White Papers

New Metallurgy: Anti-PTASCC Solutions For All Petroleum Refineries

It is known that the conventional stainless steels such as Type 316L, Type 317L, Type 321(H) and Type 347(H) have higher risk to occur PTASCC (PolyThionic Acid Stress Corrosion Cracking) in Hydrotreating units, Hydrocracking units and Delayed Coker units etc of petroleum refineries. PTASCC occurs by the combination of 3 factors; formation of Polythionic acid due to exposure the metal sulfide scale to oxygen and water in the aqueous phase, residual tensile stress and sensitized microstructure having the Cr carbide precipitation at the grain boundary by welding.