Stamicarbon material developments and application of X2CrNiMoN 25 22 2 and Safurex^®

From the very beginning in the 60s, Stamicarbon engineers have been involved in development of new materials for use in urea plants.

In close cooperation with DSM and steel manufacturers, Stamicarbon has built a track record of successful material developments, experiments and introductions such as those for X2CrNiMoN 25 22 2, a widely used austenitic stainless steel for urea applications. This steel is far less susceptible to condensation corrosion than urea grade 316L.

X2CrNiMoN 25 22 2 is available on the free market and is being used by all licensors, few knowing that the origins date back from Stamicarbon developments.

However, X2CrNiMoN 25 22 2 remains vulnerable for stress corrosion cracking (SCC) in HP carbamate condenser service. Chloride contaminated boiler feed water entering the shell side of the HPCC is likely to initiate stress corrosion cracking of the austenitic stainless steel tubes, starting from the outside surface of the tubes in the crevices between tube and tubesheet.

The search for more SCC resistant materials has led Stamicarbon to the development of special duplex steels, including material fabrication and welding procedures, quality control and assurance during manufacturing.
These duplexes, such as X2CrNiMoN 22 5 3, have resulted in improved SCC resistance and increased understanding of material properties.

All these developments have resulted in a new material called Safurex^®.