Patent US2139067A successfully refreshed from Google Patents.
US2139067A
Expired / Lapsed
US
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Continuous heating furnace
Assignee: National Tube Co
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Filing: 1937-02-11
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Granted: 1938-12-06
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Expires: 1957-02-11
Abstract
No abstract record available.
Inventors
- 👤 John J Boax
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:25
CPC Classifications
F; F27; F27B; F27B9/00; F27B9/14; F27B9/20; F27B9/24; F27B9/243
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) | 1941-12-05 | 1942-06-06 | 1942-12-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1945-12-05 | 1946-06-06 | 1946-12-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1949-12-05 | 1950-06-06 | 1950-12-06 | $7700.00 | Window Closed / Lapsed |