prEN ISO 17640

• Abstract:

  This document specifies techniques for the manual ultrasonic testing of fusion-welded joints in metallic materials of thickness ≥8 mm which exhibit low ultrasonic attenuation (especially that due to scatter) at object temperatures from 0 °C to 60 °C. It is primarily intended for use on full penetration welded joints where both the welded and parent material are ferritic.; Where material-dependent ultrasonic values are specified in this document, they are based on steels having an ultrasonic sound velocity of (5 920 ± 50) m/s for longitudinal waves and (3 255 ± 30) m/s for transverse waves.; This document specifies four testing levels, each corresponding to a different probability of detection of imperfections. Guidance on the selection of testing levels A, B, and C is given in Annex A.; This document specifies that the requirements of testing level D, which is intended for special applications, be in accordance with general requirements. Testing level D can only be used when defined by specification. This includes tests of metals other than ferritic steel, tests on partial penetration welds, tests with automated equipment, and tests at object temperatures outside the range 0 °C to 60 °C.; This document can be used for the assessment of discontinuities, for acceptance purposes, by either of the following techniques:; a) evaluation based primarily on length and echo amplitude of the discontinuity;; b) evaluation based on characterization and sizing of the discontinuity by probe movement techniques.

• Status: Not Published
• Publication Date: 02-Apr-2028
• ICS: 25.160.40 - Welded joints and welds
• Technical Committee: CEN/TC 121 - Welding
• Drafting Committee: CEN/TC 121/WG 21 - Testing of welds
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 10-Sep-2026
• Completion Date: 10-Sep-2026
• Ref Project: oSIST prEN ISO 17640:2026 - Non-destructive testing of welds - Ultrasonic testing - Techniques, testing levels, and assessment (ISO/DIS 17640:2026)

• Revises: EN ISO 17640:2018 - Non-destructive testing of welds - Ultrasonic testing - Techniques, testing levels, and assessment (ISO 17640:2018)
• Effective Date: 20-Nov-2024

Overview

prEN ISO 17640:2026 defines a comprehensive framework for the non-destructive ultrasonic testing (UT) of fusion-welded joints in metallic materials. Developed by CEN and aligned with ISO international standards, this document specifies manual ultrasonic testing procedures for full penetration welded joints, particularly where both the welded material and parent material are ferritic steels with low ultrasonic attenuation. It is applicable for object thicknesses of 8 mm and above, and temperatures ranging from 0 °C to 60 °C. The standard also introduces four testing levels, each offering varying levels of detection reliability and assessment criteria for weld imperfections.

Key Topics

• Manual Ultrasonic Testing Techniques: Provides details on the use of manual ultrasonic testing on fusion-welded joints, focusing on techniques that ensure reliable detection of weld discontinuities.
• Testing Levels A to D: Defines four levels-A, B, C, D-each corresponding to a different probability of detection and testing coverage. Levels A to C are covered with specific guidance, while level D applies to special cases such as non-ferritic steels, partial penetration welds, or automated testing.
• Assessment Methods: Describes two primary assessment approaches:
  • Based on discontinuity length and echo amplitude.
  • By characterization and sizing using probe movement techniques.
• Requirements for Personnel and Equipment: Emphasizes that personnel must be appropriately qualified (e.g., in accordance with ISO 9712) and that ultrasonic equipment must meet relevant international standards.
• Preparation and Execution: Outlines the necessary information, scanning surface preparation, test volume coverage, and reporting requirements prior to and during ultrasonic weld testing.

Applications

prEN ISO 17640 serves a critical role across industries where the integrity and quality of welded joints are essential, including:

• Steel Fabrication: Ensures that welded structures, such as pressure vessels, pipelines, and structural steelwork, meet rigorous testing requirements.
• Power and Energy: Applied in the quality assurance of welds in power generation equipment, including nuclear and conventional plants.
• Shipbuilding and Offshore: Used to verify the structural soundness of welded joints subject to severe operational stresses and environmental conditions.
• Transportation: Supports quality assurance procedures for welded components in rail, automotive, and aerospace industries.
• Plant Maintenance: Assists in routine inspections and maintenance assessments to identify potential in-service discontinuities or degradation in welds.

The standard facilitates regulatory compliance, product safety, and quality assurance by offering clear, harmonized methods for ultrasonic non-destructive testing of welds.

Related Standards

prEN ISO 17640:2026 is closely aligned with a family of international and European standards that support robust non-destructive testing workflows:

• ISO 5577: Vocabulary for ultrasonic inspection in non-destructive testing.
• ISO 9712: Qualification and certification of non-destructive testing personnel.
• ISO 11666: Acceptance levels for ultrasonic testing of welds.
• ISO 16810: General principles of ultrasonic testing.
• ISO 16811: Sensitivity and range setting in ultrasonic testing.
• ISO 17635: General rules for non-destructive testing of welds in metallic materials.
• ISO 22232 Series: Characterization and verification of ultrasonic test equipment (instruments, probes, combined equipment).
• ISO 23279: Characterization of discontinuities in welds by ultrasonic testing.

Summary

By standardizing ultrasonic testing techniques and acceptance criteria for welded joints, prEN ISO 17640:2026 enhances the reliability, safety, and reproducibility of weld assessments. Its structured approach ensures that industries can confidently carry out ultrasonic testing and meet essential quality and regulatory requirements, contributing to improved asset integrity and operational performance.

SLOVENSKI STANDARD
01-oktober-2026
Neporušitveno preskušanje zvarnih spojev - Ultrazvočno preskušanje - Tehnike,
stopnje preskušanja in ocenjevanje (ISO/DIS 17640:2026)
Non-destructive testing of welds - Ultrasonic testing - Techniques, testing levels, and
assessment (ISO/DIS 17640:2026)
Zerstörungsfreie Prüfung von Schweißverbindungen - Ultraschallprüfung - Techniken,
Prüfklassen und Bewertung (ISO/DIS 17640:2026)
Essais non destructifs des assemblages soudés - Contrôle par ultrasons - Techniques,
niveaux d'essai et évaluation (ISO/DIS 17640:2026)
Ta slovenski standard je istoveten z: prEN ISO 17640
ICS:
25.160.40 Varjeni spoji in vari Welded joints and welds
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 17640
ISO/TC 44/SC 5
Non-destructive testing of welds —
Secretariat: AFNOR
Ultrasonic testing — Techniques,
Voting begins on:
testing levels, and assessment
2026-09-09
Essais non destructifs des assemblages soudés — Contrôle par
Voting terminates on:
ultrasons — Techniques, niveaux d'essai et évaluation
2026-12-02
ICS: 25.160.40
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 has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
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 17640:2026(en)
DRAFT
ISO/DIS 17640:2026(en)
International
Standard
ISO/DIS 17640
ISO/TC 44/SC 5
Non-destructive testing of welds —
Secretariat: AFNOR
Ultrasonic testing — Techniques,
Voting begins on:
testing levels, and assessment
Essais non destructifs des assemblages soudés — Contrôle par
Voting terminates on:
ultrasons — Techniques, niveaux d'essai et évaluation
ICS: 25.160.40
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 has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
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: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 17640:2026(en)
ii
ISO/DIS 17640:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 2
5 General . 3
6 Information required prior to testing . 3
6.1 Items to be specified .3
6.2 Specific information required before testing .4
6.3 Written test procedure .4
7 Requirements for personnel and equipment . 4
7.1 Personnel qualifications .4
7.2 Test equipment .4
7.3 Probe parameters .5
7.3.1 Test frequency .5
7.3.2 Angles of incidence .5
7.3.3 Transducer size .5
7.3.4 Adaptation of probes to curved scanning surfaces .5
7.3.5 Coupling medium .6
8 Testing volume . 6
9 Preparation of scanning surfaces . 6
10 Parent metal testing . 7
11 Range and sensitivity setting . 8
11.1 General .8
11.2 Reference for sensitivity setting.8
11.3 Evaluation and recording levels .8
11.4 Transfer correction .9
11.5 Signal-to-noise ratio .9
11.6 Checking of settings .9
12 Testing levels . 10
13 Testing techniques .11
13.1 General .11
13.2 Manual scan path.11
13.3 Testing for imperfections perpendicular to the testing surface .11
13.4 Location of discontinuities .11
13.5 Evaluation of indications .11
13.5.1 General .11
13.5.2 Maximum echo amplitude .11
13.5.3 Discontinuity length . .11
13.5.4 Discontinuity height .11
13.5.5 Characterization of discontinuities . 12
14 Test report .12
Annex A (normative) Test setups for various types of welded joints according to testing levels . 14
Bibliography .30

iii
ISO/DIS 17640:2026(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 44, Welding and allied processes, Subcommittee
SC 5, Testing and inspection of welds.
Any feedback, question or request for official interpretation related to any aspect of this document should be
directed to the Secretariat of ISO/TC 44/SC 5 via your national standards body. A complete listing of these
bodies can be found at www.iso.org/members.html. Official interpretations, where they exist, are available
from this page: https://committee.iso.org/sites/tc44/home/interpretation.html.
This fifth edition cancels and replaces the fourth edition (ISO 17640:2018), which has been technically
revised. The main changes compared to the previous edition are :
— update of normative references
— modifications to Clause 7, 11.3 and Annex A.

iv
DRAFT International Standard ISO/DIS 17640:2026(en)
Non-destructive testing of welds — Ultrasonic testing —
Techniques, testing levels, and assessment
1 Scope
This document specifies techniques for the manual ultrasonic testing of fusion-welded joints in metallic
materials with low sound attenuation (especially that due to scatter) of minimum thickness 8 mm. It is
primarily intended for use on full penetration welded joints where both the welded and parent materials are
ferritic. It applies at object temperatures from 0 °C to 60 °C.
Where material-dependent ultrasonic values are specified in this document, they are based on steels having
an ultrasonic sound velocity of (5 920 ± 50) m/s for longitudinal waves and (3 255 ± 30) m/s for transverse
waves.
This document specifies four testing levels, A, B, C and D, each corresponding to a different probability of
detection of imperfections.
Guidance on the selection of testing levels A, B, and C is given in Annex A.
This document specifies that the requirements of testing level D, which is intended for special applications,
be in accordance with general requirements. Testing level D can only be used when defined by specification.
This includes tests of metals other than ferritic steel, tests on partial penetration welds, tests with automated
equipment, and tests at object temperatures outside the range 0 °C to 60 °C.
This document can be used for the assessment of discontinuities, for acceptance purposes, by either of the
following techniques:
a) evaluation based primarily on length and echo amplitude of the discontinuity;
b) evaluation based on characterization and sizing of the discontinuity by probe movement techniques.
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 inspection — Vocabulary
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
ISO 11666, Non-destructive testing of welds — Ultrasonic testing — Acceptance levels
ISO 16810, Non-destructive testing — Ultrasonic testing — General principles
ISO 16811, Non-destructive testing — Ultrasonic testing — Sensitivity and range setting
ISO 17635, Non-destructive testing of welds — General rules for metallic materials
ISO 22232-1, Non-destructive testing — Characterization and verification of ultrasonic test equipment — Part
1: Instruments
ISO 22232-2, Non-destructive testing — Characterization and verification of ultrasonic test equipment — Part
2: Probes
ISO/DIS 17640:2026(en)
ISO 22232-3, Non-destructive testing — Characterization and verification of ultrasonic test equipment — Part
3: Combined equipment
ISO 23279, Non-destructive testing of welds — Ultrasonic testing — Characterization of discontinuities in welds
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5577 and ISO 17635 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Symbols
The symbols in Table 1 apply.
Table 1 — Symbols
Symbol Definition Unit
D diameter of the disk-shaped reflector (flat-bottomed hole) mm
DSR
h extension of the discontinuity in depth direction mm
H reference level —
H evaluation level —
EV
H recording level —
R
l length of the discontinuity mm
l projected length of the discontinuity in the x-direction mm
x
l projected length of the discontinuity in the y-direction mm
y
p full skip distance mm
a
t thickness of parent material mm
x position of the discontinuity in the longitudinal direction mm
y position of the discontinuity in the transverse direction mm
z position of the discontinuity in the depth direction mm
a
If the joined parts are not of equal thickness, t represents the smallest thickness.
Indications shall be considered to be originating from either longitudinal or transverse discontinuities,
depending on the direction of their major dimension with respect to the weld axis, x, in accordance with
Figure 1.
ISO/DIS 17640:2026(en)
Key
1 origin
XYZ orthonormal coordinate system
Figure 1 — Coordinate system for defining the location of discontinuities
5 General
The purpose of this document is to describe general techniques of ultrasonic weld testing, using standard
criteria, for the most commonly used welded joints at object temperatures in the range 0 °C to 60 °C.
The specific requirements of this document cover the test equipment, preparation, performance of testing,
and reporting. The parameters specified, in particular those for the probes, are compatible with the
requirements of ISO 11666 and ISO 23279 .
a) If the joined parts are not of equal thickness, the smallest thickness shall be considered.
b) The techniques used shall be specified.
6 Information required prior to testing
6.1 Items to be specified
These include:
a) method for setting the reference level;
b) method to be used for the evaluation of discontinuities;
c) acceptance levels;
d) testing level;
e) manufacturing and operation stage(s) at which the testing is to be carried out;
f) qualification of personnel;
g) extent of the testing for transverse discontinuities;
h) requirements for additional tandem testing (according to ISO 16826);
i) parent metal testing prior to and/or after welding;
j) whether or not a written test procedure is required;

ISO/DIS 17640:2026(en)
k) requirements for written test procedures.
6.2 Specific information required before testing
Before any testing of a welded joint can begin, the operator shall have access to the following essential
information:
a) written test procedure, if required (see 6.3);
b) type(s) of parent material and product form (i.e. cast, forged, rolled);
c) manufacturing or operation stage at which testing is to be made, including heat treatment, if any;
d) time and extent of any post-weld heat treatment;
e) joint preparation and dimensions;
f) requirements for surface conditions;
g) welding procedure or relevant information on the welding process;
h) reporting requirements;
i) acceptance levels;
j) extent of testing, including requirements for transverse discontinuities, if relevant;
k) testing level;
l) personnel qualification level;
m) procedures for corrective actions when unacceptable discontinuities are revealed.
6.3 Written test procedure
The definitions and requirements in this document normally satisfy the need for a written test procedure.
Where this is not the case, or where the techniques described in this document are not applicable to the
welded joint to be tested, additional written test procedures shall be used, if required by specification.
7 Requirements for personnel and equipment
7.1 Personnel qualifications
a) Personnel performing testing in accordance with this document shall be qualified to an appropriate
level in ultrasonic testing in accordance with ISO 9712 or equivalent in the relevant industrial sector.
b) In addition to a general knowledge of ultrasonic weld testing, personnel shall also be familiar with
testing problems specifically associated with the type of welded joints to be tested.
7.2 Test equipment
Any equipment used for testing in conjunction with this document shall comply with the requirements of
ISO 22232-1, ISO 22232-2, ISO 22232-3.

ISO/DIS 17640:2026(en)
7.3 Probe parameters
7.3.1 Test frequency
The frequency shall be within the range 2 MHz to 5 MHz and shall be selected to consider the properties of
the test object and to comply with the specified acceptance levels, e.g. those of ISO 11666 .
Higher frequencies may be used to improve range resolution if this is necessary when using standards for
acceptance levels based on characterization of discontinuities, e.g. ISO 23279 .
Lower frequencies may be used for testing at long sound paths and/or when the material shows higher
attenuation.
7.3.2 Angles of incidence
a) When testing is carried out with transverse waves and techniques that require the ultrasonic beam to
be reflected from an opposite surface, care shall be taken to ensure that the angle between the beam
and the normal to the opposite reflecting surface is between 35° and 70°.
b) Where more than one beam angle is used, at least one of the angle-beam probes used shall conform to
this requirement.
c) One of the beam angles used shall ensure that the weld fusion faces are tested at, or as near as possible
to, normal incidence.
d) When the use of two or more beam angles is specified, the difference between the nominal beam angles
shall be 10° or greater.
e) Angles of incidence at the opposite reflecting surface (at half skip) and at the test surface (at full skip),
when curved, may be determined by drawing a sectional view of the weld or in accordance with the
techniques given in ISO 16811 .
f) Where angles of incidence cannot be determined as specified by this document, the test report shall
contain a comprehensive description of the scans used and the extent of any incomplete coverage
caused, together with an explanation of the difficulties encountered.
7.3.3 Transducer size
The transducer size shall be chosen according to the ultrasonic path and the frequency to be used.
The smaller the transducer, the smaller the length and width of the near field, and the larger the beam spread
in the far field at a given frequency.
Small probes having 6 mm to 12 mm diameter transducers (or rectangular transducers of equivalent area)
are therefore most useful when working at short sound paths.
For longer sound paths, i.e. greater than 100 mm for straight-beam probes and greater than 200 mm for
angle-beam probes, a transducer size of 12 mm to 24 mm is more suitable.
7.3.4 Adaptation of probes to curved scanning surfaces
a) The gap, g, between test surface and bottom of the probe shall not be greater than 0,5 mm.

ISO/DIS 17640:2026(en)
For flat probes on cylindrical or spherical surfaces, especially for concave surfaces, this requirement can be
checked with Formula (1):
(1)
where
a is the dimension of the probe in the direction of curvature, in mm;
D is the diameter of the test object, in mm.
b) If a value for g larger than 0,5 mm results from Formula (1), the probe shall be adapted to the surface
and the sensitivity and range shall be set accordingly.
c) For spherical or complex shaped surfaces, Formula (1) shall be applied in both length and width direction
of the probe (possible differences in curvature and/or probe dimensions).
7.3.5 Coupling medium
a) The coupling medium shall be in accordance with ISO 16810.
b) The coupling medium used for range and sensitivity setting and for the test shall be the same.
8 Testing volume
The testing volume (see Figure 2) is defined as the zone which includes weld and parent material and the
width of the heat-affected zone on each side of the weld or at least 10 mm if the width of the heat-affected
zone is not known.
a) In all cases, scanning shall cover the whole testing volume.
b) If individual sections of this volume cannot be covered in at least one scanning direction, or if the
angles of incidence with the opposite surface do not meet the requirements of 7.3.2, alternative or
supplementary ultrasonic techniques or other non-destructive techniques shall be agreed upon.
This may, in some cases, require removal of the weld reinforcement.
Supplementary techniques can require testing using dual-transducer angle-beam probes, creeping wave
probes, further ultrasonic techniques or any other suitable method, e.g. liquid penetrant, magnetic particle,
radiographic testing. In selecting alternative or supplementary techniques, due consideration should be
given to the type of weld and probable orientation of any imperfections to be detected.
9 Preparation of scanning surfaces
a) Scanning surfaces shall be wide enough to permit the testing volume (see Figure 2) to be fully covered.
b) Alternatively, the width of the scanning surfaces may be smaller if equivalent coverage of the testing
volume can be achieved by scanning from both the upper and the lower surface of the joint.
c) Scanning surfaces shall be even and free from foreign matter likely to interfere with probe coupling (e.g.
rust, loose scale, weld spatter, notches, grooves).
d) Waviness of the test surface shall not result in a gap between the probe and test surfaces greater than
0,5 mm.
Requirement Clause 9, list item c) and Clause 9, list item d) shall be ensured by dressing, if necessary. Local
variations in surface contour, e.g. along the edge of the weld, which result in a gap beneath the probe of up
to 1 mm, can only be permitted if at least one additional beam angle is employed from the affected side at

ISO/DIS 17640:2026(en)
the weld. This additional scanning is necessary to compensate for the reduced weld coverage that will occur
with a gap of this dimension.
e) Scanning surfaces and surfaces from which the sound beam is reflected shall allow undisturbed
coupling and reflection.
10 Parent metal testing
a) The parent metal, in the scanning zone area (see Figure 2), shall be tested with straight-beam probes
prior to or after welding, unless it can be demonstrated (e.g. by previous testing during the fabrication
process) that the angle-beam testing of the weld is not influenced by the presence of the imperfections
or high attenuation.
b) Where imperfections are found, their influence on th
...