Patent US3963472A successfully refreshed from Google Patents.
US3963472A
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US
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Process for preventing corrosion by incorporative soluble metal chromates in fertilizer solutions
Assignee: Union Oil Company of California
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Filing: 1969-06-27
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Granted: 1976-06-15
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Expires: 1989-06-27
Abstract
Abstract A soluble chromate or dichromate is incorporated in a system comprising a metal and an orthophosphate-containing liquid to inhibit corrosion of the system under highly turbulent conditions. The system in which the chromate or dichromate is incorporated is a system in which the metal surface is normally passivated against corrosion by an orthophosphate-containing film; however under the erosive conditions experienced by the system, the phosphate film is destroyed. The incorporation of the chromate or dichromate in the system prevents corrosion under such conditions. In a typical system, a chromate or dichromate is incorporated in an ammonium phosphate solution which is exposed to contact with a ferrous metal.
Inventors
- 👤 Donald C. Young
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:53
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/08; C23F11/18; C23F11/185; C05; C05B; C05B7/00; Y; Y10; Y10S; Y10S71/00; Y10S71/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
142 words
In the method wherein an aqueous fertilizer solution having a solute concentration from 5 to 60 weight percent and a pH of 4 to about 13 and containing about 10 percent ammonium, expressed as nitrogen and 31 weight percent phosphate, expressed as P 2 O 5 , with about 50 percent of said phosphate as acyclic polyphosphate and the balance as orthophosphate is prepared, stored and handled and, in such method, contacts a metal which, under quiescent conditions, is passivated against corrosion from said solution by an orthophosphate-containing film, the improved method for preventing corrosion when said contact is under turbulent conditions which erode said film and thereby destroy said passivity that comprises incorporating an inhibitor consisting essentially of a soluble ammonium, alkali metal or alkaline earth metal chromate or dichromate in said solution in an effective amount to inhibit said corrosion.
Claim 2
Dependent Claim
142 words
In the method wherein an aqueous fertilizer solution having a solute concentration from 5 to 60 weight percent and a pH of 4 to about 13 and containing about 10 percent ammonium, expressed as nitrogen and 31 weight percent phosphate, expressed as P 2 O 5 , with about 50 percent of said phosphate as acyclic polyphosphate and the balance as orthophosphate is prepared, stored and handled and, in such method, contacts a metal which, under quiescent conditions, is passivated against corrosion from said solution by an orthophosphate-containing film, the improved method for preventing corrosion when said contact is under turbulent conditions which erode said film and thereby destroy said passivity that comprises incorporating an inhibitor consisting essentially of a soluble ammonium, alkali metal or alkaline earth metal chromate or dichromate in said solution in an effective amount to inhibit said corrosion.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein said metal is a ferrous metal.
Claim 4
Dependent Claim
10 words
The method of claim 1 wherein said metal is steel.
Claim 5
Dependent Claim
15 words
The method of claim 1 wherein an alkali metal chromate is incorporated in said solution.
Claim 6
Dependent Claim
15 words
The method of claim 1 wherein ammonium chromate or dichromate is incorporated in said solution.
Claim 7
Dependent Claim
15 words
The method of claim 1 wherein said solution contains sulfate, aluminum, iron and magnesium impurities.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-06-15 | 1979-12-15 | 1980-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-15 | 1983-12-15 | 1984-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-15 | 1987-12-15 | 1988-06-15 | $7700.00 | Window Closed / Lapsed |