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US4636327A
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Aqueous acid composition and method of use
Assignee: Hydrochem LLC
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Filing: 1985-05-01
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Granted: 1987-01-13
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Expires: 2005-05-01
Abstract
Abstract Aqueous acid compositions are described which comprise (a) hydroxyethylethylenediaminetriacetic acid, and (b) a compatible acid corrosion inhibitor. The compositions are useful in removing iron oxide scale from metal surfaces.
Inventors
- 👤 Wayne W. Frenier
- 👤 David A. Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:41
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/02; C23G1/08; C23G1/088
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
54 words
An aqueous acid composition which can remove iron oxide scale from ferrous metal surfaces, the composition having a pH of between about 1 and about 3, and comprising (a) hydroxyethylethylenediaminetriacetic acid (HEDTA) dissolved therein in an amount of at least about 1% by weight of the composition, and (b) a compatible acid corrosion inhibitor.
Claim 2
Dependent Claim
54 words
An aqueous acid composition which can remove iron oxide scale from ferrous metal surfaces, the composition having a pH of between about 1 and about 3, and comprising (a) hydroxyethylethylenediaminetriacetic acid (HEDTA) dissolved therein in an amount of at least about 1% by weight of the composition, and (b) a compatible acid corrosion inhibitor.
Claim 3
Dependent Claim
12 words
The composition defined by claim 1 additionally comprising a non-oxidizing inorganic acid.
Claim 4
Dependent Claim
18 words
The composition defined by claim 2 wherein said inorganic acid is HCl or H 2 SO 4 .
Claim 5
Dependent Claim
16 words
The composition defined by claim 3 wherein said inorganic acid is H 2 SO 4 .
Claim 6
Dependent Claim
13 words
The composition defined by claim 1 wherein said HEDTA is generated in situ.
Claim 7
Dependent Claim
34 words
The composition defined by claim 4 wherein said HEDTA is generated in situ; said pH is from about 1 to about 2; and said acid corrosion inhibitor is an organic amine-based acid corrosion inhibitor.
Claim 8
Dependent Claim
16 words
The composition defined by claim 1 wherein said pH is from about 1 to about 2.
Claim 9
Dependent Claim
16 words
The composition defined by claim 4 wherein said pH is from about 1 to about 2.
Claim 10
Dependent Claim
29 words
A process for removing a predominantly iron oxide scale from a ferrous metal surface, said process comprising contacting said scale with an aqueous acid composition defined by claim 1.
References Cited (Backward Citations)
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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) | 1990-01-12 | 1990-07-14 | 1991-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-12 | 1994-07-14 | 1995-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-12 | 1998-07-14 | 1999-01-13 | $7700.00 | Window Closed / Lapsed |