US4289639A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and composition for removing sulfide-containing scale from metal surfaces
Assignee: Hydrochem LLC
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Filing: 1980-10-03
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Granted: 1981-09-15
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Expires: 2000-10-03
Abstract
Abstract An aqueous cleaning composition is described herein which contains glyoxylic acid dissolved in an aqueous non-oxidizing acid. This cleaning solution is effective in removing acid-soluble, sulfide-containing scale from metal surfaces (e.g. refinery equipment) without the evolution of gaseous hydrogen sulfide.
Inventors
- 👤 Gary R. Buske
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:13
CPC Classifications
C; C02; C02F; C02F5/00; C02F5/08; C11; C11D; C11D7/00; C11D7/02; C11D7/04; C11D7/08; C11D7/22; C11D7/26; C11D7/264; C23; C23G; C23G1/00; C23G1/02
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
41 words
An aqueous acid composition comprising an aqueous non-oxidizing acid having glyoxlic acid dissolved therein; 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.
Claim 2
Dependent Claim
41 words
An aqueous acid composition comprising an aqueous non-oxidizing acid having glyoxlic acid dissolved therein; 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.
Claim 3
Dependent Claim
15 words
The composition defined by claim 1 wherein said acid is hydrochloric acid or sulfuric acid.
Claim 4
Dependent Claim
12 words
The composition defined by claim 2 wherein said acid is hydrochloric acid.
Claim 5
Dependent Claim
13 words
The compostion defined by claim 1 additionally comprising a compatible acid corrosion inhibitor.
Claim 6
Dependent Claim
12 words
The compostion defined by claim 4 comprising a compatible amine-based corrosion inhibitor.
Claim 7
Dependent Claim
28 words
The composition defined by claim 2 wherein the concentration of said acid is from about 5 to about 15 percent and said glyoxlic acid is present in excess.
Claim 8
Dependent Claim
67 words
In the 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 the improvement comprising using glyoxlic acid as said aldehyde.
Claim 9
Dependent Claim
67 words
In the 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 the improvement comprising using glyoxlic acid as said aldehyde.
Claim 10
Dependent Claim
15 words
The method defined by claim 7 wherein said acid is hydrochloric acid or sulfuric acid.
Claim 11
Dependent Claim
12 words
The improvement defined by claim 8 wherein said acid is hydrochloric acid.
References Cited (Backward Citations)
US4220550A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-14 | 1985-03-16 | 1985-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-14 | 1989-03-16 | 1989-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-14 | 1993-03-16 | 1993-09-15 | $7700.00 | Window Closed / Lapsed |