Issued Patents All Time
Showing 26–40 of 40 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4983803 | Method of making a subsurface well safety valve | Ronald E. Pringle | 1991-01-08 |
| 4926945 | Subsurface well safety valve with curved flapper and method of making | Ronald E. Pringle | 1990-05-22 |
| 4844166 | Method and apparatus for recompleting wells with coil tubing | Walter S. Going, III, Ronald E. Pringle | 1989-07-04 |
| 4791991 | Subsurface well safety valve with hydraulic strainer | Jeffrey L. Knieriemen | 1988-12-20 |
| 4771831 | Liquid level actuated sleeve valve | Ronald E. Pringle | 1988-09-20 |
| 4718488 | Pump-out plug system for a well conduit | Ronald E. Pringle | 1988-01-12 |
| 4703805 | Equalizing means for a subsurface well safety valve | — | 1987-11-03 |
| 4694908 | Method and apparatus of injecting fluid into a well conduit by coil tubing | Donald E. Newton | 1987-09-22 |
| 4688593 | Well reverse flow check valve | Ronald E. Pringle | 1987-08-25 |
| 4605070 | Redundant safety valve system and method | — | 1986-08-12 |
| 4600055 | Tubular well tool receiving conduit | Douglas Glenn Durst | 1986-07-15 |
| 4562854 | Piston actuated chemical injection valve | Ronald E. Pringle, John Johnson | 1986-01-07 |
| 4531581 | Piston actuated high temperature well packer | Ronald E. Pringle | 1985-07-30 |
| 4444403 | Thermal and/or corrosion seal for a well tool | — | 1984-04-24 |
| 4362214 | Tubing retrievable variable setting differential pressure actuated well safety valve | Ronald E. Pringle | 1982-12-07 |