1、BSI BS854bb PART87 82 Lb2qbb OOb4LLil T BS 5466 : Part 7 : 1982 IS0 4542- 1981 UDC 669.058 : 620.193.2 O British Standards Institution. No part of this publication may be photocopied or otherwise reproduced without the prior permission in writing of BSI. Methods for Corrosion testing of metallic coa
2、tings Part 7. Guidance on stationary outdoor exposure corrosion tests IS0 title : Metallic and other non-organic coatings - General rules for stationary outdoor exposure corrosion tests1 Mthodes dessai de la corrosion des revtements mtalliques Partie 7. Directives pour les essais de corrosion statiq
3、ues en milieu extrieur Korrosionsprfverfahren fr metallische Uberzge Teil 7. Anleitung fr die Durchfhrung von statischen Korrosionsprfungen durch das Aussetzen im Freien British Standards Institution BSI BSmSLibb PARTm7 82 m Lb2Libb 00bllL42 I m BS 5466 : Part 7 : 1982 Contents National foreword Coo
4、perating organizations Methods O. Introduction 1. Scope and field of application 2. Reference 3. Test specimens 4. Operating conditions 5. Test procedure Page Inside front cover Back cover National foreword This Part of BS 5466 has been prepared under the direction of the Surface Coatings (other tha
5、n Paints) Standards Committee. It is identical with IS0 4542-1981 Metallic and other non-organic coatings - General rules for stationary outdoor exposure corrosion tests,-prepared with the active participation and approval of the United Kingdom, by Technical Committee 107, Metallic and other non-org
6、anic coatings, of the International Organization for Standardization (ISO). It is intended to publish further Parts as the international work progresses. Terminology and conventions. The text of the international standard has been approved as suitable for publication as a British Standard without de
7、viation. Some terminology and certain conventions are not identical with those used in British Standards; attention is especially drawn to the following. 6. Test report Page 5 Annexes A. Outdoor corrosion factors characterizing B. Example of monthly tabulation of the results of C. Example of yearly
8、tabulation of the results of exposure conditions 6 recording outside corrosion factors 7 recording outdoor corrosion factors 8 The comma has been used throughout as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Where the word
9、s International Standard appear, referring to this standard, they should be read as British Standard. Cross-reference International standard Corresponding British Standard IS0 4540- 1980 BS 5466 Methods for corrosion testing of metallic coatings Part 6 : 1982 Rating of results of corrosion tests on
10、electroplated coatings cathodic to the substrate (Identical) BSI BSaS11bb PART*7 82 W Lb211bb 00611143 3 BS 5466 : Part 7 : 1982 British Standard Methods for Corrosion testing of metallic coatings Part 7. Guidance on stationary outdoor exposure corrosion tests O Introduction 3 Test specimens Corrosi
11、on testing under outdoor exposure conditions is carried 3.1 T out irr order to : The following types of test specimens may be used : a) obtain data on the behaviour of protective coatings in natural atmospheric environments; b) assess the corrosion resistance of different protective coatings under p
12、articular types of atmospheric conditions; - specially prepared specimens covered with the protec- tive coating to be tested; - coated production articles or parts thereof. c) compare the results of testing under given laboratory and outdoor exposure conditions; It should be noted, however, that the
13、 performance of specially prepared specimens may differ from that of production articles. dl investigate the mechanism Of corrosion Of particular If production articles are used for testing, they should be selected to give the maximum possible information concerning the type of failure likely to aff
14、ect the performance of the article in use. protective coatings; e) determine the duration of effective protection; fl obtain information on the corrosivity of the atmosphere at various locations; 3.2 Shape and dimensions g) resistance to corrosion. show the influence of the design of components on I
15、t involves exposure of coated test specimens to the action of atmospheric factors under field conditions and periodic obser- vations of the test specimens over a period that may extend for several years. The atmospheric conditions at a field station depend not only on geographical location and atmos
16、pheric composition, but also on additional local factors which may either be constant or may vary periodically or accidentally in a particular micro- climate. 1 Scope and field of application To minimize edge effects and to obtain representative corrosion, the surface area of the test specimens shou
17、ld be as Iarge as possible and, in any case, not less than 50 cm2 (5cm x 10cm). If the coated articles used are smaller than 50 cm2 in area, specimens of the same kind may be combined to total the re- quired minimum surface area, but the results obtained will not necessarily be strictly comparable w
18、ith those obtained on specially prepared test specimens of the specified minimum area. 3.3 Preparation Clean the test specimens thoroughly before exposure to remove any contaminants that may affect the performance of the coating system being tested. The cleaning method to be This International Stand
19、ard gives guidance on methods of Sta- employed depends upon the nature of the and the con- tionary testing, in natural outdoor atmospheric conditions, of taminants, but shall not include the use of any abrasives or protective metallic, conversion and other non-organic coatings. solvents which may at
20、tack the surfaces of the test specimens. Mobile corrosion testing is not included in this International Standard, but it may be-necessary, in some circumstances, to supplement stationary tests with mobile tests. NOTE - If the effect of controlled damage, such as scribing or bending, is to be studied
21、, it should be carried out at this stage. 2 Reference 3.4 Marking IS0 4540, Metallic coatings - Coatings cathodic to the Mark the test specimens in such a way that no confusion substrate - Rating of electroplated test specimens subjected during the exposure test is possible. Markings should be legib
22、le to corrosion tests. and durable over the whole- period of exposure and should be 1 L ES1 BSm54bb PARTm7 82 W 3624bb 0064344 5 W BS 5466 : Part 7 : 1982 made on those areas of the test specimens that are not subjec- ted to visual assessment and that have no functional purpose. Test specimens may b
23、e marked by one of the following methods : a) positional notch coding before the protective coating is applied (preferred method); b) stamping appropriate numbers (with a numbering stamp); ci hanging on the test specimen a number plate made of a corrosion-resistant material, hanging free of the spec
24、imen and attached by means of a loose-fitting, non-metallic thread, for example nylon thread; d) painting with suitably durable paints on the reverse side of the test specimen. Numbers should preferably be marked on the front (test) side of the test specimens, at their bottom edge. The holes on whic
25、h number plates are hung should be situated near the bottom edge of the specimen so that the plate itself cannot come into direct contact with either the test specimen to which the plate is attached or with neighbouring test specimens after they have been positioned in the frame. Mark test specimens
26、 with figures and letters so that the follo- wing information is indicated : a) the type of coating; b) a serial number; c) the place and conditions of testing. The markings should be minimized, preferably by using a sim- ple code that enables them to be associated with the informa- tion required (s
27、ee clause 6). 3.5 Number Select the number of test specimens in any one series of tests according to the type of specimen, the number required to eva- luate a particular physical property and the number expected to be removed for examination during the period of exposure. The number of test specimen
28、s of each type used for a given evalua- tion should not be less than three for test specimens having a surface area of at least 50 cm2. If the specimens have smaller surface areas, take a correspondingly greater number of test specimens. 3.6 Standard specimens It is desirable that standard test spec
29、imens of solid metals, for example zinc, copper or low alloy steel, should be included alongside the test specimens of the coating system being examined in order to be able to assess the prevailing corrosive conditions. Therefore, such metals should be chosen from those for which data concerning per
30、formance in a variety of locations have been established. The standard test specimens should be stored under the conditions specified in 3.7. 2 3.7 Storage Store the test specimens before exposure in a clean, dry at- mosphere in an air-conditioned, temperature-controlled room with a relative humidit
31、y of 50 % or less, or sealed in a desic- cator, or by sealing the specimens into evacuated plastics bags containing a desiccant. 4 Operating conditions 4.1 Corrosion environment Select the test conditions bearing-in mind that the data ob- tained for a given set of test specimens should correspond wi
32、th, or be similar to, the actual conditions of use of metals, coatings or articles. Before exposure, assess the corrosion fac- tors indigenous to the place where testing is to be carried out. The factors affecting corrosion vary with the nature of the material being tested and may include any or all
33、 of the follow- ing : a) atmospheric humidity and its fluctuations; b) air temperature and its fluctuations; c) atmospheric precipitation; d) solar radiation; e) hours of sunshine; f) periods) of wetting of the surface; g) direction and speed of winds; h) atmospheric pollution, both chemical (such a
34、s the presence of gases and vapours) and physical (such as dust, smoke and foreign matter); j) dust composition. The recommended methods and frequency of monitoring these factors are given in annex A. 4.2 Atmospheric field stations and types of exposure 4.2.1 Location of field stations An outdoor fi
35、eld station comprises an area of ground (testing ground) or a building (.e. a roof) where suitable equipment for fixing the test specimens is placed. A fence round the exposure site is recommended in order to prevent the possibility of inter- ference with the Specimens. The location of the field sta
36、tion should be such as to permit periodic observations of the test specimens and daily recording or evaluation of the atmospheric factors specified in 4.1. It is advantageous to locate the field stations near to or at a meteoro- logical station. BSI BS*S4bb PARTm7 82 m Lb24bb7 00bYL45 7 m BS 5466 :
37、Part 7 : 1982 The location of the field station should be selected mainly from the point of view of the ease of examination. Two kinds of field station for atmospheric corrosion testing are distinguished : The roof should be inclined so as to enable water to flow down and should normally ensure prot
38、ection against rain water, water dripping from the roof and water rebounding from the ground. It should also ensure complete or partial shielding of the test specimens from solar radiation. a) permanent field stations, established in places of defi- The maximum height of the roof should be not more
39、than 3 m nite environmental atmospheric conditions that are charac- and it should overlap the racks by not more than 3 m. teristic of a given macroclimatic area or, within this area, of 4.2.2.3 Sheds for enclosed exposure a given microclimatic area; b) special testing field stations, established per
40、iodically for The design of the shutter shed should ensure protection a predetermined period of time only, in places of specific ch- against atmospheric precipitation, solar radiation and wind, but should allow the air flow from the outside to be maintained. matic and corrosive conditions. The exter
41、ior surfaces of the shed walls and doors should be 4.2.2 Types of exposure painted white. Depending upon the purpose of testing, the following modes of exposure of the test specimens may be used : The shed roof should be impervious and properly inclined with eaves and drain gutters. a) open space ex
42、posure, .e. direct exposure to all atmos- pheric contaminants; b) exposure either under a cover that protects the test specimens completely from solar radiation and atmospheric precipitation, or in a partly enclosed space, such as shutter sheds, where the test specimens are protected also by shut- t
43、ered side-walls; c) closed space exposure, where the external circumstan- ces may have only limited influence on the test specimens. 4.2.2.1 Racks or frames for full exposure For open-space exposure, the test specimens should be placed directly on racks or frames which enable large numbers of test s
44、pecimens to be exposed. The racks or frames, in addition to meeting the exposure requirements (see 4.41, should : a) either be made of materials sufficiently corrosion- resistant under the specified conditions or be protected by coatings resistant to the conditions; b) be secured so as to prevent un
45、desirable displacement and movement of the test specimens; c) be designed so that the lowest edge of the test specimens is not less than 0,5 m from the ground, thus preventing spray reaching the test specimens when it rains. The shutters should be of the venetian blind type, fixed and stable, so tha
46、t air exchange is possible between the inside of the shed and the outside atmosphere and so that no rain or snow can penetrate to the interior of the shed. The wooden floor of the shed should be at least 0,5 m above ground level. The internal dimensions of the shutter shed should be chosen according
47、 to the number of test specimens which are to be placed on racks or shelves inside the shed. The design of the racks and shelves and the positioning of specimens should be such as to ensure free air circulation between the test specimens and to prevent the formation of specific microclimatic conditi
48、ons at particurar remote spaces in the shed. The shutter shed should be placed on an open space in the testing station. If more than one shed is placed on the same station, the distance between them should be such that the presence of one shed will not affect the climatic conditions in- side another
49、. It is recommended that the minimum distance between sheds be equal to twice their height. 4.3 Measuring instruments The following measuring instruments may be used to record the exposure conditions : a) hygrothermograph, to record the temperature and the absolute and relative humidities. To monitor the data ob- tained from this instrument, maximum-minimum ther- mometers and psychrometers are used; The height of the vegetation in the neighbourhood of the racks should not be greater than 0,2 m. Objects which may screen the test specimens from solar radia- tio
