BS EN 14430-2004 Vitreous and porcelain enamels-High voltage test.pdf

BRITISH STANDARD BS EN 14430:2004 Vitreous and porcelain enamels High voltage test The European Standard EN 14430:2004 has the status of a British Standard ICS 25.220.50 ? BS EN 14430:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 6 December 2004 © BSI 6 December 2004 ISBN 0 580 44982 3 National foreword This British Standard is the official English language version of EN 14430:2004. The UK participation in its preparation was entrusted to Technical Committee STI/36, Vitreous enamel coatings, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 10, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments 标准分享网 w w w .b z f x w .c o m 免费下载 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN 14430 September 2004 ICS 25.220.50 English version Vitreous and porcelain enamels - High voltage test Emaux vitrifiés - Essai sous haute tensionEmails und Emaillierungen - Hochspannungsprüfung This European Standard was approved by CEN on 9 July 2004. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels © 2004 CENAll rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14430:2004: E EN 14430:2004 (E) 2 Contents page Foreword3 Introduction.4 1 Scope 5 2 Normative references5 3 Terms and definitions .5 4 Principle6 5 Apparatus .6 6 Specimens6 7 Test voltage6 7.1 Test A: Detection of defects (3.1) which extend down to the metal bases (e.g. open pores)6 7.2 Test B: Detection of defects and weak spots (3.2).8 8 Procedure .8 9 Test report8 Bibliography10 标准分享网 w w w .b z f x w .c o m 免费下载 EN 14430:2004 (E) 3 Foreword This document (EN 14430:2004) has been prepared by Technical Committee CEN/TC 262 “Metallic and other 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 an identical text or by endorsement, at the latest by March 2005, and conflicting national standards shall be withdrawn at the latest by March 2005. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 14430:2004 (E) 4 Introduction There are 2 different objectives for high voltage testing of vitreous and porcelain enamels. Test A is used to detect and locate defects, which 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 defect 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 the 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; or b) to verify that the enamel coating is safe to be used as a dielectric. Test A and Test B require the same test equipment (see Clause 6) and follow the same test procedure (see Clause 9). However, for test B the applied voltage is higher than in test A (see Clause 7). 标准分享网 w w w .b z f x w .c o m 免费下载 EN 14430:2004 (E) 5 1 Scope This document describes 2 test methods of high voltage testing: Test A is used to detect and locate defects in vitreous and porcelain enamels; Test B is used to detect and locate defects and weak spots in vitreous and porcelain enamels. The tests are performed using DC, pulsed DC, or AC 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 locating 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. NOTE This document extends the range of application of the test given in ISO 2746, which is restricted to coating thicknesses of minimum 660 µm. 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. EN ISO 2178, Non-magnetic coatings on magnetic substrates Measurement of coating thickness Magnetic method (ISO 2178:1982) EN ISO 2360, Non-conductive coatings on non-magnetic electrically conductive basis metals Measurement of coating thickness Amplitude-sensitive eddy current method (ISO 2360:2003) IEC/TR2 60479-1, Effects of current on human beings and livestock Part 1: General aspects 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 defect area of an enamel layer where an open path connects the enamel surface with the metal base NOTE Examples of defects are cracks or pores. 3.2 weak spot area of an enamel layer where the dielectric strength falls below the required value, as determined by the application of high voltage because of blisters, foreign body inclusions, spalling or cracks EN 14430:2004 (E) 6 4 Principle A 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, pulsed DC or AC. The test voltage might be different in each case. NOTE 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 be applicable to such border areas. 5 Apparatus 5.1 High voltage generator, as described in 5.1.1, 5.1.2 or 5.1.3. 5.1.1 Direct-current (DC) voltage generator, conforming to the requirements of IEC/TR2 60479-1, able to deliver a DC-voltage corresponding to the testing voltage, adjustable and measurable at the test probe with limiting deviations % 5 % 10 + . 5.1.2 Pulsed DC-voltage generator, conforming to the requirements of IEC/TR2 60479-1, able to deliver a DC-voltage corresponding to the testing voltage. The voltage shall be adjustable and measurable at the test probe with limiting deviations % 20 % 10 + for test voltages greater than 10 kV and limiting deviations % 0 % 10 4+ for test voltages less than 10 kV. 5.1.3 Alternating-current (AC) voltage generator. NOTE The output voltage of an AC-voltage generator varies, depending on the test conditions. Some generators can deliver up to 50kV. The actual voltage cannot be measured or defined. 5.2 Test electrode, made out of metal wire or conductive rubber that is unaffected by a spark discharge. NOTE Alternative test electrodes may be used. 5.3 Indicator, 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 EN ISO 2178 or EN ISO 2360. 6 Specimens The specimens can be commercial items, parts thereof or test pieces which have been subjected to the same processing, and which for testing purposes are representative of the commercial item. No special preparation of specimens is required. 7 Test voltage 7.1 Test A: Detection of defects (3.1) which extend down to the metal bases (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 defects. 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. NOTE 1 Other voltages may be chosen by mutual agreement between interested parties. 标准分享网 w w w .b z f x w .c o m 免费下载 EN 14430:2004 (E) 7 - the voltage of pulsed DC- and AC-voltage generators shall be agreed between the interested parties. Table 1 Test voltage 4 Layer thickness µm Test voltage V 100 1 100 110 1 150 120 1 200 130 1 240 140 1 290 150 1 370 160 1 420 170 1 450 180 1 510 190 1 560 200 1 600 210 1 660 220 1 690 230 1 750 240 1 800 250 1 850 260 1 900 270 1 940 280 1 990 290 2 030 300 2 070 400 2 520 500 2 900 750 3 820 1 000 4 600 1 500 6 450 2 000 8 000 EN 14430:2004 (E) 8 7.2 Test B: Detection of defects and weak spots (3.2) Test voltages used to detect defects and weak spots in the enamel layer depend not only on the dielectric strength of air, but also on the dielectric strength of the enamel. DC voltages shall be agreed between the interested parties and shall be higher than those given in Table 1. The test voltage of pulsed DC- and AC-voltage generators shall be agreed between the interested parties. 8 Procedure Ensure that the surface of the enamel layer under test is free from impurities and has a temperature of 40°C maximum. NOTE 1 If possible, the test temperature should not exceed 30°C as the breakdown voltage appreciably decreases at temperatures higher than 30°C. The surface of the enamel shall be dry. This is less important if a pulsed DC or AC generator is used. The negative pole or earth/return terminal of the generator shall be connected to the substrate (base) of the sample. The positive pole shall be connected to the test electrode. Using the pulsed DC-voltage test, a capacitive connection may be used instead of a direct connection. For all- side enamelled components only capacitive earthing is possible. NOTE 2 Using the AC-voltage test earthing is not mandatory. Switch on the generator, adjust the voltage to the test requirement, place the electrode on the test piece and check the voltage. If the voltage has reduced, remove the cause or adjust as necessary. Move the test electrode systematically over the enamel surface at a speed of 40 cm/s maximum for DC and AC. Pulsed DC may require lower electrode speed. NOTE 3 If the enamel coating is to be used as a dielectric for electric apparatus, alternative electrodes and conditions (such as time under current) can be used. See for example procedures given in EN 60335-1, EN 60335-2-15 and EN 60335-2-30. Defects and weak spots are indicated by a visible spark and simultaneously by an optical and/or acoustic signal. Measure the thickness of the enamel coating where a spark discharge (or discharges) occurs. 9 Test report The test report shall include the following information: a) all information necessary for the identification of the sample tested; b) reference to this document, i.e. EN 14430:2004; c) type of test (A or B), the type of test voltage and thickness range of the enamel; d) type of test instrument used; e) number and position of spark or contact points; f) thickness of the enamel coating where a spark discharge (or discharges) occurs; 标准分享网 w w w .b z f x w .c o m 免费下载 EN 14430:2004 (E) 9 g) result(s), including the results of the individual determinations; h) any deviations from the procedure specified; i) any unusual features observed during the test; j) date of the test. EN 14430:2004 (E) 10 Bibliography 1 ISO 2746, Vitreous and porcelain enamels Enamelled articles for service under highly corrosive conditions High voltage test 2 NEN 2708, Email : Bepaling van fouten in geëmailleerde produkten door middel van een hoogspanningsproef (Vitreous and porcelain enamels: Determination of defects in enameled metal articles - High voltage test) 3 DIN 55670, Lacke und ähnliche Beschichtungsstoffe Prüfung von Lackierungen, Anstrichen und ähnliche Beschichtungen aus Poren und Risse mit Hochspannung (Paints and varnishes, Method for testing paint coatings and similar coatings for pores and cracks, using high voltage) 4 H. Nix: Mitteilungen VDEFA - Heft 10 1987 p 136-139: Schichtdickenmessung mit Geräten nach dem m