Issued Patents 1989
Showing 1–4 of 4 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4888313 | Refractory ceramics for contact with molten metal | Wen-Cheng Wei | 1989-12-19 |
| 4880058 | Stage cementing valve | Hiram E. Lindsey, Jr. | 1989-11-14 |
| 4862966 | Liner hanger with collapsible ball valve seat | Hiram E. Lindsey, Jr., Roger P. Allwin | 1989-09-05 |
| 4828037 | Liner hanger with retrievable ball valve seat | Hiram E. Lindsey, Jr., Roger P. Allwin | 1989-05-09 |