SIST EN ISO 20339:2017
(Main)Non-destructive testing - Equipment for eddy current examination - Array probe characteristics and verification (ISO 20339:2017)
Non-destructive testing - Equipment for eddy current examination - Array probe characteristics and verification (ISO 20339:2017)
The purpose of this standard is to identify the functional characteristics of an eddy current array probe and its interconnecting elements and to provide methods for their measurement and verification. The evaluation of these characteristics permits a well-defined description and comparability of an eddy current equipment. Probes and interconnecting elements are selected to satisfy the requirements of the intended application. The design is influenced by the instrument with which they are used. This standard gives acceptance criteria for the characteristics (as recommendations).
Zerstörungsfrei Prüfung - Ausrüstung zur Wirbelstromprüfung - Array-Prüfkopfeigenschaften und -überprüfung (ISO 20339:2017)
Dieses Dokument legt die Funktionskenngrößen von Wirbelstrom-Sensorarrays und zugehörigen Verbindungselementen fest und stellt Verfahren für deren Messung und Verifi¬zierung bereit.
Die Beurteilung dieser Kenngrößen ermöglicht eine genaue Beschreibung und die Vergleichbarkeit von Wirbelstrom-Sensorarrays.
Sofern relevant gibt dieses Dokument Empfehlungen für Annahmekriterien der Kenngrößen.
Essais non destructifs - Appareillage pour examen par courants de Foucault - Caractéristiques des capteurs multiéléments et vérifications (ISO 20339:2017)
ISO 20339:2017Foucault et de leurs éléments d'interconnexion, et fournit des méthodes pour les mesurer et les vérifier.
L'évaluation de ces caractéristiques permet de donner une description bien définie des capteurs multiéléments à courants de Foucault et d'assurer la possibilité de les comparer.
Le cas échéant, le présent document donne des recommandations relatives aux critères d'acceptation pour les caractéristiques.
Neporušitvene preiskave - Oprema za preiskave z vrtinčnimi tokovi - Značilnosti vrste sonde in preverjanje (ISO 20339:2017)
Namen tega standarda je določanje funkcijskih značilnosti sonde za vrtinčne tokove in njenih povezovalnih elementov ter navajanje metod za merjenje in preverjanje s temi instrumenti. Ocena teh značilnosti omogoča dobro opredeljen opis in primerjavo opreme za preiskave z vrtinčnimi tokovi. Sonde in njihovi povezovalni elementi so izbrani za izpolnjevanje zahtev predvidene uporabe. Na zasnovo vpliva oprema, s katero se uporabljajo. Ta standard podaja merila sprejemljivosti za značilnosti (v obliki priporočil).
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 20339:2017
01-julij-2017
1HSRUXãLWYHQHSUHLVNDYH2SUHPD]DSUHLVNDYH]YUWLQþQLPLWRNRYL=QDþLOQRVWL
YUVWHVRQGHLQSUHYHUMDQMH ,62
Non-destructive testing - Equipment for eddy current examination - Array probe
characteristics and verification (ISO 20339:2017)
Zerstörungsfrei Prüfung - Ausrüstung zur Wirbelstromprüfung - Array-
Prüfkopfeigenschaften und -überprüfung (ISO 20339:2017)
Essais non destructifs - Appareillage pour examen par courants de Foucault -
Caractéristiques des capteurs multiéléments et vérifications (ISO 20339:2017)
Ta slovenski standard je istoveten z: EN ISO 20339:2017
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
SIST EN ISO 20339:2017 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 20339:2017
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SIST EN ISO 20339:2017
EN ISO 20339
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2017
EUROPÄISCHE NORM
ICS 19.100
English Version
Non-destructive testing - Equipment for eddy current
examination - Array probe characteristics and verification
(ISO 20339:2017)
Essais non destructifs - Appareillage pour examen par Zerstörungsfreie Prüfung - Technische Ausrüstung für
courants de Foucault - Caractéristiques des capteurs die Wirbelstromprüfung - Kenngrößen von
multiéléments et vérifications (ISO 20339:2017) Sensorarrays und deren Verifizierung (ISO
20339:2017)
This European Standard was approved by CEN on 5 February 2017.
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, Serbia, 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
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20339:2017 E
worldwide for CEN national Members.
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SIST EN ISO 20339:2017
EN ISO 20339:2017 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 20339:2017
EN ISO 20339:2017 (E)
European foreword
This document (EN ISO 20339:2017) has been prepared by Technical Committee ISO/TC 135 "Non-
destructive testing" in collaboration with 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 October 2017, and conflicting national standards shall
be withdrawn at the latest by October 2017.
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.
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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 20339:2017 has been approved by CEN as EN ISO 20339:2017 without any modification.
3
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SIST EN ISO 20339:2017
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SIST EN ISO 20339:2017
INTERNATIONAL ISO
STANDARD 20339
First edition
2017-03
Non-destructive testing — Equipment
for eddy current examination — Array
probe characteristics and verification
Essais non destructifs — Appareillage pour examen par courants
de Foucault — Caractéristiques des capteurs multiéléments et
vérifications
Reference number
ISO 20339:2017(E)
©
ISO 2017
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SIST EN ISO 20339:2017
ISO 20339:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
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SIST EN ISO 20339:2017
ISO 20339:2017(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Probe and interconnecting elements characteristics . 2
4.1 General characteristics . 2
4.1.1 Application . 2
4.1.2 Probe types . 2
4.1.3 Interconnecting elements . 2
4.1.4 Physical characteristics . 2
4.1.5 Safety . 3
4.1.6 Environmental conditions . 3
4.2 Electrical characteristics . 3
4.3 Functional characteristics . 3
5 Verification . 4
5.1 Level of verifications . 4
5.2 Characteristics to be verified . 4
6 Measurement of electrical and functional characteristics of an array probe .5
6.1 Electrical characteristics . 5
6.1.1 General. 5
6.1.2 Measurement conditions . 5
6.1.3 Impedance of coil elements . 5
6.1.4 Impedance of a pattern . 5
6.1.5 Channel assignment — Sequencing . 6
6.1.6 Cross-talk. 6
6.2 Functional characteristics . 6
6.2.1 General. 6
6.2.2 Measurement conditions . 6
7 Surface array probes . 8
7.1 Reference blocks . 8
7.2 Probe motion . 9
7.3 Reference signal — Normalization . 9
7.4 Edge effect (measurable in the case of simple geometry, e.g. metal sheets, disks).10
7.5 Response to a slot .11
7.6 Response to a hole .12
7.7 Length of coverage .12
7.8 Variation in sensitivity between patterns.12
7.9 Minimum slot length for constant probe response .13
7.10 Lift-off effect .13
7.11 Effect of probe clearance on slot response .13
7.12 Effective depth of detection of a sub-surface slot .14
7.13 Resolution .14
7.14 Defective element or pattern .14
8 Coaxial array probes .14
8.1 General conditions .14
8.2 Reference blocks .14
8.3 Reference signal .16
8.4 Absence of defective elements.17
8.5 Position mark of the probe (mainly for positioning) .17
8.6 End effect .17
8.7 Length of coverage .17
8.8 Homogeneity of axial response . .18
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SIST EN ISO 20339:2017
ISO 20339:2017(E)
8.9 Eccentricity effect .19
8.10 Fill effect .19
8.11 Effective depth of penetration .19
8.12 Effective depth of detection under ligament .19
9 Influence of interconnecting elements .19
Annex A (informative) Simulation of surface probe resolution .20
iv © ISO 2017 – All rights reserved
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SIST EN ISO 20339:2017
ISO 20339:2017(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.
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 on 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 the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 135, Non-destructive testing,
Subcommittee SC 4, Eddy current testing.
© ISO 2017 – All rights reserved v
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SIST EN ISO 20339:2017
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SIST EN ISO 20339:2017
INTERNATIONAL STANDARD ISO 20339:2017(E)
Non-destructive testing — Equipment for eddy current
examination — Array probe characteristics and
verification
1 Scope
This document identifies the functional characteristics of eddy current array probes and their
interconnecting elements and provides methods for their measurement and verification.
The evaluation of these characteristics permits a well-defined description and comparability of eddy
current array probes.
Where relevant, this document gives recommendations for acceptance criteria for the characteristics.
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 12718, Non-destructive testing — Eddy current testing — Vocabulary
ISO 15548-1, Non-destructive testing — Equipment for eddy current examination — Part 1: Instrument
characteristics and verification
ISO 15548-2:2013, Non-destructive testing — Equipment for eddy current examination — Part 2: Probe
characteristics and verification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12718 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
element
single physical component such as a coil, a GMR or a Hall probe which has a basic function of excitation
or reception
3.2
pattern
single physical and electronic arrangement of simultaneously active elements
3.3
sequencing
chronology of the activation of patterns
3.4
threshold
lowest acceptable sensitivity value defined in an application document
© ISO 2017 – All rights reserved 1
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SIST EN ISO 20339:2017
ISO 20339:2017(E)
4 Probe and interconnecting elements characteristics
4.1 General characteristics
4.1.1 Application
Probes and interconnecting elements are selected to satisfy the requirements of the intended
application.
The design is influenced by the instrument with which they are used.
4.1.2 Probe types
The probe is described by the following:
— type of material to be examined, i.e. ferromagnetic, non-ferromagnetic with high or low conductivity;
— the geometry of the examined zone;
— whether it is conformable or not;
— family, e.g. coaxial probe, surface probe;
— the receiver type;
— the number of elements (transmitters and/or receivers);
— shape and assembly of elements and spacing;
— purpose of the examination, e.g. detection of discontinuities, sorting or thickness measurement, etc.;
— specific features, e.g. focused, shielded, etc.;
— the function of the elements (transmission or reception) as well as the type of measurement (absolute
or differential) may coexist in the same array probe depending on the patterns, the sequencing and
the instrument software.
4.1.3 Interconnecting elements
They may include the following:
— active devices, e.g. multiplexer (built-in or external), amplifier;
— cables and/or extensions;
— connectors;
— slip rings;
— rotating heads;
— polarizers.
4.1.4 Physical characteristics
The following are to be stated among others:
— external size and shape;
— weight;
— information for mechanical mounting;
2 © ISO 2017 – All rights reserved
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SIST EN ISO 20339:2017
ISO 20339:2017(E)
— model number and serial number;
— material of probe housing;
— composition and thickness of facing material;
— presence and purpose of core or shield;
— type of interconnecting elements (see 4.1.3);
— at least one position mark (electrical centre; see 8.5).
4.1.5 Safety
The probe and its interconnecting elements shall meet the applicable safety regulations regarding
electrical hazard, surface temperature, or explosion.
Normal use of the probe should not create a hazard.
4.1.6 Environmental conditions
The temperature and humidity for normal use, storage and transport should be specified for the probe
and its interconnecting elements.
The tolerance of the probe and its interconnecting elements to the effects of interference noise and
electromagnetic radiation shall conform to electromagnetic compatibility (EMC) regulations.
Materials used in the manufacture of the probe should be resistant to contaminants.
4.2 Electrical characteristics
The electrical characteristics of a probe connected to a specified length and type of cable are the
following:
— recommended range of excitation voltage for safe operation;
— recommended range of excitation frequencies.
The electrical characteristics of any extension cable are the following:
— resistance and capacitive reactance per length unit.
4.3 Functional characteristics
The functional characteristics of an array probe shall be determined for a defined system.
The measurement of the functional characteristics of a probe requires the use of reference blocks. The
material used for the reference block is determined by the application.
The functional characteristics of a probe are the following:
— angular sensitivity;
— response to elementary discontinuities or variations (hole, slot, deposit, etc.);
— length and width of coverage for a given pattern;
— area of coverage for a given pattern;
— minimum dimensions of discontinuities for constant response;
— penetration characteristics;
© ISO 2017 – All rights reserved 3
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SIST EN ISO 20339:2017
ISO 20339:2017(E)
— geometric effects;
— cross-talk;
— number of dead elements.
These characteristics cannot be used alone to establish the performance (e.g. resolution, largest
undetectable discontinuity, etc.) of the probe in a given test system for a given application.
When relevant, the functional characteristics shall be measured on the probe with the interconnecting
elements required by the application.
5 Verification
5.1 Level of verifications
Two levels of verification may be required:
a) basic level: addresses detection performance;
b) advanced level: addresses characterization performance:
— verification of a motion system where there is a need for mechanization of some measurements
(movement of the probe);
— digitization and scanning speed: number of measurement points per millimetre.
The qualification of a process which may imply an agreement between manufacturer and customer is
not considered in this document.
5.2 Characteristics to be verified
The characteristics to be verified are listed in Table 1.
Table 1 — Array probe characteristics
Characteristic Basic level Advanced level
Outer dimensions I M
Conformability of the probe I M
Area of coverage I M
Number of elements I M
Arrangement M M
Excitation frequencies M M
Nature of elements I I
Element dimensions I I
Distances between elements I I
Assembly I I
External or built-in multiplexer I I
Length and type of supplied cable I I
I: measured by the manufacturer or design data, reported on the technical specification.
M: measured by the manufacturer and/or the user.
The manufacturer should add what type and orientation of discontinuity the probe is designed for.
Where more information on the elements is needed by the user (e.g. for simulation), then it may be part of a specific
agreement.
4 © ISO 2017 – All rights reserved
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SIST EN ISO 20339:2017
ISO 20339:2017(E)
6 Measurement of electrical and functional characteristics of an array probe
6.1 Electrical characteristics
6.1.1 General
The electrical characteristics alone do not define the probe characteristics in its application.
The methods and measuring instruments given below are for guidance; other equivalent methods
and instrumentation can be used. When characteristics are measured using modelling, this shall be
clearly stated.
6.1.2 Measurement conditions
Array probes (surface probes and coaxial probes) are in most cases specific to one application.
They are delivered with a cable, the design of which depends on the number of elements and which
cannot be removed for measurements. The characteristics of the cable are generally proprietary
information.
The manufacturer provides a cable, the length of which is compatible in terms of resonance and
attenuation with the future use of the probe as described by the customer.
The following measurements are only applicable to elements consisting of coils.
In the case where receiving elements are not coils, specific measurements shall be defined.
The measurements are made at the probe connector which is at one end of the connecting cable,
without the use of interconnecting elements of the inspection system. The probe is placed in air and
away from any conductive or magnetic material. These measurements are only possible if no electronic
components (such as amplifiers, multiplexers, etc.) are active in the probe.
The measurements are made for each element of the probe accessible at the probe connector. The other
elements are left open circuit.
When the probe is designed for use under particular conditions, e.g. temperature or pressure, then any
additional measurements that are required shall be specified in the application document.
6.1.3 Impedance of coil elements
The impedance of all coil elements shall be measured using an impedance meter or impedance analyser
as long as the measurement is not prevented by built-in amplifiers. The measured impedance can be
given as the values of an equivalent circuit (resistance, inductance and capacitance) or as curve vs.
frequency (Bode plot or Nyquist plot).
6.1.4 Impedance of a pattern
This measurement is not normally performed by the user as it is not possible once the probe is
assembled. It is the manufacturer’s responsibility.
— Impedance mode
Measure the complex impedance at the central frequency
— Separate transmit receive
Feed a voltage with the central frequency at the input of the transmitting element and measure the
voltage at the output
Repeat the measurements on each pattern.
© ISO 2017 – All rights reserved 5
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...
SLOVENSKI STANDARD
oSIST prEN ISO 20339:2016
01-februar-2016
1HSRUXãLWYHQRSUHVNXãDQMH2SUHPD]DSUHLVNDYH]YUWLQþQLPLWRNRYL=QDþLOQRVWL
YUVWHVRQGHLQSUHYHUMDQMH ,62',6
Non-destructive testing - Equipment for eddy current examination - Array probe
characteristics and verification (ISO/DIS 20339:2015)
Zerstörungsfrei Prüfung - Ausrüstung zur Wirbelstromprüfung - Array-
Prüfkopfeigenschaften und -überprüfung (ISO/DIS 20339:2015)
Essais non destructifs - Appareillage pour examen par courants de Foucault -
Caractéristiques des capteurs multiéléments et vérifications (ISO/DIS 20339:2015)
Ta slovenski standard je istoveten z: prEN ISO 20339
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
oSIST prEN ISO 20339:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 20339:2016
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oSIST prEN ISO 20339:2016
DRAFT INTERNATIONAL STANDARD
ISO/DIS 20339
ISO/TC 135/SC 4 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2015-12-03 2016-03-03
Non-destructive testing — Equipment for eddy current
examination — Array probe characteristics and verification
Essais non destructifs — Appareillage pour examen par courants de Foucault — Caractéristiques des
capteurs multiéléments et vérifications
ICS: 19.100
ISO/CEN PARALLEL PROCESSING
This draft has been developed within the European Committee for Standardization
(CEN), and processed under the CEN lead mode of collaboration as defined in the
Vienna Agreement.
This draft is hereby submitted to the ISO member bodies and to the CEN member
bodies for a parallel five month enquiry.
Should this draft be accepted, a final draft, established on the basis of comments
received, will be submitted to a parallel two-month approval vote in ISO and
THIS DOCUMENT IS A DRAFT CIRCULATED
formal vote in CEN.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
To expedite distribution, this document is circulated as received from the
IN ADDITION TO THEIR EVALUATION AS
committee secretariat. ISO Central Secretariat work of editing and text
BEING ACCEPTABLE FOR INDUSTRIAL,
composition will be undertaken at publication stage.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 20339:2015(E)
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. ISO 2015
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oSIST prEN ISO 20339:2016
ISO/DIS 20339:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
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oSIST prEN ISO 20339:2016
Contents
1 Scope . 3
2 Normative references . 3
3 Terms and definitions . 3
4 Probe and interconnecting elements characteristics . 3
5 Verification . 6
6 Measurement of electrical and functional characteristics of a probe. . 7
7 Surface probes . 10
8 Coaxial probes. . 17
9 Influence of interconnecting elements . 22
ANNEX 1 (Informative) . 23
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oSIST prEN ISO 20339:2016
1 Scope
The purpose of this standard is to identify the functional characteristics of an eddy current
array probe and its interconnecting elements and to provide methods for their measurement
and verification.
The evaluation of these characteristics permits a well-defined description and comparability
of an eddy current array probe.
This standard gives recommendations for acceptance criteria for the characteristics.
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 15548-2, Non-destructive testing - Equipment for eddy current examination - Part 2:
Probe characteristics and verification
ISO 12718, Non-destructive testing - Eddy current testing - Vocabulary
3 Terms and definitions
For the purposes of this standard the definitions given in ISO 12718 apply, as well as the
following definitions
Element:
single physical component (coil, GMR, Hall probe) which has a basic function (excitation,
reception)
Pattern:
single physical and electronic arrangement of simultaneously active elements
Sequencing:
chronology of the activation of patterns
4 Probe and interconnecting elements characteristics
4.1 General characteristics
4.1.1 Application
Probes and interconnecting elements are selected to satisfy the requirements of the intended
application.
The design is influenced by the instrument with which they are used.
4.1.2 Probe types
The probe is described by:
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oSIST prEN ISO 20339:2016
- type of material to be examined i.e. ferromagnetic, non-ferromagnetic with high or low
conductivity;
- the geometry of the examined zone;
- whether it is conformable or not;
- function e.g. separate or combined transmit receive probe;
- family e.g. coaxial probe, surface probe;
- measurement mode e.g. absolute, differential;
- the receiver type;
- the number of elements (transmitters and/or receivers);
- shape of elements and spacing;
- purpose of the examination e.g. detection of discontinuities, sorting or thickness
measurement etc.;
- specific features e.g. focused, shielded, etc.
4.1.3 Interconnecting elements
They may include:
- active devices, e.g. multiplexer (built-in or external), amplifier;
- cables and/or extensions;
- connectors;
- slip rings;
- rotating heads;
- transformers;
- polarizers.
4.1.4 Physical characteristics.
The following are to be stated amongst others:
- external size and shape;
- weight;
- information for mechanical mounting;
- model number and serial number;
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oSIST prEN ISO 20339:2016
- material of manufacture of probe housing;
- composition and thickness of facing material;
- presence and purpose of core or shield;
- type of interconnecting elements, (see 4.1.3);
- at least one position mark (electrical centre, see 8.4).
4.1.5 Safety
The probe and its interconnecting elements shall meet the applicable safety regulations
regarding electrical hazard, surface temperature, or explosion.
Normal use of the probe should not create a hazard.
4.1.6 Environmental conditions
The temperature and humidity for normal use, storage and transport should be specified for
the probe and its interconnecting elements.
The tolerance of the probe and its interconnecting elements to the effects of interference
noise and electromagnetic radiation shall conform to electromagnetic compatibility (EMC)
regulations.
Materials used in the manufacture of the probe should be resistant to contaminants.
4.2. Electrical Characteristics
The electrical characteristics of a probe connected to a specified length and type of cable
are:
- recommended range of excitation current and voltage for safe operation;
- recommended range of excitation frequencies;
- cross-talk.
The electrical characteristics of any extension cable are:
- resistance and capacitive reactance per length unit.
4.3. Functional Characteristics
The functional characteristics of an array probe shall be determined for a defined system.
The measurement of the functional characteristics of a probe requires the use of reference
blocks. The material used for the reference block is determined by the application.
The functional characteristics of a probe are:
- directionality;
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- response to elementary discontinuities or variations (hole, slot, deposit.);
- length and width of coverage for a given pattern;
- area of coverage for a given pattern;
- minimum dimensions of discontinuities for constant response ;
- penetration characteristics;
- geometric effects;
- number of dead elements.
These characteristics cannot be used alone to establish the performance (e.g. resolution,
largest undetectable discontinuity…) of the probe in a given test system, for a given
application.
When relevant, the functional characteristics shall be measured on the probe with the
interconnecting elements required by the application.
5 Verification
5.1 Level of verifications
Two levels of verification may be required:
Basic level: addresses detection performance.
Advanced level: addresses characterisation performance:
- Verification of a motion system where there is a need for mechanisation of some
measurements (movement of the probe);
- Digitisation and scanning speed: number of measurement points per mm.
The qualification of a process which may imply an agreement between manufacturer and
customer is not considered in this standard.
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5.2 Characteristics to be verified
Characteristic Basic level Advanced level
Outer dimensions I M
Conformability of the probe I M
Area of coverage I M
Number of elements I M
Assembly M M
Excitation frequencies M M
Nature of elements I I
Element dimensions I I
Distances between elements I I
Arrangement I I
External or built-in multiplexer I I
Length and type of supplied
I I
cable
I: measured by the manufacturer or design data, reported on the technical specification.
M: measured by the manufacturer and/or the user.
Note 1: The manufacturer should add what type and orientation of discontinuity the probe is designed
for.
Note 2: Where more information on the elements is needed by the user (e.g. for simulation), then it
may be part of a specific agreement.
6 Measurement of electrical and functional characteristics of a probe.
6.1 Electrical characteristics
6.1.1 General
The electrical characteristics alone do not define the probe characteristics in its application.
The methods and measuring instruments given below are for guidance; other equivalent
methods and instrumentation or modelling can be used.
6.1.2 Measurement conditions
Array probes (surface probes and coaxial probes) are in most cases specific to one
application.
They are delivered with a cable the design of which depends on the number of elements and
which cannot be removed for measurements. The characteristics of the cable are generally
proprietary information.
The manufacturer provides a cable the length of which is compatible in terms of resonance
and attenuation with the future use of the probe as described by the customer.
The following measurements are only applicable to elements consisting of coils.
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The measurements are made at the probe connector which is at one end of the connecting
cable, without the use of interconnecting elements of the inspection system. The probe is
placed in air and away from any conductive or magnetic material. These measurements are
only possible if no electronic components (such as amplifiers, multiplexers…) are active in
the probe.
The measurements are made for each element of the probe accessible at the probe
connector. The other elements are left open circuit.
When the probe is designed for use under particular conditions e.g. temperature or pressure,
then any additional measurements that are required shall be specified in the application
document.
6.1.3 Receiving element (or elements) impedance
The resistance, the inductance and capacitance shall be measured using an impedance
meter. The impedance measured values can be given as a curve against frequency.
6.1.4 Impedance of a pattern
This measurement is not normally performed by the user as it is not possible once the probe
is assembled. It is of the manufacturer’s responsibility.
Carry out the measurements using a network analyser or an impedance meter.
Feed a current with the central frequency at the input and measure the voltage at the output.
Repeat the measurements on all the patterns
Verify the homogeneity of the results.
In case of significant deviation, apply the adequate corrections (connections…)
6.1.5 Channel assignment - Sequencing
Verification of channel assignment is essential. The following operating procedure is for
guidance.
Measurements are carried out at the central frequency.
Produce a C-scan type cartography of a defect at angle with the direction of scanning: a slot
at 45° (Block A1) for a surface probe, a helix on a tube wall (block B2) for coaxial probes.
The value of the angle shall be chosen in accordance with the scanning step and the
dimensions of a pattern.
Verify the channel assignment and the uniformity of the signals obtained on those channels
In the case of complex configurations, the verification procedure is left to the manufacturer’s
initiative.
Note: the case of static probes in which scanning is performed electronically is not covered by this
measurement; a case-by-case procedure shall be produced.
6.1.6 Cross-talk
Cross-talk always exists in array probes. It is actually attenuated by multiplexing non-
neighbouring elements.
The level of cross-talk is very much dependent on the application; therefore, acceptance
criteria cannot be given in this standard.
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6.2 Functional Characteristics
6.2.1 General
This standard characterises commonly used probe types. Probes which are designed for
special (unusual) applications shall be characterised in accordance with an application
document which follows the methodology of this standard. The characteristics described in
this standard can give useful information about such probes.
The functional characteristics are defined for two classes of probes: surface probes and co-
axial probes.
6.2.2 Measurement conditions
6.2.2.1 General
A general purpose eddy current instrument characterised in accordance with ISO 15548-1
can be used, provided that it has the required accuracy.
Alternatively sufficient instrumentation comprising a voltage/current generator, synchronous
detection amplifier and a voltmeter or oscilloscope can be used.
When the probe does not feature a connecting cable, then the characteristics of the cable
used for the measurements shall be documented.
The probe characteristics are measured within the frequency range specified by the probe
manufacturer using reference blocks containing known features such as slots and holes.
The reference blocks shall be made from the material, metallurgical properties and surface
finish specified in the application document. Its geometry shall comply with the requirements
included in the following chapters. Where necessary, blocks made with ferromagnetic
material could be demagnetized before use.
The reference block can be replaced by any other device the equivalence of which shall be
demonstrated for the measured characteristic, (alternative blocks, electric circuit, coil, ball,
etc.).
The functional characteristics can be affected by the presence of any perturbing
electromagnetic field or ferromagnetic material in the zone of influence of the probe. Care
shall be taken to avoid these effects when making the measurements described below.
The measurement conditions for each characteristic shall be recorded e.g. excitation
frequency and voltage/current, details of the reference block, etc.
The measured values are the amplitude of the signal and, when applicable, the phase of the
signal.
6.2.2.2 Measurement of the amplitude of the signal.
a) Absolute measurements
The amplitude of the signal is the length of the vector joining the balance point to the point
corresponding to the maximum excursion of the signal from the balance point, unless
otherwise specified in an application document, see figure 1a.
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A
Figure 1a: Amplitude measurement for an absolute signal
b) Differential measurements
The amplitude of the signal is the length of the line joining the two extreme points of the
signature i.e. peak to peak value, unless otherwise specified in an application document, see
figure 1b.
A
Figure 1b: amplitude measurement for a differential signal
c) Other measurements
The method shall be specified in an application document.
6. 2.2.3 Measurement of the phase angle of a signal.
The phase angle is the angle between the reference line and the line representing the signal
amplitude determined in 6.2.2.2
The reference line for the measurement of phase angle shall be specified.
For the span and polarity of measurements, refer to ISO 15548-2, clause 6.2.2.3
7 Surface probes
Unless otherwise specified, the measurements shall be conducted with constant probe
clearance, which will be specified in the application document.
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7.1 Reference Blocks
The design shall be optimised in order to avoid any end effect. For each of these reference
blocks, the length and width shall be at least the length and width of the probe increased by
at least twice the length of the zone of action of the probe as defined in the probe
specifications. When this feature is not known, it shall be replaced by the largest (active)
dimension of the probe in the scanning plane. A verification can be made after having
measured the length of coverage as described in 7.5.
The thickness of the reference block shall be at least three times the standard depth of
penetration for the lowest frequency nominated in the probe specification.
The material used to manufacture the block shall be sound and homogeneous. The physical
properties (electrical conductivity) shall be close to those of the application.
Each block shall have a reception sheet including dimensional measu
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