US2821772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making fluid-tight heat exchange tubes
Assignee: SAWHILL TUBULAR PRODUCTS Inc
•
Filing: 1952-03-29
•
Granted: 1958-02-04
•
Expires: 1972-03-29
Abstract
No abstract record available.
Inventors
- 👤 Halton A Billetter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:25
CPC Classifications
B; B21; B21D; B21D53/00; B21D53/02; B21D53/08; B21C; B21C37/00; B21C37/06; B21C37/08; B21C37/09; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/4935; Y10T29/49377
Claims Analysis
Total Claims: 0
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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) | 1961-02-03 | 1961-08-05 | 1962-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-02-03 | 1965-08-05 | 1966-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-02-03 | 1969-08-05 | 1970-02-04 | $7700.00 | Window Closed / Lapsed |