Seats for gate valves

Claim 1

A gate valve structure comprising a valve body having a valve chamber therein and inlet and outlet flow passages communicating with the valve chamber, an expanding valve assembly including a gate element and segment slidably mounted within the valve chamber for movement between open and closed positions of the gate valve structure with said gate element and segment expanding away from each other at the fully open and closed position, said gate element and segment having ports therethrough alignable with said flow passages in the open positions of the valve assembly, an annular recess in the valve body surrounding each flow passage and opening into the valve chamber, a seat element fitted within each recess, each seat element having a port therein aligned with the adjacent flow passage and a skirt extending from opposed sides of the associated port alongside the adjacent gate assembly, each skirt at least at a locatIon adjacent the flow passage having opposed projections of a width greater than the width of the gate assembly, and a spacer extending alongside the gate assembly in a direction generally parallel to the longitudinal axis of the flow passages and positioned between facing projections on the seat elements to maintain a minimum clearance between the seat elements and gate assembly.