Corrosion inhibiting compositions and the process for using same
AssigneeThe Mogul Corporation
InventorRichard J. Lipinski
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Abstract
This invention is directed to corrosion inhibiting compositions and to a process for inhibiting corrosion and the deposition of mineral scale on metal in aqueous systems. The invention comprises adding to a water system effective amounts of an inhibiting composition comprising a water-soluble carboxylic acid and/or the salt thereof containing at least one hydroxyl group per molecule, an amino alkylene phosphonic acid or its derivative, a dispersing amount of a water-soluble polymeric dispersing agent and other inhibitors such as the molybdates, azoles and various inorganic metal compounds.
Claims34
A composition for inhibiting mineral scale and corrosion of metal in the presence of water which comprises, parts based on a million parts by weight of water from about:
- (a) 0.1 to 30 parts by weight of an azole,
- (b) up to 100 parts by weight of water-soluble carboxylic acids having at least one hydroxyl group per molecule and/or the alkali metal salts of said carboxylic acids, and
- (c) 0 to 100 parts by weight of a metal molybdate,
- wherein the carboxylic acids, the alkali metal salts of said carboxylic acids, or combinations of the carboxylic acids and the alkali metal salts thereof, either alone or with the molybdates are present in an amount of at least about 3.0 parts per million, and
- (d) a corrosion inhibiting amount of at least one amino methylene phosphonic acid and the derivatives thereof having the formula:
- ##STR10## wherein R.sub.1 is a monovalent radical selected from the class consisting of the formulae:
- ##STR11## wherein R is ##STR12## and Y has a value of 1 to 8, X has a value of 1 to 4 and M is a radical selected from the class consisting of hydrogen, an alkali or alkaline earth metal, ammonium, an amino radical, and an alkyl or substituted alkyl radical having 1 to 4 carbon atoms.
A process of inhibiting mineral scale and corrosion of metal in an aqueous system which comprises adding to the water, parts based on a million parts by weight of water from about:
- (a) 0.1 to 30 parts by weight of an azole,
- (b) 0 to 100 parts by weight of a carboxylic acid having at least one hydroxyl group per molecule and/or the alkali metal salts thereof, and
- (c) 0 to 100 parts by weight of a metal molybdate,
- wherein either the carboxylic acids, the alkali metal salts of the carboxylic acids or combinations of the carboxylic acids and the alkali metal salts thereof, each alone or with the molybdate are present in an amount of at least 3.0 parts per million, and
- (d) a corrosion inhibiting amount of at least one amino methylene phosphonic acid and the derivatives thereof having the formula:
- ##STR13## wherein R.sub.1 is a monovalent radical selected from the class consisting of the formulae:
- ##STR14## wherein R is ##STR15## and Y has a value of 1 to 8, X has a value of 1 to 4, and M is a radical selected from the class consisting of hydrogen, an alkali or alkaline earth metal, ammonium, an amino radical, and an alkyl or substituted alkyl radical having 1 to 4 carbon atoms.
Dependencies are inferred from the claim text.