Abstract: Seat structure of valves comprising a seat ring, at least one fixing member secured to a valve body and a concave provided between the body and the fixing member for setting the seat ring therein. The seat ring is provided with an inclined contact face to close a flow passage with a close contact with an inclined sealing face of a closure member and a deflective mounting plate to be sandwiched between the body and the fixing member so that the seat ring may be retained movably in response to a flow pressure in the concave both from one direction and from opposite direction of the flow passage. At the opposite side of the contact face, friction face is provided to slidably engage on a corresponding face provided at the fixing member or a substitute therefor. Said face is so inclined as to form a wedge with the inclined sealing face of the closure member.

Abstract: A butterfly valve of the type including a valve casing, a seat ring provided in the valve casing and a butterfly rotatably provided in the valve casing. The butterfly valve further includes a pair of semicircular sealing projections formed on the sheet ring. The sealing projections are arranged and configured such that one sealing projection engages with one side of the butterfly while another sealing projection engages with another side of the butterfly whereby a butterfly valve with an excellent seal is formed.