Combustion turbines have been in service in Saudi Arabia for many years. Over this period, it has become apparent that the unique conditions of high sulfur gas fuel (sometimes with liquid carryover) and wind blown sand and salt particles result in a serious turbine hot corrosion problem. Metallurgical study of service blades and vanes, together with site analyses, served as background for a detailed laboratory coating evaluation. As a result, two corrosion resistant coatings fan electron beam physical vapor deposited CoCrAlY overlay and a pack diffusion Rh-Pt aluminide) were selected for application to turbine blades and vanes installed in Westinghouse W501D units for service in Saudi Arabia. State-of-the-art inlet air filtration was also installed to further reduce the possibility of hot corrosion. Comparisons were made between the two coatings after as much as 20,000 hr of service, and results were correlated with laboratory pressurized rig tests conducted under simulated conditions. In general, the performance of the CoCrAlY overlay coating was superior to that of the Rh-Pt aluminide diffusion coating.

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