Duplex and Superduplex stainless steel grades for wet fluegas desulphurisation systems

Abstract

The corrosion risks in a wet flue gas desulphurization systemenvironment are reported. Uniform and localized corrosionresistance of different stainless steels is studied by electrochemicaltests. The effects of chloride content, fluoride content, pH andtemperature on corrosion resistance are discussed. The results showthat duplex UNS S32205 or superduplex UNS S32520 gradesare prime substitutes for austenitic 317LNM or super austenitic likeUNS S34565 grades in many aggressive environments. The lifecycle costs of scrubbers constructed of stainless steels plates or cladplates are compared. The excellent corrosion resistance of duplexand superduplex stainless steels, combined with their increasedmechanical properties and moderate alloy cost afford very costeffective solutions for wet flue gas desulphurization.