Unscheduled downtime of Flue Gas Desulfurization (FGD) systems in the late 1970’s and early 1980’s was often traced to corrosion of the material components. A concerted effort by the FGD industry (A/E firms, EPRI, alloy producers, lining suppliers, research institutions, et al) was mounted to define the problems and provide cost effective solutions. The industry today has a much better (if not total) understanding of the complexity of the corrosive environments of wet scrubber systems and this knowledge was gained only after years of investment in research and development programs. The results of these programs have led to improved alloy metallurgy, non-metallic coatings, process designs and fabrication/inspection techniques. The benefits of this effort are that today the industry is fully enjoying the “reliability in performance” in FGD systems with minimal interruption, a phenomenon which was almost non existent about 20 years ago. This paper briefly describes the chronology of the various factors leading to where the industry is today regarding alloy trends, case histories, and some corrosion data. Also
discussed are the future trends, prospects and challenges this industry will be facing in the 21st century.
Keywords: FGD, Ni alloys, Ni-Cr-Mo alloys, 6Mo alloys, wallpapering, alloy 59, UNS NO6059, alloy C-276, N10276, localized corrosion, acid dew point corrosion, scrubbers