Patent US3276431A successfully refreshed from Google Patents.
Patent US2965523A successfully refreshed from Google Patents.
US2965523A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Scale removal from ferrous metal surfaces
Assignee: Dow Chemical Co
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Filing: 1957-02-12
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Granted: 1960-12-20
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Expires: 1977-02-12
Abstract
No abstract record available.
Inventors
- 👤 James P Engle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:23
CPC Classifications
C; C23; C23G; C23G1/00
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
199 words
THE METHOD OF REMOVING ADHERING SCALE FROM A SCALE-COATED FERROUS METAL SURFACE WHICH IS SUBJECT TO STRESS-CRACKING DUE TO RESIDUAL CHLORIDE WHICH COMPRISES THE STEPS OF (1) SUBJECTING THE ADHERING SCALE TO THE ACTION OF AN AQUEOUS SOLUTION CONTAINING BETWEEN 5 AND 30 PERCENT PHOSPHORIC ACID AT FROM 100* F. TO 200* F. FOR A SUFFICIENT TIME TO LOOSEN AT LEAST THE MORE EXPOSED PORTIONS OF THE SCALE AND EXPOSE NEW AREAS OF SAID ADHEREING SCALE, (2) REMOVING THE SO-USED AUQUEOUS-ACID SOLUTION, (3) SUBJECTING THE THUS LOOSENED SCALE TO THE ACTION OF AN AQUEOUS SOLUTION OF A CAUSTIC SELECTED FROM THE CLASS CONSISTING OF THE HYDROXIDES AND CARBONATES OF THE ALKALI METALS AT FROM 175* TO 212* F. TO DISSOLVE THE THUS LOOSENED SCALE, (4) REMOVING THE SO-USED CAUSTIC SOLUTION, (5) SUBJECTING THE CAUSTIC-TREATED LOOSENED SCALE AND NEWLY EXPOSED AREAS OF ADHERING SCALE TO THE FURTHER ACTION OF AN AQUEOUS SOLUTION CONTAINING BETWEEN 5 AND 30 PERCENT PHOSPHORIC ACID TO DISSOLVE SAID CAUSTIC-TREATED LOOSENED SCALE AND TO LOOSEN ADHERING SCALE FROM NEWLY EXPOSED AREAS OF SAID SCALE FOR FROM 1 TO 8 HOURS, (6) REMOVING THE SOUSED AQUEOUS ACID SOLUTION AND (7) FLUSHING THE THUSTREATED FERROUS SURFACE WITH WATER.
Claim 2
Independent Claim
199 words
THE METHOD OF REMOVING ADHERING SCALE FROM A SCALE-COATED FERROUS METAL SURFACE WHICH IS SUBJECT TO STRESS-CRACKING DUE TO RESIDUAL CHLORIDE WHICH COMPRISES THE STEPS OF (1) SUBJECTING THE ADHERING SCALE TO THE ACTION OF AN AQUEOUS SOLUTION CONTAINING BETWEEN 5 AND 30 PERCENT PHOSPHORIC ACID AT FROM 100* F. TO 200* F. FOR A SUFFICIENT TIME TO LOOSEN AT LEAST THE MORE EXPOSED PORTIONS OF THE SCALE AND EXPOSE NEW AREAS OF SAID ADHEREING SCALE, (2) REMOVING THE SO-USED AUQUEOUS-ACID SOLUTION, (3) SUBJECTING THE THUS LOOSENED SCALE TO THE ACTION OF AN AQUEOUS SOLUTION OF A CAUSTIC SELECTED FROM THE CLASS CONSISTING OF THE HYDROXIDES AND CARBONATES OF THE ALKALI METALS AT FROM 175* TO 212* F. TO DISSOLVE THE THUS LOOSENED SCALE, (4) REMOVING THE SO-USED CAUSTIC SOLUTION, (5) SUBJECTING THE CAUSTIC-TREATED LOOSENED SCALE AND NEWLY EXPOSED AREAS OF ADHERING SCALE TO THE FURTHER ACTION OF AN AQUEOUS SOLUTION CONTAINING BETWEEN 5 AND 30 PERCENT PHOSPHORIC ACID TO DISSOLVE SAID CAUSTIC-TREATED LOOSENED SCALE AND TO LOOSEN ADHERING SCALE FROM NEWLY EXPOSED AREAS OF SAID SCALE FOR FROM 1 TO 8 HOURS, (6) REMOVING THE SOUSED AQUEOUS ACID SOLUTION AND (7) FLUSHING THE THUSTREATED FERROUS SURFACE WITH WATER.
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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) | 1963-12-20 | 1964-06-20 | 1964-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-12-20 | 1968-06-20 | 1968-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-12-20 | 1972-06-20 | 1972-12-20 | $7700.00 | Window Closed / Lapsed |