Process side stress corrosion cracking (SCC) was observed on a carbon steel branched, transgranular cracks were ultimately attributed to CO and CO2 in These findings prompted a company wide inspection program at similar units. heat exchanger tube. The the process environment. SCC has been found in the analogous equipment at all plant locations which have performed internal inspections. At a few of these locations, SCC has occured at gas compositions leaner in CO than previously reported in the literature. Replacements have been made with type 304 L SS which is not susceptible to CO-CO2 SCC.