Acidic Corrosion

Low make up feed water pH can cause serious acid attack on metal surfaces in the preboiler and boiler system. Feed water can also become acidic from contamination of the system (process contamination of condensate or cooling water contamination from condensers).
Acidic corrosion

Acidic corrosion can also be caused by chemical cleaning operations (overheating of the cleaning solution, excessive exposure of metal to cleaning agent, high cleaning agent concentration).

In the boiler and feed water system, acidic attack can take the form of general thinning, or it can be localized at areas of high stress.