ISO 12710:2002
(Main)Non-destructive testing — Ultrasonic inspection — Evaluating electronic characteristics of ultrasonic test instruments
Non-destructive testing — Ultrasonic inspection — Evaluating electronic characteristics of ultrasonic test instruments
ISO 12710 describes a set of procedures for the measurement of any performances in an ultrasonic test instrument that has a display screen. This International Standard establishes the procedures for measuring performance characteristics of components of pulse-echo ultrasonic non-destructive testing instruments including both analog and digital type instruments with screen displays. The aim is to establish uniformity of evaluation techniques, to form a basis for data correlation and for interpretation of results obtained from different laboratories and at different times. Note that ISO 12710 establishes no acceptance criteria; such criteria should be specified by user parties. The usual components of ultrasonic non-destructive testing instruments and the performance characteristics for which procedures for measuring these characteristics are described including: line regulation; battery discharge time; battery charge time; pulse shape; pulse amplitude; pulse rise time; pulse length; pulse frequency spectrum; vertical linearity; frequency response; noise and sensitivity; dB controls; horizontal linearity; clock (pulse repetition rate); delay and width; resolution; alarm level; gain uniformity; analog output; back-echo gate linearity.
Essais non destructifs — Contrôle aux ultrasons — Évaluation des caractéristiques électroniques des instruments d'essai aux ultrasons
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 12710
First edition
2002-09-15
Non-destructive testing — Ultrasonic
inspection — Evaluating electronic
characteristics of ultrasonic test
instruments
Essais non destructifs — Contrôle aux ultrasons — Évaluation des
caractéristiques électroniques des instruments d'essai aux ultrasons
Reference number
ISO 12710:2002(E)
©
ISO 2002
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ISO 12710:2002(E)
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ISO 12710:2002(E)
Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative reference. 2
3 Terms, definitions and symbols . 2
4 Abbreviations . 2
5 Summary of procedure. 3
6 Apparatus. 3
7 Power-supply section measurements. 5
8 Pulser section measurements . 8
9 Receiver section measurements . 12
10 Time base section measurements. 16
11 Gate/alarm section measurements. 18
12 Reporting format . 19
Bibliography. 22
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ISO 12710:2002(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
The main task of technical committees is to prepare International Standards. Draft International Standards adopted
by the technical committees are circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 12710 was prepared by Technical Committee ISO/TC 135, Non-destructive testing, Subcommittee SC 3,
Acoustical methods.
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ISO 12710:2002(E)
Introduction
In ultrasonic non-destructive testing, pulse/echo signals are used to detect and evaluate imperfections or flaws
inside a structural material. The pulse/echo ultrasonic signals are generated by various types of electronic
instruments.
This International Standard describes a set of procedures for the measurement of performance characteristics in
an ultrasonic test instrument that has a display screen. The procedures are used for ultrasonic test instruments
operating in a nominal frequency range from 100 kHz to 25 MHz, although the procedures are also applicable to
measurements on instruments utilizing higher-frequency components. The recommended techniques are designed
to use commercially-available instrumentation. An ultrasonic test instrument that cannot be completely described as
a combination of the electronic sections discussed in this practice can be partially evaluated. Each portion of the
ultrasonic test instrument that is evaluated should fit the description for the corresponding section.
Implementation of these practices may require more detailed procedural instruction. Competence in the use of the
electronic instrumentation specified is a prerequisite for effective use of these procedures. Careful selection of the
specific measurements to be made is recommended. If the related parameter is not relevant to the intended
application, its measurement may be unnecessary; e.g., vertical linearity may be irrelevant for an application using
a single-level flaw alarm, while horizontal linearity might be required only for accurate flaw-depth or thickness
measurement from the instrument display.
No minimum interval between instrument evaluations is recommended or implied. The accuracy of each
measurement is dependent upon the combined accuracy of each of the electronic measuring instruments (which
should be described in the specifications and calibrations for these instruments) and the precision associated with
reading the values of each part of the system. It is assumed that the precision of measuring the vertical and
horizontal values from the screen of the ultrasonic test instrument is ± 1 mm.
Specifically, this International Standard intends to provide techniques and procedures to achieve the following
objectives:
a) To measure performance characteristics of components of ultrasonic test instruments.
b) To check and ensure consistent performance of such components during the life span of the instrument.
c) To select and specify characteristics necessary for proper overall performance of the instrument.
d) To achieve interchangeability with similar components or similar overall instruments for same type inspections.
e) To provide a base for the correlation and comparison of performance results from different instruments and
testing sources.
NOTE These procedures are not intended to preclude the use or application of ultrasonic test equipment for which some or
all of the measurement techniques of this document are not applicable. Additionally, it is not intended, nor is it applicable, as a
specification defining the performance of ultrasonic test systems. If such performance criteria are required, they must be agreed
upon by the using parties.
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INTERNATIONAL STANDARD ISO 12710:2002(E)
Non-destructive testing — Ultrasonic inspection — Evaluating
electronic characteristics of ultrasonic test instruments
1 Scope
1.1 This International Standard establishes the procedures for measuring performance characteristics of
components of pulse-echo ultrasonic non-destructive testing instruments including both analog and digital type
instruments with screen displays. The aim is to establish uniformity of evaluation techniques, to form a basis for
data correlation and for interpretation of results obtained from different laboratories and at different times. Note that
this International Standard establishes no acceptance criteria; such criteria should be specified by user parties.
The usual components of ultrasonic non-destructive testing instruments and the performance characteristics for
which procedures for measuring these characteristics are included and listed in 1.2 to 1.6.
1.2 Power supply section:
line regulation
battery discharge time
battery charge time
1.3 Pulser section:
pulse shape
pulse amplitude
pulse rise time
pulse length
pulse frequency spectrum
1.4 Receiver section:
vertical linearity
frequency response
noise and sensitivity
dB controls
1.5 Time base section:
horizontal linearity
clock (pulse repetition rate)
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ISO 12710:2002(E)
1.6 Gate section/alarm section:
delay and width
resolution
alarm level
gain uniformity
analog output
back-echo gate linearity
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent edition of the normative document indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
IEC 60050-111, International Electrotechnical Vocabulary — Chapter 111: Physics and chemistry
3 Terms, definitions and symbols
For the purposes of this International Standard the terms, definitions and symbols listed in IEC 60050-111 as well
as the following apply.
T the measured rise time
m
T the actual rise time of the instrumentation
r
T the oscilloscope rise time
s
4 Abbreviations
ASTM American Society for Testing and Materials
DAC/EDAC distance amplitude correction/electronic distance-amplitude compensation
EN European Norme (European Standard)
IEC International Electrotechnical Commission
ISO International Organization for Standardization
JIS Japanese Industrial Standard
PRF pulse repetition frequency
RF radio frequency
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ISO 12710:2002(E)
5 Summary of procedure
5.1 Performance measurements
The electronic performance of each section is measured by identifying that portion of the electrical circuit of the
instrument which comprises the section, applying the recommended stimulus or load or both, and performing the
required measurements using commercially available electronic test equipment. These data are then summarized
in tabular or graphical form as performance-related values which can be compared with corresponding values of
other ultrasonic test instruments or of values for the same instrument obtained earlier (see clause 12 for a
suggested reporting format).
5.2 Ultrasonic test Instruments and Interactions
5.2.1 Power supply section
The power supply section is that portion of the total instrument circuitry which supplies the regulated DC voltages
required to power all other sections of the ultrasonic test instrument, including the high voltage (i.e pulser) circuitry.
5.2.2 Pulser section
The pulser section is that portion of the total instrument circuitry that generates the electrical pulse used to energize
the search unit. The pulser section may also include the pulse-shape modification controls such as pulse length,
damping or tuning controls.
5.2.3 Receiver section
The receiver section is that portion of the total instrument circuitry that amplifies, or modifies or both, the radio
frequency (RF) pulses received from the search unit. This includes the RF amplifiers, detectors, video amplifiers,
suppression and filtering circuits, and the cathode ray tube vertical deflection circuits. Some instruments may not
contain all of these circuits.
NOTE For EDAC operation, reject or threshold, although part of the receiver section, should be turned off while making
measurements unless otherwise specified by the user.
5.2.4 Time base section
The time base section provides the linear horizontal sweep or baseline. It includes the horizontal deflection circuit
and the clock and delay circuits which control PRF and positioning of signals on the baseline.
5.2.5 Gate/alarm section
This section monitors the signals in the receiver section to detect the presence or absence of significant
indications. The gate may include attenuator or gain controls. This section is considered separate from the receiver
section for the purposes of this International Standard. The alarm signal may be audible, or a mark on voltage or
current sensitive paper or some combination of these. It also may be a voltage proportional to the amplitude.
6 Apparatus
6.1 Ultrasonic test Instrument, being any electronic instrument comprised of a power supply, pulser, clock,
receiver and a sweep display section to generate, receive and display electrical signals related to ultrasonic waves
for examination purposes.
NOTE Some ultrasonic test instruments do not include a screen display. Some sections of this International Standard may
not apply to these instruments, or may be applicable only with modifications. Such modifications should be made only by
personnel competent in electronics.
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ISO 12710:2002(E)
6.2 Voltmeter, being any instrument capable of measuring the AC line voltage and DC battery voltage required
as described in 7.1 or 7.2.
6.3 Variable transformer, such as an autotransformer or other device capable of supplying variable AC power
to the ultrasonic test instrument over the full range specified by the manufacturer.
6.4 Pulser load, consisting of a 50 ohm non-inductive resistor, preferably mounted in a shielded coaxial
assembly, unless otherwise requested by the using parties. The resistor shall be able to withstand the maximum
peak pulser voltage. It is recommended that the complex impedance of the resistor be checked at frequencies from
100 kHz to 25 MHz in order to ensure that the magnitude is 50 ohms ± 2 ohms, and that the phase angle is less
than ± 5°.
NOTE Other impedances may be used if specified.
6.5 Spectrum analyser, of any type (with probe assembly if required) that is capable of analysing the electrical
pulse from the pulser module and displaying the frequency components of the pulse as described in 8.3. A
recording of the display (photograph or chart recorder) shall be included in the report.
6.6 Oscilloscope probe, being a 100 × or 50 × wide band high input impedance (W 10 kΩ) attenuating probe to
reduce the pulse amplitude, as delivered to the oscilloscope and the spectrum analyser, to a level that i) will not
harm the equipment and ii) will allow for frequency and time analysis without significantly altering the pulse shape.
The probe output impedance shall match the input impedance of the measurement instrument. (If the impedance is
high, a terminating resistance may be required at the input to match the output impedance of the probe.) The
frequency bandwidth shall be at least as wide as that of the instruments to be measured. The probe shall be able to
withstand the pulser output voltage.
NOTE More than one probe may be needed to match the various test instruments used.
6.7 Function generator, capable of producing an internally or externally triggered single-cycle sine wave or five
cycles of a sine wave, the frequency of which is variable over the range of the frequency capabilities of the
ultrasonic test instrument to be measured. The frequency read-out shall be accurate to 1 %. Square or rectangular
waves in single or burst mode shall be provided. The generator shall be capable of being triggered from a signal
derived from the instrument clock to provide wave trains coherent with the display. An adjustable delay of at least
10 µs is required.
NOTE A free running (i.e. non-triggered) single-cycle sine wave may not be used for receiver evaluation.
6.8 Electronic gate, with a variable delay and width and triggerable from either the ultrasonic test instrument
pulser section output pulse or the clock section logic signal. The gate step output (i.e. the output that represents the
location of the gate) shall be sufficient to trigger the function generator.
NOTE Some function generators incorporate the gate delay and width functions, in which case an electronic gate will not
be needed.
6.9 Calibrated oscilloscope, capable of displaying all portions of the pulser output with sufficient time base
expansion, triggering capability and frequency response to enable measurement of the pulse rise time, amplitude
and length, as well as fulfilling the requirements of other measurements.
6.10 Calibrated attenuator, capable of providing a measuring range of 60 dB in 1 dB steps with an accuracy of
± 0,5 dB and having a frequency bandwidth at least as great as the highest frequency of interest. Most attenuators
have a nominal input and output impedance of 50 ohms, but other impedances may be specified. Proper
termination rules shall be observed. An impedance matching probe shall be used to protect the attenuator if it is to
be used to reduce pulse output.
6.11 Terminators, used to match the impedances of instruments and cables used (see 6.4); they shall be of a
non-inductive, feed-through style.
6.12 Cables, coaxial, with maximum length of 2 m and a 50 ohm characteristic impedance. Other lengths and
impedances may be used if authorized, but lengths shall be kept as short as possible in order to minimize the
effects of cable capacitance on measurements.
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ISO 12710:2002(E)
6.13 Search unit, of the desired type, size and frequency required for the procedures selected for 6.15, 7.1.1,
7.2.1, 7.2.1.2, 10.2 or 10.3.
6.14 Immersion tank, (optional) consisting of an ultrasonic immersion system that will enable continuous
variations of the distance between the search unit and a reflector over a water path range that will provide a time
range comparable to the end use of the ultrasonic test instrument. A distance (position) scale of precision needed
for the procedure described in 10.2 shall be incorporated.
6.15 Reference block, of any suitable material, containing certain features, such as flat-bottom holes, side-drilled
holes, wedges, flat steps of different thickness or hemi-steps, which can be used to provide ultrasonic echo signals.
6.16 Camera or recorder, such as a screen camera or display recorder, suitable for measuring pulse
characteristics, and useful in making other measurements.
7 Power-supply section measurements
7.1 AC-powered instrument line regulation
7.1.1 Connect the variable transformer (6.3), the voltmeter (6.2) and a search unit (6.13) that matches the
nominal frequency of the instrument, to the ultrasonic test instrument (6.1) as shown in Figure 1. Although Figure 1
shows an immersion set-up, the evaluation may be performed by either the contact or the immersion method. The
primary requirement is that the signal from the reference reflector does not vary due to coupling or position
variations during the evaluation. Contact tests may require clamping of the search unit to the reference block. A
block with permanently bonded search unit(s) is quite helpful.
7.1.2 Adjust the variable transformer for 100 % nominal line voltage and obtain a 50 % full-scale indication from
the reference block (6.15). Decrease the variable transformer output voltage until the reference reflector indication
changes its amplitude, width or horizontal position by 10 %.
NOTE Damage may result from going, in either direction, beyond the manufacturer's line voltage specification.
7.1.3 The ultrasonic test instrument display may turn off before any significant signal change is noted.
7.1.4 Increase the variable transformer output voltage(s) at which the 10 % change or turn-off occurs. The upper
limit will usually be the manufacturer's specification. These are the input voltage limits.
7.2 Battery-powered instruments
7.2.1 Discharge time
7.2.1.1 With the battery in the fully-charged condition, connect a search unit (6.13) to the instrument and
obtain a 50 % full-scale indication from a suitable reference block (6.15). This evaluation may be performed by
either the contact or the immersion method. The primary requirement is that the signal from the reference reflector
does not vary due to coupling or position changes during the battery discharge time period.
7.2.1.2 Instrument controls that affect power drain, such as PRF, display brightness, sweep range, etc., shall
be set to the maximum levels corresponding to good examination practices in order to provide the maximum
practical power supply loading condition.
7.2.1.3 At time intervals u 15 min, record the amplitude of the signal from the reference block and plot these
values versus time as shown in Figure 2 until the signal amplitude, horizontal sweep length or position changes
10 % or until the instrument display turns off. The discharge time is the time required for a change of the stated
amount or until the display turns off, whichever occurs first. Record this value.
7.2.1.4 The data recording may be minimized by making an initial reading and then beginning the periodic
measurements at a later time near the anticipated discharge time.
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ISO 12710:2002(E)
Key
1 Line voltage
2 Variable transformer
3 Voltmeter
4 Ultrasonic test instrument
5 Search unit
6 Reference block
Figure 1 — Set-up for voltage regulation measurements
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ISO 12710:2002(E)
Figure 2 — Typical battery discharge characteristics
7.2.1.5 With the battery discharged in accordance with 7.2.1.3, disconnect the battery from the ultrasonic test
instrument (6.1) and connect to a DC voltmeter (6.2). Measure and record the remaining voltage of the battery.
7.2.2 Charge time
7.2.2.1 With the instrument battery discharged in accordance with 7.2.1, turn the instrument power switch to
the OFF or CHARGE position, connect the battery charger to the battery and begin charging the battery.
7.2.2.2 At time intervals u 5 min, disconnect the charger, connect the DC voltmeter (6.2) to the battery
terminals and record the battery voltage versus time as shown in Figure 3. The battery charge curve shown in
Figure 3 is typical for Ni-Cd and sealed lead batteries used in most ultrasonic test instruments. The fully-charged
condition corresponds to the maximum voltage value shown in Figure 3. Record these values in minutes.
7.2.2.3 The data recording may be minimized by making an initial reading and then beginning the periodic
measurements at a later time near the anticipated charge time. Enough data should be acquired to reliably indicate
the shape of the curve (see Figure 3) in the region of full charge.
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ISO 12710:2002(E)
Figure 3 — Typical Ni-Cd and lead acid battery charge characteristics
8 Pulser section measurements
8.1 General
Broadband pulsers generally produce negative spikes, such as is shown in Figure 4 a). If highly-damped (pulse
length minimum), the exponential tail will be quite short. Another type of broadband pulse used in some
instruments is a rectangular pulse (sometimes square), shown in Figure 4 b).
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ISO 12710:2002(E)
a) Spike (broad band)
b) Square (broad band)
Figure 4 — Pulse shapes (slopes exaggerated)
8.2 Method
With the instrument turned on and no load connected to the pulser section output, connect the oscilloscope (6.9) to
the pulser section using a 100 × or 50 × probe if needed. Adjust the oscilloscope gain and triggering controls to
obtain a display of a pulser-module output pulse. Figure 5 shows the set-up. The Early Sync Trigger should be
used, but if it is not available, an oscilloscope with built-in vertical signal delay will be needed to observe the
leading edge of the pulse.
NOTE 1 Pulses involve very high frequency components. It is important to keep earth connections of probes short and close
to the point of contact.
NOTE 2 In some commercial instruments, the PRF is under microprocessor control and not accessible to the operator. In
such instruments the PRF does not necessarily follow the clock schedule and the oscilloscope display may appear unstable.
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ISO 12710:2002(E)
Key
1 Pulser section
2 Wide band oscilloscope
3 High impedance probe (50 ohm output)
4 50 ohm attenuator (optional)
5 Non-inductive 50 ohm load (omitted in some tests)
6 Spectrum analyser
a
Early Sync
NOTE 1 Signal leads should be kept as short as possible.
NOTE 2 Probe needs an output of 50 ohm in order to match input attenuator or spectrum analyser or both.
Figure 5 — Instrumentation for pulse measurements
8.3 Pulse rise time, length and amplitude
8.3.1 Set-up
Start with the set-up of Figure 5 with the 50 ohm load connected. Obtain a display on the oscilloscope screen that
clearly shows the leading edge of the pulse.
8.3.2 Pulse rise time
8.3.2.1 The rise time of the broadband pulse is the time interval T (in nanoseconds), between the 10 % and
r
90 % points (relative to peak amplitude) on the leading edge of the pulse (see Figure 4), whether the deflection is
positive or negative.
NOTE The measured rise time includes the inherent rise times of the oscilloscope and probe if used. The actual rise time
of the instrumentation is given by:
22 2
TT=−T
rm s
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ISO 12710:2002(E)
where
T is the measured rise time in nanoseconds;
m
T is the oscilloscope rise time in nanoseconds.
s
If only the bandwidth of the oscilloscope and probe are known, a close approximation to T can be calculated from:
s
T = 350 /BW
s
where BW is the bandwidth in MHz.
8.3.2.2 Measure and record the pulse rise time minimum at minimum pulse length and pulse rise time
maximum at maximum pulse length.
8.3.2.3 Remove the 50 ohm load and repeat 8.3.2.2.
8.3.3 Pulse length
8.3.3.1 The pulse length of a tuned pulse is measured from 10 % of the peak amplitude of the first peak
amplitude of the first large half cycle to the end of the last cycle that exceeds the 10 % level. This is illustrated in
Figure 4 a).
8.3.3.2 The pulse length of the untuned pulse is the time between 10 % of peak on the leading edge and 10 %
of peak on the trailing edges illustrated in Figures 4 a) and 4 b).
8.3.3.3 With the 50 ohm load in place for either pulse, measure and record pulse length minimum and pulse
length maximum.
8.3.3.4 Remove the 50 ohm load and repeat 8.3.3.3.
8.3.4 Pulse amplitude
8.3.4.1 The pulse amplitude of a broad band pulse is the peak amplitude as shown in Figures 4 a) and 4 b).
8.3.4.2 With the 50 ohm load connected (see Figure 5), measure and record the pulse amplitude minimum for
minimum pulse length and pulse amplitude maximum for maximum pulse length.
8.3.4.3 Remove the 50 ohm load and repeat 8.3.4.2.
8.4 Pulse frequency spectrum
8.4.1 Use the set-up of Figure 5. Start with sufficient attenuation to assure that the spectrum analyser input
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