Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
98 words
A method for inhibition of the corrosion of iron and steel surfaces in contact with water which consists of: (a) adding to the water a limited amount of an alkali metal hexametaphosphate to provide a concentration therein up to about 30 parts per million, insufficient, used alone, to prevent said corrosion; and (b) adding to the water a sufficient amount of a phosphate buffer, selected from the group consisting of orthophosphoric acid and alkali metal dihydrogen orthophosphate, to maintain the pH of said water at a value from about 6.5 to about 7.5, whereby said corrosion is inhibited.
Claim 2
Independent Claim
98 words
A method for inhibition of the corrosion of iron and steel surfaces in contact with water which consists of: (a) adding to the water a limited amount of an alkali metal hexametaphosphate to provide a concentration therein up to about 30 parts per million, insufficient, used alone, to prevent said corrosion; and (b) adding to the water a sufficient amount of a phosphate buffer, selected from the group consisting of orthophosphoric acid and alkali metal dihydrogen orthophosphate, to maintain the pH of said water at a value from about 6.5 to about 7.5, whereby said corrosion is inhibited.
Claim 3
Dependent Claim
22 words
The method of claim 1 wherein said phosphate buffer and hexametaphosphate are added in weight proportions from about 2/1 to about 1/2.
Claim 4
Dependent Claim
20 words
The method of claim 1 wherein said phosphate buffer is added at a concentration from 5 to about 20 ppm.
Claim 5
Dependent Claim
26 words
The method of claim 1 wherein said phosphate buffer is added at a concentration sufficient to maintain the pH of said water from 6.8 to 7.1.
Claim 6
Dependent Claim
39 words
The method of claim 1 wherein said phosphate buffer is added at a concentration sufficient to react with hydroxyl ions liberated at cathodic regions of said iron and steel surfaces to maintain the pH of said water substantially neutral.
Claim 7
Dependent Claim
44 words
The method of claim 1 wherein said hexametaphosphate is added initially at a concentration from 10 to about 30 ppm until said surfaces are coated with a passivating film and, thereafter, is added at a reduced concentration, from about 0.1 to about 5 ppm.
Claim 8
Independent Claim
107 words
A method for inhibition of the corrosion of iron and steel surfaces of municipal water system in contact with water which consists of: (a) adding to the water of the municipal water system a limited amount of an alkali metal hexametaphosphate to provide a concentration therein up to about 30 parts per million, insufficient, used alone, to prevent said corrosion; and (b) adding to said water a sufficient amount of a phosphate buffer, selected from the group consisting of orthophosphoric acid and alkali metal dihydrogen orthophosphate, to maintain the pH of said water at a value from about 6.5 to about 7.5, whereby said corrosion is inhibited.
Claim 9
Independent Claim
107 words
A method for inhibition of the corrosion of iron and steel surfaces of municipal water system in contact with water which consists of: (a) adding to the water of the municipal water system a limited amount of an alkali metal hexametaphosphate to provide a concentration therein up to about 30 parts per million, insufficient, used alone, to prevent said corrosion; and (b) adding to said water a sufficient amount of a phosphate buffer, selected from the group consisting of orthophosphoric acid and alkali metal dihydrogen orthophosphate, to maintain the pH of said water at a value from about 6.5 to about 7.5, whereby said corrosion is inhibited.
Claim 10
Dependent Claim
22 words
The method of claim 1 wherein said phosphate buffer and hexametaphosphate are added in weight proportions from about 2/1 to about 1/2.
Claim 11
Dependent Claim
20 words
The method of claim 1 wherein said phosphate buffer is added at a concentration from 5 to about 20 ppm.
Claim 12
Dependent Claim
26 words
The method of claim 1 wherein said phosphate buffer is added at a concentration sufficient to maintain the pH of said water from 6.8 to 7.1.
Claim 13
Dependent Claim
39 words
The method of claim 1 wherein said phosphate buffer is added at a concentration sufficient to react with hydroxyl ions liberated at cathodic regions of said iron and steel surfaces to maintain the pH of said water substantially neutral.
Claim 14
Dependent Claim
44 words
The method of claim 1 wherein sid hexametaphosphate is added initially at a concentration from 10 to about 30 ppm until said surfaces are coated with a passivating film and, thereafter, is added at a reduced concentration, from about 0.1 to about 5 ppm.