| 摘要 |
<p>A valve adapted for insertion in a radially enlarged portion of the kelly saver sub to retain mud in the kelly when the drill pipe is disconnected therefrom, including a tubular body with a downwardly extending closure member supported thereby, and a piston having an axial passage for the flow of drilling mud therethrough, axially movble within the body. The plug may be removed from the bore by the application of an upwardly directed tension force thereto, so that wire line tools may be run through the bore and the passage.</p> |
