Effect of Different Vanadate Salt Composition on Oil Ash Corrosion of Boilers

Corrosion in oil-fired boilers is accelerated in the presence of V, Cl and S which derive from low-grade fuels or the environment. 10CrMo9-10 steel is commonly used in such boilers. In order to evaluate the salts corrosion behavior of such low Cr steels, samples were immersed in several vanadate salt combinations of Cl, S, Na and Ca in air at 600 A degrees C. Even during short-term exposure, different dominant corrosion mechanisms could be identified such as active oxidation, sulfidation and acidic or basic fluxing, depending on the exact salt composition. The aggressiveness of the different salt mixtures was ranked with regard to the metal loss. It is also demonstrated that corrosion can be reduced by the addition of a calcium-containing inhibitor.