US 6,082,707 A · Valve seat and method

Abstract

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.

Claims23

Dependent claims

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;
and
a 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.

A valve for a flow passage operable for controlling flow through said flow passage, said valve being operable to contain an internal pressure within said flow passage relative to an external pressure such as a valve bonnet pressure, a positive differential pressure being defined when said internal pressure is greater than said external pressure, and a negative differential pressure being defined when said internal pressure is less than said external pressure, said valve comprising:

a valve body, said valve body defining said flow passage through said valve body between first and second openings in said valve body;
a valve closure member mounted within said flow passage, said valve closure member being movable between a first position when said first and second openings are in communication with each other, and a second position when said first and second openings are restricted from communication with each;
a valve seat element encircling said flow passage for sealing engagement with said valve closure member;
a seal bearing member, said seal bearing member being mountable within said valve body so as to be responsively moveable between a first position when said differential pressure is positive and a second position when said differential pressure is negative, said valve seat element and said seal bearing member in said first position providing a first effective geometry of said valve seat element and said seal bearing member such that said positive differential pressure acting on said first effective geometry produces a first resultant force that urges said valve seat element into sealing engagement with said valve closure member, said valve seat element and seal bearing member in said second position of said seal bearing member providing a second effective geometry of said valve seat element and said seal bearing member such that said negative differential pressure acting on said second effective geometry produces a second resultant force that urges said valve seat element into sealing engagement with said valve closure member and
a seal seat element positioned such that said seal bearing member is between said valve seat element and said seal seat element.

2 more elements

A method for making a valve, said valve having a valve body defining a flow path, said method comprising:

mounting a closure member within said valve body such that said closure member is rotatable between an open position and a closed position;
providing an axially moveable valve seat element to be axially engageable with said closure member for sealing with said closure member;
providing said axially moveable valve seat element with a geometry reactive to a pressure internal to said flow path and a pressure external to said flow path to produce a resultant force on said axially moveable valve seat element to urge said axially movable valve seat element in the same direction for engageably sealing with said closure member when said pressure internal to said flow path is larger than said pressure external to said flow path and which said pressure internal to said flow path is less than said pressure external to said flow path.

Dependencies are inferred from the claim text.

Valve seat and method

Life of this patent

Valve seat and method

Life of this patent

Abstract

Claims23