Abstract: A sealing structure for use in valves, including butterfly valves, having a body with a flow passage and a movable valve disc in the flow passage. Two sealing surfaces are mounted in the body to engage the disc when it is in a closed position to provide a bubble-tight seal. The sealing structure includes an annular seal retaining cavity with a slot opening to the flow passage. A metal seal ring having a lip portion (which has a first seat) projecting through the slot into the passage is contained within the cavity adjacent to a primary heat-destructible seal ring, which has a second seat. The first seat and the second seat are engageable with the sealing surface of the disc to provide two axial seals. When the valve is closed, a radially-directed force is developed at the second seat (on the heat-destructible seal) and at the first seat (on the lip portion of the metal seal) in response to contact with the disc to effect a heat-destructible seal and a second, metal-to-metal seal, respectively.

Abstract: A sealing structure capable of various uses and particularly in butterfly valves having a body with a flow passage and a movable valve disc in the flow passage and having a sealing surface. The sealing structure is mounted in the body to engage the disc in the closed position of the latter to provide a high performance (i.e. bubble-tight) seal. The sealing structure includes an annular seal retaining cavity with a slot opening to the flow passage. The structure includes a seal ring of Teflon, PFA or the like retained in the cavity and sealing one axial side of the ring from the other. It also has a tongue-like extension projecting through the slot into the passage and having a seat at its end engageable with the sealing surface of the disc. The seal and cavity structures have shoulders normally (in open position of the valve) abutting each other to seal the interior of the cavity (the abutment occurring from expansion of the seal ring into place in the cavity).