| 摘要 |
A valve assembly comprising a tubular member (2) having an axial bore (4) which is selectively opened and closed by a gate valve. The gate valve includes a sliding gate (5), a first actuating stem (9,27) engagable with one side of the gate and a second actuating stem on the opposite side or the gate and also engagable with the gate. The actuating stems can move the gate between open and closed positions, and an intermediate position in which the gate can be run into and withdrawn from a support with the tubular member.
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