Valve provided with a thermally-actuated mechanism for pressing valve seats against a valve gate body

Claim 1

A valve comprising: a valve housing containing a fluid supply conduit and a fluid discharge conduit for conveying fluid which flows through the valve, said fluid supply and discharge conduits being interconnected by a flexible seal device; within the valve housing, a valve gate body which contains an opening and is movable relative to the fluid supply and discharge conduits to open or close the fluid passageway for said flow through the valve; contact resistant valve seat materials arranged on surfaces of the supply and discharge conduit and valve gate body for being pressed together to form substantially fluid-tight seals between those conduits and the gate valve body; at least one heat-expandable metal structure comprising at least one column connected between the fluid supply and discharge conduits so that its thermally-induced expansion and contraction relieves and applies a relatively high force for compressing the valve seat materials on the fluid supply and discharge conduits against those on the valve gate body; means for heating and cooling said expandable metal structure; and, means for repositioning the valve gate body when the force compressing it between the fluid supply and discharge conduits is relieved.