US4636327A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Aqueous acid composition and method of use
Assignee: Hydrochem LLC
•
Filing: 1985-05-01
•
Granted: 1987-01-13
•
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 03:19
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)
US3438901A
Cited
FR1577582A
Cited
US3527609A
Cited
US3721629A
Cited
US3664870A
Cited
JPS5028063A
Cited
US4250048A
Cited
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 |