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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7793 : Part 2 : 1996 I
2、CS 25.220.50 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Vitreous enamel coatings for use on bolted steel panels Part 2. Specification for coatings on bolted steel panels for use in industrial liquid storage tanks Licensed Copy: London South Bank University, London South B
3、ank University, Fri Dec 08 11:48:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 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 August 1996 BSI 1996 Th
4、e following BSI references relate to the work on this standard: Committee reference STI/36 Draft for comment 95/124271 DC ISBN 0 580 25831 9 BS 7793 : Part 2 : 1996 Amendments issued since publication Amd. No.DateText affected Committees responsible for this British Standard The preparation of this
5、British Standard was entrusted to Technical Committee STI/36, Vitreous enamel coatings, upon which the following bodies were represented: Agricultural Engineers Association Association of Manufacturers of Domestic Electrical Appliances British Bathroom Council British Iron and Steel Producers Associ
6、ation Institute of Vitreous Enamellers Metal Sink Manufacturers Association Vitreous Enamel Development Council Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7793 : Part 2 : 1996 BSI 1996i Contents Page Co
7、mmittees responsibleInside front cover Forewordii Specification 1Scope1 2References1 3Definitions1 4Information and requirements to be agreed and documented1 5Raw materials1 6Vitreous enamel quality2 7Finished panels2 8Inspection at the construction site2 Annex A(informative) Guidance notes4 Tables
8、1Minimum quality requirements for vitreous enamel for use in liquid storage tanks2 2Requirements for finished vitreous enamelled panels for use in liquid storage tanks3 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:12 GMT+00:00 2006, Uncontrolled Copy, (
9、c) BSI ii BSI 1996 BS 7793 : Part 2 : 1996 Foreword This British Standard has been prepared by Technical Committee STI/36. It specifies the requirements to be met by vitreous enamel coatings for use in industrial liquid storage tanks. The quality of the vitreous enamel coating is one of the most sig
10、nificant aspects of the manufacture of this type of tank for storage of industrial liquids. This standard has been prepared in recognition of the need for a specification equivalent, although not necessarily technically identical, to standards in existence in other European countries, which specify
11、a minimum quality for the vitreous enamel. BS 7793 consists of one other Part: Part 1. Specification for coatings on bolted steel panels for use in agricultural slurry tanks. Further Parts of BS 7793, specifying requirements for vitreous enamelled coatings on bolted steel panels, are in preparation.
12、 Compliance with a British Standard does not of itself confer immunity from legal obligations. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 19961 BS 7793 : Part 2 : 1996 Specification 1 Scope This Britis
13、h Standard specifies requirements for vitreous enamel coatings as applied to panels for use in the construction of tanks for storing general industrial and municipal treatment liquids. These tank coatings and their application should not be confused with glass coated reaction vessels such as are man
14、ufactured and used by the chemical industry, which are coated with glass on the inside surfaces only and are designed for both high temperature and high pressure. This British Standard applies to the vitreous enamelling elements of the manufacturing process, however the same quality criteria outline
15、d in clause 7 apply to the tank as built. In addition to the definitive requirements, this standard also requires the item detailed in clause 4 to be documented. For compliance with this British Standard, both the definitive requirements and the documented item have to be satisfied. 2 References 2.1
16、 Normative references This British Standard incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the editio
17、n cited applies; any subsequent amendments to, or revisions of, the cited publication apply to this British Standard only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Inform
18、ative references This British Standard refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purpo
19、ses of this British Standard, the following definitions apply. 3.1 vitreous enamel Any coating based on silica glass applied to steel sheet at high temperature such that it bonds to the steel sheet. 3.2 vitreous enameller The person undertaking and controlling the process of applying the vitreous en
20、amel coating to the steel sheet. 3.3 supplier Any person supplying materials for use by the vitreous enameller in the enamelling process. 3.4 inspection area That area inside a boundary 25 mm from any panel edge or hole, and outside a boundary 25 mm from any opening or hole within the body of the pa
21、nel. 3.5 defect Any break in the surface of the vitreous enamel. 3.6 discontinuity Any defect, area or spot that allows an electric current to pass when tested with the high voltage test apparatus used in accordance with clause 7. 3.7 raw materials Any material or substance which is used as part of
22、the coating applied to the steel prior to fusing. 4 Information and requirements to be agreed and documented The following item to be agreed between the contracting parties, which are specified in the clauses referred to, shall be fully documented. Both the definitive requirements specified througho
23、ut this British Standard and the following documented item shall be satisfied before a claim of compliance with the standard can be made and verified. a) The steel to be used (see 5.2). 5 Raw materials 5.1 Vitreous enamel The vitreous enameller shall specify the requirements of all raw materials to
24、be used in the vitreous enamelling process and ensure that they will produce a coating that will meet the minimum quality requirements listed in tables 1 and 2 when processed through the intended vitreous enamelling plant. The vitreous enameller or the supplier shall carry out tests and record confo
25、rmity of the raw materials in accordance with table 1, and shall make certified copies of these records available for subsequent inspection. 5.2 Steel The most suitable grade of steel to be used in the enamelling process shall be agreed between the vitreous enameller and the steel supplier, and the
26、steel supplier shall give due regard to the requirements of the enamelling process. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 BSI 1996 BS 7793 : Part 2 : 1996 Table 1. Minimum quality requirements for v
27、itreous enamel for use in liquid storage tanks PropertyMinimum specificationMinimum inspection frequency Test method Resistance to distilled water and water vapour AnnuallyBS 1344 : Part 9 liquid phase2.5 g/m2in 24 h vapour phase3.5 g/m2in 24 h Resistance to citric acid at room temperature Class AMo
28、nthly or with each batch BS 1344 : Part 2 Resistance to boiling citric acid 4 g/m2in 24 hAnnuallyBS 1344 : Part 8 Resistance to sulfuric acid at room temperature Class SAMonthly or with each batch BS 1344 : Part 3 Resistance to hydrochloric acid at room temperature: 10 % solution for 60 min Class AA
29、nnuallyBS 1344 : Part 3 Resistance to condensing hydrochloric acid vapour AnnuallyBS 1344 : Part 10 liquid phase6.0 g/m2in 24 h vapour phase7.5 g/m2in 24 h Resistance to hot sodium hydroxide solution 3.0 g/m2in 5 hAnnuallyBS 1344 : Part 17 Resistance to hot detergent solutions 5.0 g/m2in 24 hAnnuall
30、yBS 1344 : Part 5 Resistance to impact: pistol test 2.0 mm max. cracking after 24 h Monthly or with each batch BS 1344 : Part 21, Force = 20 N Adhesion strengthClass 2Monthly or with each batch Annex D of BS EN 10209 : 1996 Scratch hardnessBetter than Mohs 5Monthly or with each batch BS 6431 : Part
31、13 Resistance to heat300 CAnnuallyBS 1344 : Part 7 Resistance to thermal shock 300 CAnnuallyBS 1344 : Part 1 6 Vitreous enamel quality Test specimens of vitreous enamelled steel shall be prepared in accordance with BS 1344 : Part 12 and tested at least at the minimum inspection frequency specified i
32、n table 1 to ensure that the enamel meets all the quality requirements set out in table 1. 7 Finished panels Tests shall be carried out within the inspection area of the finished panel and shall meet the specification as set out in table 1. For the purposes of these tests, any panel surface coming i
33、nto contact with the stored liquid shall be considered as an inside surface. 8 Inspection at the construction site The high voltage test, BS 1344 : Part 11, is not appropriate at the construction site. If it is necessary to inspect vitreous enamelled panels at the construction site this shall be car
34、ried out on a panel surface in contact with the stored liquid using a low voltage web swab tester with an electrolyte solution consisting of tap water containing an industrial low suds wetting agent at a concentration of 8 ml/l of water. The tester shall have an excitation voltage of %, and be set s
35、uch that the alarm sounds or9 V 2 5 + 10 indicates when the electrical resistance of the vitreous enamel surface drops below 90 000 V10 %. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 19963 BS 7793 : Par
36、t 2 : 1996 Table 2. Requirements for finished vitreous enamelled panels for use in liquid storage tanks TestSpecificationInspection frequencyInspection method Enamel thickness0.20 mm 2 0.50 mmSee note 3 Defects inside surfaceNo discontinuities100 %Inspect using high voltage apparatus set at 1000 V (
37、see note 1 below). outside surfaceMax. 3 visible defects per m2total panel area 100 %Visual inspection (see note 2 below). both surfacesMax. defect size 1 mm100 %Visual inspection. Colour outside surfaceWithin limits set by the vitreous enameller See note 3Inspection using a colour comparator approv
38、ed prior to production by the vitreous enameller. NOTE 1. The test apparatus shall conform to the requirements of BS 1344 : Part 11, except that it should be calibrated such that the minimum voltage at the test probe is 1000 V1 %. NOTE 2. It is permissible, when agreed between the contracting partie
39、s, to repair defects with a material approved by the vitreous enameller for the purpose, applied according to the repair material manufacturers instructions. NOTE 3. Inspection sampling frequency shall be determined according to BS 6001 : Part 1. Licensed Copy: London South Bank University, London S
40、outh Bank University, Fri Dec 08 11:48:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 BSI 1996 BS 7793: Part 2: 1996 Annex Annex A (informative) Guidance notes A.1 Assessed capability Users of this standard are advised to consider the desirability of quality system assessment and registration again
41、st the appropriate part of BS EN ISO 9000 by a third party certification body. A.2 Handling and fixing Every care should be taken to avoid damaging the vitreous enamel when handling finished panels at the construction site. Preferably, suction pads should be used. The vitreous enameller should provi
42、de advice on correct handling procedures. In particular, care should be taken in the use of fork lift trucks, hoists and other lifting equipment. Where suction pads are not available, load spreader bars fitted with at least two hooks should be used. The vitreous enameller should provide advice on th
43、e recommended torque that should be applied to bolts that bear on vitreous enamelled panels. Welding and grinding should not take place near vitreous enamelled panels. A.3 Repairing damage at the construction site The vitreous enameller should provide advice on methods of repairing damage to vitreou
44、s enamelled panels at the construction site. A.4 Change of use The vitreous enameller should make contracting parties aware that changes to the operating environment resulting from changes to the usage of the tank can affect the durability of vitreous enamelled panels. Licensed Copy: London South Ba
45、nk University, London South Bank University, Fri Dec 08 11:48:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 1996 BS 7793 : Part 2 : 1996 List of references(see clause 2) Normative references BSI publications BRITISH STANDARDS INSTITUTION, London BS 1344Methods of testing vitreous enamel finishes
46、 BS 1344 : Part 1 : 1994Determination of resistance to thermal shock of coatings on articles other than cooking utensils and fabricated sheet steel components BS 1344 : Part 2 : 1975Resistance to citric acid at room temperature BS 1344 : Part 3 : 1988Determination of resistance to sulphuric acid at
47、room temperature BS 1344 : Part 5 : 1984Determination of resistance to hot detergent solutions used for washing textiles BS 1344 : Part 7 : 1984Determination of resistance to heat BS 1344 : Part 8 : 1984Determination of resistance to boiling citric acid BS 1344 : Part 9 : 1987Determination of resist
48、ance to boiling water and water vapour BS 1344 : Part 10 : 1987Determination of resistance to condensing hydrochloric acid vapour BS 1344 : Part 11 : 1975High voltage test for articles for use under highly corrosive conditions BS 1344 : Part 12 : 1975Production of specimens for testing coatings on s
49、heet steel BS 1344 : Part 13 : 1975Production of specimens for testing coatings on cast iron BS 1344 : Part 17 : 1975Resistance to hot sodium hydroxide solution BS 1344 : Part 21 : 1993Determination of resistance of vitreous enamelled articles to impact : pistol test BS 6001Sampling procedures for inspection by attributes BS 6001 : Part 1 : 1991Specification for sampling plans indexed by acceptable quality level (AQL) for lot-by-lot inspection BS 6431Ceramic floor and wall tiles BS 6431 : Part 13 : 1986Method for determination of scratch hardness of surface
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