Utilities worldwide are facing increased demand for additional electricity, reduced plant emissions and greater efficiency. Part of the solution is achieved by increasing boiler temperature, pressure and coal ash corrosion resistance of the materials of boiler construction. In this paper, a new nickel-base tube alloy meeting this challenge is characterized with emphasis on its corrosion resistance. An alloy development strategy is described as well as a testing methodology to verify corrosion performance. The role of certain key elements in influencing requisite coal ash corrosion resistance is shown and the influence of several important environmental factors on the alloy of choice is discussed.
Key words: coal ash corrosion, oxidation, sulfldation, alkali sulfates, laboratory testing, alloying elements, ferric steels, austenitic stainless steels, nickel alloys