Abstract
It has been long known that chlorides are enriched on the heating surfaces e.g. in refuse fired or pulverised coal fired boilers. The actual conditions of chloride enrichment and the potential importance of this phenomenon in accelerated corrosion in each environment are, however, somewhat disputable. The results of some failure analyses of actual corrosion cases from the pulp and paper industry, and owing features thought to be typical of chloride accelerated corrosion in oxidative conditions, are reviewed. Corrosion morphology and deposit chemistry almost identical to known cases of chloride accelerated corrosion in refuse fired boilers or in coal fired boilers were found. Underdeposit formation of porous, non protective magnetite as a corrosion product seems to be the prerequisite of this type of corrosion. These findings are discussed also on the basis of thermodynamic predominance domain diagrams known as Pourbaix-diagrams. The results suggest a possibility of applying a generic type model to analyse chlorine accelerated oxidation, or more generally, bioxidant corrosion.
