Through conduit gate valve with double expanding gate assembly

Claim 1

In a gate valve having a body with a valve chamber intersecting a flow passage, an expanding metal gate valve assembly mounted for movement in the body and within the chamber between opened and closed positions across the flow passage, the gate assembly comprised of a gate element and a segment having smooth parallel faces for engaging metal backed sealing rings mounted in recesses in the body about the flow passage, the gate element having a vee recess and the segment having a complementary vee face fitted into this recess with the gate element and segment in a collapsed condition for providing a minimum dimension between their parallel faces, whereby the gate assembly moves in collapsed condition between opened and closed position and is actuated into a substantially expanded maximum dimension between these parallel faces for tightly engaging the sealing rings at the opened and closed position, the improvement comprising: (a) gate assembly control means integral with the gate assembly for restraining metal-to-metal engagement of the sealing rings against the parallel face of the gate element and segment in their collapsed condition during movements between opened and closed positions; (b) said gate assembly control means in said gate assembly having a parallel edge aligned with the axis of movement between opened and closed positions, metal guide strips mounted on said edges and positioned to ride in metal-to-metal contact with said sealing rings and said metal guide strips having a thickness of a dimension greater than the minimum dimension but less than the maximum dimension of said gate assembly in its collapsed and expanded conditions, respectively; and (c) in said gate assembly, said gate element and segment mount said metal guide strips to said edges of said gate element and said segment by elastic suspension means, and said elastic suspension means biasing said gate element and said segment into the collapsed condition during movement of said gate assembly between opened and closed positions.