Valve vented redundant stem seal system

摘要

A valve includes a stem seal assembly that prevent fluid flow in a first direction and vents in a second direction opposite the first direction. The assembly includes a packing assembly positioned within a valve stem opening of a valve body of the valve to seal a valve stem to the valve body. The packing assembly includes a first seal and a second seal preventing passage of fluid from a body cavity of the valve body to an exterior of the valve body along the valve stem while venting fluid from an exterior of the valve body to the body cavity along the valve stem. The packing assembly isolates the first seal and the second seal so that a load applied to the first seal ring is not transferred to the second seal ring.

主权项

1. A valve having a stem seal assembly comprising:
a valve body defining a flow passage and a body cavity perpendicular to the flow passage; the valve body further defining a stem opening extending from an exterior of the body into the body cavity; a valve member moveable between an open position and a closed position, the valve member blocking the flow passage in the closed position, and allowing flow through the flow passage in the open position; a valve stem having a valve stem axis coupled to the valve member, the valve stem extending from the body cavity to an exterior of the valve body through the valve stem opening for moving the valve member from the closed position to the open position; a spring energized first seal ring positioned within the valve stem opening to seal the valve stem to the valve body, the first seal ring comprising:
a chevron profile defining a first and a second leg extending radially outward from an interior radius defined in an apex of the chevron profile, the first and second legs sealing the stem and the body to opposing annular surfaces;a back ring having a chevron channel that receives the apex of the chevron profile, the back ring having a greater stiffness to radial movement than the first and second legs to limit radial deformation of the first and second legs; andan annular seal standoff having a first end and a second end, wherein the first end is positioned on a supportive shoulder of the stem seal assembly and the second end inserts into the interior radius defined in the apex of the chevron profile to support the chevron profile on the standoff; a second seal ring positioned within the valve stem opening to seal the valve stem to the valve body; and a load ring assembly stationarily mounted to and defining a portion of the valve body between the first seal ring and the second seal ring that isolates the first seal ring and the second seal ring so that a force applied to the first seal ring in a direction toward the second seal ring transfers to the load ring assembly.