Corrosion is a general term that indicates the conversion of a metal into a soluble compound. In the case of boiler metal, corrosion is the conversion of steel into rust. In boiler, two types of corrosion are Prevalent:
1) Oxygen pitting corrosion, seen on the tubes and in the boiler section.
2) Low pH corrosion, seen in the condensate return system. Corrosion of either type can lead to failure of critical parts of the boiler system, deposition of corrosion products in critical heat exchange areas and overall efficiency loss.