1、BRITISH STANDARD AEROSPACE SERIES BS 4F 68:2002 Controlled storage of vulcanized rubbers for use in aerospace applications ICS 49.025.40 BS 4F 68:2002 This British Standard, having been prepared under the direction of the Engineering Sector Policy and Strategy Committee, was published under the auth
2、ority of the Standards Policy and Strategy Committee on 4 October 2002 BSI 4 October 2002 The following BSI references relate to work on this British Standard: Committee reference ACE/25 Draft for comment 00/706508 DC ISBN 0 580 40306 8 Committees responsible for this British Standard The preparatio
3、n of this British Standard was entrusted to Technical Committee ACE/25, Rubber, elastomeric and sealant materials for aerospace purposes, upon which the following bodies were represented: British Hydromechanics Research Group (BHR) British Narrow Fabrics Association (BNFA) British Rubber Manufacture
4、rs Association Ltd (BRMA) UK Defence Standardization Society of British Aerospace Companies (SBAC) Amendments issued since publication Amd. No. Date CommentsBS 4F 68:2002 BSI 4 October 2002 i Contents Page Committee responsible inside front cover Foreword ii 1S c o p e 1 2 Normative references 1 3 C
5、lassification of rubbers 1 4S t o r a g e 2 Annex A (normative) Storage conditions 4 Annex B (normative) Methods of inspection and testing 6 Annex C (informative) Previous rubber groupings 8 Bibliography 9 Table 1 Group A rubbers 1 Table 2 Group B rubbers 2 Table 3 Group X rubbers 2 Table 4 Initial
6、and extension periods for materials and unassembled components in storage 3 Table A.1 Periods for rotation of tyres in storage 5 Table C.1 Classification of rubbers according to rate of deterioration 8BS 4F 68:2002 ii BSI 4 October 2002 Foreword This British Standard has been prepared by Technical C
7、ommittee ACE/25. It supersedes BS 3F 68:1977, which is withdrawn. It was first published in 1968 under the direction of the Aerospace Standards Committee at the request of the Society of British Aerospace Companies Ltd. This new edition of BS F 68 incorporates technical changes only. It does not rep
8、resent a full review or revision of the standard, which will be undertaken in due course. This standard takes into account accumulated experience since it was first published, reflects changes in the grouping of rubbers and in their storage periods, and refers to the inclusion of stockists in the di
9、stribution chain and the steps to be taken to secure agreement on the division of the storage period. This new edition extends the range of products considered. Although vulcanized rubbers made to well-controlled specifications, properly packaged and stored under good conditions, will remain in a fu
10、lly serviceable condition for many years, nevertheless, some rubbers are more susceptible than others to degradation by such factors as heat, light, ozone, oxygen, humidity, etc. Because of these factors a system of storage control is necessary to ensure that such rubbers are issued in a serviceable
11、 condition. For the convenience of users of this standard, the grouping of rubbers specified in BS 2F 68:1973 is given in Annex C. NOTE This standard is not intended to be used as a design document. This publication does not purport to include all the necessary provisions of a contract. Users are re
12、sponsible for its 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, pages i and ii, pages 3 to 9 and a back cover. The BSI copyright date displayed in this
13、document indicates when the document was last issued.BS 4F 68:2002 BSI 4 October 2002 1 1 Scope 1.1 This British Standard specifies requirements for the storage, and inspection during storage, of vulcanized rubber, whether in the form of materials or as components to be used for aerospace purposes.
14、These requirements also apply to items made from cellular rubber. 1.2 The requirements of this standard do not apply to rubber components contained within mechanical assemblies, e.g. pumps and valves. NOTE In such cases the recommendations of the assembly supplier for exercising the assembly and lif
15、ing of the rubber need to be sought and applied. 1.3 The storage periods quoted apply only if the storage conditions specified in Annex A are complied with and if the packaging complies from the date of cure with the requirements of BS F 69, as far as is practicable, making allowance for subsequent
16、manufacturing operations. 1.4 The storage period comprises the whole period of existence of the rubber from the date of cure. This period will generally be divided between manufacturing (including assembly) and storage (e.g. in manufacture, by stockists, by aircraft constructors and operators) and t
17、he division of this period should be mutually agreed between the interested parties. 1.5 These requirements are based on the classification of rubbers into groups as defined in Clause 3. 2 Normative references The following referenced documents are indispensable for the application of this document.
18、 For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. BS F 69, Specification for packaging and identification of vulcanized rubber items. Defence Standard 81-39, Packaging of rubber hoses, plas
19、tics hoses, and hose assemblies 1) . 3 Classification of rubbers Rubbers are classified into three groups of differing sensitivity to ageing as follows: a) Group A rubbers with a high sensitivity to ageing as listed in Table 1; b) Group B rubbers with an intermediate sensitivity to ageing as listed
20、in Table 2; c) Group X rubbers with a low sensitivity to ageing as listed in Table 3. Any new rubbers introduced which are not listed in Table 1, Table 2, or Table 3 shall be considered as belonging to group A until their storage capabilities have been established. Table 1 Group A rubbers 1) Availab
21、le from: UK Defence Standardization, Kentigern House, 65 Brown Street, Glasgow G2 8EX. Abbreviation a Chemical name a Common name NR Isoprene rubber, natural Natural rubber BR Butadiene rubber Polybutadiene IR Isoprene rubber, synthetic Polyisoprene AU Polyester urethane rubber Polyurethane b EU Pol
22、yether urethane rubber Polyurethane b SBR Styrene-butadiene rubber SBR PNR Polynorbornene rubber Polynorbornene PS Polysulfide rubber Polysulfide a In accordance with BS ISO 1629 (with the exception of PNR and PS). b Owing to the extreme susceptibility of some types of polyurethane to degradation by
23、 moisture, special care and/or inspection in storage may be required.BS 4F 68:2002 2 BSI 4 October 2002 Table 2 Group B rubbers Table 3 Group X rubbers 4 Storage 4.1 Requirements 4.1.1 Storage Materials and unassembled components shall be packaged in accordance with the requirements of BS F 69 and s
24、tored under the conditions specified in Annex A. 4.1.2 Inspection in storage of group A and group B rubbers When packaged and stored in accordance with the requirements of 4.1.1, materials and unassembled components of group A or group B rubbers should remain in good condition for at least the appro
25、priate initial period given in Table 4 reckoned from the date of cure. (Some items of group A rubbers in thicknesses of less than 1.5 mm, or group A cellular rubbers, may need more frequent inspection.) Inspection during storage shall follow either procedure A see 4.1.2a) or procedure B see 4.1.2b).
26、 Batches which fail inspection and/or testing shall be considered as unserviceable. a) Procedure A. Not later than the expiry of the initial periods as given in Table 4, representative samples of a batch shall be inspected and/or tested in accordance with Annex B and, if found to be satisfactory, th
27、e batch shall then be considered suitable for the stated extension period (see Table 4). Further renewals of the extension period may be made, subject to satisfactory further inspection and/or testing. b) Procedure B. Components may be maintained in store without periodic inspection. After the expir
28、y of the initial periods given in Table 4, representative samples of a batch shall be inspected and/or tested in accordance with Annex B before use or issue to a customer. Subsequently all remaining items of the inspected batch should remain fully serviceable without further inspection until at leas
29、t the expiry of the extension period given in Table 4. Abbreviation a Chemical name a Common name NBR Acrylonitrile-butadiene rubber Nitrile rubber HNBR Hydrogenated NBR Hydrogenated nitrile rubber NBR/PVC Blend of acrylonitrile-butadiene rubber and polyvinyl chloride Nitrile PVC ECO Copolymer of et
30、hylene oxide and chloromethyloxirane Epichlorohydrin rubber ACM Copolymer of ethyloacrylate (or other acrylates) and a small amount of a monomer which facilitates vulcanization Acrylic rubber CR Chloroprene rubber Chloroprene IIR Isobutene-isoprene rubber Butyl rubber aIn accordance with BS ISO 1629
31、. Abbreviation a Chemical name a Common name CSM Chlorosulfonylpolyethylene Chlorosulfonated polyethylene EPM Ethylene-propylene copolymer EPM or EPR EPDM Ethylene-propylene diene modified EPDM FKM Fluoro rubber having substituent fluoro, perfluoroalkyl or perfluoroalkoxy groups on the polymer chain
32、 Fluorocarbon rubber FVMQ Fluorosilicone rubber Fluorosilicone VMQ/PVMQ Silicone rubber Silicone a In accordance with BS ISO 1629.BS 4F 68:2002 BSI 4 October 2002 3 Table 4 Initial and extension periods for materials and unassembled components in storage 4.1.3 Inspection in storage of group X rubber
33、s No periodic inspection is required for materials or unassembled components of group X rubbers. 4.2 Repackaging All samples withdrawn for testing and/or inspection and found to be satisfactory shall be repackaged to the original specification before being returned to storage. 4.3 Inspection before
34、final assembly Items of all groups shall be inspected and/or tested immediately prior to final assembly. Group Initial period a Extension period(s) a years years Group A rubbers 5 2 Group B rubbers 7 3 Group X rubbers See 4.1.3, 4.3 and 1.2 a See also 1.4.BS 4F 68:2002 4 BSI 4 October 2002 Annex A (
35、normative) Storage conditions A.1 General requirements NOTE The storage requirements specified in A.1 are based on the guidelines given in BS ISO 2230. A.1.1 Temperature The temperature of the store shall be between 5 C and 25 C. A.1.2 Humidity Moist conditions shall be avoided. Storage conditions s
36、hall be such that condensation does not occur. The relative humidity shall be below 75 %. A.1.3 Light Vulcanized rubber shall be protected from light, in particular direct sunlight and intense artificial light with a high ultraviolet content. Unless the articles are packaged in opaque containers, it
37、 is advisable to cover any windows of storage rooms with a red or orange coating or screen. A.1.4 Ozone As ozone is particularly deleterious, storage rooms shall not contain any equipment that is capable of generating ozone, such as mercury vapour lamps, high voltage electrical equipment, electric m
38、otors or other equipment giving rise to electric sparks or silent electrical discharges. A.1.5 Deformation Vulcanized rubber shall, wherever possible, be stored in a relaxed condition free from tension, compression or other deformation. If it is impossible to avoid deformation it should be kept to a
39、 minimum, since deformation can lead to deterioration and to permanent changes of shape. Where articles are packaged in a strain-free condition they shall be stored in their original packaging. In case of doubt the manufacturers advice shall be sought. High stacking should be avoided, and heavy pack
40、ages should not be stacked vertically. A.1.6 Contact with liquid and semi-solid materials Vulcanized rubber shall not be allowed to come into contact with liquid or semi-solid materials (in particular, solvents, oils and greases) at any time during storage, unless so packaged by the manufacturer. A.
41、1.7 Contact with metals Certain metals (in particular, copper, manganese and iron) are known to have deleterious effects on vulcanized rubber. Vulcanized rubber shall not, therefore, be stored in contact with metals except when bonded to them but shall be protected by wrapping or by separation with
42、a layer of suitable material, e.g. paper or polythene, as specified in BS F 69. Plasticized PVC film shall not be used for wrapping. A.1.8 Contact with dusting powder Any dusting powder used shall be free from constituents having a deleterious effect on vulcanized rubber. A.1.9 Contact between vario
43、us rubbers Contact between vulcanized rubbers of different composition shall be avoided. NOTE This applies particularly to vulcanized rubbers of different colours. A.1.10 Articles with rubber-to-metal bonds The metal part of bonded metal items shall not come into contact with the vulcanized rubber o
44、f other metal parts. Any temporary protective used on the metal shall be such that it will not adversely affect the rubber or bond. A.1.11 Containers, wrapping and covering materials The materials of any containers, wrappings and coverings shall be free from substances deleterious to vulcanized rubb
45、er, e.g. copper naphthenate, creosote, sulfur-containing compounds.BS 4F 68:2002 BSI 4 October 2002 5 A.1.12 Rotation of stocks Vulcanized rubber shall remain in store for as short a time as possible. Therefore articles shall be issued from stores in strict rotation so that the articles remaining in
46、 store are those of latest manufacture or delivery. A.1.13 Cleaning Great care shall be taken in cleaning vulcanized rubbers. Cleaning with soap and water is generally the least harmful but should not be used for polyurethane rubbers or fabric composites with exposed fabric. Organic solvents (such a
47、s trichloroethylene, carbon tetrachloride, or petroleum spirit), abrasives and sharp objects shall not be used. Articles that have been cleaned shall be dried at room temperature. NOTE Vulcanized rubber accidentally contaminated, however cleaned, will not be as satisfactory as uncontaminated rubber.
48、 A.2 Requirements for the storage of specific items A.2.1 Tyres A.2.1.1 General Where tyres are delivered wrapped, the wrappers shall be left on during storage. A.2.1.2 Preferred method Tyres shall be stored vertically in special racks embodying support tubes so that each tyre is supported at two po
49、ints. Two-thirds of the tyre shall be above the support tubes and one-third below. By this method the tyre is supported by its tread and distortion is reduced to a minimum. The tyres shall be turned to new positions as specified in Table A.1. Table A.1 Periods for rotation of tyres in storage A.2.1.3 Alternative method Tyres shall be stacked by laying them flat one on top of the other on a clean, level floor. The height of the stack shall be limited to four tyres, which shall all
