| 摘要 |
An expanding gate valve according to the present invention includes a gate system incorporating a pair of segments, one segment being formed to define opening cam surface means and the other segment being formed to define closed cam surface means. Spreader means is positioned in stationary manner within the valve chamber of the valve and includes opening and closing cam surface means that is engageable respectively with the cam surface means of the segments to achieve wedging, mechanically energized sealing enhancement between the segments and the valve seats as the gate segments reach the open or closed positions thereof during operation. The body structure of the valve is formed to define a valve chamber of generally cylindrical configuration within which may be located a pair of partially cylindrical seat carrier elements that properly position a pair of seat rings in relation to the valve body and the planar sealing surfaces of the gate segments. The valve mechanism also includes a back seating system capable of establishing both a metal-to-metal seal and a deformed seal between a tapered seat formed in the bonnet and a tapered seal structure carried by a gate drive element.
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