ISO 16831:2012

INTERNATIONAL ISO
STANDARD 16831
First edition
2012-04-01

Non-destructive testing — Ultrasonic
testing — Characterization and
verification of ultrasonic thickness
measuring equipment
Essais non destructifs — Contrôle par ultrasons — Caractérisation et
vérification des appareils de mesure de l'épaisseur par ultrasons




Reference number
ISO 16831:2012(E)
©
ISO 2012

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ISO 16831:2012(E)

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©  ISO 2012
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ISO 16831:2012(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 General requirements for compliance.1
5 Manufacturer's technical specification for ultrasonic thickness measuring equipment.2
5.1 General .2
5.2 General attributes.2
5.3 Display.2
5.4 Transmitter.3
5.5 Receiver.3
5.6 Other information .3
6 Calibration blocks .3
6.1 General .3
6.2 Material .3
6.3 Shape and size.4
7 Performance requirements for ultrasonic thickness measuring equipment .5
8 Probes.6
9 Group 1 tests .7
9.1 General .7
9.2 Equipment required for Group 1 tests .7
9.3 Stability against temperature .7
9.4 Low battery warning.7
9.5 Battery operational time .8
9.6 Operational voltage range .8
9.7 Operational current range .8
9.8 Operational temperature range.9
9.9 Pulse repetition frequency, PRF .9
9.10 Transmitter pulse shape, rise-time and peak voltage .9
9.11 Receiver frequency range of operation.11
9.12 Minimum and maximum measurable thicknesses.11
9.13 Accuracy and resolution.11
9.14 Range of velocity setting (calibration) .11
9.15 Calibration mechanisms.11
9.16 Calibration setting storage.12
9.17 Data storage.12
9.18 Printing .12
9.19 Display and recall .13
9.20 Display response time .13
10 Group 2 tests .13
10.1 General .13
10.2 Equipment required for Group 2 tests .13
10.3 General characteristics.14
10.4 General mechanical state and external aspects .14
11 Group 3 tests .14
11.1 General .14
11.2 General mechanical state and external aspects .14
11.3 Calibration mechanisms.14
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ISO 16831:2012(E)

11.4 Calibration setting storage .14
11.5 Data storage .15
Bibliography .16

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ISO 16831:2012(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 2.
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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16831 was prepared by Technical Committee ISO/TC 135, Non-destructive testing, Subcommittee SC 3,
Ultrasonic testing.
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ISO 16831:2012(E)
Introduction
This International Standard is based on EN 15317:2007, Non-destructive testing — Ultrasonic testing —
Characterization and verification of ultrasonic thickness measuring equipment.
The following International Standards are linked.
ISO 16810, Non-destructive testing — Ultrasonic testing — General principles
ISO 16811, Non-destructive testing — Ultrasonic testing — Sensitivity and range setting
ISO 16823, Non-destructive testing — Ultrasonic testing — Transmission technique
ISO 16826, Non-destructive testing — Ultrasonic testing — Examination for discontinuities perpendicular to
the surface
ISO 16827, Non-destructive testing — Ultrasonic testing — Characterization and sizing of discontinuities
ISO 16828, Non-destructive testing — Ultrasonic testing — Time-of-flight diffraction technique as a method for
detection and sizing of discontinuities


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INTERNATIONAL STANDARD ISO 16831:2012(E)

Non-destructive testing — Ultrasonic testing —
Characterization and verification of ultrasonic thickness
measuring equipment
1 Scope
This International Standard specifies methods and acceptance criteria for assessing the performance of
instruments formeasuring thickness using pulse-echo ultrasound.
This International Standard covers both direct (digital) reading and waveform display types using single or
dual element probes.
This International Standard can be used for verifying equipment covered by EN 12668 when used for
thickness measurement.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 5577, Non-destructive testing — Ultrasonic inspection — Vocabulary
EN 1330-4, Non destructive testing — Terminology — Part 4 : Terms used in ultrasonic testing
EN 10025-2, Hot rolled products of structural steels — Part 2 : Technical delivery conditions for non-alloy
structural steels
EN 12668-2, Non-destructive testing — Characterization and verification of ultrasonic examination
equipment — Part 2: Probes
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5577 and EN 1330-4 apply.
4 General requirements for compliance
Ultrasonic thickness measuring equipment complies with this standard if it satisfies all the following conditions:

a) ultrasonic instrument and probe comply with the technical requirements of this standard;
b) either a declaration of conformity, issued by an organization certified in accordance with ISO 9001; or
a certificate issued by an organization accredited according to ISO/IEC 17050-1 and ISO/IEC 17050-2, or
a test report issued by an organization performing in-house calibration;
c) ultrasonic instrument and probe are clearly marked to identify the manufacturer, type and series, and
carr\ a unique serial number;
d) user instruction manual for the particular type and series of the ultrasonic equipment is available;
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ISO 16831:2012(E)
e) manufacturer's technical specification for the appropriate type and series of ultrasonic equipment which
defines the performance criteria in accordance with this standard is available.
NOTE The manufacturer's technical specification does not in itself constitute the certificate of measured values
required in b).
5 Manufacturer's technical specification for ultrasonic thickness measuring
equipment
5.1 General
The manufacturer's technical specification for a particular model of ultrasonic thickness measuring equipment
shall contain, as a minimum, the information listed in 5.2 to 5.5. Values obtained from the tests described in

Clause 7 shall be quoted as nominal values with tolerances given as indicated.
5.2 General attributes
The following shall be detailed:

a) size;
b) mass (at an operational stage);
c) type(s) of power supply;
d) type(s) of probe sockets;
e) battery operational time (as new, at maximum power consumption with a specified duty cycle);
f) temperature and voltage (mains and/or battery) ranges, in which operation complies with the technical
specification – if a warm-up period is necessary, the duration of this shall be stated;
g) form of indication given when a low battery voltage takes the ultrasonic instrument performance outside of
specification;
h) pulse repetition frequencies (PRFs) (switched positions and/or variable ranges);
i) if available, monitor outputs to indicate when the measurement values fall outside a set tolerance;
j) if equipment can measure through coatings;
k) minimum measurable and maximum measurable thicknesses on a defined material;
NOTE A minimum measurable thickness of zero cannot be verified and therefore not specified.
l) accuracy and resolution shall be stated in mm for steel (longitudinal waves).
5.3 Display
The following shall be detailed:
a) type of display (alphanumeric or graphical and also whether LED, LCD or CRT);
b) dimension of alphanumeric display;
c) dimension of graphical display.
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ISO 16831:2012(E)
5.4 Transmitter
The following shall be detailed:
a) shape of transmitter pulse;
b) at each pulse energy setting with the output connected to a suitable specified probe or a defined artificial
load:
1) transmitter pulse voltage (peak-to-peak);
2) pulse rise time;
3) pulse duration (for square wave, the range over which the pulse duration can be set).
5.5 Receiver
The following shall be detailed:

a) characteristics of gain control if user selected;
b) frequency range of operation.
5.6 Other information
In addition to the information given in 5.2 to 5.5, details should be supplied on the principles of:
a) data output and storage facilities (memory capacity);
b) calibration setting storage;
c) calibration mechanisms;
d) display and recall facilities;
e) display response time;
f) number of pixels to display the waveform;
g) printer output.
Where applicable, these details should also include sampling rates used, effect of pulse repetition frequency
or display range on the sampling rate and response time.
In addition, the principles of any algorithm used to process data for display should be described.
6 Calibration blocks
6.1 General
In order to verify the ultrasonic thickness measuring equipment, it is necessary to take measurements on
defined calibration blocks. These blocks are specified in 6.2 and 6.3.

6.2 Material
Blocks shall be manufactured from steel grade S355J0 specified in EN 10025-2.
Blocks shall be rough-machined before heat treatment which shall consist of:
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ISO 16831:2012(E)
⎯ austenitizing at 920 °C for 30 min;
⎯ rapid cooling (quenching) in water;
⎯ tempering by heating to 650 °C for 3 h; and then
⎯ cooling in air.
-1
The velocity for longitudinal waves in the calibration block material shall be (5 920 ± 30) ms
.
The surfaces used for measurement shall be machined to an Ra value not greater than 0,8 μm.
Prior to final machining, the block shall be proved free from internal discontinuities.
It is permissible to chromium plate or electroless nickel plate the surfaces of the block to a maximum of 0,5 %
of the block thickness.
NOTE If chromium plating is used, care should be taken to use a thickness of plating that will avoid separation.
6.3 Shape and size
6.3.1 Accuracy blocks
These calibration blocks shall be cylinders with diameter, D, and length, L, and as shown in Table 1.
Table 1 – Size of calibration blocks
Block Diameter Length
D L
A ≥0,5L Minimum specified thickness
B ≥0,5L L + 0,25 (L – L )
A E A
C ≥0,5L L + 0,50 (L – L )
A E A
D ≥0,5L L + 0,75 (L – L )
A E A
E ≥0,5L Maximum specified thickness

where

L is the height of block A; and
A
L is the height of block E.
E
NOTE If L < 0,1 L the subtraction of L may be omitted.
A E A
D shall not be <3 times the probe face diagonal dimension.
The values 0,25, 0,5 and 0,75 may be varied by up to 10 % of the value in question.
-4
The overall height of the block shall be ≤3 (10 L) across the measurement faces.
-4
The fixed dimension for L shall be measured at the centre of the block to an accuracy of 10 L.
The blocks shall be permanently, circumferentially marked with the actual length L, e.g. L = 50,333 mm, and a
unique identity (serial number).
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ISO 16831:2012(E)
6.3.2 Resolution block (see Figure 1)

Key
w step width
r step height
L length of block C (see Table 1)
Figure 1 – Resolution block
Where w shall be ≥3 times the diagonal dimension of the probe face and r shall be less than or equal to the
specified resolution.
The block shall provide a minimum of five steps.
7 Performance requirements for ultrasonic thickness measuring equipment
To comply with this standard, ultrasonic thickness measuring equipment shall
...