Condensate Corrosion

Definition

The acidic attack on mild steel condensate piping by carbonic acid in the returned condensate. It can dissolve a steam-condensate system back into the boiler in molecular form.

As steam cools and condenses, CO2 dissolves back into the condensate and reforms carbonic acid, but the buffer system has been broken apart so very little buffering capacity remains. In untreated condensate the pH can fall sharply and become severely corrosive, aggressively attacking steel and forming channels along the bottom of the pipe. The damage occurs a pipe-length away from where the alkalinity originated, completing the carbonate cycle.

Related concepts

Upstream Alkalinity Removal · Boiler Alkalinity Breakdown · Neutralizing Amine Treatment

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Part of The Blueprint of Water · ⚡ electrochemistry