Corrosion inhibitor

Definition

Corrosion inhibitors are additives dosed into cleaning acid to protect metal surfaces while hydrogen dissolves scale. The chapter used inhibited hydrochloric acid with high doses of inhibitor.

Inhibitor residual measured in the bulk water can be on target while deposits isolate the metal beneath them, so the surface stays unprotected. Inhibitor demand rises with cycles of concentration because more dissolved species compete for treatment surface area. Phosphate-based inhibitors carry the added risk of calcium phosphate precipitation at high pH.

Related concepts

Chemical Demand · Corrosion control by pH · Acid cleaning of scale

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