Valve seat-to-seat connection for easy installation and removal of seat

#The invention relates to a valve seat - to - body connection that provides for positive fluid tight sealing of the connection, while still allowing ready removal of the valve seat and the particular valve seat utilizable therein. The replacement of valve seats for high pressure environments has long posed many problems in the art. Normally, the tighter the fit, the better the seal, however the tighter the fit, the harder it is to remove.

#In order to alleviate some of the problems raised by providing valve seat - to - body connections in high pressure and temperature environments, some manufacturers carry seats in stock with four or more "press fit" size ranges, while other manufacturers weld in the valve seats (making repair prohibitive), and still others settle for seats that have a very limited service range. It has been suggested that other ways could be provided for effecting a tight seal between a valve seat and body (or associated members). For instance, U.S. Pat. Nos. 3,166,291, 3,421,733, 3,752,178, and 3,765,440 suggest the introduction of a material of plastic consistency behind rubber or Teflon seal members for providing a back-up seal, and for forcing the rubber or Teflon members into tighter fitting engagement. U.S. Pat. No. 3,374,261 suggests such an introduction of a special material into a seal area after seal failure has occurred in order to "patch up" the failed seal.

#While all of the above proposals can result in an effective seal, none of them can provide a valve seat - to - body connection that is normally readily detachable (while still having enough securement to prevent the valve seat from falling out during installation), allowing ready replacement thereof, yet may be selectively tightly sealed to prevent ready removal thereof and prevent fluid leakage between the valve seat and valve body even under conditions of continuous high pressure and high temperature. According to the present invention a valve seat is provided for furnishing a metal to metal seal between a valve seat and valve body that is easy to replace and that has a wide service range, not being affected by temperature, pressure, chemical attack, aging, etc.

#FIG. 1 is a side elevational view of an exemplary valve for utilizing the apparatus of the present invention; and

#FIG. 2 is a cross-sectional view taken along lines 2--2 of FIG. 1 showing in detail exemplary valve seat - to - body sealing means according to the present invention.

#A typical valve that may utilize the novel apparatus according to the present invention is shown generally at 10 in the drawings. The valve 10 preferably is a ball or a gate valve, but any type valve may utilize apparatus according to the present invention. The valve 10 includes a metallic valve body 12 having a bore 14 therein, a valve gate 16, which may be rotatable or translatable into position to block the bore 14, and a valve seat 18 interposed between the valve body 12 and the valve gate 16. The bore 14 is adapted to carry fluid under high pressure and temperature. The valve body 12 has a section 13 thereof adapted to receive the valve seat 18 therein, the inside diameter of the section 13 being slightly greater but generally corresponding to the outside diameter of a metallic valve seat body member 20 of valve seat 18.

#The metallic valve seat body member 20 has a bore 21 therethrough corresponding to the bore 14 in body 12. The valve seat body member 20 also has a first section A thereof having an outside diameter that is slightly less but generally corresponds to the inside diameter of the section 13 of body 12, and the member 20 also has a second section B having an outside diameter less than the outside diameter of section A. Preferably the section B is located nearest to the bore 14 in body 12, furthermost into section 13 of body 12, for a reason to be explained hereinafter.

#To provide some sealing while allowing ready detachment of the member 20 from the body 12, a resilient metallic ring 24 is provided, the ring 24 being adapted to be disposed around the section B of the member 20 in engagement with surface 22 thereof. Preferably the ring 24 is tubular in cross-section. The outside diameter of the ring 24 is slightly greater than the inside diameter of the section 13 of the body 12, and the inside diameter of the ring 24 is slightly less than the outside diameter of the section B of member 20. In this way, when the member 20 is inserted into mounted relationship with the body 12 (at section 13 thereof), the amount of interference developed between the ring 24 and body 12 and member 20 is enough to produce initial sealing pressures and to prevent the member 20 from "falling out" of engagement with the body 12, but is not enough to cause yielding of the resilient ring 24. The member 20 is thus also readily detachable from the body 12.