Assessment of sigma phase embrittlement in austenitic stainless steels such as Type 304H, commonly used in fluid catalytic cracking (FCC) units. Other austenitic stainless steels used in other refining process units are also discussed. The detection and measuring of the amount of sigma phase were made using metallography.
Cases where alkaline-carbonate stress corrosion cracking (ACSCC) occurred, including a cold wall Fluid Catalytic Cracking (FCC) Unit regenerator and a mercaptan oxidation unit. This paper discusses work done to monitor on-going ACSCC risks through sour water sampling, chemical analysis, and ionic modeling.