Patent US2163976A successfully refreshed from Google Patents.
US2163976A
Expired / Lapsed
US
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Flow preventer for oil wells
Assignee: Individual
•
Filing: 1938-01-22
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Granted: 1939-06-27
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Expires: 1958-01-22
Abstract
No abstract record available.
Inventors
- 👤 William K Edwards
- 👤 Thompson Orland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:05
CPC Classifications
E; E21; E21B; E21B33/00; E21B33/10; E21B33/12
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1942-06-26 | 1942-12-26 | 1943-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1946-06-26 | 1946-12-26 | 1947-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1950-06-26 | 1950-12-26 | 1951-06-27 | $7700.00 | Window Closed / Lapsed |