US4098720A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Corrosion inhibition
Assignee: WR Grace and Co Conn
•
Filing: 1976-01-14
•
Granted: 1978-07-04
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Expires: 1996-01-14
Abstract
Abstract Low toxicity, low pollution potential compositions and methods for inhibiting corrosion of ferrous and non-ferrous metallic parts in aqueous systems. The compositions have no chromate, no polyphosphate and no borate and consist essentially of alkali metal nitrite, alkali metal carbonate or bicarbonate and an azole. Preferably the compositions also include an alkali metal silicate and small amounts of an alkali metal hydroxide. In the corrosion inhibiting method, the aforesaid compositions are added to the system water in amounts sufficient to provide from about 100 to 10,000 parts per million ("ppm") of alkali metal nitrite, the primary inhibitor.
Inventors
- 👤 Chih M. Hwa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:47
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/08
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
57 words
A corrosion inhibiting composition free of any polyphosphate, chromate and borate and consisting essentially of: ______________________________________
Weight Percent based on total
weight, dry weight basis
______________________________________
Alkali metal nitrite
4 to 80
Alkali metal carbonate
2 to 60
Water-soluble
mercaptobenzothiazole
compound 0.1 to 10
Alkali metal hydroxide
0.1 to 20
Alkali metal silicate
0.1 to 30
______________________________________
Claim 2
Dependent Claim
57 words
A corrosion inhibiting composition free of any polyphosphate, chromate and borate and consisting essentially of: ______________________________________
Weight Percent based on total
weight, dry weight basis
______________________________________
Alkali metal nitrite
4 to 80
Alkali metal carbonate
2 to 60
Water-soluble
mercaptobenzothiazole
compound 0.1 to 10
Alkali metal hydroxide
0.1 to 20
Alkali metal silicate
0.1 to 30
______________________________________
Claim 3
Dependent Claim
34 words
Composition as defined in claim 1 containing 40 to 60 percent nitrite, 20 to 40 percent carbonate, 1.5 to 6 percent mercaptobenzothiazole compound, 2 to 6 percent hydroxide and 6 to 12 percent silicate.
Claim 4
Dependent Claim
12 words
Composition as defined in claim 2 wherein the nitrite is sodium nitrite.
Claim 5
Dependent Claim
13 words
Composition as defined in claim 3 wherein the mercaptobenzothiazole compound is sodium mercaptobenzothiazole.
Claim 6
Dependent Claim
53 words
Composition as defined in claim 4 further including from 0.01 to 10 weight percent of a water-soluble acrylic polymer having a molecular weight of from about 200 to 15,000,000 and repeated groups with the formula: ##STR10## wherein R is hydrogen or a methyl group, or a water-soluble salt or ester of such polymer.
Claim 7
Dependent Claim
39 words
Method for inhibiting corrosion of metallic parts in contact with an aqueous fluid comprising maintaining in the said fluid sufficient amounts of the composition of claim 1 to provide at least about 100 ppm. of nitrite, as sodium nitrite.
Claim 8
Dependent Claim
39 words
Method for inhibiting corrosion of metallic parts in contact with an aqueous fluid comprising maintaining in the said fluid sufficient amounts of the composition of claim 4 to provide at least about 100 ppm. of nitrite, as sodium nitrite.
Claim 9
Dependent Claim
39 words
Method for inhibiting corrosion of metallic parts in contact with an aqueous fluid comprising maintaining in the said fluid sufficient amounts of the composition of claim 5 to provide at least about 100 ppm. of nitrite, as sodium nitrite.
Claim 10
Dependent Claim
17 words
Method of claim 6 wherein the sodium nitrite concentration is from about 1000 to about 4000 ppm.
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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) | 1981-07-03 | 1982-01-02 | 1982-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-03 | 1986-01-02 | 1986-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-03 | 1990-01-02 | 1990-07-04 | $7700.00 | Window Closed / Lapsed |