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1、BRITISH STANDARD AEROSPACE SERIES BS 2X 27: 1991 (Superseding BS X 27) Specification for Cellulose finishing scheme for aerospace purposes Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27:1991 This British Standard, having been prepa
2、red under the direction of the Aerospace Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 28 June 1991 BSI 03-2000 The following BSI references relate to the work on this standard: Committee reference ACE/44 Draft for comment 87/75011 DC I
3、SBN 0 580 19499 X Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Aerospace Standards Policy Committee (ACE/-) to Technical Committee ACE/44, upon which the following bodies were represented: Metal Finishing Association Ministry of Defen
4、ce Oil and Colour Chemists Association Paintmakers Association of Great Britain Society of British Aerospace Companies Limited Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27:
5、1991 BSI 03-2000i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definitions1 3Materials1 4Performance1 5Inspection2 6Marking2 Appendix A Preparation of test panels3 Appendix B Method for determination of flexibility and adhesion3 Appendix C Method for determination of sc
6、ratch resistance3 Appendix D Method for determination of resistance to blushing3 Appendix E Method for determination of specular gloss3 Appendix F Method for determination of resistance to natural weathering3 Appendix G Method for assessment of colour3 Appendix H Type approval3 Table 1 Paint system
7、performance2 Table 2 Dry film mass per unit area3 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27:1991 ii BSI 03-2000 Foreword This British Standard, prepared under the direction of the Aero
8、space Standards Policy Committee, is one of a series for paints and varnishes suitable for aerospace purposes. This revision supersedes BS X 27:1966 which is withdrawn. During its preparation, the requirements specified in BS X 30:1966 have been incorporated and this standard is withdrawn. It has be
9、en assumed in the drafting of this specification that the execution of its provisions is entrusted to appropriately qualified and experienced people. The quality assurance authority and approving authority referred to in this standard are as stated in the contract or order, or the accredited represe
10、ntative of the authority stated as instructed by the prime contractor. WARNING. This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and in no way absolves either the des
11、igner, the producer, the supplier or the user from statutory obligations relating to health and safety at any stage of manufacture or use. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applicati
12、on. 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, pages i and ii, pages 1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) an
13、d may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27:1991 BSI 03-20001 1 Scope This British Standard specifies requirements
14、for the materials and performance of a cellulose finishing scheme suitable for application to metallic surfaces for aerospace purposes. Colour is not specified in this standard but should be stated by the purchaser in the contract or order. A method for assessing colour is given in Appendix G and in
15、formation on application for type approval is given in Appendix H. NOTE 1The titles of the publications referred to in this standard are listed on the inside back cover. NOTE 2The latest revision of an Aerospace Series standard is indicated by a prefix number. 2 Definitions For the purposes of this
16、British Standard the definitions given in BS 2015 apply. 3 Materials 3.1 General The materials for a cellulose finishing scheme shall consist of the following: a) a pretreatment (etching) primer which shall comply with BS X 32; b) a finish which shall be based on a cellulose nitrate vehicle. The fin
17、ish shall be high gloss, semi-gloss or matt and shall be tested in accordance with BS 3900-D5. NOTE 1Gloss levels of these finishes can be increased by polishing after application. NOTE 2The finish should be suitable for application over the pretreatment primer by brushing or by spraying when dilute
18、d with the appropriate thinner in accordance with the manufacturers instructions. 3.2 Shelf life The shelf life shall be such that, when stored in their original sealed containers and at a temperature between 0 C and 35 C, the materials shall comply with clause 4 for not less than 12 months after th
19、e date of despatch. 4 Performance 4.1 General Unless otherwise specified in this standard all tests shall be carried out at a temperature of 23 2 C. 4.2 Condition The paints shall be in a condition suitable for application by brushing or, when thinned in accordance with the manufacturers instruction
20、s, by spraying. When examined in accordance with BS 3900-A2, the paints in the original containers or in laboratory sample containers shall be free from extraneous matter. They shall show no skinning, gelling or other defect which will prevent satisfactory application to produce a defect free film.
21、4.3 Through-dry time When the paint system prepared on a degreased hard aluminium panel is tested in accordance with BS 3900-C3, it shall become through-dry after a period of not more than 2 h from the time of application of the final coat. 4.4 Application properties and finish When applied to a deg
22、reased hard aluminium panel measuring 300 mm 100 mm (or larger) and allowed to dry in a vertical position for 24 h, the paint system shall result in an opaque even finish, free from runs and sags. 4.5 Paint system properties The paint system prepared in accordance with Appendix A shall comply with T
23、able 1. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27:1991 2 BSI 03-2000 Table 1 Paint system performance 5 Inspection Before despatch a representative sample of each batch of the finish taken in accordance with BS 3900-A1 shall b
24、e tested by the manufacturer to ensure compliance with 4.2 to 4.4 and test 4 given in Table 1. NOTESamples of the material and its ingredients may be taken at any stage of manufacture or from any portion of the consignment for inspection by the quality assurance authority. 6 Marking Each container s
25、hall be legibly and durably marked with the following details: a) the description of the material; b) the number of this British Standard, i.e. BS 2X 271); c) the manufacturers name and recognized trade mark; d) the batch number; e) the date of manufacture. TestTest panelNumber of coatsTest methodRe
26、quirement 1. FlexibilitySoft aluminium 2 coat systemAppendix BNo cracking or loss of adhesion 2. Scratch resistance Hard aluminium 2 coat systemAppendix CNo penetration to the substrate, scratch free from jagged edges of overall width greater than 2 mm 3. Resistance to blushing Hard aluminium 2 coat
27、 systemAppendix DNo blushing or other defects 4. Specular glossHard aluminium 2 coat systemAppendix EGloss 75 units Semi-gloss 50 5 units Matt 5 units 5. Resistance to weathering (type test) Hard aluminium 2 coat systemAppendix FNo cracking, flaking, blistering or other defect. Change in colour and
28、gloss to be to the satisfaction of the Approving Authority 1) Marking BS 2X 27 on or in relation to a product represents a manufacturers declaration of conformity, i.e. a claim by or on behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of the claim is t
29、herefore solely the responsibility of the person making the claim. Such a declaration is not to be confused with third party certification of conformity, which may also be desirable. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27:1
30、991 BSI 03-20003 Appendix A Preparation of test panels A.1 Preparation of substrate A.1.1 Except where otherwise specified in these appendices, make the test panels from smooth (unabraded) hard aluminium sheet, 0.7 mm thick, complying with alloy 1200-H18 of BS 1470. A.1.2 Solvent clean the test pane
31、l surface in accordance with BS 3900-A3. A.2 Paint application A.2.1 Apply all coats to the test panels by spraying. A.2.2 Unless otherwise specified in these appendices, allow to dry in a vertical attitude with free access of air for the time specified at 23 2 C and 50 5 % r.h. A.3 Paint system A.3
32、.1 Apply one coat of pretreatment primer to the test panels and allow to dry for 1 h. A.3.2 Apply one coat of the appropriate finish selected from Table 2 to give a single coat mass per unit area complying with Table 2. Table 2 Dry film mass per unit area Appendix B Method for determination of flexi
33、bility and adhesion Prepare and coat a soft aluminium test panel complying with alloy 1200-0 of BS 1470, measuring approximately 100 mm 50 mm 0.3 mm, in accordance with Appendix A and allow to dry for 24 h. Test in accordance with BS 3900-E1 around a 6 mm mandrel in a type 1 apparatus at 0 0.5 C. Ap
34、pendix C Method for determination of scratch resistance Prepare and coat a test panel measuring approximately 100 mm 50 mm in accordance with Appendix A and allow to dry for 24 h. Test in accordance with BS 3900-E2 under a load of 600 g. Appendix D Method for determination of resistance to blushing
35、Prepare and coat a test panel measuring at least 300 mm 100 mm in accordance with Appendix A and allow to dry for 2 h under the following conditions: Examine visually for defects. Appendix E Method for determination of specular gloss Prepare and coat a test panel measuring approximately 100 mm 50 mm
36、 in accordance with Appendix A and allow to dry for 24 h. Test in accordance with BS 3900-D5 using the 60 geometry apparatus. Appendix F Method for determination of resistance to natural weathering F.1 Test piece Prepare and coat in accordance with Appendix A an edge-rounded test panel with an expos
37、ed surface on one face only measuring at least 225 mm 100 mm and allow to dry for 168 h. F.2 Test procedure Expose the test piece for 18 months in the open at an angle corresponding to maximum sunlight (in the UK, facing south at an angle of 45). Examine with normal corrected vision, strip half the
38、panel using a suitable paint remover and examine the underlying metal for signs of corrosion. Appendix G Method for assessment of colour Prepare and coat a test panel measuring approximately 100 mm 50 mm in accordance with Appendix A and allow to dry for 24 h. Test in accordance with BS 3900-D1. App
39、endix H Type approval H.1 When the manufacturer is required to prove compliance with this standard, this is to be done by providing the following: a) evidence that the material complies with all the requirements of this British Standard; b) wet samples of all the material for which approval is sough
40、t; c) declaration of composition including percentage and nature of all ingredients. SchemeMass per unit area g/m2 Primer10 3 Finish, gloss40 8 Finish, semi-gloss or matt34 7 Finish, aluminium lightweight 17 3 relative humidity65 % to 70 % temperature21 C to 25 C air speed1 m/s Licensed Copy: sheffi
41、eldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27:1991 4 BSI 03-2000 NOTEProvisional approval may be granted on the basis of short-term tests before natural weathering tests can be completed. Such provisional approval may be issued only in special circums
42、tances and after consideration of evidence supplied by the manufacturer on the durability of materials of the same or similar formulation, definition of the type of medium and the names of the manufacturers of any proprietary resins used, in addition to the details supplied in c) above. H.2 After ap
43、proval has been given, there is to be no change in the formulation unless approval for the change has been sought and given by the approving authority. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27:1991 BSI 03-2000 Publications re
44、ferred to BS X 32, Specification for pretreatment primer for aerospace purposes. BS 1470, Specification for wrought aluminium and aluminium alloys for general engineering purposes: plate, sheet and strip. BS 2015, Glossary of paint terms. BS 3900, Methods of tests for paints. BS 3900:Group A, Tests
45、on liquid paints (excluding chemical tests). BS 3900-A1, Sampling. BS 3900-A2, Examination and preparation of samples for testing. BS 3900-A3, Standard panels for paint testing. BS 3900:Group C, Tests associated with paint film formation. BS 3900-C3, Through-dry test. BS 3900:Group D, Optical tests
46、on paint films. BS 3900-D1, Visual comparison of the colour of paints. BS 3900-D5, Measurement of specular gloss of non-metallic paint films at 20, 60 and 85. BS 3900:Group E, Mechanical tests on paint films. BS 3900-E1, Bend test (cylindrical mandrel). BS 3900-E2, Scratch test. Licensed Copy: sheff
47、ieldun sheffieldun, na, Tue Nov 28 14:17:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2X 27: 1991 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in E
48、urope and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our pr
49、oducts and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 7400. BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publicatio