Patent ID: 7708939
Filing Date: 2010-05-04
Classification: C02F,C23F

Abstract:
1. A method for inhibiting corrosion of a metallic substance in an aqueous system, wherein said metallic substance is selected from the group consisting of copper, nickel, aluminum, zinc, tin, lead, beryllium, carbon steel, alloys of the metallic substance, and galvanized coatings of the metallic substance, comprising the steps: a. providing source water to derive said aqueous system, said aqueous system containing greater than 2500 mg/L TDS and less than 200 mg/L CaCO3, and corrosive ammonia and/or ammonium ions; b. elevating and maintaining the pH of said aqueous system such that said aqueous system possesses a pH of approximately 9.0 or greater, wherein said aqueous system contains an amorphous silica corrosion inhibitor, and said ammonia and/or ammonium ions have the ability to penetrate a corrosion inhibitor film formed by the amorphous silica corrosion inhibitor; and c. adding at least one azoles inhibitor to said aqueous system at a total residual of at least 0.25 mg/L, to inhibit corrosion of said metallic surface.