Interesting little story about stainless steels. This week we got back a wastewater RO filtration unit from a customer. All the stainless on this unit was 316. The sch 40 piping was welded and not subsequently finished in any way. It was all quite corroded at all the welds. The filter canister was a bead blasted finish, and eaten completely through in several places! The high pressure Can pump had an electropolish finish, and was still bright and shiny everywhere. Interestingly, the hot dip galvanized frame still looked great! I don't know what they were processing, but it sure raised hell with stainless steel.
Gary H. Lucas