1、BSI Standards PublicationBS EN ISO 2746:2015Vitreous and porcelain enamels High voltage testBS EN ISO 2746:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 2746:2015. It supersedes BS EN 14430:2004 which is withdrawn.The UK participation in its preparati
2、on was entrusted to Technical Committee STI/36, Vitreous enamel coatings.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. Users are responsible for its correct ap
3、plication. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 81970 4 ICS 25.220.50 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy
4、Committee on 31 October 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 2746 October 2015 ICS 25.220.50 Supersedes EN 14430:2004English Version Vitreous and porcelain enamels - High voltage test (ISO 2746:2015) E
5、maux vitrifis - Essai sous haute tension (ISO 2746:2015) Emails und Emaillierungen - Hochspannungsprfung (ISO 2746:2015) This European Standard was approved by CEN on 29 August 2015. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving t
6、his 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
7、 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 Aus
8、tria, 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, Slovakia, Slovenia, Spain, Swed
9、en, Switzerland, Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN
10、 national Members. Ref. No. EN ISO 2746:2015 EBS EN ISO 2746:2015EN ISO 2746:2015 (E) 3 European foreword This document (EN ISO 2746:2015) has been prepared by Technical Committee ISO/TC 107 “ Metallicand other inorganic coatings“ in collaboration with Technical Committee CEN/TC 262 “Metallic andoth
11、er inorganic coatings” the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of anidentical text or by endorsement, at the latest by April 2016, and conflicting national standards shall bewithdrawn at the latest by Apr
12、il 2016. Attention is drawn to the possibility that some of the elements of this document may be the subject ofpatent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patentrights. This document supersedes EN 14430:2004. According to the CEN-CENELEC Internal R
13、egulations, the national standards organizations of thefollowing 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, I
14、taly, Latvia, Lithuania, Luxembourg, Malta,Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,Turkey and the United Kingdom. Endorsement notice The text of ISO 2746:2015 has been approved by CEN as EN ISO 2746:2015 without any modification. BS EN ISO 2746:
15、2015ISO 2746:2015(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 25 Apparatus . 26 Specimens 27 Test voltage . 37.1 Test A: Detection of defects (3.1) which extend down to the metal basis (e.g. open pores) 37.2 Test B: Detection of defects and we
16、ak spots (3.2) 48 Procedure. 49 Test report . 4Bibliography 6 ISO 2015 All rights reserved iiiContents PageBS EN ISO 2746:2015ISO 2746:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepa
17、ring 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 l
18、iaison 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 D
19、irectives, 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
20、 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 dec
21、larations 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 meaning of ISO specific terms and expressions related to conformity assessment, as well as information
22、about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationISO 2746 was prepared by the European Committee for Standardization (CEN) Technical Committee CEN/TC 262, Metallic and other inorganic coatings, in collabora
23、tion with Technical Committee ISO/TC 107, Metallic and other inorganic coatings, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).This third edition cancels and replaces the second edition (ISO 2746:1998) which has been technically revised. This editio
24、n has also been adopted as a European standard, which supersedes EN 14430:2004.iv ISO 2015 All rights reservedBS EN ISO 2746:2015ISO 2746:2015(E)IntroductionThere are two different objectives for high voltage testing of vitreous and porcelain enamels.Test A is used to detect and locate defects, whic
25、h extend down to the metal base (e.g. open pores). This is a non-destructive test usually applied to thin enamel coatings. The test serves to monitor either that the parts produced are free from defects at the chosen test voltage, or to count the number of existing defects, e.g. to determine the def
26、ect density (defects/m2) of enamelled architecture panels.Test B is used to detect and locate defects, which extend down to the metal base (e.g. open pores) and to detect weak spots. This is a destructive test, i.e. the test can generate open pores with an electric discharge through weak spots in th
27、e enamel coating. This test is usually applied to thick enamel coatings and serves:a) to verify that an enamel coating is safe to be used under highly corrosive conditions, e.g. to test the enamel coating of vessels used in the chemical industry, orb) to verify that the enamel coating is safe to be
28、used as a dielectric.Test A and test B require the same test equipment (see Clause 5) and follow the same test procedure (see Clause 8). However, for test B the applied voltage is higher than in test A (see Clause 7). ISO 2015 All rights reserved vBS EN ISO 2746:2015BS EN ISO 2746:2015Vitreous and p
29、orcelain enamels High voltage testWARNING This International Standard may not be compliant with some countries health and safety legislations and calls for the use of substances and/or procedures that may be injurious to health if adequate safety measures are not taken. This International Standard d
30、oes not address any health hazards, safety or environmental matters and legislations associated with its use. It is the responsibility of the user of this International Standard to establish appropriate health, safety and environmentally acceptable practices and take suitable actions to comply with
31、any national and international regulations. Compliance with this International Standard does not of itself confer immunity from legal obligations.1 ScopeThis International Standard describes two test methods of high voltage testing: Test A is used to detect and locate defects in vitreous and porcela
32、in enamels; Test B is used to detect and locate defects and weak spots in vitreous and porcelain enamels.The tests are performed using DC or pulsed DC high voltage.The tests are applicable to dry surfaces of enamel coatings. In the case of moist surfaces, care should be taken to ensure that the loca
33、ting of any defects is correctly performed.Since test voltages depend on the coating thickness, the test method, especially with test A, may not be suitable for test specimens for which the coating thickness varies to a large extent.2 Normative referencesThe following documents, in whole or in part,
34、 are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 2178, Non-magnetic coatings on magnetic substrate
35、s Measurement of coating thickness Magnetic methodISO 2360, Non-conductive coatings on non-magnetic electrically conductive basis materials Measurement of coating thickness Amplitude-sensitive eddy-current methodIEC/TS 60479-1, Effects of current on human beings and livestock Part 1: General aspects
36、IEC/TS 60479-2, Effects of current on human beings and livestock Part 2: Special aspects3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1defectarea of an enamel layer where an open path connects the enamel surface with the metal basisNote 1 to en
37、try: Examples of defects are cracks or pores.INTERNATIONAL STANDARD ISO 2746:2015(E) ISO 2015 All rights reserved 1BS EN ISO 2746:2015ISO 2746:2015(E)3.2weak spotarea of an enamel layer where the dielectric strength falls below the required value, as determined by the application of high voltage bec
38、ause of blisters, foreign body inclusions, spalling or cracks4 PrincipleA high voltage electrode is passed over the enamel surface. Defects (Test A) or defects and weak spots (Test B) are indicated by a spark and a simultaneous optical and/or acoustic signal. The applied voltage can be DC or pulsed
39、DC. The test voltage might be different in each case.At distances smaller than 2 cm of the edges/borders of the enamelled parts, an electrical arc can occur between the test electrode and edges/borders with no or only a limited enamel coating thickness. The high voltage technique may, therefore, not
40、 be applicable to such border areas.5 Apparatus5.1 High voltage generator.5.1.1 Direct-current (DC)-voltage generator, conforming to the requirements of IEC/TS 60479-1, able to deliver a DC-voltage corresponding to the testing voltage, adjustable and measurable at the test probe with limiting deviat
41、ion +5 %/-10 %. The total internal resistance shall be high enough to give the short circuit current of the generator an arithmetical mean from 2 mA to 3 mA maximum. The peak value of the current during a spark discharge shall be between 10 mA and 50 mA and the amount of charge per impulse shall be
42、25 C maximum.The negative pole of the generator shall be earthed (USA: grounded) and the positive pole shall be connected to the test electrode by a screened high voltage cable of suitable length.5.1.2 Pulsed DC-voltage generator, conforming to the requirements of IEC/TS 60479-2 able to deliver a DC
43、-voltage corresponding to the testing voltage. The voltage shall be adjustable and measurable at the test probe with limiting deviations +20 %/-10 % for test voltage greater than 10 kV and limiting deviations +40 %/-10 % for test voltages less than 10 kV.5.2 Test electrode, made out of metal wire or
44、 conductive rubber that is unaffected by a spark discharge.NOTE Alternative test electrodes can be used providing they are unaffected by a spark discharge.5.2.1 Insulated hand-piece, provided externally with an earthed cover for DC-voltage and pulsed DC-voltage devices. Pulsed DC-voltage generators
45、can produce an electric shock to users because of capacitive coupling between cable and hand-piece during operation.5.2.2 Brush holder, of metal wire (used for the test brush), constructed such that it is completely unaffected by the spark discharge and covers as large an area as possible when sweep
46、ing the enamel surface.5.3 Indicator device, able to give a clear optical and/or acoustic signal at each spark discharge.5.4 Coating thickness measurement device, such as that described in ISO 2178 or ISO 2360.6 SpecimensThe specimens can be commercial items, parts thereof or test pieces which have
47、been subjected to the same processing, and which for testing purposes are representative of the commercial item.2 ISO 2015 All rights reservedBS EN ISO 2746:2015ISO 2746:2015(E)No special preparation of specimens is required.7 Test voltage7.1 Test A: Detection of defects (3.1) which extend down to t
48、he metal basis (e.g. open pores)For a correct determination of these defects, the appropriate test voltage shall be used. This voltage depends on the length of the defect gap, which corresponds to the thickness of the enamel layer. Too low a voltage will not result in the determination of all defect
49、s. Too high a voltage will result in a breakdown of thin residual enamel layers (destructive testing). In order to look for defects which extend down to the metal base (e.g. open pores), the test voltage shall be as follows: DC-voltages shall be set to the values given in Table 1.Other voltages may be chosen by mutual agreement between interested parties. voltage of pulsed DC-voltage generators shall be agreed between the interested parties.Table 1 shows the minimum voltage needed to arc through a defect which is open to both the surface an
