초록 ▼

Apparatus and methods are disclosed for a valve seat wherein the geometry of the seat is such that the resultant axial forces due to the differential between internal and external pressure across the valve seat result in a resultant axial force that urges the valve seat into sealing engagement with

Apparatus and methods are disclosed for a valve seat wherein the geometry of the seat is such that the resultant axial forces due to the differential between internal and external pressure across the valve seat result in a resultant axial force that urges the valve seat into sealing engagement with the plug or other type of closure member, regardless of the direction of the differential pressure. Thus the valve seat is urged against the closure member regardless of whether the line pressure or bonnet pressure is higher. In the same manner, a resultant axial force urges a seal seat of the preferred embodiment into sealing engagement with the valve body. An axially moveable seal bearing ring is positioned between the valve seat and the seal seat that alters the effective geometry of the seat elements when it moves between a first position and a second position. The seal bearing ring moves responsively to the direction of the differential pressure across the seat elements. In the present configuration, when valve flow path pressure is greater than bonnet pressure, then seal bearing ring is urged against valve seat and effectively becomes part of the geometry of the valve seat. When bonnet pressure is greater than valve flow path pressure, then seal bearing ring is urged against seal seat and effectively becomes part of the geometry of the seal seat. The valve therefore effects a primary and secondary seal when the valve is closed so that even if the primary seal leaks, then the valve maintains its seal because the reversed differential across the secondary or downstream seat assembly causes the valve to maintain a gas tight seal.

대표청구항 ▼

[ What is claimed is:] [1.] A valve assembly for a valve having valve body that defines a flow path such that flow through the valve is axially directed with respect to said flow path, said flow path having a flow path pressure, a valve bonnet pressure external to said flow path pressure, comprising

[ What is claimed is:] [1.] A valve assembly for a valve having valve body that defines a flow path such that flow through the valve is axially directed with respect to said flow path, said flow path having a flow path pressure, a valve bonnet pressure external to said flow path pressure, comprising:a closure member mounted for movement within said flow path to control flow through said flow path; anda seat assembly with a valve seat, said seat assembly being mounted between said closure member and said valve body, said seat assembly having an effective seat geometry such that either a positive or negative differential pressure between said flow path pressure and said valve bonnet pressure produces a resultant force to urge said valve seat in an axial direction toward said closure member and away from said valve body into sealing engagement with said closure member.