Tungstate based corrosion inhibitors
AssigneeNalco Company
InventorsCraig W. Myers, Steven R. Hatch, Donald A. Johnson, Phillip E. Bureman
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Abstract
A trace amount of a tungstate added together with an ortho-phosphate and/or phosphonite is disclosed for inhibiting corrosion by a nitrogen fertilizer solution. In particular, an ammonium nitrate fertilizer solution is in contact with ferrous metal storage tanks, piping, and equipment surfaces. Tungstate added with an iron stabilizer including a dispersant polymer is also effective for inhibiting corrosion.
Claims14
A method for inhibiting corrosion of a ferrous metal surface exposed to a nitrogen fertilizer solution, the method comprising:
- adding to the nitrogen fertilizer solution from about 1 ppm to about 5 ppm of an alkali metal tungstate;
- an effective amount of an ortho-phosphate, a phosphonate, and/or a phosphonite;
- and optionally an effective amount of an iron stabilizer.
A method for inhibiting corrosion of a ferrous metal surface exposed to a nitrogen fertilizer solution, the method comprising:
- adding to the nitrogen fertilizer solution from about 1 ppm to about 5 ppm of an alkali metal tungstate;
- an effective amount of ortho-phosphate, a phosphonate, and/or a phosphonite;
- and an effective amount of an iron stabilizer, the iron stabilizer being a dispersant polymer including an acrylic acid/acrylamide/acrylamido methane sulfonic acid terpolymer and/or a 3:1 ratio of acrylamide to acrylic acid copolymer.
A composition for inhibiting corrosion of a ferrous metal surface exposed to a nitrogen fertilizer solution, the composition comprising:
- about 1 ppm to about 5 ppm of an alkali metal tungstate;
- an effective amount of an ortho-phosphate, a phosphonate, and/or a phosphonite;
- and optionally an effective amount of an iron stabilizer.
Dependencies are inferred from the claim text.