1、BRITISH STANDARD BS1344-11: 1998 ISO2746:1998 Methods of testing vitreous enamel finishes Part11: High voltage test for enamelled articles for service under highly corrosive conditions ICS25.220.50BS1344-11:1998 This British Standard, having been prepared under the directionof the Sector Board for M
2、aterials and Chemicals, was published under the authority ofthe Standards Board and comesinto effect on 15 June 1998 BSI 04-1999 ISBN 0 580 29981 3 Amendments issued since publication Amd. No. Date CommentsBS1344-11:1998 BSI 04-1999 i Contents Page National foreword ii Foreword iii Text of ISO2746 1
3、BS1344-11:1998 ii BSI 04-1999 National foreword This Part of BS1344, Methods of testing vitreous enamel finishes, reproduces verbatim ISO2746:1998 and implements it as the UK national standard. It supersedes BS1344-11:1975 which is withdrawn. The UK participation in its preparation was entrusted to
4、Technical Committee STI/36, Vitreous enamel coatings, which has the responsibility to: 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 i
5、nternational and European developments and promulgate them in the UK. The standard is now published in22 parts: Part1: Determination of resistance to thermal shock of coatings on articles other than cooking utensils and fabricated sheet steel components; Part2: Resistance to citric acid at room temp
6、erature; Part3: Determination of resistance to sulphuric acid at room temperature; Part4: Resistance to abrasion (obsolescent); Part5: Determination of resistance to hot detergent solutions used for washing textiles; Part6: Resistance to alkali; Part7: Determination of resistance to heat; Part8: Det
7、ermination of resistance to boiling citric acid; Part9: Determination of resistance to boiling water and water vapour; Part10: Determination of resistance to condensing hydrochloric acidvapour; Part11: High voltage test for enamelled articles for service under highly corrosive conditions; Part12: Pr
8、oduction of specimens for testing coatings on sheet steel; Part13: Production of specimens for testing coatings on cast iron; Part14: Apparatus for testing with acid and neutral liquids and theirvapours; Part15: Apparatus for testing with alkaline liquids; Part16: Resistance to thermal shock of coat
9、ings on cooking utensils; Part17: Resistance to hot sodium hydroxide solution; Part18: Determination of fluidity behaviour Fusion flow test; Part19: Apparatus for determination of resistance to hot detergent solutions used for washing textiles; Part20: Low voltage test for detecting and locating def
10、ects; Part21: Determination of the resistance of vitreous enamelled articles to impact Pistol test; Part22: Determination of resistance to thermal shock of coatings for fabricated sheet steel components such as burners and pan supports for cookers.BS1344-11:1998 BSI 04-1999 iii Various steels suitab
11、le for vitreous enamelling are described in BS EN10209 and in BS1449-2. 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
12、 found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Stan
13、dards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi toiv, theISO title page, pagesii toiv, pages 1 and 2, an inside bac
14、k cover and abackcover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover.iv blankBS1344-11:1998 ii BSI 04-1999 Contents Page Foreword iii 1 Scope 1 2 Definition 1 3 Principle 1 4 Appar
15、atus 1 5 Test specimens and sampling 1 6 Procedure 1 7 Test report 2 Annex A (informative) Bibliography Inside back coverBS1344-11:1998 BSI 04-1999 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The wo
16、rk 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-governm
17、ental, 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. Draft International Standards adopted by the technical committees are circulated to the member bodies for voti
18、ng. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO2746 was prepared by Technical Committee ISO/TC107, Metallic and other inorganic coatings, Subcommittee SC6, Vitreous and porcelain enamels. This second editio
19、n cancels and replaces the first edition (ISO2746:1973), which has been technically revised. Annex A of this International Standard is for information only. Descriptors: Non-metallic coatings, protective coatings, enamels, vitreous enamels, porcelain enamels, tests, high voltage tests, detection, de
20、fects.iv blankBS1344-11:1998 BSI 04-1999 1 1 Scope This International Standard specifies a test method for vitreous and porcelain enamelled articles using high voltage. This high voltage test is used to detect defects in enamel coatings that extend down to the metal base, and to locate weak spots in
21、 enamel coatings. This test method applies to voltages not less than2kV and a coating thickness not less than6604m. 2 Definition For the purposes of this International Standard, the following definition applies. 2.1 weak spot area of an enamel coating where the coating thickness as determined by the
22、 application of high voltage falls below the required value due to the presence of blisters, foreign body inclusions, spalling or cracks 3 Principle The high voltage test is carried out at a direct current (d.c.) voltage of greater than2kV by passing a positive electrode over the enamel surface; the
23、 high voltage generator locates defects and weak spots as a spark discharge and a simultaneous optical and/or acoustic signal. 4 Apparatus 4.1 High voltage generator, capable of delivering a d.c.voltage of greater than2kV corresponding to the test voltage (see6.1). It shall be capable of providing a
24、djustable and measurable voltages to within 5%. The total internal resistance shall be high enough to give the short circuit current of the generator an arithmetical mean from2mA to3mA maximum. The peak value of the current during a spark discharge shall be between10mA and50mA maximum and the amount
25、 of charge per impulse shall be254C 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. 4.2 Test electrode, with the following attachments: 4.2.1 Insulated han
26、d-piece, provided externally with an earthed metal cover. 4.2.2 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 sweeping the enamel surface. 4.2.3 Protective resistor, placed
27、between the hand-piece and the test brush to limit the peak current value(10mA to50mA maximum) during the electric spark discharge. It shall be designed such that dangerous reduction of this protective effect, for instance caused by contamination, or the formation of an arc be avoided during operati
28、on. 4.3 Device, capable of giving a clear optical and/or acoustic signal at each spark discharge. 5 Test specimens and sampling NOTEThe test specimens can be commercial items. No special preparation of test specimens is required. The number of test specimens and the sampling plan shall be agreed bet
29、ween the interested parties. 6 Procedure 6.1 Apply the test voltage taking into account the end-use of the enamelled article and the dielectric strength and coating thickness of the enamel. Ensure that the applied test voltage is at least three times the breakdown voltage for a layer of air of the s
30、ame thickness. NOTE 1The coating thickness of the enamel can be estimated using the test methods given in ISO2178 or ISO2360. NOTE 2For the interelectrode gap of1mm the breakdown voltage in air between the electrodes is approximately1kV for the case where one electrode is tipped and the other electr
31、ode is spheroidized. 6.2 Ensure that a) the surface of the enamel coating under test is dry and free from impurities; b) the enamel coating has a temperature that is above the dewpoint and does not exceed30C; c) the metallic base material is earthed.BS1344-11:1998 2 BSI 04-1999 6.3 Switch on the cur
32、rent, adjust the voltage to the test requirement and move the test brush to cover as large an area as possible over the enamel surface at a speed of40cm/s maximum, controlling the voltage accordingly. If the voltage at the brush falls by more than10% without a spark discharge occurring, investigate
33、and remove the cause (see6.2). Note the positions of any defects or weak spots indicated by a spark discharge on the enamel surface, and measure the thickness of the enamel coating at those points. 7 Test report The test report shall include the following information: a) reference to this Internatio
34、nal Standard, i.e.“determined in accordance with ISO2746:1998”; b) the number of test specimens and the sampling plan used; c) the test voltage; d) the number and the position of contact points; e) the thickness of the enamel coating where a defect (or defects) occurs.BS1344-11:1998 BSI 04-1999 Anne
35、x A(informative) Bibliography 1 ISO2178:1982, Non-magnetic coatings on magnetic substrates Measurement of coating thickness Magnetic method. 2 ISO2360:1982, Non-conductive coatings on non-magnetic basis metals Measurement of coating thickness Eddy current method.BS1344-11: 1998 ISO2746:1998 BSI 389
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