Drill string safety valve
US4391328A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 20, 1981 |
| Grant date | Jul 5, 1983 |
| Priority date | — |
| Expiry date | May 20, 2001 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B34/08
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A multi position safety valve retainable within an internal portion of a drill string casing (s) and responsive to the greater differential pressure in an internal fluid passage to displace a valve head (32) relative to a valve seat (VS) from its normal partially open position to either a wide open or a closed position. The valve head (32) is attached to a valve stem (30) that extends through a valve chamber and slideably mounted in opposite closed ends of a valve body and returnable to and maintained in the partially open position by opposing compression springs (34) (36) situated between opposite ends (22) of the valve body (VB) and one side of an intermediate abutment (30c) of the valve stem (30) and an intervening disc (38) on the opposite side thereof. The disc 38 is moveable into and out of seating engagement with an intermediate stop (20a) by one spring (34) and the intermediate abutment (30c) of the valve stem respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.