Corrosion of Boiler Tubes

Abstract

The reduction of the number of boiler tube failures to a minimum is now a matter of national importance. Revolutionary improvement is not expected in the nature of the tubes. Tubes fail rapidly by local, and less rapidly by general, corrosion. The removal of scale by shot blasting before use will reduce the extent of losses due to pitting, and so will additions of 0·2–0·5 per cent of copper. Metallurgical data regarding tubes, and chemical data regarding feed waters are summarized in the paper, from the author's extensive records. After discussing how corrosion occurs at cracks in oxide, scale, or paint, suggestions are made for preventing corrosion in locomotive, marine, and stationary boilers. Recommendations include simplification and standardization of boiler water tests by a suitable British Standards Committee, and the suggested Specification is sketched in outline. The paper is concluded by Appendixes comprising (i) a questionnaire (with answers) on the present-day practice as regards the manufacture of boiler tubes in Great Britain; (ii) a list of reports published by the American Railroad Engineering Association; and (iii) a bibliography of selected items on corrosion, for the index prepared and maintained at the Chemical Research Laboratory, Teddington.