Evaporators Made of Duplex Stainless Steel: A New Approach to Reduced Costs

Abstract

Evaporators in big MSF-plants have traditionally been made of mild steel which should be corrosion resistant enough to cope with an environment of de-aerated seawater. However, experiences have proven that the environment is not always free of oxygen and corrosion has frequently occurred, especially during shut-down periods. One consequence is that a corrosion allowance has to be added and yet, protective layers in form of epoxy coatings and metallic linings are applied. Another alternative is to use solid stainless steel for the evaporator vessels. This paper will discuss the possibility of using two grades of ferritic-austenitic, or duplex, stainless steel for evaporators.