equal to the absorbed dose in grays multiplied by the equality
factor (QF) of the radiation (see also dose equivalent).
NOTE: 1 Sv = 100 rem.
soft-radiation
Radiation of restively low penetrating power.
source
The origin of radiation.
source shift radiography
A method for determining the depth of a discontinuity by the
use of two offset sources.
source size
The apparent dimensions as viewed along the beam axis of
that portion of the source from which ionizing radiation is
emitted.
NOTE: For the purpose of calculating geometric unsharpness,
the effective dimensions must always be taken.
source-to-film distance
(SFD)
The distance from the source of primary radiation to a film
set for a radiographic exposure.
specific activity
The activity per unit mass of radio nuclide (see also activity).
spectral sensitivity
The variation in radiation dose with X-ray energy to produce
a given film density.
step wedge
A block of material in the form of a series of steps usually
used for the preparation of exposure charts.
stereo-radiography
The production of a pair of radiographs suitable for
stereoscopic viewing.
subject contrast
The difference in radiation intensity between the adjacent
areas in a test object arising from differences in attenuation
characteristics in those areas.
survey matter
See dose rate meter.
target
The metal insert in the anode of an X-ray tube on which the
electron beam impinges (See Figure 7.7).
Fo c u s i n g c u p
F i l a m e nt
Anode
Ta rg et
Cath o d e
Pr i m a r y b e a m
Fo c a l s p ot
FIGURE 7.7 DIAGRAMMATIC VIEW OF PRINCIPAL
COMPONENTS OF AN X-RAY TUBE
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70
Term
Definition
tenth value layer (TVL)
The thickness of a specified substance which when
introduced into a beam of radiation, reduce the value of a
specified radiation quantity by a factor of ten.
tomography
The radiography of a predetermined layer of material.
tube current
The current passing between the cathode and anode during
the operation of an X-ray tube.
tube diaphragm
A device, normally fixed to a tube shield or head to limit the
extent of the emergent X-ray beam.
tube voltage
The potential difference between the anode and the cathode
of an X-ray tube during operation.
unsharpness
Loss of image definition (see also film unsharpness,
geometric unsharpness, movement unsharpness and screen
unsharpness).
Van der Graff generator
A high voltage generator for producing X-rays usually with
energies of 1 MeV to 4 MeV.
X-radiation
Penetrating electromagnetic radiation other than annihilation
radiation originating in the extra-nuclear part of the atom and
having wavelengths much shorter than visible light.
NOTE: Also known as X-rays.
X-ray film
A photographic film which is usually coated on both sides
with an emulsion designed for use with X-rays and gamma
rays.
X-ray paper
White paper coated on one side with emulsion, suitable for
some purposes as an alternative to X-ray film.
Xero-radiography
Radiography using a photoconductive plate instead of
radiographic film or paper.
7.2 COMPUTERIZED RADIOGRAPHY
aliasing
Pre-sampled high spatial frequency signals beyond the
Nyquist frequency (given by the pixel distance) reflected
back into the image at lower spatial frequencies.
basic spatial resolution
Read-out value of unsharpness measured with duplex wire
IQI according to EN 462-5 divided by 2 as effective pixel
size of CR system.
CEN speed S CEN
Defines the speed of CR systems and is calculated from the
reciprocal dose value, measured in Grays, which is necessary
to obtain a specified minimum SNR of a CR system.
computed radiography
system (CR system)
Complete system of a storage phosphor imaging plate (IP)
and corresponding read-out unit (scanner or reader) and
system software, which converts the information of the IP
into a digital image.
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71
AS 1929—2009
Term
Definition
computed radiography
system class
Particular group of storage phosphor imaging plate systems,
which is characterized by a SNR (Signal-to-Noise Ratio)
range shown in Table 1 and by a certain basic spatial
resolution value (e.g. derived from duplex wire IQI) in a
specified exposure range.
CR phantom
Device containing an arrangement of test targets to evaluate
the quality of a CR system, as well as monitoring the quality
of the chosen system.
gain/amplification
Opto-electrical gain selling of the scanning system.
laser beam jitter
Lack of smooth movement of the plate laser-scanning device,
causing lines in the image consisting of a series of steps.
linearized signal intensity
Numerical signal value of a picture element (pixel) of the
digital image, which is proportional to the radiation dose.
The linearized signal intensity is zero, if the radiation dose is
zero.
modulation transfer function Normalized Magnitude of the Fourier-transform (FT) of the
(MTF)
differentiated edge spread function (ESF) of the linearized
PSL (photo stimulated luminescence) intensity, measured
perpendicular to a sharp edge. MTF describes the contrast
transmission as a function of the object size. MTF
characterizes the unsharpness of the CR system in
dependence on the scanning system and IP-type.
scanner slippage
Slipping of an IP in a scanner transport system resulting in
fluctuation of intensity of horizontal image lines.
signal-to-noise ratio (SNR)
Quotient of mean value of the linearized signal intensity and
standard deviation of the noise at this signal intensity. The
SNR depends on the radiation dose and the CR system
properties.
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SECT ION
8
COND I T I O N
MON I TOR I NG
8.1 GENERAL
Term
Definition
analysis
Careful scrutiny of constituent parts of a system in order
to thoroughly understand the whole.
breakdown maintenance
Maintenance performed after a machine has failed.
catastrophic failure
Sudden, unexpected failure of a machine resulting in
considerable damage to the machine and/or associated
machines or components.
condition-based maintenance
Maintenance performed as governed by condition
monitoring programmes.
condition monitoring
Direction and collection of information and data that
indicate the state of a machine.
NOTE: The machine state deteriorates if faults or failures
occur.
diagnostics
Examination of symptoms and syndromes to determine
the nature of faults or failures (kind, situation, extent).
failure
Termination of the ability of an item to perform a required
function.
NOTE: Failure is an event as distinguished from fault which
is a state.
fault
Condition of a component that occurs when one of its
components or assemblies degrades or exhibits abnormal
behaviour, which may lead to the failure of the machine.
NOTES:
function
1
A fault may be the result of a failure, but can exist
without a failure.
2
Planned actions or lack of external resources are not a
fault.
Appropriate action of any machine or part of a system.
NOTE: The function is the action and activity assigned to,
required of, or expected of a machine or system.
machine
Mechanical system designed expressly to perform a
specific task, such as the forming of material or the
transference and transformation of motion, force or
energy.
NOTE: This is also sometimes referred to as equipment.
machine characteristics
© Standards Australia
Distinguishing attributes, qualities and properties of a
machine and its subsystems which, by their presence and
the relative magnitudes of their effects, define the
configuration, performance, behaviour and capabilities of
the machine.
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Term
Definition
machine system
Machine train (deprecated), mechanical system in which
the principal subsystem is a specific machine, and whose
other subsystems are components and auxiliaries whose
individual functions are integrated to support the actions
and work of the machine.
predictive maintenance
Maintenance emphasizing prediction of failure and taking
action based on the condition of the equipment to prevent
failure or degradation.
preventive maintenance
Maintenance performed according to a fixed schedule, or
according to a prescribed criterion that detects or prevents
degradation of a functional structure, system or
component, in order to sustain or extend its useful life.
proactive maintenance
Type of maintenance emphasizing the routine detection
and correction of root cause conditions that would
otherwise lead to failure.
Examples: High lubricant contamination, misalignment
and unbalance.
prognostics
Analysis of the symptoms of faults to predict future
condition and remaining useful life.
system
Grouping of associated entities, which is characterized by
a mental construct.
NOTE: One of the associated entities if the boundary of the
system.
8.2 MACHINE CHARACTERISTICS
critical machinery
Machinery which is required to accomplish a major part
of an economic process.
maintainability
Ability of a machine or part of a system to be retained in,
or restored to, a state in which it can perform the
required function(s).
performance
Behaviour, characteristics and efficiency of a
technological process, running in a machine.
reliability
Reliability that a machine will perform its required
functions without failure for a specified time period
when used under specified conditions.
8.3 OPERATION AND MAINTENANCE
alignment
Condition whereby the axes of machine system
components are either coincident, parallel or
perpendicular, according to design criteria.
reliability centred
maintenance (RCM)
Disciplined logic used to identify those cost effective and
technologically feasible maintenance tasks that realise the
inherent reliability of equipment at a minimum
expenditure of resources over the life of the equipment.
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Term
Definition
thermal growth
Change in the dimensions of a system component caused
by expansion due to changes in temperature.
8.4 FAULTS
abnormality
Deviation from a standard condition
alarm
Operational signal or message designed to notify
personnel when a selected anomaly, or a logic
combination of anomalies, requiring corrective actions is
encountered.
NOTE: An alarm is a more severe anomaly zone than an
alert and should be identified with a red indicator.
alert
Operational signal or warning message designed to notify
personnel when a selected anomaly, or a logical
combination of anomalies, requiring heightened
awareness is encountered.
NOTE: An alert is the first zone of an anomaly and should
be identified with a yellow indicator.
anomaly
Irregularity or abnormality in a system.
distortion
Departure from normal shape or configuration.
failure mode
Effect by which failure is observed.
fault progression
Characterization of the change in severity of a fault over
time.
sign
Characteristic parameter of a signal, which shows
information about a state.
syndrome
Group of signs or symptoms that collectively indicate or
characterize an abnormal condition. See Sympton (8.9).
tribological wear
Wear that occurs as a result of relative motion at the
surface.
8.5 DATA COLLECTION (ACQUISITION)
attenuation
Decrease in strength of a signal, usually as a result of the
distance a signal travels or the density of the medium
through which it travels.
background noise
Unwanted noise present in a signal which cannot be
attributed to a specific cause.
dynamic range
Ratio of the largest magnitude to the smallest magnitude
that a transducer or analyser can detect.
NOTE: Dynamic range is generally expressed in decibels as
20 times the logarithm to the base 10 of the ratio of the
largest magnitude to the smallest magnitude.
thermography
© Standards Australia
Use of infrared imagers, whereby the temperatures of a
wide variety of targets can be measured remotely and
without contact by measuring the infrared energy
radiating from the surface of the target and converting this
measurement to an equivalent surface temperature.
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Term
Definition
time window
Time required for a digital analyser to take the number of
samples required to accurately reconstruct the input
signal.
triboelectric noise
Noise generated into a shielded cable, caused by bending
or motion of the cable.
8.6 DATA CHARACTERISTICS
asynchronous
Vibration components that are not related to rotating
speed.
NOTE: Also known as ‘non-synchronous’ (deprecated).
descriptor
Feature, data item derived from raw or processed
parameters or external observation
noise floor
Level of noise present in a system with no exciting signal
present.
off line
(In condition monitoring and diagnostics) Continuous
collection of data.
signal-to-noise ratio
Ratio of the peak magnitude of a wave to that of the noise
floor of the wave.
NOTE: Signal-to-noise ratio is generally expressed in
decibel (dB).
subsynchronous components
(Phased-locked components on a spectrum of a vibration
signal) frequency components that occur at less than one
times the shaft rotational speed.
synchronous components
(On a spectrum of a vibration signal) Frequency
components that occur at integer multiples of the shaft
rotation speed.
NOTE: Also known as ‘phased-locked components’.
thermal vector
Vibratory force brought about as a result of uneven
thermal distribution in a system.
vibration signature
Measure of all frequencies comprising the vibratory
movement of a system.
8.7 DATA (SIGNAL) PROCESSING
electrical current analysis
(ECA)
Technique which uses the line current of an electrical
machine to extract information about the health of the
electrical machine.
frequency domain
Display of frequencies present in a sample of a waveform.
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8.8 ANALYSIS
Term
Definition
cost effectiveness
Term giving the cost of equipment, cost of replacement
and/or the cost of lost production versus the cost of
accomplishing specific maintenance activities.
NOTE: The cost effectiveness in any situation is defined by
the machine owner.
critical speed map
Rectangular plot of the natural frequency of a system
(y-axis) versus the bearing or support stiffness (x-axis).
cross-channel analysis
Use of an analyser with two or more input channels to
calculate such functions as phase, coherence and transfer
function
failure modes and effects
analysis (FMEA)
structured procedure to determine equipment functions
and functional failures, with each failure being assessed
as to the cause of the failure and the effects of the failure
on the system
NOTE: The technique may be applied to a new system based
on analysis or an existing system based on historical data.
failure mode effects and
criticality analysis (FMECA)
FMEA with a classification process based on the severity
of the faults.
NOTE: This is in comparison with the criticality thresholds.
failure rate
Number of failures within a population divided by the
number of life units used by that population.
NOTE: Failure rate is always measured during an interval
under stated conditions.
fault frequency
Frequency generated by a specific fault.
frequency analysis
Machine analysis performed by examining a frequency
domain display.
NOTE: The frequencies that are present are used to
determine the forcing functions.
pareto analysis
Simple method for separating the major causes (‘vital
few’) of a problem from the minor ones (‘trivial many’)
risk assessment
Process of balancing risk with cost, schedule and other
management considerations.
NOTE: It consists of identifying risks, assessing those risks,
determining a course of action and tracking the effectiveness
of the decision.
root cause
set of conditions and/or actions that occur at the
beginning of a sequence of events that result in the
initiation of a failure mode.
root cause failure analysis
(RCFA)
After a failure, the logical systematic examination of an
item, its construction, application and documentation in
order to identify the failure mode and determine the
failure mechanism and its basic cause
NOTE: Root cause failure analysis is often used to provide a
solution to chronic problems.
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8.9 DIAGNOSTICS
Term
Definition
baseline
Descriptor or group of descriptors which provides a
criterion of the normal behaviour of a machine under
various process states.
NOTE: The baseline should be decided under steady-state
condition parameters of the machine. The machine
behaviour may change because some condition parameters,
such as temperature, are changing even if the process states
are steady.
confidence level
Estimate of the likelihood that a calculated reliability
will be achieved or bettered.
NOTES:
diagnosis
1
Reliability calculations are made on the basis of
available evidence. The degree of trust that can be
placed on the calculation is a function of the extent of
the sample size.
2
The diagnostic confidence level is a figure of merit that
indicates the degree of certainty that the diagnosis is
correct.
Result of the diagnostics process.
NOTE: This gives more detailed information about the
kind, situation and extent of a monitored fault or failure.
parameter
Measurable variable.
symptom
Perception, made by means of human observations and
measurements (descriptors), which may indicate the
presence of one or more faults with a certain probability.
8.10 PROGNOSTICS
availability
Probability that a machine will, when used under
specified conditions, operate satisfactorily and
effectively.
prognosis
Result of the prognostics process.
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SECT I O N
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9
I NF RA RE D
T H E RM O G RA PH Y
Term
Definition
apparent temperature
Uncompensated reading from an infrared thermographic
camera containing all radiation incident on the detector,
regardless of its source.
attenuating media
Windows, filters, atmospheres, external optics, materials
or other media that attenuate the infrared radiation
emitted from as source.
blackbody
Ideal perfect emitter and absorber of thermal radiation at
all wavelengths
NOTE: This is described by Planck’s law.
emissivity (ε)
Ratio of a target surface’s radiance to that of a
blackbody at the same temperature and over the same
spectral interval.
infrared thermographic
camera (IRT Camera)
Instrument that collects that infrared radiant energy from
a target surface and produces an image in monochrome
(black and white) or colour, where the grey shades or
colour hues are related to target surface apparent
temperature distribution.
NOTE: Such images are sometimes called ‘infrared
thermograms’.
image processing
Converting an image to digital form and further
enhancing the image to prepare it for computer visual
analysis.
NOTE: In the case of an infrared image or thermogram this
could include temperature scaling, spot temperature
measurements thermal profiles, image manipulations
substraction and storage.
infrared (IR)
That portion of the electromagnetic continuum extending
from the red visible wavelength, 0.75 µm to 1000 µm.
NOTE: Because of instrument design considerations and
the infrared transmission characteristics of the atmosphere,
most infrared measurements are made between 0.75 µm and
15 µm wavelengths.
isotherm
Enhancement feature applied to an image, which marks
an interval of equal apparent temperatures.
infrared thermography (IRT)
Acquisition and analysis of thermal information from
non-contact thermal imaging devices.
radiation, thermal
Mode of heat flow that occurs by emission and
absorption of electromagnetic radiation, propagating at
the speed of light.
NOTE: Unlike conductive and convective heat flow, it is
capable of propagating across a vacuum. A form of heat
transfer which allows infrared thermography to work since
infrared energy travels from the target to the detector by
radiation.
© Standards Australia
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AS 1929—2009
Term
Definition
Reflectivity (ρ)
Ratio of the total reflected energy from the surface to
total incident energy on that surface.
NOTES:
1
ρ = 1 − ε − τ, for a perfect mirror that approaches 1.0;
for a blackbody the reflectivity is 0.
2
Technically, reflectivity is the ratio of the intensity of
the reflected radiation to the total radiation, reflectance
is the ratio of the reflected flux to the incident flux. In
thermography, the two items are often used
interchangeably.
reflected apparent
temperature (T refl)
Apparent temperature of other objects that are reflected
by the target into the infrared thermographic camera.
repeatability
Capability of an instrument to repeat exactly a reading
on a fixed target over a short or long term interval.
NOTE: Repeatability is expressed in ± degrees on a
percentage of full scale.
signal processing
Manipulation of a temperature signal or image data for
the purposes of enhancing or controlling a process.
Example 1
For infrared radiation thermometers: peak
hold, sample hold and averaging.
Example 2
For scanners and imagers: isotherm
enhancement, image averaging, alignment,
image subtraction and image filtering.
spatial measurement
resolution
Measurement spot size in terms of working distance.
target
Object surface to be measured.
thermogram
Thermal map or image of a target where the grey tones
or colour hues represent the distribution of infrared
thermal radiant energy over the surface of the target.
Transmissivity
transmittance (τ)
Proportion of infrared radiant energy impinging on an
object surface, for any given spectral interval, that is
transmitted through the object.
NOTE: In an infrared radiation thermometer this is
expressed in milliradians or as a ratio of the target spot size
(containing 95% of the radiant energy, according to
common usage) to the working distance. In scanners and
imagers it is most often expressed in milliradians.
NOTES:
working distance
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1
τ=1−ε−ρ
where
τ is transmissivity;
ε is emissivity;
ρ is reflectivity
2
For a blackbody transmissivity = 0. This is fractional
quantity of incident radiation transmitted by matter.
Distance from the target to the instrument, usually to the
primary optic.
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NOTES
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