2014 Ramesh SMT Sandvik Lean Duplex SAF2304 A solution for HEX tubing in ammonia condensers and coolers
Carbon steel is the most commonly used material for construction for heat exchanger tubing’s in Ammonia plants primarily because of its low cost. However, more than 50% of the yearly maintenance replacements are in carbon steel, which means that the initial low cost does not always justify the high maintenance cost. Over the years, many Corrosion Resistant Alloys have been developed for moderate to severe corrosive environments, resulting in reduction of maintenance costs. There have been many studies by various organizations to find a middle path between a low cost / low corrosion resistance carbon steels and high cost I high corrosion resistance alloys. Lena duplex is one such solution.
SAF 2304TM has been one such development. This material has fairly good pitting and chloride stress corrosion cracking resistance to cooling water in coolers and condensers. They also have good stress corrosion cracking resistance and exceptional corrosion resistance against ammonia, caustic and other weak acids and salts. This material also has very good erosion corrosion resistance. This paper will focus on corrosion properties of lean duplex in comparison with carbon steel and normal austenitic stainless steels. This paper also presents a case to compare the life cycle costs and return on investments with lean duplex against Carbon steel.