Dear Mark Mor, I am sure your process licensor knows the best. But as you are telling us that Cl- is a problem for you, I dont understand why you are using such high Cl- (123 ppm) as wash water. In most of the refineries they use wash water ex-reflux drum boot. When they want to use wash water ex-desalter, they first treat it. I am not a chemical/process engr. but common sense tells me that one should try minimise injecting cl- rich water. Also getting high Cl- (24 ppm plus) even after using two desalters is a bit too much. Unless you solve the problem of Cl-, your preheat train corrosion, Column top corrosion and corrosion of fin coolers are going to stay. So, just check one thing - whether your production group has deviated from the original process description regarding desalter operatio. Also, the reasons for such deficient performance by these desalters. Cheers