The number of countries, which suffer from a shortage of fresh water resources, is increasing
continuously. For this reason, the number of desalination projects (production of fresh water from sea
water) is booming. In the past, carbon steel, clad steels, copper-nickel alloys, or austenitic stainless
steel grades such as 316L were the primary materials used for the walls of thermal process evaporation
cells. More recently the duplex grades UNS S32304 and UNS S32205 have been selected for this
application. This paper provides some of the technical reasons, which brought about this change in the
choice of materials selected. Initially, the results of an extensive corrosion study, performed in a
representative environment for evaporation cells and including both duplex and austenitic grades, are
presented and discussed. Then a joint corrosion testing program conducted in cooperation with a well
established desalination plant designer and run under actual plant conditions is outlined. The results of
these field tests led to the development of a new concept for evaporation cells based on utilizing duplex
stainless steels.