I was wondering if anyone could help with a corrosion problem that we have encountered in a SS 304 De-emulsifier tank. The tank has been in service for a year and a recent inspection has found external leak of the product on a course weld and the internal inspection showed advanced corrosion (so advanced in places that there are pinholes in the 5/16″ thk. course welds, cracks starting the HAZ and going down to the metal base in the bottom head. Internally the weld was rusted. We did not believe that the chlorine levels would be sufficient to cause any issues when we originally installed the tank. The de-emulsifier pH was 4.0. Does anyone have any ideas of what could have caused this?