1、BRITISH STANDARD BS 6270-3: 1991 Code of practice for Cleaning and surface repair of buildings Part 3: Metals (cleaning only)BS6270-3:1991 This British Standard, having been prepared under the directionof the Elements and Components (of Diverse Materials)for Buildings Standards Policy Committee, was
2、published under the authorityof the Standards Boardand comes into effect on 31October 1991 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ECB/30 Draft for comment 89/12587 DC ISBN 0 580 19679 8 Committees responsible for this British Standard The pr
3、eparation of this British Standard was entrusted by the Elements and Components (of Diverse Materials) for Buildings Standards Policy Committee (ECB/-) to Technical Committee ECB/30, upon which the following bodies were represented: Aluminium Federation Brick Development Association British Cement A
4、ssociation British Ceramic Research Ltd. British Steel Industry Concrete Society Council for the Care of Churches Department of the Environment (Building Research Establishment) Ecclesiastical Architects and Surveyors Association Glassfibre Reinforced Cement Association Historic Buildings and Monume
5、nts Commission for England Local Authority Organizations National GRP Construction Federation National Trust Patent Glazing Contractors Association Royal Institute of British Architects Society for Protection of Ancient Buildings Steel Window Association Stone Federation Amendments issued since publ
6、ication Amd. No. Date CommentsBS6270-3:1991 BSI 09-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Preliminary considerations 1 4 Choice of method 2 5 Services 2 6 Means of access to work 3 7 Protection of buildings 3 8 Protection of workers and
7、 public 3 9 Aluminium 3 10 Cuprous metals (copper, brass and bronze) 3 11 Ferrous metals 6 12 Lead 6 13 Zinc (including zinc-coated steel) 6 Appendix A Bibliography 9 Appendix B First aid treatments 9 Table 1 Summary of factors affecting choice of method and frequency of maintenance 2 Table 2 Cleani
8、ng of aluminium 4 Table 3 Cleaning of cuprous metals (copper, brass and bronze) 5 Table 4 Cleaning stainless steel 7 Table 5 Cleaning lead 8 Publication(s) referred to Inside back coverBS6270-3:1991 ii BSI 09-1999 Foreword This Part of BS6270 has been prepared under the direction of the Elements and
9、 Components (of Diverse Materials) for Buildings Standards Policy Committee. It is intended to give building owners, architects, surveyors, engineers and contractors general background information when considering cleaning. Part3 of BS6270 describes the main methods in common use for cleaning of met
10、als and alloys and draws attention to some of the problems encountered in practice. However, in view of the widely differing ages and locations of buildings, only general guidance is given to enable the user to select the most appropriate method for the particular building concerned. This Part of BS
11、6270 should be used in conjunction with section1ofBS6270-1:1982. Where the code recommends seeking specialist advice, information may be obtained from organizations represented on the committee (see the committees responsible on the inside front cover). WARNING. This British Standard calls for the u
12、se of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. A British Standard does not purport to include all the ne
13、cessary 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 obligations. In particular attention is drawn to the Control of Substances Hazardous to Health Regulations (198
14、9). Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the i
15、nside front cover.BS6270-3:1991 BSI 09-1999 1 1 Scope This Part of BS6270 gives recommendations for the cleaning of metals and alloys which are not intended to be covered with a protective coating, renewable on site in the course of maintenance. Structural repairs are not covered by this code. Whils
16、t in a few cases it may be possible to effect surface repairs to metals, because of the specialist nature of such processes and the wide range of metals involved, no recommendations are given in this code. No recommendations are given for the cleaning of wrought iron or mild steel which are normally
17、 provided with a protective coating. NOTE 1For the preparation of iron and steel surfaces prior to protective coating, reference should be made to BS5493. NOTE 2Where work on features of historic or artistic importance is being considered, guidance from specialists should be sought, since the genera
18、l recommendations given in this code may need to be supplemented. NOTE 3For guidance on the structural use of steel and aluminium, reference should be made to BS5950 and CP118 1)respectively. NOTE 4Where there is any doubt about the structural nature of defects, advice should be sought from a charte
19、red civil or structural engineer or other appropriately qualified person. NOTE 5The cleaning recommendations in this standard may not, in some cases, be effective against agents applied during acts of vandalism. NOTE 6The titles of the publications referred to in this code are listed on the inside b
20、ack cover. See also Appendix A for a bibliography. 2 Definitions For the purposes of this code the definitions given in BS6100 or in the British Standard for the given material or component apply, together with the following. structural repairs repairs required to ensure that a structure will contin
21、ue to carry existing loads, and/or to enable the structure to carry additional loads, with an acceptable factor of safety 3 Preliminary considerations 3.1 General Since there is no such thing as a maintenance-free construction, the following essential points should be borne in mind. a) The past hist
22、ory of the building should be examined, first checking any records that may exist. b) The need for surface repairs should be distinguished from the need for structural repairs (see clause2). If in doubt, specialist advice should be sought. c) Where cleaning and/or surface repair work is to be undert
23、aken, the causes of the dirt, corrosion or defects should be established. 3.2 Reasons for cleaning 3.2.1 Introduction It is convenient to classify reasons for cleaning under two headings: aesthetics and maintenance. In practice, cleaning a building for aesthetic reasons may reveal the need for maint
24、enance. Dirt does not necessarily harm building materials and a visually acceptable and established pattern of weathering need not be disturbed. However, the primary aim should be to keep the structure or components free from deterioration. If maintenance has been sufficiently frequent, the dirt wil
25、l be loose and corrosive products will not have had time to do serious harm. The principal factors affecting frequency of cleaning are given inTable 1. 3.2.2 Aesthetics Even where maintenance is not required, cleaning may be required in order to: a) reveal the nature, colour or details of an existin
26、g building; b) unify the appearance of a building which has been altered, extended or repaired; c) facilitate the choice of suitable materials for a proposed extension or for repairs; d) reflect more light on to other buildings; e) promote personal or civic pride. 3.2.3 Maintenance It may prove nece
27、ssary to clean the building for the following reasons: a) to remove harmful deposits from the fabric; b) to expose defects or corrosion in order to establish the extent and nature of repairs needed. It should be borne in mind that the cost of normal maintenance cleaning of metalwork is only a fracti
28、on of the cost of restoration after neglect. 3.3 Buildings of architectural or historic interest Where the building concerned is statutorily listed or in a conservation area, the local authority may discourage or even prohibit the cleaning of individual buildings, so as to conserve the uniform appea
29、rance of whole streets or areas. 1) In course of revision.BS6270-3:1991 2 BSI 09-1999 Where work on features of historic or artistic importance is being considered, guidance from specialists should be sought, since the general recommendations given in this code may need to be supplemented. Care shou
30、ld be taken not to remove traces of the original design, surface treatment or colouring where these may be of architectural or historic interest. NOTEScheduled monument consent from the Secretary of State for the Environment is required before any works are carried out on a scheduled ancient monumen
31、t. Listed building consent from the local planning authority is required before any works are carried out for the demolition of a listed building or for its alteration or extension in any manner which would affect its character as a building of special architectural or historic interest. 4 Choice of
32、 method As there are many ways of cleaning buildings, and a wide range of building and materials has to be considered, it is not possible to recommend general methods to suit every case encountered in practice. Each project should be considered carefully in the light of all available methods and of
33、previous experience with the building in question or other similar buildings. It is essential to identify correctly the type of metal and any special finishes. Any one building is likely to display a variety of surfaces and sometimes a variety of materials. Each surface and material needs to be clea
34、ned by an appropriate method, which might mean that more than one method needs to be used when cleaning the whole building. Unless adequate protection, is provided, treatment of one material or surface may harm another adjacent material or surface,e.g.sealants and movement joint fillers may be affec
35、ted by chemical cleaning agents. Where heavy soiling, deposits and corrosion have occurred, treatments intended for cleaning neglected metalwork are likely to damage or remove completely some surface finishes. In such cases, it is necessary to decide whether to proceed with the basic cleaning method
36、 and accept some deterioration of the surface or to use a more severe cleaning method and subsequently replace the damaged surface. If the metal is pitted or perforated, it will be more difficult to wash down and clean. Attempting to clean metals which are found to be perforated may cause damage to
37、fixings, adhesives, etc. Given the relative cost of different methods, the choice of method should take into account all the factors listed inTable 1. After choosing a method, a trial area should be cleaned using this method. Before tenders are invited, the chosen method and the finish to be achieve
38、d should be agreed. Table 1 Summary of factors affecting choice of method and frequency of maintenance 5 Services Before choosing a method, it is necessary to ascertain which of the services listed below are adequate and in working order: a) water supply; b) drainage; c) electricity. Factor to be co
39、nsidered Remarks 1 Type and condition of metal See clause 4 2 Type and condition of finish 3 Amount and type of deposits to be removed 4 Type and use of building See notes 1 and 2 5 Location of building See notes 1, 3 and 4 6 Effect of method on structural elements See note 5 7 Adjacent materials or
40、 surface See clause 4 8 Disturbance to public and occupants: dirt, dust, noise, chemicals See clause 8 9 Availability of services See clause 5 10 Means of access See clause 6 11 Speed of work 12 Likely weather conditions See note 1 NOTE 1The height of a building and its relationship to public ways m
41、ay make the use of abrasion or chemicals hazardous particularly in very windy conditions (see clause 8). NOTE 2Buildings of architectural or historic interest need special consideration (see 3.4). NOTE 3The type of environment may be significant, e.g.industrial or marine. NOTE 4The nature and condit
42、ion of adjoining buildings also may influence the extent and method of work. NOTE 5Certain cleaning processes can give rise to increased stresses following reductions in the cross section of structural elements.BS6270-3:1991 BSI 09-1999 3 6 Means of access to work The choice of the means of access d
43、epends on the geometry and construction of the building, the type of work and the duration of the work. The cost of access should be treated as part of the total cost and not considered in isolation, since expensive systems may sometimes prove to be more economical in total cost. Reference should be
44、 made to clause7 ofBS6270-1:1982, BS5516, BS5973, BS5974 and BS6037. 7 Protection of buildings Before any cleaning work is done, it is necessary to consider what protection or temporary support the building or adjacent buildings will require. The principal precautions to be considered are described
45、in clauses7 and 8 of BS6270-1:1982. 8 Protection of workers and public To ensure protection of the public, the area where work is being carried out may need to be close sheeted. In addition, protective barriers may be required to prevent people passing under or near the working area. All electric ca
46、bles and fittings likely to be affected by the work should be disconnected or suitably protected before any work is begun. Apart from taking these and other safety precautions common to all construction work, special measures are necessary when using certain cleaning methods, which are dealt with in
47、 clause9 of BS6270-1:1982. Recommended first aid treatments are given inAppendix B. 9 Aluminium 9.1 Types of finish The following types of finish are dealt with in this clause. a) Mill finish. Aluminium which has been given no special protective treatment but forms a natural protective oxide film on
48、 its surface. When subjected to exposure and weathering, the lustre of the bare metal is likely to change to a dull matt grey. b) Anodized. Aluminium protected by a uniform oxide coating produced by an electrolytic process. Anodized coatings may be coloured. In case of doubt, the following method ma
49、y be used to determine whether a surface is anodized. Thoroughly clean a small area and rub a clean pencil eraser on the surface. If there is no protective coating the surface of the eraser will turn black. 9.2 Cleaning 9.2.1 The surface of mill finish or anodized aluminium will be scratched or removed by abrasives and acid or alkali based agents. Furthermore, reaction with certain metallic salts can accelerate corrosion. Thus it is essential to select an appropriate cleaning method, as given inTable 2. Anodized finishes should be treated with care, as they cannot b
