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US3779818A
Expired / Lapsed
US
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Method for preventing the formation of rust on the surface of coiled steel strip and an inhibitor for accomplishing same
Assignee: Bethlehem Steel Corp
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Filing: 1971-04-01
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Granted: 1973-12-18
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Expires: 1991-04-01
Abstract
Abstract Method for preventing the formation of rust on coiled steel comprising temper rolling annealed cold rolled steel strip, coating the steel strip with a liquid phase-vapor phase corrosion inhibitor and coiling the steel strip. The liquid phase-vapor phase inhibitor consists of an aqueous solution of a non-volatile nitrite of an alkali metal or an alkaline earth metal or volatile amine which is soluble in water and not subject to autodecomposition at ambient temperature. The volatile base compounds are, for example, ammonium hydroxide or ammonium carbonate. The nitrite radical is present in an amount of about 0.07% by weight up to the solubility of the nitrite compound. The base compound is about 0.1% by weight up to about 25% by weight of the aqueous solution. The aqueous solution has a pH of not less than about 8 to about 13.
Inventors
- 👤 C Shoemaker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 17:13
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/08; C23F11/02
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
16 words
The method of claim 1 in which the nitrite compound of step (b) is sodium nitrite.
Claim 2
Dependent Claim
16 words
The method of claim 1 in which the nitrite compound of step (b) is potassium nitrite.
Claim 3
Dependent Claim
17 words
The method of claim 1 in which the nitrite compound of step (b) is dissopropyl ammonium nitrite.
Claim 4
Dependent Claim
16 words
The method of claim 1 in which the base compound of step (b) is ammonium hydroxide.
Claim 5
Dependent Claim
16 words
The method of claim 1 in which the case compound of step (b) is ammonium carbonate.
Claim 6
Dependent Claim
27 words
The method of claim 1 in which the aqueous solution of step (b) has a nitrite radical to base ratio of from about 0.07:1 to about 10:1.
Claim 7
Dependent Claim
54 words
The method of claim 1 in which the nitrite radical of step (b) is present in the solution in the amount of from 0.7% up to the solubility of the nitrite compound and the base compound of step (b) is present in the solution in an amount of from 1% to 10% by weight.
Claim 8
Dependent Claim
19 words
The method of claim 1 in which only one side of the strip is coated with nitrite inhibitor solution.
Claim 9
Dependent Claim
18 words
The method of claim 1 in which both sides of the strip are coated with nitrite inhibitor solution.
Claim 10
Independent Claim
132 words
The method for preventing the formation of speckled rust within the laps of cold rolled and annealed coils of steel, comprising: a. temper rolling steel strip, b. coating the steel strip with a cOrrosion inhibitor consisting essentially of an aqueous solution of sodium nitrite and ammonium hydroxide, wherein the nitrite radical is present in an amount of from about 0.07% by weight up to the solubility of the sodium nitrite and the ammonium hydroxide represents from about 0.1% to about 25% by weight of said aqueous solution, said solution having a pH of not less than 8, and c. coiling the steel strip into tight coils while wet from said aqueous solution whereby the formation of speckled rust on the surfaces of the steel within the laps of the coils is prevented.
Claim 11
Independent Claim
197 words
A method for preventing the formation of speckled rust within the laps of cold rolled and annealed coils of steel, comprising: a. coating a side of steel strip with a corrosion inhibitor consisting essentially of an aqueous solution of at least one nitrite compound taken from the group consisting of alkali metal nitrites, alkaline earth metal nitrites, and amines not subject to auto-decomposition at ambient temperature wherein a nitrite radical is present in an amount of from about 0.07% by weight up to the solubility of the nitrite compound and a base compound in which the principal portion of the base is at least one volatile compound taken from the group consisting of ammonium hydroxide and ammonium carbonate in which said base represents from about 0.1% to about 25% by weight of said aqueous solution, said solution having a pH of not less than 8, b. temper rolling the steel strip under conditions in which the corrosion inhibitor solution is not dried, and c. coiling the steel strip into tight coils while wet from said aqueous solution whereby the formation of speckled rust on the surfaces of the steel within the laps of the coils is prevented.
Claim 12
Dependent Claim
20 words
The method of claim 12 in which only one side of the steel strip is coated with nitrite inhibitor solution.
Claim 13
Dependent Claim
18 words
The method of claim 12 in which both sides of the strip are coated with nitrite inhibitor solution.
Claim 14
Independent Claim
146 words
The method for preventing the formation of speckled rust within the laps of cold rolled and annealed coils of steel, comprising: a. coating a side of steel strip with a corrosion inhibitor consisting essentially of an aqueous solution of sodium nitrite and ammonium hydroxide, wherein the nitrite radical is present in an amount of from about 0.07% by weight up to the solubility of the sodium nitrite and the ammonium hydroxide represents from about 0.1% to about 25% by weight of said aqueous solution, said solution having a pH of not less than 8, b. temper rolling the steel strip under conditions in which the corrosion inhibitor solution is not dried, and c. coiling the steel strip into tight coils while wet from said aqueous solution whereby the formation of speckled rust on the surfaces of the steel within the laps of the coils is prevented.
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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) | 1976-12-17 | 1977-06-18 | 1977-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-17 | 1981-06-18 | 1981-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-17 | 1985-06-18 | 1985-12-18 | $7700.00 | Window Closed / Lapsed |