| 摘要 |
<p>Apparatus and methods for sealing a parallel expanding gate valve (16) are provided using upper and lower wedges (44, 50) separate from and located between the gate segments (18, 20). The gate segments (18, 20) are symmetrical with respect to each other and have upper (24, 32) and lower (26, 34) tapered surfaces. Inclined surfaces (46, 48) on the upper wedge (44) press the inner upper tapered surfaces (24, 32) of the gate segments (18, 20). The inner lower tapered surfaces (26, 34) of the gate segments (18, 20) also press against inclined wedging surfaces (52, 54) on the lower wedge (50). This wedging action forces the gate segments (18, 20) outward with respect to each other and with substantial force against sealing assemblies (36, 38) to close and seal the gate valve (16). A port (56) is provided through at least one of the gate segments (18, 20), and is closed and opened by movement of the upper wedge (44) along the axis (14) of the valve stem (12).</p> |
