1、BS ISO 20669:2017Non-destructive testing Pulsed eddy current testingof ferromagnetic metalliccomponentsBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 20669:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 20669:2017.
2、The UK participation in its preparation was entrusted to Technical Committee WEE/46, Non-destructive testing.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. User
3、s are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 92545 0 ICS 19.100 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of t
4、he Standards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 20669:2017 ISO 2017Non-destructive testing Pulsed eddy current testing of ferromagnetic metallic componentsEssais non destructifs Contrle par courants de Fouca
5、ult pulss de composants mtalliques ferromagntiquesINTERNATIONAL STANDARDISO20669First edition2017-03Reference numberISO 20669:2017(E)BS ISO 20669:2017ISO 20669:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise s
6、pecified, 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 o
7、r ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 20669:2017ISO 20669:2017(E)Foreword iv1 Scope . 12 Normative references 13 Terms and definit
8、ions . 14 General principles . 24.1 Principles of PEC testing . 24.2 Characteristics of PEC testing 44.2.1 Advantages 44.2.2 Limitations 44.3 Influence factors 54.3.1 Coating 54.3.2 Tested component . 54.3.3 Temperature 54.3.4 Probe 54.3.5 Reference zone 54.3.6 Other factors 55 Qualification of pers
9、onnel 66 Equipment . 66.1 Testing system . 66.2 PEC instrument . 66.3 Probe 66.4 Sensitivity adjustment 66.5 Test pieces . 76.5.1 Reference blocks 76.5.2 Spacers . 86.5.3 Metal sheet cover . 86.6 Maintenance and verification of equipment 87 On-site testing . 87.1 Preparation of documentation 87.1.1
10、Document prerequisites 87.1.2 Site investigation 87.1.3 Preparation of testing procedure and record sheets 87.2 Preparation of the component to be tested 97.2.1 Surface preparation . 97.2.2 Identification . 97.3 Selection of the references 97.3.1 Principles 97.3.2 Reselection of references . 107.3.3
11、 Record of references 107.4 Performing test 107.5 Safety 108 Interpretation and evaluation of test results 109 Verification of test results 1010 Documentation 1110.1 General 1110.2 General written testing procedure . 1110.3 Testing record . 1210.4 Testing report 12Bibliography .13 ISO 2017 All right
12、s reserved iiiContents PageBS ISO 20669:2017ISO 20669:2017(E)ForewordISO (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 commit
13、tees. 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 In
14、ternational 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
15、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. I
16、SO 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 d
17、ocument 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 ISOs adherence to the World Trade
18、 Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 135, Non-destructive testing, Subcommittee SC 4, Eddy current methods.iv ISO 2017 All rights reservedBS ISO 20669
19、:2017INTERNATIONAL STANDARD ISO 20669:2017(E)Non-destructive testing Pulsed eddy current testing of ferromagnetic metallic components1 ScopeThis document specifies the pulsed eddy current (PEC) testing technique used to perform thickness measurement on ferromagnetic metallic components with or witho
20、ut the presence of coating, insulation and weather sheeting.This document applies to the testing of in-service components made of carbon steel and low-alloy steel in the temperature of 100 C to 500 C (temperature measured at metal surface). The range of wall thickness of components is from 3 mm to 6
21、5 mm and the range of thickness of coatings is from 0 mm to 200 mm. The tested components also include piping of diameter not less than 50 mm.The technique described in this document is sensitive to the geometry of the component and applying the technique to components outside of its scope will resu
22、lt in unpredictable inaccuracy. This document does not apply to the testing of crack defects and local metal loss caused by pitting.This document does not establish evaluation criteria. The evaluation criteria shall be specified by the contractual agreement between parties.2 Normative referencesThe
23、following documents are referred to in 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 15
24、548-3, Non-destructive testing Equipment for eddy current examination Part 3: System characteristics and verificationISO 16809, Non-destructive testing Ultrasonic thickness measurement3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 12718 and the follo
25、wing apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp3.1coatingmaterial which covers the surface of a t
26、ested component in the forms of adhesive, adsorbed layer, bundle, twine or inlay, etc. such as paint, plastic, asphalt, rock-wool, foam, metal mesh, cement, carbon (glass) fibre, marine organism, etc.Note 1 to entry: For the purpose of this document, the word coating is used to describe any protecti
27、ve or insulative layer on the component to be tested.3.2coversheet metal protective layer on the outside of the coating ISO 2017 All rights reserved 1BS ISO 20669:2017ISO 20669:2017(E)3.3excitation pulse durationtime needed for the energy to travel through the actual thickness of the componentNote 1
28、 to entry: It needs to be long enough to penetrate the full thickness3.4decay raterate of change in electromagnetic field measured by the receiver sensor after the transmitter has been switched offNote 1 to entry: For example, the bending point of one of the typical measurement methods (see Figure 1
29、).3.5bending pointpoint where the received signal decay rate changes from linear to exponential3.6characteristic timetime measured between the end of the excitation pulse and the bending pointNote 1 to entry: Its value is proportional to the magnetic permeability, electrical conductivity and the thi
30、ckness squared.3.7pulse repetition frequencyprfnumber of pulses generated per second, expressed in Hertz (Hz)4 General principles4.1 Principles of PEC testingAccording to ISO 12718, pulsed eddy currents are eddy currents generated by a pulsed electromagnetic field.Similar to sinusoidal eddy currents
31、, induced pulsed eddy currents are modified by any local variation in the material properties.The pulse is characterized by its duration (T), which enables to generate induced currents with a very high intensity.The time interval between two measurements is linked to the material thickness.2 ISO 201
32、7 All rights reservedBS ISO 20669:2017ISO 20669:2017(E)Key1 excitation signal waveform2 detection signal waveform3 decay curve4 bending pointFigure 1 Pulsed eddy current signalThe transmission signal from the probe shows a very broad spectrum of frequencies.The received signal also has a frequency (
33、or time) spectrum, the analysis of which provides information coming from different depths in the material.The instrument is specific to the technique, as it must be capable of generating pulses.Probes are of the separate transmit-receive type.The measurement technique varies from one instrument to
34、another, depending on the manufacturer.For example, the measurement techniques could be: use of characteristic time at the bending point; measurement of the time required for a specific decay; measurement of the decay curve slope, etc.See Figure 2. ISO 2017 All rights reserved 3BS ISO 20669:2017ISO
35、20669:2017(E)Key1 sender coil2 receiver devices3 primary magnetic field4 secondary magnetic field5 eddy currents6 cover/sheeting7 insulation8 tested componentNOTE Cladding and insulation form the coating.Figure 2 Basic principle of pulsed eddy current testing technique4.2 Characteristics of PEC test
36、ing4.2.1 AdvantagesThe following characteristics of the method represent the main advantages of PEC testing technique: the method does not require removing the insulation on the product tested; the test can be performed while the plant is in operation; no coupling medium, such as water, is needed.4.
37、2.2 LimitationsThe component geometry shall be known to enable the instrument to be set up properly e.g. excitation pulse length and pulse repetition frequency.There is a number of influencing factors that need to be controlled or taken into account when deploying the technique.4 ISO 2017 All rights
38、 reservedBS ISO 20669:2017ISO 20669:2017(E)4.3 Influence factors4.3.1 CoatingThe nature of the coating can have an influence on the accuracy and sensitivity of the technique. Coating/insulation parameters such as electrical conductivity, magnetic permeability, and thickness should be taken into acco
39、unt.For a coating with ferromagnetic material, extra magnetization may be needed to saturate it for more accurate testing results. It is also important to reduce the vibration, often occurring with such cover, to improve the reliability of the test. Indeed, signals corrupted by too high vibration sh
40、all not be recorded.4.3.2 Tested componentThe tested component may have an influence on the accuracy and sensitivity of the technique, parameters such as material properties of tested component, variation in material properties (from pipe to pipe for example), and variation in thicknessshould be tak
41、en into account.Vibration of the tested component during testing can also lead to the inaccuracy of testing results.4.3.3 TemperatureThe temperature variation inside a component can influence the electromagnetic characteristics of the tested component, and can therefore influence the testing results
42、 accuracy.Temperature variation shall not exceed 20 C.4.3.4 ProbeThe probe shall be selected to suit the component geometry.Other factors influence the accuracy of the technique, including: probe active area; probe motion or probe speed (for dynamic scan); probe position with respect to the componen
43、t; pulse length.4.3.5 Reference zoneThe reference zone is the zone on which the calibration is performed.The differences between test zones and reference zone in physical characteristics such as magnetic permeability and conductivity can influence the testing results. If the differences are too sign
44、ificant, the reference zone shall be reselected.4.3.6 Other factorsCare shall be taken to avoid the presence, modification or movement of conductive or magnetic pieces in the zone of influence of the probe, otherwise test results may be affected. ISO 2017 All rights reserved 5BS ISO 20669:2017ISO 20
45、669:2017(E)5 Qualification of personnelIt is assumed that eddy current testing is performed by qualified and capable personnel. In order to ensure that this is the case, it is recommended that the personnel be certified in accordance with ISO 9712 or equivalent.6 Equipment6.1 Testing systemThe test
46、employs a PEC instrument, a probe and interconnecting cables. This combination, together with some mechanical equipment holding the probe, forms the testing system.All essential parts of the system shall be defined in a written procedure agreed at the time of enquiry or order (see 10.2).6.2 PEC inst
47、rumentThe PEC instrument shall meet the following requirements:a) the repetition frequency and the pulse duration of the excitation signal shall be adjustable and the pulse rise time shall be significantly smaller than the decay time;b) the data acquisition card resolution and sampling frequency sha
48、ll match the required accuracy of the test, and the number of points collected shall be sufficient to enable the assessment of the target defect;c) the system shall have an adjustable sensing duration to ensure that the acquired waveform is long enough to obtain the information necessary for the wal
49、l thickness measurement;d) the display shall be suitable for the measurement method employed, e.g. log/log display for bending point;e) the instrument shall enable the user to store the raw data of an inspection.6.3 ProbeThe following probe characteristics shall be made available to the user: active area dimensions; pulse frequency range; acceptable lift-off range.Cables can be extended to connect the probe and instrument under the condition that the sensitivity and the accuracy of the test results are not chan
