US4237090A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for inhibiting corrosion in aqueous systems
Assignee: United States Department of Energy
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Filing: 1978-11-15
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Granted: 1980-12-02
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Expires: 1998-11-15
Abstract
Abstract This invention is a method for inhibiting corrosion in aqueous systems containing components composed of aluminum, copper, iron, or alloys thereof. The method comprises (a) incorporating in the aqueous medium 2-10 ppm by weight of tolyltriazole; an effective amount of a biodegradable organic biocide; 500-1000 ppm by weight of sodium metasilicate; 500-2000 ppm by weight of sodium nitrite; and 500-2000 ppm by weight of sodium tetraborate, all of these concentrations being based on the weight of water in the system; and (b) maintaining the pH of the resulting system in the range of 7.5 to 8.0. The method permits longterm operation with very low corrosion rates and bacteria counts. All of the additives to the system are biodegradable, permitting the treated aqueous medium to be discharged to the environment without violating current regulations. The method has special application to solar systems in which an aqueous medium is circulated through aluminum-alloy heat exchangers.
Inventors
- 👤 James R. DeMonbrun
- 👤 Charles R. Schmitt
- 👤 James M. Schreyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:11
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/08; C02; C02F; C02F1/00; C02F1/50; C02F5/00; C02F5/08; C02F5/10; C02F5/12; C02F5/125
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
120 words
In a system wherein an aqueous liquid is in contact only with a metallic material selected from the group consisting of aluminum and aluminum alloys, the method for retarding corrosion of said metallic material, comprising: (a) incorporating in said system: (1) 2-10 ppm by weight of tolytriazole, (2) an effective amount of a biodegradable organic biocide; (3) 500-1000 ppm by weight of sodium metasilicate, (4) 500-2000 ppm by weight of sodium nitrite, and (5) 500-2000 ppm by weight of sodium tetraborate, all of these concentrations being based on the weight of water in said system, and (b) maintaining the pH of the resulting solution at a value in the range of 7.5 to 8.0 by the addition of boric acid.
Claim 2
Dependent Claim
120 words
In a system wherein an aqueous liquid is in contact only with a metallic material selected from the group consisting of aluminum and aluminum alloys, the method for retarding corrosion of said metallic material, comprising: (a) incorporating in said system: (1) 2-10 ppm by weight of tolytriazole, (2) an effective amount of a biodegradable organic biocide; (3) 500-1000 ppm by weight of sodium metasilicate, (4) 500-2000 ppm by weight of sodium nitrite, and (5) 500-2000 ppm by weight of sodium tetraborate, all of these concentrations being based on the weight of water in said system, and (b) maintaining the pH of the resulting solution at a value in the range of 7.5 to 8.0 by the addition of boric acid.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein said system is a closed system.
Claim 4
Dependent Claim
10 words
The method of claim 1 wherein said liquid is circulated.
Claim 5
Dependent Claim
126 words
In a closed system wherein a recirculated aqueous solution is in contact with a metallic material selected from the group consisting of aluminum and aluminum alloys, the method for retarding corrosion of said material consisting of: (a) incorporating in said system a composition consisting essentially of: (1) 2-10 ppm by weight of tolyltriazole, (2) an effective amount of a biodegradable organic biocide, (3) 500-1000 ppm by weight of sodium metasilicate, (4) 500-2000 ppm by weight of sodium nitrite, and (5) 500-2000 ppm by weight of sodium tetraborate, all of these concentrations being based on the weight of water in said system, and (b) maintaining the pH of the resulting solution at a value in the range of 7.5 to 8.0 by the addition of boric acid.
Claim 6
Dependent Claim
126 words
In a closed system wherein a recirculated aqueous solution is in contact with a metallic material selected from the group consisting of aluminum and aluminum alloys, the method for retarding corrosion of said material consisting of: (a) incorporating in said system a composition consisting essentially of: (1) 2-10 ppm by weight of tolyltriazole, (2) an effective amount of a biodegradable organic biocide, (3) 500-1000 ppm by weight of sodium metasilicate, (4) 500-2000 ppm by weight of sodium nitrite, and (5) 500-2000 ppm by weight of sodium tetraborate, all of these concentrations being based on the weight of water in said system, and (b) maintaining the pH of the resulting solution at a value in the range of 7.5 to 8.0 by the addition of boric acid.
Claim 7
Dependent Claim
14 words
The method of claim 4 wherein said solution comprises an organic compound and water.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |