Throttle-shutoff valve

Claim 1

A valve comprising a body having an inlet and outlet separated by a partition; a seat assembly carried by said partition, said seat assembly including a central aperture having an inner wall defining a generally cylindrical flow passage communicating with said inlet and outlet and further including an annular, renewable, flat-surfaced seating ring surrounding said aperture; a valve member adapted for reciprocal movement within said body relative to said seat assembly between an open position where there is substantially unrestricted flow through said flow passage and a closed position to shut off flow through said flow passage, said valve member including a beveled plug section adapted to extend into said flow passage without seating against said aperture and to cooperate with said aperture, as said valve member is moved from and towards the closed position, to vary the flow through said flow passage and further including an annular, renewable, flat-surfaced seating ring surrounding said plug section and adapted to engage said seat assembly seating ring and cooperate therewith to provide a fluid tight seal when said valve member is in a closed position, said seat assembly and valve member seating rings being made from a metallic material having a Brinell hardness greater than 500 with the Brinell hardness of one differing from that of the other by at least 10; and means for adjustably moving said valve member between the open and closed position.