Due to its poor corrosion resistance, carbon steel is often replaced by stainless steel to build storage tanks for use in water treatment units, food, chemical and para chemical industries. For years, 316L has been widely used. Recently, duplex (austenitic-ferritic) stainless steels have been selected due to improved corrosion resistance and higher mechanical properties. Corrosion resistance properties of duplex and austenitic stainless steels of the 300 series are presented and
compared in relation to the problems, which are generally experienced in storage tanks. In addition, a user-friendly software package has been developed to estimate and compare investment and life cycle costs for tanks made of different materials. This software takes into account API (USA) and CODRES (French) calculation codes. Some cost simulations, as well as actual construction costs, are presented and discussed.
Duplex stainless steels appear to be very cost competitive, since investment costs are generally close to that of coated carbon steel and lower than that of 316L. Life cycle costs of duplex stainless steel tanks are always far lower due to their superior corrosion resistance. This allows maintenance operations to be minimized or eliminated.