CORROSIVE DEGRADATION AND FAILURE OF VERTICAL FURNACE WALL TUBES OF ABOILER

The failures of vertical furnace wall tubes of a co-generation boiler have been investigated. The thinned section failures, often accompanie d by buckling prior to failure, were found to be due to acid attack as a consequence of ''hideout''. The local corrosion and consequent thic k and non-protective iron-oxide deposition at the sites of attack prod uced hot spots, which is evident from the microstructure of those regi ons. Decarburization by hydrogen generated during the corrosion proces s also contributed to the loss in strength of the material. The possib ility of ''alkali attack'' as opposed to acid attack was ruled out by the various findings of this investigation. (C) 1997 Published by Else vier Science Ltd.