Sprayed metal coatings are produced industrially by melting the coating metal in a stream of hot gas and projecting it in the form of a dispersed spray on to the surface to be coated. The coating metal may be introduced into the hot gas stream either as powder or as wire.
The principal change made in this edition of B.S. 2569. Part 1, have been in the requirements for the composition of coating metals to bring these into line with current British Standards for non-ferrous metals. In the specified thicknesses of coatings, In the description of the method of preparing a reference surface, and in the lest for adhesion. The latter incorporates only minor amendments to the procedure given in the 1955 edition, made with the object of increasing the case of performance and the reliability of the test, but t is hoped that a better test will be developed in the future. Attention is drawn to the fact that, as with other type of surface coating, design of the article may be most important in achieving maximum protection: an Appendix has been introduced giving some broad guidance on design features.
It is essential that the purchaser should state the symbol for the coating required, which indicates the coating metal and its nominal thickness: merely to ask for a coating complying with the requirements of B.S. 2569: Part I without this Information is insufficient.
Recommendation concerning the use of sprayed metal coatings, with and without superimposed paint systems, for the protection of iron and stee1 structures from corrosion are given In British Standard Code of Practice CP 2008, 'The protection of iron and steel structures from corrosion '.
For the protection of iron and steel by sprayed metal coatings against corrosion at elevated temperatures reference should be made to B.S. 1569 : Part 2.
