pH maintenance of the feed, boiler and condensate system is essential for corrosion control.

Historically many low pressure boiler systems monitor alkalinity because this correlates very closely with pH. pH control is important for the following reasons:

• Low pH results in acid attack.
• High pH results in caustic gouging, caustic cracking foaming and carryover.
• Corrosion rates are pH dependent
• Speed of oxygen scavengers are very dependent on pH values (optimum value for hydrazine pH 9.0 to 10.0)
• Modern polymers water treatment chemicals have an optimum pH operating range.

The boiler pH depends the boiler pressure, system metals, feed water quality and type of chemical treatment in use