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1、BRITISH STANDARD BS 1344-11: 1998 ISO 2746:1998 Methods of testing vitreous enamel finishes Part 11: High voltage test for enamelled articles for service under highly corrosive conditions ICS 25.220.50 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy,
2、 (c) BSI BS 1344-11:1998 This British Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 June 1998 BSI 04-1999 ISBN 0 580 29981 3 Amendments issued since publication
3、Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1344-11:1998 BSI 04-1999i Contents Page National forewordii Forewordiii Text of ISO 27461 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006,
4、 Uncontrolled Copy, (c) BSI BS 1344-11:1998 ii BSI 04-1999 National foreword This Part of BS 1344, Methods of testing vitreous enamel finishes, reproduces verbatim ISO 2746:1998 and implements it as the UK national standard. It supersedes BS 1344-11:1975 which is withdrawn. The UK participation in i
5、ts preparation was entrusted to 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 inter
6、ests informed; monitor related international and European developments and promulgate them in the UK. The standard is now published in 22 parts: Part 1: Determination of resistance to thermal shock of coatings on articles other than cooking utensils and fabricated sheet steel components; Part 2: Res
7、istance to citric acid at room temperature; Part 3: Determination of resistance to sulphuric acid at room temperature; Part 4: Resistance to abrasion (obsolescent); Part 5: Determination of resistance to hot detergent solutions used for washing textiles; Part 6: Resistance to alkali; Part 7: Determi
8、nation of resistance to heat; Part 8: Determination of resistance to boiling citric acid; Part 9: Determination of resistance to boiling water and water vapour; Part 10: Determination of resistance to condensing hydrochloric acid vapour; Part 11: High voltage test for enamelled articles for service
9、under highly corrosive conditions; Part 12: Production of specimens for testing coatings on sheet steel; Part 13: Production of specimens for testing coatings on cast iron; Part 14: Apparatus for testing with acid and neutral liquids and their vapours; Part 15: Apparatus for testing with alkaline li
10、quids; Part 16: Resistance to thermal shock of coatings on cooking utensils; Part 17: Resistance to hot sodium hydroxide solution; Part 18: Determination of fluidity behaviour Fusion flow test; Part 19: Apparatus for determination of resistance to hot detergent solutions used for washing textiles; P
11、art 20: Low voltage test for detecting and locating defects; Part 21: Determination of the resistance of vitreous enamelled articles to impact Pistol test; Part 22: Determination of resistance to thermal shock of coatings for fabricated sheet steel components such as burners and pan supports for coo
12、kers. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1344-11:1998 BSI 04-1999iii Various steels suitable for vitreous enamelling are described in BS EN 10209 and in BS 1449-2. A list of organizations represented on this committee can be
13、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 Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Fin
14、d” 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 Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal
15、 obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, the ISO title page, pages ii to iv, pages 1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This wil
16、l be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Licensed Cop
17、y: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1344-11:1998 ii BSI 04-1999 Contents Page Forewordiii 1Scope1 2Definition1 3Principle1 4Apparatus1 5Test specimens and sampling1 6Procedure1 7Test report2 Annex A (informative) BibliographyInside back c
18、over Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1344-11:1998 BSI 04-1999iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of pre
19、paring 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
20、 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 voting. Publi
21、cation as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 2746 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings, Subcommittee SC 6, Vitreous and porcelain enamels. This second edition ca
22、ncels and replaces the first edition (ISO 2746:1973), 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, defec
23、ts. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1344-11:1998 BSI 04-19991 1 Scope This International Standard specifie
24、s 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 enamel coatings. This test method applies to voltages not less than 2 kV and a coating
25、 thickness not less than 660 4m. 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 application of high voltage falls below the required value due to the presence of
26、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 than 2 kV by passing a positive electrode over the enamel surface; the high voltage generator locates defects and weak spots as a spark discharge and a
27、 simultaneous optical and/or acoustic signal. 4 Apparatus 4.1 High voltage generator, capable of delivering a d.c. voltage of greater than 2 kV corresponding to the test voltage (see 6.1). It shall be capable of providing adjustable and measurable voltages to within 5 %. The total internal resistanc
28、e 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 maximum and the amount of charge per impulse shall be 25 4C maximum. The negative pole of
29、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 hand-piece, provided externally with an earthed metal cover. 4.2.2 Br
30、ush 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 between the hand-piece and the test brush to limit the peak curren
31、t value (10 mA to 50 mA 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 operation. 4.3 Device, capable of giving a clear optical and/or acous
32、tic 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 between the interested parties. 6 Procedure 6.1 Apply the test vo
33、ltage 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 same thickness. NOTE 1The coating thickness of the enamel can b
34、e estimated using the test methods given in ISO 2178 or ISO 2360. NOTE 2For the interelectrode gap of 1 mm the breakdown voltage in air between the electrodes is approximately 1 kV for the case where one electrode is tipped and the other electrode is spheroidized. 6.2 Ensure that a) the surface of t
35、he 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 exceed 30 C; c) the metallic base material is earthed. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c)
36、BSI BS 1344-11:1998 2 BSI 04-1999 6.3 Switch on the current, 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 of 40 cm/s maximum, controlling the voltage accordingly. If the voltage at the brush falls by more
37、than 10 % without a spark discharge occurring, investigate and remove the cause (see 6.2). 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 includ
38、e the following information: a) reference to this International Standard, i.e. “determined in accordance with ISO 2746:1998”; 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 wher
39、e a defect (or defects) occurs. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1344-11:1998 BSI 04-1999 Annex A (informative) Bibliography 1 ISO 2178:1982, Non-magnetic coatings on magnetic substrates Measurement of coating thickness Mag
40、netic method. 2 ISO 2360:1982, Non-conductive coatings on non-magnetic basis metals Measurement of coating thickness Eddy current method. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1344-11: 1998 ISO 2746:1998 BSI 389 Chiswick High Ro
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