oSIST prEN ISO 18491:2025
(Main)Welding and allied processes - Measurement of arc energies (ISO/DIS 18491:2025)
Welding and allied processes - Measurement of arc energies (ISO/DIS 18491:2025)
This document specifies the measuring of parameters needed to calculate arc energies for arc welding processes.
Schweißen und verwandte Verfahren - Messen der Schweißenergie (ISO/DIS 18491:2025)
Soudage et techniques connexes - Mesure des énergies de l'arc (ISO/DIS 18491:2025)
Varjenje in sorodni postopki - Merjenje energije loka (ISO/DIS 18491:2025)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-junij-2025
Varjenje in sorodni postopki - Merjenje energije loka (ISO/DIS 18491:2025)
Welding and allied processes - Measurement of arc energies (ISO/DIS 18491:2025)
Schweißen und verwandte Verfahren - Messen der Schweißenergie (ISO/DIS
18491:2025)
Soudage et techniques connexes - Mesure des énergies de l'arc (ISO/DIS 18491:2025)
Ta slovenski standard je istoveten z: prEN ISO 18491
ICS:
25.160.01 Varjenje, trdo in mehko Welding, brazing and
spajkanje na splošno soldering in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
International
Standard
ISO/DIS 18491
ISO/TC 44/SC 10
Welding and allied processes —
Secretariat: DIN
Measurement of arc energies
Voting begins on:
Soudage et techniques connexes — Mesure des énergies de l'arc
2025-04-09
Voting terminates on:
ICS: 25.160.01
2025-07-02
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
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INTERNATIONAL STANDARD UNTIL
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Reference number
ISO/DIS 18491:2025(en)
DRAFT
ISO/DIS 18491:2025(en)
International
Standard
ISO/DIS 18491
ISO/TC 44/SC 10
Welding and allied processes —
Secretariat: DIN
Measurement of arc energies
Voting begins on:
Soudage et techniques connexes — Mesure des énergies de l'arc
ICS: 25.160.01 Voting terminates on:
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 2025
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
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Published in Switzerland Reference number
ISO/DIS 18491:2025(en)
ii
ISO/DIS 18491:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 2
5 Welding equipment and measuring devices . 3
6 Determination of arc energy . 3
7 Measurement parameters . 4
7.1 General .4
7.2 Arc voltage . .4
7.3 Welding current .4
7.4 Total instantaneous energy or average instantaneous power .4
7.5 Welding speed and length of the run .5
8 Calibration and validation of measuring instruments . 5
Annex A (informative) Range of power source types and measurement methods . 6
Annex B (informative) Conversion factors . 8
Bibliography . 9
iii
ISO/DIS 18491:2025(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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of
(a) patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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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 10, Quality management in the field of welding.
This second edition cancels and replaces the first edition (ISO/TR 18491:2015), which has been technically
revised.
The main changes are as follows:
— update of normative references in Clause 2;
— update of vocabulary throughout this document in Clause 3 "Terms and defintions", Clause 4 "General",
Clause 5 "Welding equipment and measuring devices", Clause 6 "Determination of arc energy", Clause 7
"Measurement parameters", Clause 8 " Calibration and validation of measuring instruments" and in
Annex A "Range of power source types and measurement methods";
— addition of a new Annex B "Conversion factors";
— update of the Bibliography.
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. Official interpretations of ISO/TC 44 documents, where they exist, are
available from this page: https://committee.iso.org/sites/tc44/home/interpretation.html.
iv
ISO/DIS 18491:2025(en)
Introduction
Welding “arc energy” or “heat input” are fundamental values used to manage the consistency of weld
metal and heat-affected zone properties. ISO 15614 requires the measurement of the welding energies
implemented during a welding procedure qualification, but it does not give details about the methods to be
used. Likewise, during the construction of a welded assembly, inspectors should make sure that the welding
energies comply with the Welding Procedure Specification (WPS). But again, the details of the methods
to be used are not specified. As a consequence, there may be a lack of consistency between the methods
used to measure the welding energies during welding of the test piece and the methods used during the
manufacturing process. This is a potential source of error which could have implications on the safety or
quality of a welded component or structure.
Moreover, the latest technological breakthroughs in microprocessors and electrical power manipulation
have yielded welding power sources and control systems that are capable of generating complex waveforms.
However, these control systems and waveforms increase the difficulties related to voltage and current
intensity measurements, as their values are manipulated at frequencies which can reach thousands of Hertz.
The measuring instruments generally used by inspectors, such as TRMS clamp meters, can no longer be
relied on to correctly measure the welding energy since differences exceeding 30 % with respect to the true
energy can sometimes be found.
This document provides guidance on how to accurately measure welding energy and calculate heat input,
both in the case of traditional welding systems and those that employ complex waveforms.
v
DRAFT International Standard ISO/DIS 18491:2025(en)
Welding and allied processes — Measurement of arc energies
1 Scope
This document specifies the measuring of parameters needed to calculate arc energies for arc welding
processes.
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 4063, Welding, brazing, soldering and cutting — Nomenclature of processes and reference numbers
ISO 17662, Welding — Calibration, verification and validation of equipment used for welding, including ancillary
activities
ISO/TR 17671 (all parts), Welding — Recommendations for welding of metallic materials
ISO/TR 25901-1, Welding and allied processes — Vocabulary — Part 1: General terms
ISO/TR 25901-3, Welding and allied processes — Vocabulary — Part 3: Welding processes
ISO/TR 25901-4, Welding and allied processes — Vocabulary — Part 4: Arc welding
IEC 60974-14, Arc welding equipment – Part 14: Calibration, validation and consistency testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TR 25901-1, ISO/TR 25901-3,
ISO/TR 25901-4 and ISO/TR 17671 (all parts) and the following 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/
3.1
power
product of arc voltage and welding current
3.2
energy
product of arc voltage and welding current and arc time
3.3
arc
...
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