| 摘要 |
<p>In accordance with an illustrative embodiment of the present invention as disclosed herein, a combination slip joint-safety valve tool includes telescoping mandrel and housing members, a full-opening valve on the housing member operable when closed to prevent upward flow of fluid through said members, and hydraulically operable valve actuator means responsive to contraction of said telescoping members for closing said valve and to extension of said members for opening said valve.</p> |
