SIST EN ISO 16828:2014

Non-destructive testing - Ultrasonic testing - Time-of-flight diffraction technique as a method for detection and sizing of discontinuities (ISO 16828:2012)

EN ISO 16828 defines the general principles for the application of the time-of-flight diffraction (TOFD) technique for both detection and sizing of discontinuities in low alloyed carbon steel components. It can also be used for other types of materials, provided the application of the TOFD technique is performed with necessary consideration of geometry, acoustical properties of the materials, and the sensitivity of the examination. Although it is applicable, in general terms, to discontinuities in materials and applications covered by ISO 16810, it contains references to the application on welds. This approach has been chosen for reasons of clarity as to the ultrasonic probe positions and directions of scanning. Unless otherwise specified in the referencing documents, the minimum requirements of this International Standard are applicable. Unless explicitly stated otherwise, this International Standard is applicable to the following product classes as defined in ISO 16811: - class 1, without restrictions; - classes 2 and 3, specified restrictions apply.

Zerstörungsfreie Prüfung - Ultraschallprüfung - Beugungslaufzeittechnik, eine Technik zum Auffinden und Ausmessen von Inhomogenitäten (ISO 16828:2012)

Diese Internationale Norm legt die allgemeinen Grundsätze für die Anwendung der Beugungslaufzeittechnik (TOFD) für das Auffinden und die Größenbestimmung von Inhomogenitäten in Bauteilen aus niedrig legierten Kohlenstoffstählen fest. Das TOFD-Verfahren kann auch auf andere Werkstoffarten angewendet werden, wenn es mit der notwendigen Berücksichtigung von Geometrie, akustischen Eigenschaften der Werkstoffe sowie Nachweisempfindlichkeit der Prüfung angewendet wird.
Obwohl es im Allgemeinen bei Inhomogenitäten in Werkstoffen anwendbar ist, die in ISO 16810 behandelt werden, sind Hinweise für die Prüfung von Schweißnähten enthalten. Dieser Weg wurde zur Verdeutlichung der Ausrichtungen des Ultraschallkopfes und der Prüfrichtungen gewählt.
Soweit in Bezugsdokumenten nichts anderes festgelegt worden ist, sind die Mindestanforderungen dieser Norm anwendbar.
Wenn es nicht ausdrücklich anders angegeben wird, ist diese Norm auf folgende in ISO 16811 festgelegte Produktklassen anwendbar:
 Klasse 1, ohne Einschränkungen;
 Klassen 2 und 3, mit den angegebenen Einschränkungen.
ANMERKUNG 1 Siehe Abschnitt 9.
Die Prüfung von Produkten der Klassen 4 und 5 erfordert Spezialverfahren, auf die auch hingewiesen wird.
ANMERKUNG 2 Siehe Abschnitt 9.
ANMERKUNG 3 Die Verfahren mit TOFD zur Inspektion von Schweißnähten sind in ISO 10863 beschrieben.
ANMERKUNG 4 Die entsprechenden Zulässigkeitskriterien sind in ISO 15626 behandelt.

Essais non destructifs - Contrôle par ultrasons - Technique de diffraction du temps de vol utilisée comme méthode de détection et de dimensionnement des discontinuités (ISO 16828:2012)

L'ISO 16828:2012 définit les principes généraux pour l'application de la technique de diffraction du temps de vol (TOFD) pour la détection et le dimensionnement des discontinuités dans les composants en acier au carbone faiblement allié. Elle peut également être employée pour d'autres types de matériaux, à condition que l'application de la technique TOFD tienne compte de la géométrie, des propriétés acoustiques des matériaux et de la sensibilité de l'examen.
Bien qu'elle soit applicable, en termes génériques, aux discontinuités des matériaux et applications couvertes par l'ISO 16810, elle contient des références aux applications sur les soudures. Cette approche a été choisie pour des raisons de clarté en termes de position des traducteurs ultrasonores et de direction de balayage.
Sauf indications contraires dans les documents de référence, les exigences minimales de l'ISO 16828:2012 sont applicables.
Sauf dispositions contraires explicites, l'ISO 16828:2012 s'applique aux classes de produits suivantes, telles que définies dans l'ISO 16811: classe 1: sans restriction; classes 2 et 3: les restrictions spécifiées s'appliquent comme établi dans l'Article 9.
L'examen des produits de classes 4 et 5 requiert des modes opératoires particuliers, qui sont également traités dans l'Article 9.
Les techniques d'utilisation de la méthode TOFD pour l'examen des soudures sont décrites dans l'ISO 10863.
Les critères d'acceptation associés sont donnés dans l'ISO 15626.

Neporušitvene preiskave - Ultrazvočne preiskave - Metoda zvočne poti za odkrivanje in ocenjevanje velikosti nezveznosti (ISO 16828:2012)

Standard EN ISO 16828 opredeljuje osnovna načela za uporabo metode zvočne poti (TOFD) za odkrivanje in ocenjevanje velikosti nezveznosti v malolegiranih komponentah iz ogljikovega jekla. Uporablja se lahko tudi za druge vrste materialov, če se metodo TOFD izvede ob upoštevanju geometrije in akustičnih lastnosti materialov ter občutljivosti preizkusa. Čeprav se standard v splošnem uporablja za nezveznosti v materialih in uporabo, ki jo zajema standard ISO 16810, se v delih nanaša tudi na zvare. Ta metoda je bila izbrana zaradi nedvoumnosti glede postavitve ultrazvočne sonde in smeri skeniranja. Minimalne zahteve tega mednarodnega standarda so veljavne, razen če je v referenčnih dokumentih drugače določeno. Ta mednarodni standard velja za naslednje razrede izdelkov, ki so opredeljeni v standardu ISO 16811, razen če ni izrecno drugače določeno: - razred 1 brez omejitev; - določene omejitve veljajo za razreda 2 in 3.

General Information

• Status: Published
• Public Enquiry End Date: 29-Nov-2013
• Publication Date: 30-Jun-2014
• ICS: 19.100 - Non-destructive testing
• Technical Committee: PKG - Testing of metallic materials
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 29-May-2014
• Due Date: 03-Aug-2014
• Completion Date: 01-Jul-2014
• Ref Project: EN ISO 16828:2014 - Non-destructive testing - Ultrasonic testing - Time-of-flight diffraction technique as a method for detection and sizing of discontinuities (ISO 16828:2012)

Relations

• Replaces: SIST EN 583-6:2009 - Non-destructive testing - Ultrasonic examination - Part 6: Time-of-flight diffraction technique as a method for detection and sizing of discontinuities
• Effective Date: 01-Jul-2014

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 16828:2014
01-julij-2014
1DGRPHãþD
SIST EN 583-6:2009
1HSRUXãLWYHQHSUHLVNDYH8OWUD]YRþQHSUHLVNDYH0HWRGD]YRþQHSRWL]D
RGNULYDQMHLQRFHQMHYDQMHYHOLNRVWLQH]YH]QRVWL,62
Non-destructive testing - Ultrasonic testing - Time-of-flight diffraction technique as a
method for detection and sizing of discontinuities (ISO 16828:2012)
Zerstörungsfreie Prüfung - Ultraschallprüfung - Beugungslaufzeittechnik, eine Technik
zum Auffinden und Ausmessen von Inhomogenitäten (ISO 16828:2012)
Essais non destructifs - Contrôle par ultrasons - Technique de diffraction du temps de vol
utilisée comme méthode de détection et de dimensionnement des discontinuités (ISO
16828:2012)
Ta slovenski standard je istoveten z: EN ISO 16828:2014
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
SIST EN ISO 16828:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 16828:2014

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SIST EN ISO 16828:2014

EUROPEAN STANDARD
EN ISO 16828

NORME EUROPÉENNE

EUROPÄISCHE NORM
March 2014
ICS 19.100 Supersedes EN 583-6:2008
English Version
Non-destructive testing - Ultrasonic testing - Time-of-flight
diffraction technique as a method for detection and sizing of
discontinuities (ISO 16828:2012)
Essais non destructifs - Contrôle par ultrasons - Technique Zerstörungsfreie Prüfung - Ultraschallprüfung -
de diffraction du temps de vol utilisée comme méthode de Beugungslaufzeittechnik, eine Technik zum Auffinden und
détection et de dimensionnement des discontinuités (ISO Ausmessen von Inhomogenitäten (ISO 16828:2012)
16828:2012)
This European Standard was approved by CEN on 9 February 2014.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16828:2014 E
worldwide for CEN national Members.

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SIST EN ISO 16828:2014
EN ISO 16828:2014 (E)
Contents Page
Foreword .3
2

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SIST EN ISO 16828:2014
EN ISO 16828:2014 (E)
Foreword
The text of ISO 16828:2012 has been prepared by Technical Committee ISO/TC 135 “Non-destructive testing”
of the International Organization for Standardization (ISO) and has been taken over as EN ISO 16828:2014 by
Technical Committee CEN/TC 138 “Non-destructive testing” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by September 2014, and conflicting national standards shall be
withdrawn at the latest by September 2014.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 583-6:2008.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 16828:2012 has been approved by CEN as EN ISO 16828:2014 without any modification.


3

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SIST EN ISO 16828:2014

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SIST EN ISO 16828:2014

INTERNATIONAL ISO
STANDARD 16828
First edition
2012-04-01

Non-destructive testing — Ultrasonic
testing — Time-of-flight diffraction
technique as a method for detection and
sizing of discontinuities
Essais non destructifs — Contrôle par ultrasons — Technique de
diffraction du temps de vol utilisée comme méthode de détection et de
dimensionnement des discontinuités




Reference number
ISO 16828:2012(E)
©
ISO 2012

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SIST EN ISO 16828:2014
ISO 16828:2012(E)

COPYRIGHT PROTECTED DOCUMENT


©  ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland

ii © ISO 2012 – All rights reserved

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SIST EN ISO 16828:2014
ISO 16828:2012(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope.1
2 Normative references.1
3 Terms, definitions, symbols and abbreviations.2
3.1 Terms and definitions .2
3.2 Abbreviations.2
3.3 Symbols.2
4 General.3
4.1 Principle of the technique.3
4.2 Requirements for surface condition and couplant .5
4.3 Materials and process type .5
5 Qualification of personnel .5
6 Equipment requirements.5
6.1 Ultrasonic equipment and display.5
6.2 Ultrasonic probes.6
6.3 Scanning mechanisms.7
7 Equipment set-up procedures .7
7.1 General.7
7.2 Probe choice and probe separation .8
7.2.1 Probe selection.8
7.2.2 Probe separation.9
7.3 Time window setting.9
7.4 Sensitivity setting.9
7.5 Scan resolution setting.10
7.6 Setting of scanning speed.10
7.7 Checking system performance.10
8 Interpretation and analysis of data.10
8.1 Basic analysis of discontinuities.10
8.1.1 General.10
8.1.2 Characterisation of discontinuities .10
8.1.3 Estimation of discontinuity position .11
8.1.4 Estimation of discontinuity length .11
8.1.5 Estimation of discontinuity depth and height .12
8.2 Detailed analysis of discontinuities .12
8.2.1 General.12
8.2.2 Additional scans.13
8.2.3 Additional algorithms.14
9 Detection and sizing in complex geometries .14
10 Limitations of the technique.14
10.1 General.14
10.2 Accuracy and resolution.15
10.2.1 General.15
10.2.2 Errors in the lateral position .15
10.2.3 Timing errors.15
10.2.4 Errors in sound velocity .15
10.2.5 Errors in probe centre separation .15
10.2.6 Spatial resolution.16
10.3 Dead zones.16
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SIST EN ISO 16828:2014
ISO 16828:2012(E)

11 TOFD examination without data recording .16
12 Test procedure.17
13 Test report.17
Annex A (normative) Reference blocks .18
Bibliography .19

iv © ISO 2012 – All rights reserved

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SIST EN ISO 16828:2014
ISO 16828:2012(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 16828 was prepared by Technical Committee ISO/TC 135, Non-destructive testing, Subcommittee SC 3,
Ultrasonic testing.
© ISO 2012 – All rights reserved v

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SIST EN ISO 16828:2014
ISO 16828:2012(E)
Introduction
This International Standard is based on EN 583-6:2008, Non-destructive testing — Ultrasonic examination —
Part 6: Time-of-flight diffraction technique as a method for detection and sizing of discontinuities.
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


vi © ISO 2012 – All rights reserved

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SIST EN ISO 16828:2014
INTERNATIONAL STANDARD ISO 16828:2012(E)

Non-destructive testing — Ultrasonic testing — Time-of-flight
diffraction technique as a method for detection and sizing of
discontinuities
1 Scope
This International Standard defines the general principles for the application of the time-of-flight diffraction
(TOFD) technique for both detection and sizing of discontinuities in low alloyed carbon steel components. It
can also be used for other types of materials, provided the application of the TOFD technique is performed
with necessary consideration of geometry, acoustical properties of the materials, and the sensitivity of the
examination.
Although it is applicable, in general terms, to discontinuities in materials and applications covered by
ISO 16810, it contains references to the application on welds. This approach has been chosen for reasons of
clarity as to the ultrasonic probe positions and directions of scanning.
Unless otherwise specified in the referencing documents, the minimum requirements of this International
Standard are applicable.
Unless explicitly stated otherwise, this International Standard is applicable to the following product classes as
defined in ISO 16811:
 class 1, without restrictions;
 classes 2 and 3, specified restrictions apply.
NOTE 1 See Clause 9.
The inspection of products of classes 4 and 5 requires special procedures, which are also addressed.
NOTE 2 See Clause 9.
NOTE 3 Techniques for the use of TOFD for weld inspection are described in ISO 10863.
NOTE 4 The related acceptance criteria are given in ISO 15626.

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 9712, Non-destructive testing — Qualification and certification of NDT personnel — General principles
ISO 16810, Non-destructive testing — Ultrasonic WHVWLQJ — General principles
ISO 16811, Non-destructive testing — Ultrasonic WHVWLQJ — Sensitivity and range setting
EN 12668-1, Non-destructive testing — Characterization and verification of ultrasonic examination
equipment — Part 1: Instruments
EN 12668-2, Non-destructive testing — Characterization and verification of ultrasonic examination
equipment — Part 2: Probes
© ISO 2012 – All rights reserved 1

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SIST EN ISO 16828:2014
ISO 16828:2012(E)
EN 12668-3, Non-destructive testing — Characterization and verification of ultrasonic examination
equipment — Part 3: Combined equipment
3 Terms, definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
scanning surface dead zone
zone where indications may be obscured due to the interface echo (lateral wave)
3.1.2
back wall dead zone
dead zone where signals may be obscured by the presence of the back wall echo
3.1.3
A-scan
display of the ultrasonic signal amplitude as a function of time
3.1.4
B-scan
display of the time-of-flight of the ultrasonic signal as a function of probe displacement
3.1.5
non-parallel scan
scan perpendicular to the ultrasonic beam direction (see Figure 4)
3.1.6
parallel scan
scan parallel to the ultrasonic beam direction (see Figure 5)
3.2 Abbreviations
⎯ TOFD: time-of-flight diffraction
3.3 Symbols

Figure 1 — Coordinate definition
2 © ISO 2012 – All rights reserved

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SIST EN ISO 16828:2014
ISO 16828:2012(E)
x coordinate parallel to the scanning surface and parallel to a predetermined reference line. In
case of weld inspection this reference line should coincide with the weld. The origin of the
axes may be defined as best suits the specimen under examination (see Figure 1);
Δx discontinuity length;
y coordinate parallel to the scanning surface, perpendicular to the predetermined reference
line (see Figure 1);
error in lateral position;
δy
z coordinate perpendicular to the scanning surface (see Figure 1);
Δz discontinuity height;
d depth of a discontinuity tip below the scanning surface;
δd error in depth;
D scanning-surface dead zone;
ds
D back wall dead zone;
dw
c sound velocity;
error in sound velocity;
δc
R
spatial resolution;
t time-of-flight from the transmitter to the receiver;
Δt time-of-flight difference between the lateral wave and a second ultrasonic signal;
error in time-of-flight;
δt
t time-of-flight at depth d;
d
t duration of the ultrasonic pulse measured at 10 % of the peak amplitude;
p
t time-of-flight of the back wall echo;
w
s half the distance between the index points of two ultrasonic probes;
error in half the probe separation;
δs
W wall thickness.
4 General
4.1 Principle of the technique
The TOFD technique relies on the interaction of ultrasonic waves with the tips of discontinuities. This
interaction results in the emission of diffracted waves over a large angular range. Detection of the diffracted
waves makes it possible to establish the presence of the discontinuity. The time-of-flight of the recorded
signals is a measure for the height of the discontinuity, thus enabling sizing of the defect. The dimension of
© ISO 2012 – All rights reserved 3

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SIST EN ISO 16828:2014
ISO 16828:2012(E)
the discontinuity is always determined from the time-of-flight of the diffracted signals. The signal amplitude is
not used in size estimation.

Key
1 transmitter d discontinuity
2 receiver e lower tip
a lateral wave f back wall echo
b upper tip
Figure 2 — Basic TOFD configuration
The basic configuration for the TOFD technique consists of a separate ultrasonic transmitter and receiver (see
Figure 2). Wide-angle beam compression wave probes are normally used since the diffraction of ultrasonic
waves is only weakly dependent on the orientation of the discontinuity tip. This enables the inspection of a
certain volume in one scan. However, restrictions apply to the size of the volume that can be inspected during
a single scan (see 7.2).
The first signal to arrive at the receiver after emission of an ultrasonic pulse is usually the lateral wave which
travels just beneath the upper surface of the test specimen.
In the absence of discontinuities, the second signal to arrive at the receiver is the back wall echo.
These two signals are normally used for reference purposes. If mode conversion is neglected, any signals
generated by discontinuities in the material should arrive between the lateral wave and the back wall echo,
since the latter two correspond, respectively, to the shortest and longest paths between transmitter and
receiver. For similar reasons the diffracted signal generated at the upper tip of a discontinuity will arrive before
the signal generated at the lower tip of the discontinuity. A typical pattern of indications (A-scan) is shown in
Figure 3. The height of the discontinuity can be deduced from the difference in time-of-flight of the two
diffracted signals (see 8.1.5). Note the phase reversal between the lateral wave and the back wall echo, and
between echoes of the upper and lower tip of the discontinuity.
Where access to both surfaces of the specimen is possible and discontinuities are distributed throughout the
specimen thickness, scanning from both surfaces will improve the overall precision, particularly in regard to
discontinuities near the surfaces.
4 © ISO 2012 – All rights reserved

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SIST EN ISO 16828:2014
ISO 16828:2012(E)

Key
X amplitude b upper tip
Y time c lower tip
a lateral wave d back wall echo
Figure 3 — Schematic A-scan of an embedded discontinuity
4.2 Requirements for surface condition and couplant
Care shall be taken that the surface condition meets at least the requirements stated in ISO 16810. Since the
diffracted signals may be weak, the degradation of signal quality due to poor surface condition will have a
severe impact on inspection reliability.
Different coupling media can be used, but their type shall be compatible with the materials to be examined.
Examples are: water (possibly containing an agent e.g. wetting, anti-freeze, corrosion inhibitor), contact paste,
oil, grease, cellulose paste containing water, etc.
The characteristics of the coupling medium shall remain constant throughout the examination. It shall be
suitable for the temperature range in which it will be used.
4.3 Materials and process type
Due to the relatively low signal amplitudes that are used in the TOFD technique, the method can be applied
routinely on materials with relatively low levels of attenuation and scatter for ultrasonic waves. In general,
application on unalloyed and low alloyed carbon steel components and welds is possible, but also on fine
grained austenitic steels and aluminium.
Coarse-grained materials and materials with significant anisotropy however, such as cast iron, austenitic weld
materials and high-nickel alloys, will require additional validation and additional data-processing.
By mutual agreement, a representative test specimen with artificial and/or natural discontinuities can be used
to confirm inspectability. Remember that diffraction characteristics of artificial defects can differ significantly
from those of real defects.
5 Qualification of personnel
Personnel performing examinations with the TOFD technique shall, as a minimum, be qualified in accordance
with ISO 9712, and shall have received additional training and examination on the use of the TOFD technique
on the product classes to be tested, as specified in a written practice.
6 Equipment requirements
6.1 Ultrasonic equipment and display
Ultrasonic equipment used for the TOFD technique shall, as a minimum, comply with the requirements of
EN 12668-1, EN 12668-2 and EN 12668-3.
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SIST EN ISO 16828:2014
ISO 16828:2012(E)
In addition, the following requirements shall apply:
⎯ receiver bandwidth shall, as a minimum, range between 0,5 and 2 times the nominal probe frequency at -
6 dB, unless specific materials and product classes require a larger bandwidth. Appropriate band filters
can be used;
⎯ transmitting pulse can either be unipolar or bipolar. The rise time shall not exceed 0,25 times the period
corresponding to the nominal probe frequency;
⎯ unrectified signals shall be digitized with a sampling rate of at least six times the nominal probe
frequency;
⎯ for general applications, combinations of ultrasonic equipment and scanning mechanisms (see 6.3) shall
be capable of acquiring and digitizing signals with a rate of at least one A-scan per 1 millimetre scan
length. Data acquisition and scanning mechanism movement shall be synchronized for this purpose;
⎯ to select an appropriate portion of the time base within which A-scans are digitized, a window with
programmable position and length shall be present. Window start shall be programmable between 0 µs
and 200 µs from the transmitting pulse, window length shall be programmable between 5 µs and 100 µs.
In this way, the appropriate signals (lateral or creeping wave, back wall signal, one or more mode
converted signals as described in 4.1) can be selected to be digitized and displayed;
⎯ digitized A-scans should be displayed in amplitude related grey or single-colour levels, plotted adjacently
to form a B-scan. See Figures 4 and 5 for typical B-scans of non-parallel and parallel scans respectively.
The number of grey or single-colour scales should at least be 64;
⎯ for archiving purposes, the equipment shall be capable of storing all A-scans or B-scans (as appropriate)
on a magnetic or optical storage medium such as hard disk, tape or optical disk. For reporting purposes, it
shall be capable of making hard copies of A-scans or B-scans (as appropriate);
⎯ equipment should be capable of performing signal averaging.
In order to achieve the relatively high gain settings required for typical TOFD-signals, a pre-amplifier may be
used, which should have a flat response over the frequency range of interest. This pre-amplifier shall be
positioned as close as possible to the
...

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Zerstörungsfreie Prüfung - Ultraschallprüfung - Beugungslaufzeittechnik, eine Technik zum Auffinden und Ausmessen von Inhomogenitäten (ISO 16828:2012)Essais non destructifs - Contrôle par ultrasons - Technique de diffraction du temps de vol utilisée comme méthode de détection et de dimensionnement des discontinuités (ISO 16828:2012)Non-destructive testing - Ultrasonic testing - Time-of-flight diffraction technique as a method for detection and sizing of discontinuities (ISO 16828:2012)19.100Neporušitveno preskušanjeNon-destructive testingICS:Ta slovenski standard je istoveten z:FprEN ISO 16828kSIST FprEN ISO 16828:2013en,fr,de01-november-2013kSIST FprEN ISO 16828:2013SLOVENSKI
STANDARD



kSIST FprEN ISO 16828:2013



EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
FINAL DRAFT
FprEN ISO 16828
August 2013 ICS 19.100 Will supersede EN 583-6:2008English Version
Non-destructive testing - Ultrasonic testing - Time-of-flight diffraction technique as a method for detection and sizing of discontinuities (ISO 16828:2012)
Essais non destructifs - Contrôle par ultrasons - Technique de diffraction du temps de vol utilisée comme méthode de détection et de dimensionnement des discontinuités (ISO 16828:2012)
Zerstörungsfreie Prüfung - Ultraschallprüfung - Beugungslaufzeittechnik, eine Technik zum Auffinden und Ausmessen von Inhomogenitäten (ISO 16828:2012) This draft European Standard is submitted to CEN members for unique acceptance procedure. It has been drawn up by the Technical Committee CEN/TC 138.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
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B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. FprEN ISO 16828:2013: EkSIST FprEN ISO 16828:2013



FprEN ISO 16828:2013 (E) 2 Contents
Page Foreword .3
kSIST FprEN ISO 16828:2013



FprEN ISO 16828:2013 (E) 3 Foreword The text of ISO 16828:2012 has been prepared by Technical Committee ISO/TC 135 “Non-destructive testing” of the International Organization for Standardization (ISO) and has been taken over as FprEN ISO 16828:2013 by Technical Committee CEN/TC 138 “Non-destructive testing” the secretariat of which is held by AFNOR. This document is currently submitted to the Unique Acceptance Procedure. This document will supersede EN 583-6:2008. Endorsement notice The text of ISO 16828:2012 has been approved by CEN as FprEN ISO 16828:2013 without any modification.
kSIST FprEN ISO 16828:2013



kSIST FprEN ISO 16828:2013



Reference numberISO 16828:2012(E)© ISO 2012
INTERNATIONAL STANDARD ISO16828First edition2012-04-01Non-destructive testing — Ultrasonic testing — Time-of-flight diffraction technique as a method for detection and sizing of discontinuities Essais non destructifs — Contrôle par ultrasons — Technique de diffraction du temps de vol utilisée comme méthode de détection et de dimensionnement des discontinuités
kSIST FprEN ISO 16828:2013



ISO 16828:2012(E)
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ISO 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56  CH-1211 Geneva 20 Tel.
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© ISO 2012 – All rights reserved
kSIST FprEN ISO 16828:2013



ISO 16828:2012(E) © ISO 2012 – All rights reserved iii Contents Page Introduction.vi 1 Scope.1 2 Normative references.1 3 Terms, definitions, symbols and abbreviations.2 3.1 Terms and definitions.2 3.2 Abbreviations.2 3.3 Symbols.2 4 General.3 4.1 Principle of the technique.3 4.2 Requirements for surface condition and couplant.5 4.3 Materials and process type.5 5 Qualification of personnel.5 6 Equipment requirements.5 6.1 Ultrasonic equipment and display.5 6.2 Ultrasonic probes.6 6.3 Scanning mechanisms.7 7 Equipment set-up procedures.7 7.1 General.7 7.2 Probe choice and probe separation.8 7.2.1 Probe selection.8 7.2.2 Probe separation.9 7.3 Time window setting.9 7.4 Sensitivity setting.9 7.5 Scan resolution setting.10 7.6 Setting of scanning speed.10 7.7 Checking system performance.10 8 Interpretation and analysis of data.10 8.1 Basic analysis of discontinuities.10 8.1.1 General.10 8.1.2 Characterisation of discontinuities.10 8.1.3 Estimation of discontinuity position.11 8.1.4 Estimation of discontinuity length.11 8.1.5 Estimation of discontinuity depth and height.12 8.2 Detailed analysis of discontinuities.12 8.2.1 General.12 8.2.2 Additional scans.13 8.2.3 Additional algorithms.14 9 Detection and sizing in complex geometries.14 10 Limitations of the technique.14 10.1 General.14 10.2 Accuracy and resolution.15 10.2.1 General.15 10.2.2 Errors in the lateral position.15 10.2.3 Timing errors.15 10.2.4 Errors in sound velocity.15 10.2.5 Errors in probe centre separation.15 10.2.6 Spatial resolution.16 10.3 Dead zones.16 Foreword.v kSIST FprEN ISO 16828:2013



ISO 16828:2012(E) iv © ISO 2012 – All rights reserved
11 TOFD examination without data recording.16 12 Test procedure.17 13 Test report.17 Annex A (normative)
Reference blocks.18 Bibliography.19
kSIST FprEN ISO 16828:2013



ISO 16828:2012(E) © ISO 2012 – All rights reserved v 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 16828 was prepared by Technical Committee ISO/TC 135, Non-destructive testing, Subcommittee SC 3, Ultrasonic testing. kSIST FprEN ISO 16828:2013



ISO 16828:2012(E) vi © ISO 2012 – All rights reserved Introduction This International Standard is based on EN 583-6:2008, Non-destructive testing — Ultrasonic examination — Part 6: Time-of-flight diffraction technique as a method for detection and sizing of discontinuities. 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
kSIST FprEN ISO 16828:2013



1 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 9712, Non-destructive testing — Qualification and certification of NDT personnel — General principles ISO 16810, Non-destructive testing — Ultrasonic WHVWLQJ —
General principles ISO 16811, Non-destructive testing — Ultrasonic WHVWLQJ — Sensitivity and range setting EN 12668-1, Non-destructive testing — Characterization and verification of ultrasonic examination equipment — Part 1: Instruments EN 12668-2, Non-destructive testing — Characterization and verification of ultrasonic examination equipment — Part 2: Probes INTERNATIONAL STANDARD ISO 16828:2012(E) Non-destructive testing — Ultrasonic testing — Time-of-flight diffraction technique as a method for detection and sizing of discontinuities 1 Scope This International Standard defines the general principles for the application of the time-of-flight diffraction (TOFD) technique for both detection and sizing of discontinuities in low alloyed carbon steel components. It can also be used for other types of materials, provided the application of the TOFD technique is performed with necessary consideration of geometry, acoustical properties of the materials, and the sensitivity of the examination. Although it is applicable, in general terms, to discontinuities in materials and applications covered by ISO 16810, it contains references to the application on welds. This approach has been chosen for reasons of clarity as to the ultrasonic probe positions and directions of scanning. Unless otherwise specified in the referencing documents, the minimum requirements of this International Standard are applicable. Unless explicitly stated otherwise, this International Standard is applicable to the following product classes as defined in ISO 16811:  class 1, without restrictions;  classes 2 and 3, specified restrictions apply. NOTE 1 See Clause 9. The inspection of products of classes 4 and 5 requires special procedures, which are also addressed. NOTE 2 See Clause 9. NOTE 3 Techniques for the use of TOFD for weld inspection are described in ISO 10863. NOTE 4 The related acceptance criteria are given in ISO 15626.
© ISO 2012 – All rights reservedkSIST FprEN ISO 16828:2013



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EN 12668-3, Non-destructive testing — Characterization and verification of ultrasonic examination equipment — Part 3: Combined equipment 3 Terms, definitions, symbols and abbreviations 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 scanning surface dead zone zone where indications may be obscured due to the interface echo (lateral wave) 3.1.2 back wall dead zone dead zone where signals may be obscured by the presence of the back wall echo 3.1.3 A-scan display of the ultrasonic signal amplitude as a function of time 3.1.4 B-scan display of the time-of-flight of the ultrasonic signal as a function of probe displacement 3.1.5 non-parallel scan scan perpendicular to the ultrasonic beam direction (see Figure 4) 3.1.6 parallel scan scan parallel to the ultrasonic beam direction (see Figure 5) 3.2 Abbreviations ⎯ TOFD: time-of-flight diffraction 3.3 Symbols
Figure 1 — Coordinate definition ISO 16828:2012(E) © ISO 2012 – All rights reservedkSIST FprEN ISO 16828:2013



3 x coordinate parallel to the scanning surface and parallel to a predetermined reference line. In case of weld inspection this reference line should coincide with the weld. The origin of the axes may be defined as best suits the specimen under examination (see Figure 1); Δx discontinuity length; y coordinate parallel to the scanning surface, perpendicular to the predetermined reference line (see Figure 1); δy error in lateral position; z coordinate perpendicular to the scanning surface (see Figure 1); Δz discontinuity height; d depth of a discontinuity tip below the scanning surface; δd error in depth; Dds scanning-surface dead zone; Ddw back wall dead zone; c sound velocity; δc error in sound velocity; R spatial resolution; t time-of-flight from the transmitter to the receiver; Δt time-of-flight difference between the lateral wave and a second ultrasonic signal; δt error in time-of-flight; td time-of-flight at depth d; tp duration of the ultrasonic pulse measured at 10 % of the peak amplitude;
tw time-of-flight of the back wall echo; s half the distance between the index points of two ultrasonic probes; δs error in half the probe separation; t wall thickness. 4 General 4.1 Principle of the technique The TOFD technique relies on the interaction of ultrasonic waves with the tips of discontinuities. This interaction results in the emission of diffracted waves over a large angular range. Detection of the diffracted waves makes it possible to establish the presence of the discontinuity. The time-of-flight of the recorded signals is a measure for the height of the discontinuity, thus enabling sizing of the defect. The dimension of ISO 16828:2012(E) © ISO 2012 – All rights reservedkSIST FprEN ISO 16828:2013



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the discontinuity is always determined from the time-of-flight of the diffracted signals. The signal amplitude is not used in size estimation.
Key 1 transmitter d discontinuity 2 receiver e lower tip a lateral wave f back wall echo b upper tip
Figure 2 — Basic TOFD configuration The basic configuration for the TOFD technique consists of a separate ultrasonic transmitter and receiver (see Figure 2). Wide-angle beam compression wave probes are normally used since the diffraction of ultrasonic waves is only weakly dependent on the orientation of the discontinuity tip. This enables the inspection of a certain volume in one scan. However, restrictions apply to the size of the volume that can be inspected during a single scan (see 7.2). The first signal to arrive at the receiver after emission of an ultrasonic pulse is usually the lateral wave which travels just beneath the upper surface of the test specimen. In the absence of discontinuities, the second signal to arrive at the receiver is the back wall echo. These two signals are normally used for reference purposes. If mode conversion is neglected, any signals generated by discontinuities in the material should arrive between the lateral wave and the back wall echo, since the latter two correspond, respectively, to the shortest and longest paths between transmitter and receiver. For similar reasons the diffracted signal generated at the upper tip of a discontinuity will arrive before the signal generated at the lower tip of the discontinuity. A typical pattern of indications (A-scan) is shown in Figure 3. The height of the discontinuity can be deduced from the difference in time-of-flight of the two diffracted signals (see 8.1.5). Note the phase reversal between the lateral wave and the back wall echo, and between echoes of the upper and lower tip of the discontinuity. Where access to both surfaces of the specimen is possible and discontinuities are distributed throughout the specimen thickness, scanning from both surfaces will improve the overall precision, particularly in regard to discontinuities near the surfaces. ISO 16828:2012(E) © ISO 2012 – All rights reservedkSIST FprEN ISO 16828:2013



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Key X amplitude b upper tip Y time c lower tip a lateral wave d back wall echo Figure 3 — Schematic A-scan of an embedded discontinuity 4.2 Requirements for surface condition and couplant Care shall be taken that the surface condition meets at least the requirements stated in ISO 16810. Since the diffracted signals may be weak, the degradation of signal quality due to poor surface condition will have a severe impact on inspection reliability. Different coupling media can be used, but their type shall be compatible with the materials to be examined. Examples are: water (possibly containing an agent e.g. wetting, anti-freeze, corrosion inhibitor), contact paste, oil, grease, cellulose paste containing water, etc. The characteristics of the coupling medium shall remain constant throughout the examination. It shall be suitable for the temperature range in which it will be used. 4.3 Materials and process type Due to the relatively low signal amplitudes that are used in the TOFD technique, the method can be applied routinely on materials with relatively low levels of attenuation and scatter for ultrasonic waves. In general, application on unalloyed and low alloyed carbon steel components and welds is possible, but also on fine grained austenitic steels and aluminium. Coarse-grained materials and materials with significant anisotropy however, such as cast iron, austenitic weld materials and high-nickel alloys, will require additional validation and additional data-processing. By mutual agreement, a representative test specimen with artificial and/or natural discontinuities can be used to confirm inspectability. Remember that diffraction characteristics of artificial defects can differ significantly from those of real defects. 5 Qualification of personnel Personnel performing examinations with the TOFD technique shall, as a minimum, be qualified in accordance with ISO 9712, and shall have received additional training and examination on the use of the TOFD technique on the product classes to be tested, as specified in a written practice. 6 Equipment requirements 6.1 Ultrasonic equipment and display Ultrasonic equipment used for the TOFD technique shall, as a minimum, comply with the requirements of EN 12668-1, EN 12668-2 and EN 12668-3. ISO 16828:2012(E) © ISO 2012 – All rights reservedkSIST FprEN ISO 16828:2013



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In addition, the following requirements shall apply: ⎯ receiver bandwidth shall, as a minimum, range between 0,5 and 2 times the nominal probe frequency at - 6 dB, unless specific materials and product classes require a larger bandwidth. Appropriate band filters can be used; ⎯ transmitting pulse can either be unipolar or bipolar. The rise time shall not exceed 0,25 times the period corresponding to the nominal probe frequency; ⎯ unrectified signals shall be digitized with a sampling rate of at least six times the nominal probe frequency; ⎯ for general applications, combinations of ultrasonic equipment and scanning mechanisms (see 6.3) shall be capable of acquiring and digitizing signals with a rate of at least one A-scan per 1 millimetre scan length. Data acquisition and scanning mechanism movement shall be synchronized for this purpose; ⎯ to select an appropriate portion of the time base within which A-scans are digitized, a window with programmable position and length shall be present. Window start shall be programmable between 0 µs and 200 µs from the transmitting pulse, window length shall be programmable between 5 µs and 100 µs. In this way, the appropriate signals (lateral or creeping wave, back wall signal, one or more mode converted signals as described in 4.1) can be selected to be digitized and displayed; ⎯ digitized A-scans should be displayed in amplitude related grey or single-colour levels, plotted adjacently to form a B-scan. See Figures 4 and 5 for typical B-scans of non-parallel and parallel scans respectively. The number of grey or single-colour scales should at least be 64; ⎯ for archiving purposes, the equipment shall be capable of storing all A-scans or B-scans (as appropriate) on a magnetic or optical storage medium such as hard disk, tape or optical disk. For reporting purposes, it shall be capable of making hard copies of A-scans or B-scans (as appropriate); ⎯ equipment should be capable of performing signal averaging. In order to achieve the relatively high gain settings required for typical TOFD-signals, a pre-amplifier may be used, which should have a flat response over the frequency range of interest. This pre-amplifier shall be positioned as close as possible to the receiving probe. Additional requirements regarding features for basic and advanced analysis of discontinuities are described in Clause 8. 6.2 Ultrasonic probes Ultrasonic probes used for the TOFD technique shall comply with at least the following requirements: ⎯ number of probes: 2 (transmitter and receiver); ⎯ type: any suitable probe (see 7.2); ⎯ wave mode: usually compression wave; the use of shear wave probes is more complex but may be agreed upon in special cases; ⎯ both probes shall have the same centre frequency within a tolerance of ± 20 %; for details on probe frequency selection, see 7.2; ⎯ pulse length of both the lateral wave and the back wall echo shall not exceed two cycles, measured at 10 % of the peak amplitude; ⎯ pulse repetition rate shall be set such that no interference occurs between signals caused by successive transmission pulses. ISO 16828:2012(E) © ISO 2012 – All rights reservedkSIST FprEN ISO 16828:2013



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Key 1 reference line 6 lateral wave 2 direction of probe displacement (x-direction) 7 discontinuity upper tip 3 transmitter 8 discontinuity lower tip 4 receiver 9 back wall reflection 5 transit time (through wall extent)
Figure 4 — Non-parallel scan, with the typical direction of probe displacement shown on the left and the corresponding B-scan shown on the right 6.3 Scanning mechanisms Scanning mechanisms shall be used to maintain a constant distance and alignment between the index points of the two probes. An additional function of scanning mechanisms is to provide the ultrasonic equipment with probe position information in order to enable the generation of position-related B-scans. Information on probe position can be provided by means of e.g. incremental magnetic or optical encoders, or potentiometers. Scanning mechanisms in TOFD can either be motor or manually driven. They shall be guided by means of a suitable guiding mechanism (steel band, belt, automatic track following systems, guiding wheels, etc.). Guiding accuracy with respect to the centre of a reference line (e.g. the centre line of a weld) should be kept within a tolerance of ± 10 % of the
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