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1、BRITISH STANDARD AEROSPACE SERIES BS F 125:1973 Incorporating Amendment Nos. 1 and 2 Specification for Rubber bonded compressed asbestos fibre jointing UDC 629.7.063:62 762.4:678.066:677.51 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:53:20 GMT+00:00 2006,
2、 Uncontrolled Copy, (c) BSI BS F 125:1973 This British Standard, having been approved by the Aerospace Industry Standards Committee, was published under the authority of the Executive Board on 19 November 1973 BSI 02-2000 The following BSI references relate to the work on this standard: Committee re
3、ference ACE/25 Draft for comment 70/7573 ISBN 0 580 07559 1 Foreword This British Standard, one of a number for rubber bonded materials, of a quality suitable for aircraft applications, to be transferred from the Procurement Executive, Ministry of Defence DTD series, supersedes DTD 378A and DTD 416.
4、 During the transfer, account has been taken of the knowledge and experience gained in the manufacture of jointing to the DTD specification, with the result that some tests have been modified and the number reduced. Since the preparation of this standard was commenced there has been certain updating
5、 of requirements in connection with materials which come in contact with aviation fuels and synthetic engine lubricating oils. As a result a swell test, originally called for in the DTD series specifications, has been reinstated for those materials in these applications. These are subjected to this
6、additional test according to application. The attention of the designer is drawn to BS F 130 “Specification for rubber bonded compressed aramid fibre jointing material for aerospace purposes”, to provide a non-asbestos jointing material. However, BS F 130 should not be considered a direct replacemen
7、t for this standard, and attention is specifically drawn to the foreword of BS F 130. As will be observed this standard has been metricated and the use of SI units introduced. NOTEInformation on SI units is given in BS 3763, “The International System of units (SI)”, and in BS 350, “Conversion factor
8、s and tables”. The following British Standards are referred to in this standard: BS 870, External micrometers. BS 903, Methods of testing vulcanized rubber Part A16: The resistance of vulcanized rubber to liquids. BS 907, Dial gauges for linear measurement. BS 970, Wrought steels in the form of bloo
9、ms, billets, bars and forgings Part 1: Carbon and carbon manganese steels, including free cutting steels. 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 Sta
10、ndard 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 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorp
11、orated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.Date of issueComments 2275May 1977 5816January 1989Indicated by a sideline in the margin Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09
12、02:53:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS F 125:1973 BSI 02-2000i Contents Page ForewordInside front cover 1Scope1 2Classification of material1 3Material1 4Quality and finish1 5Thickness1 6Creep test1 7Flexibility2 8Resistance to aviation fuel2 9Resistance to engine lubricants2 10Swell
13、test (Type 2 materials only)2 11Swell test (Type 3 materials only)2 12Test and inspection requirements2 13Identification2 Appendix A Method of carrying out creep test3 Appendix B Method of test for flexibility8 Appendix C Method of test for resistance to aviation fuel8 Appendix D Method of test for
14、resistance to engine lubricants8 Appendix E Method of carrying out swell test for Type 2 materials8 Appendix F Method of carrying out swell test for Type 3 materials9 Figure 1 Typical arrangement of creep test apparatus4 Figure 2 Details of creep test apparatus5 Table 1 Sheet thickness and tolerance
15、s1 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:53:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:53:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS F 125:197
16、3 BSI 02-20001 1 Scope This British Standard specifies, for aerospace purposes, the requirements for the construction and testing of rubber bonded compressed asbestos fibre jointing material, with or without wire mesh reinforcement and, when required by the purchaser, having graphite treated surface
17、s. NOTEThe treatment of the surfaces of the material with graphite is now permitted when specifically requested by the purchaser. It is recognized that in certain environments such treated material can give rise to corrosion. It is therefore the responsibility of the user to ensure that no corrosion
18、 hazard exists when graphite treated material is specified. In practice corrosion has not been experienced with non-graphite treated jointing and a specific corrosion test has therefore been excluded. However, manufacturers of aerospace equipment are required to notify the Inspecting Authority in th
19、e event of any intended change in materials. 2 Classification of material The jointing material is classified according to its application. The three types referred to in this standard are as follows. Type 1. For general application where normal bolt loading can be employed in the design. Type 2. Ma
20、terials of 0.25 mm and 0.5 mm thickness for use in contact with aviation fuels where control of swell characteristics is required. Type 3. Materials of 0.25 mm and 0.5 mm thickness for use in contact with synthetic engine lubricating oils of the di-ester type where control of swell characteristics i
21、s required. 3 Material 3.1 The material shall consist of well opened chrysotile asbestos fibres, bonded with a suitable rubber or blend of rubbers, and shall be supplied in the form of sheets. The asbestos fibres shall be finely divided and uniformly dispersed throughout the jointing. 3.2 Where a wi
22、re mesh reinforcement is specified in the contract or order, this shall normally be steel wire gauze, of aperture size 0.25 mm to 0.95 mm, with wire diameter 0.12 mm to 0.32 mm, and approximately central in the thickness of the sheet. Alternative wire mesh sizes may be supplied by agreement between
23、the purchaser and the supplier. 4 Quality and finish The sheets of jointing shall be solid run (single ply) of uniform texture, smooth on both sides and free from local irregularities. The surfaces of the sheet shall not be treated with graphite unless specifically requested by the purchaser. 5 Thic
24、kness 5.1 The nominal thickness of the material shall be as specified in the contract or order. The preferred thicknesses are 0.25, 0.5, 0.75, 1, 1.5, 2 and 3 mm. 5.2 The maximum permissible variation of any sheet from the nominal thickness and the maximum permissible variation in thickness between
25、any points not more than 250 mm apart shall be in accordance with Table 1. 5.3 The thickness shall be measured with a ratchet micrometer which complies with the provisions of BS 870 and has an anvil of 6 mm to 16 mm diameter. The reading shall be taken after three clicks of the ratchet. 6 Creep test
26、 Three test pieces shall be submitted to test in accordance with Appendix A. When thus described the median creep value shall be not more than 10 % for all thicknesses of jointing. NOTE 1For the purpose of this standard the term “creep value” is that reduction in thickness of the test piece expresse
27、d as a percentage of its original thickness when tested in accordance with Appendix A. NOTE 2Material less than 0.5 mm in thickness may not be tested due to difficulties in taking satisfactory measurements. Table 1 Sheet thickness and tolerances Nominal thickness of sheet Maximum permissible variati
28、on from nominal thickness Maximum permissible variation between points not more than 250 mm apart mm Up to and including 0.5 Over 0.5 up to and including 1.0 Over 1.0 up to and including 2.0 Over 2.0 mm 0.05 0.10 0.15 0.20 mm 0.05 0.10 0.10 0.15 Licensed Copy: London South Bank University, London So
29、uth Bank University, Sat Dec 09 02:53:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS F 125:1973 2 BSI 02-2000 7 Flexibility The flexibility of the material shall be such that, when subjected to the treatment described in Appendix B, it shall not crack or separate into layers. 8 Resistance to aviat
30、ion fuel The resistance of the material to aviation fuel shall be such that, after being subjected to the treatment described in Appendix C, the test piece shall still comply with the requirements of Clause 7 and shall show no signs of tackiness. 9 Resistance to engine lubricants The resistance of t
31、he material to engine lubricants shall be such that, after being subjected to the treatments described in Appendix D, the test piece shall still comply with the requirements of Clause 7 and shall show no signs of tackiness. 10 Swell test (Type 2 materials only) Two test pieces in their “as received”
32、 state shall be submitted to test in accordance with Appendix E. The limits of swell shall be between 15 % and 30 % of their original thickness. 11 Swell test (Type 3 materials only) Two test pieces in their “as received” state shall be submitted to test in accordance with Appendix F. The limits of
33、swell shall be between 5 % and 30 % of their original thickness. 12 Test and inspection requirements The following tests shall be carried out. 12.1 Each sheet of material (Types 1, 2 and 3) shall be examined for compliance with Clauses 4 and 5. 12.2 A representative test piece, selected by the Inspe
34、ctor from one sheet of any thickness manufactured from any batch of material (Types 1, 2 and 3), shall be tested for compliance with the requirements of Clause 6. Where a batch consists of a number of thicknesses of material it is only necessary to carry out a creep test on the thickest material use
35、d in that batch. 12.3 A representative test piece, selected by the Inspector from sheets of any one thickness manufactured from each batch of material (Types 1, 2 and 3), shall be tested for compliance with the requirements of Clauses 7, 8 and 9. 12.4 A representative test piece, selected by the Ins
36、pector from one sheet of any thickness manufactured from any batch of Type 2 material, shall be tested for compliance with the requirements of Clause 10. 12.5 A representative test piece, selected by the Inspector from one sheet of any thickness manufactured from any batch of Type 3 material, shall
37、be tested for compliance with the requirements of Clause 11. 12.6 A type approval test for corrosion resistance for all types of material shall be a matter of agreement between the supplier and the purchaser. Any changes in formulation shall be notified to the Inspecting Authority. 13 Identification
38、 The jointing shall be identified for ordering purposes by the number of this British Standard (BS F 125), material type (e.g. 2) and its thickness (e.g. 0.5). Thus Type 2 material 0.5 mm thick would be identified as BS F 125/2/0.5. Wire reinforced and/or graphite treated material shall be identifie
39、d as agreed between the manufacturer and the supplier. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:53:20 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS F 125:1973 BSI 02-20003 Appendix A Method of carrying out creep test A.1 Apparatus The general arrangeme
40、nt and details of the apparatus are given in Figure 1 and Figure 2. 1) The two heated compression platens shall be made of steel complying with the requirements of BS 970 150M28. The appropriate faces shall be plane parallel and ground to a surface finish of not more than 0.4 4m. 2) The heating of t
41、he apparatus shall be controlled to give a uniform temperature rise from room temperature to 300 5 C in 30 1 min. The difference between the temperature of the two platens shall not exceed 5 C at any time. 3) The sheathed thermocouple junctions shall be firmly pressed against the ends of the locatin
42、g holes. 4) The dial gauge shall comply with the requirements of BS 907 and shall be graduated in units of 0.002 mm. The dial gauge holder shall be water-cooled under conditions which are sensibly constant to those pertaining to the jig yield determination (see A.4). 5) The two platens shall be plac
43、ed between the loading anvils of a compression loading device. One anvil of the device shall be self-aligning. Means shall be provided for measuring the applied load to an accuracy of 500 N. 6) The assembly shall be shielded from draughts or any severe changes in ambient temperature when in use. A.2
44、 Preparation of test pieces The test piece shall be an annular ring cut from the jointing material under test to an external diameter of 75 mm and an internal diameter of 55 mm. It shall be cut with a die which leaves no burred edges and the bore and outside diameters shall be concentric. The specim
45、ens shall be conditioned in a desiccator at room temperature for at least 24 h immediately prior to the test. A.3 Test procedure 1) Ensure that the apparatus is at room temperature prior to commencement of test. 2) Measure the thickness of each test piece to an accuracy of 0.01 mm at three points ap
46、proximately 120 apart, the average reading being recorded as the initial thickness (t). 3) Lock the dial gauge into its holder so that the tip of the silica rod protrudes below the surface of the upper platen to allow contact with the lower platen when the test piece is in position. 4) Position the
47、test piece concentrically between two rings of thin aluminium foil having external and internal concentric diameters 100 mm and 40 mm respectively. Place the test piece and aluminium foil centrally between the platens. 5) Apply a force of 90 0.5 kN in 25 5 s and maintain this load constant throughou
48、t the test period. 6) Wait for a period of 5 min. 7) Switch on the heaters and control the equipment to give a uniform temperature rise to 300 5 C in 30 1 min. Note the dial gauge readings at temperatures of 50 C (t50) and 300 C (t300). 8) Allow the apparatus to cool and repeat the test with each of
49、 the other test pieces. A.4 Correction for jig distorting Since the movement indicated by the dial gauge depends on the thermal and mechanical characteristics of the jig in addition to the effect produced by the test piece, it is necessary to make a correction by carrying out a dummy test on a steel annulus in order to determine the correction for jig distortion. For this purpose the annulus shall be made of the same steel as that used for the platens i.e. complying with the requirements of BS 970 150M28. It shall have a similar profile to th
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