kSIST FprEN ISO 16826:2025

SLOVENSKI STANDARD
oSIST prEN ISO 16826:2024
01-april-2024
Neporušitvene preiskave - Ultrazvočne preiskave - Preiskave za odkrivanje
nehomogenosti, ki potekajo pravokotno na površino (ISO/DIS 16826:2024)
Non-destructive testing - Ultrasonic testing - Testing for discontinuities perpendicular to
the surface (ISO/DIS 16826:2024)
Zerstörungsfreie Prüfung - Ultraschallprüfung - Prüfung auf Inhomogenitäten senkrecht
zur Oberfläche (ISO/DIS 16826:2024)
Essais non destructifs - Contrôle par ultrasons - Contrôle des discontinuités
perpendiculaires à la surface (ISO/DIS 16826:2024)
Ta slovenski standard je istoveten z: prEN ISO 16826
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
oSIST prEN ISO 16826:2024 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN ISO 16826:2024
oSIST prEN ISO 16826:2024
DRAFT
International
Standard
ISO/DIS 16826
ISO/TC 135/SC 3
Non-destructive testing —
Secretariat: DIN
Ultrasonic testing — Testing for
Voting begins on:
discontinuities perpendicular to the
2024-02-19
surface
Voting terminates on:
ICS: 19.100
2024-05-13
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
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POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
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.
Reference number
ISO/DIS 16826:2024(en)
oSIST prEN ISO 16826:2024
DRAFT
ISO/DIS 16826:2024(en)
International
Standard
ISO/DIS 16826
ISO/TC 135/SC 3
Non-destructive testing —
Secretariat: DIN
Ultrasonic testing — Testing for
Voting begins on:
discontinuities perpendicular to the
surface
Voting terminates on:
ICS: 19.100
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2024
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: +41 22 749 01 11
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 16826:2023(en)
ii
oSIST prEN ISO 16826:2024
ISO/DIS 16826:2023(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test equipment and test personnel . 1
5 Tandem technique . 2
5.1 General .2
5.2 Probe movement .3
5.3 Time base setting .3
5.4 Sensitivity setting .3
5.5 Determination of test zones .3
5.6 Depth-gain diagram for tandem technique .5
5.7 Corrections of sensitivity .6
5.8 Test objects with concentric surfaces .6
5.8.1 General .6
5.8.2 Scanning on a concave surface .6
5.8.3 Scanning on a convex surface .7
6 LLT technique . 8
6.1 General .8
6.2 Time base setting and determination of depth position of a discontinuity .9
6.3 Sensitivity setting .10
6.4 Determination of the depth position of the intersection of the beam axes .10
6.5 Sensitivity diagram for LLT technique .11
6.6 Correction of sensitivity .11
Annex A (informative) Nomograms for tandem distances for convex and concave surfaces .12

iii
oSIST prEN ISO 16826:2024
ISO/DIS 16826:2023(en)
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 135, Non-destructive testing, Subcommittee
SC 3, Ultrasonic testing.
This second edition cancels and replaces the first edition (ISO 16823:2012), which has been technically
revised.
The main changes are as follows:
— document technically revised,
— improved figures and formulas,
— editorial improvements.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
oSIST prEN ISO 16826:2024
ISO/DIS 16826:2023(en)
Introduction
The following documents 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 — Testing 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

v
oSIST prEN ISO 16826:2024
oSIST prEN ISO 16826:2024
DRAFT International Standard ISO/DIS 16826:2023(en)
Non-destructive testing — Ultrasonic testing — Testing for
discontinuities perpendicular to the surface
1 Scope
This document specifies the principles for the tandem technique and the longitudinal-longitudinal-
transverse (LLT) wave technique for the detection of discontinuities perpendicular to the surface or almost
perpendicular to the surface.
The general principles required for the ultrasonic testing of industrial products are described in ISO 16810.
The tandem or LLT techniques can be used for the detection of embedded planar discontinuities.
This document has been prepared for the testing of metallic materials with a thickness between 40 mm and
500 mm with parallel or concentric surfaces.
The procedures provided in this document may be used for testing of other materials or smaller thickness if
special measures are taken according to a written testing procedure.
Phased array techniques can also be applied for the tandem technique and the LLT technique, but additional
steps or verifications can be needed.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 testing — Vocabulary
ISO 16810, Non-destructive testing — Ultrasonic testing — General principles
ISO 16811, Non-destructive testing — Ultrasonic testing — Sensitivity and range setting
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5577 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Test equipment and test personnel
The requirements of ISO 16810 on test equipment and test personnel apply unless stated othe
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