| 摘要 |
<p>An improved wellhead valve (34) includes a tubularbody (38) with a central passage (46) therethrough and with a downwardly facing valve seat (52) surrounding a portion of the passage, a cylindrical sealing surface (50) above the valve seat, internal threads (48) above the sealing surface and external threads, a valve member (56) positioned within said passage below a valve seat and biased toward engagement with said valve seat, and a plug (70) having external threads for engagement with the internal threads of the body and having a sealing means (90) for sealing against the cylindrical sealing surface and a projection extending downwardly from said sealing means.The plug when positioned within the central passage (46) with its sealing means engages the sealing surface closing flow through the body (38) and the plug is movable downwardly so that its sealing means is below the sealing surface (50) and its projection engages the valve member (56) to move it out of engagement with the valve seat (52) so that flow through the central passage (46) is open and further rotation of the plug provides retrieval of the valve body from within the wellhead housing.</p> |
