Patent US4220550A successfully refreshed from Google Patents.
US4220550A
Expired / Lapsed
US
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Composition and method for removing sulfide-containing scale from metal surfaces
Assignee: Hydrochem LLC
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Filing: 1978-12-06
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Granted: 1980-09-02
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Expires: 1998-12-06
Abstract
Abstract Sulfide-containing scale is removed from metal surfaces by contacting the encrusted surface with an aqueous acid cleaning solution having an aldehyde (e.g., formaldehyde) dissolved or dispersed in the acid in an amount sufficient to prevent the evolution of hydrogen sulfide gas.
Inventors
- 👤 Wayne W. Frenier
- 👤 Michael D. Coffey
- 👤 James D. Huffines
- 👤 Donald C. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:52
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/02; C23G1/04; C23G1/06; Y; Y10; Y10S; Y10S507/00; Y10S507/927; Y10S507/932; Y10S507/939
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
57 words
A method of chemically cleaning acid-soluble, sulfide-containing scale from a metal surface comprising contacting said scale with an aqueous acid cleaning composition comprising an aqueous non-oxidizing acid having at least one aldehyde dissolved or dispersed therein, which aldehyde is present in an amount at least sufficient to prevent or substantially prevent the evolution of hydrogen sulfide gas.
Claim 2
Independent Claim
57 words
A method of chemically cleaning acid-soluble, sulfide-containing scale from a metal surface comprising contacting said scale with an aqueous acid cleaning composition comprising an aqueous non-oxidizing acid having at least one aldehyde dissolved or dispersed therein, which aldehyde is present in an amount at least sufficient to prevent or substantially prevent the evolution of hydrogen sulfide gas.
Claim 3
Dependent Claim
23 words
The method defined by claim 1 wherein said acid is hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, glycolic acid, or citric acid.
Claim 4
Dependent Claim
15 words
The method defined by claim 2 wherein said acid is hydrochloric acid or sulfuric acid.
Claim 5
Dependent Claim
17 words
The method defined by claim 1 wherein said aldehyde is formaldehyde, paraformaldehyde, acetaldehyde, glyoxal, beta-hydroxybutyraldehyde or methyl-3-cyclohexene-carboxaldehyde.
Claim 6
Dependent Claim
18 words
The method defined by claim 1 wherein said acid is sulfuric acid and wherein said aldehyde is formaldehyde.
Claim 7
Dependent Claim
11 words
The method of claim 1 additionally comprising a compatible acid-corrosion inhibitor.
Claim 8
Dependent Claim
12 words
The method of claim 5 additionally comprising a compatible amine-based corrosion inhibitor.
Claim 9
Dependent Claim
62 words
An aqueous acid composition comprising an aqueous acid having dissolved or dispersed therein at least one aldehyde; said composition having, as one of its chemical properties, the capability of dissolving acid-soluble, sulfide-containing scale from a metal surface without the evolution of hydrogen sulfide gas, provided that the aldehyde is present in excess of the acid required to dissolve the sulfide containing scale.
Claim 10
Dependent Claim
62 words
An aqueous acid composition comprising an aqueous acid having dissolved or dispersed therein at least one aldehyde; said composition having, as one of its chemical properties, the capability of dissolving acid-soluble, sulfide-containing scale from a metal surface without the evolution of hydrogen sulfide gas, provided that the aldehyde is present in excess of the acid required to dissolve the sulfide containing scale.
Claim 11
Dependent Claim
23 words
The composition defined by claim 8 wherein said acid is hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, glycolic acid, or citric acid.
Claim 12
Dependent Claim
15 words
The composition defined by claim 9 wherein said acid is hydrochloric acid or sulfuric acid.
Claim 13
Dependent Claim
12 words
The composition defined by claim 10 wherein said acid is sulfuric acid.
Claim 14
Dependent Claim
13 words
The composition defined by claim 8 wherein said aldehyde is formaldehyde or acetaldehyde.
Claim 15
Dependent Claim
11 words
The composition defined by claim 12 wherein said aldehyde is formaldehyde.
Claim 16
Dependent Claim
11 words
The composition defined by claim 11 wherein said aldehyde is formaldehyde.
Claim 17
Dependent Claim
13 words
The composition defined by claim 8 additionally comprising a compatible acid corrosion inhibitor.
Claim 18
Dependent Claim
12 words
The composition defined by claim 14 comprising a compatible amine-based corrosion inhibitor.
Claim 19
Dependent Claim
28 words
The composition defined by claim 14 wherein the concentration of said sulfuric acid is from about 5 to about 15 percent and said formaldehyde is present in excess.
Claim 20
Dependent Claim
13 words
The method defined by claim 1 wherein said aldehyde is an aliphatic aldehyde.
Claim 21
Dependent Claim
23 words
The method defined by claim 1 wherein the temperature of the aqueous acid cleaning composition is from about 140° to about 160° F.
Claim 22
Dependent Claim
23 words
The method defined by claim 5 wherein the temperature of the aqueous acid cleaning composition is from about 140° to about 160° F.
Claim 23
Dependent Claim
43 words
The method defined by claim 1 wherein said aqueous acid cleaning composition is generated in situ by adding an aqueous non-oxidizing acid to an aqueous composition having at least one aldehyde dissolved or disbursed therein which in contact with said acid-soluble sulfide-containing scale.
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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) | 1983-09-02 | 1984-03-03 | 1984-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-02 | 1988-03-03 | 1988-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-02 | 1992-03-03 | 1992-09-02 | $7700.00 | Window Closed / Lapsed |