| abstract |
A method of inhibiting the deposition of calcium phosphate scale from an aqueous system treated with a corrosion inhibitor formulation containing a phosphono-carboxylic acid and a polyphosphate comprises adding to the aqueous system a minor amount of hydrolyzed polymaleic anhydride having a molecular weight in the range of from 300 to 5000 as determined by calculation following osmometric measurement on the polymaleic anhydride before hydrolysis, or a water-soluble salt or a hydrolyzed copolymer of polymaleic anhydride. |