| 摘要 |
A mudsaver valve (10) with bi-directional snap action in opening and closing the valve. The mudsaver valve (10) is adjustable for different mud weights a nd is easily assembled and disassembled in the field. Furthermore, elevated pressure from below is readily transmitted past the valve seat (75), so that the standpipe pressure of the well can be determined through the valve (10) when the pumps are stopped and still connected to the drillstring. One embodiment of the mudsaver valve (10) also contains a mechanism whereby the valve (10) may be locked open by an accessory tube (235) whenever a pipe get s struck and becomes inaccessible, thereby permitting wireline operations through the valve so that the pipe may be freed.
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