Patent ID: 6391384
Filing Date: 2002-05-21
Classification: C23F

Abstract:
A method for supplying a corrosion inhibiting solution for inhibiting the corrosion of the interior surface of metal pipes which transport water, the method comprising:mixing zinc ion source and aqueous phosphoric acid to provide an aqueous phosphate mixture, the zinc ion source selected from the group consisting of zinc metal, zinc metal oxide and mixtures thereof, the aqueous mixture having less than about 3 weight percent impurities and the aqueous phosphoric acid in an amount which is effective for providing a solution having a pH of less than about 2 to provide a corrosion inhibiting concentrate solution, the zinc in the zinc ion source being present in an amount effective for providing a zinc ion concentration of at least about 0.05 weight percent in the solution, the phosphoric acid being in an amount effective for providing phosphate concentration of at least about 10 weight percent in the solution, the solution having less than about 1 weight percent sulfate ions and less than about 1 weight percent chloride ions; and mixing the corrosion inhibiting concentrate solution into the water which is being directed into the metal pipes, the corrosion inhibiting concentrate being mixed into the water being transported at a rate which will be effective for depositing a zinc and phosphate film onto the interior surface of the metal pipes.