CORROSION RESISTANT MATERIALS FOR SEAWATER RO PLANTS1

A survey of corrosion resistant materials employed in Seawater Reverse Osmosis (SWRO) desalination plants in Saudi Arabia and the GCC countries has been carried out with special reference to stainless steels. The history of the application of these materials is reviewed along with the major corrosion problems encountered in those plants with main emphasis on SWCC RO desalination plants. The two SS alloys 316L and 317L have been used in the construction of two SWCC SWRO plants at the remote area plants of Al-Birk and Umm Lujj with no noticeable corrosion damage in either plant after their operation for over 5 years and 3 years, respectively. Similarly, other SS alloys 317LN, 904L, 254SMO and 329 performed well, without any significant corrosion when they were used in the construction of SWRO plants or parts there of in the GCC countries. These plants are in continuous operation for years. The paper also discusses the role of different alloying additions in determining the corrosion resistance and mechanical properties of stainless steels relevant to SWRO desalination appli-cations. The possibility of some new cost-effective materials with emphasis on better corrosion resistance and mechanical properties are reviewed. Finally, like in MSF plants, the feasibility of using deaerated seawater feed in RO plants, hitherto not much used in RO plants is discussed