Patent ID: 8033294

Claim:
A valve for controlling fluid flow, comprising: a valve body defining: an inlet port; an outlet port; and an aperture fluidly coupling the inlet port and the outlet port; a bonnet assembly comprising: a first bonnet; and a second bonnet, wherein the first bonnet and the second bonnet are substantially coaxially opposed; a first closure member to sealingly engage a first seating surface; and a second closure member to sealingly engage a second seating surface opposite the first seating surface, wherein the second closure member includes a compliant seal to be positioned in a bore defined by the valve body when the second closure member is not in use to substantially prevent fluid flow through the valve from affecting the compliant seal, wherein the second seating surface comprises a tapered surface and a surface adjacent the tapered surface, wherein a tapered portion of the second closure member is to sealingly engage the tapered surface and the compliant seal is to sealingly engage the surface adjacent the tapered surface.