Valve vented redundant stem seal system

Patent metadata

Field	Value
Publication number	US-9989157-B2
Application number	US-201514690689-A
Country	US
Kind code	B2
Filing date	Apr 20, 2015
Priority date	Dec 21, 2011
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

A valve stem packing assembly can seal a valve stem to a valve body having a body cavity. The packing assembly includes a packing ring circumscribing the valve stem within a stem opening extending axially through the valve body. A primary dynamic seal is positioned to seal a dynamic leak path between the packing ring and the valve stem. A secondary dynamic seal is spaced axially apart and functionally independent from the primary dynamic seal and positioned to redundantly seal the dynamic leak path. A primary static seal is positioned to seal a static leak path between the packing ring and the valve body. A secondary static seal is spaced axially apart and functionally independent from the primary static seal and positioned to redundantly seal the static leak path.

First claim

What is claimed is:

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 valve 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 stem opening for moving the valve member from the closed position to the open position;
a packing assembly sealing between the valve stem and the stem opening, the packing assembly including:
a packing ring circumscribing the valve stem within the stem opening;
a primary dynamic seal positioned to seal a dynamic leak path between the packing ring and the valve stem;
a unitary secondary dynamic seal spaced axially apart and functionally independent from the primary dynamic seal and positioned to redundantly seal the dynamic leak path;
a primary static seal positioned to seal a static leak path between the packing ring and the valve body; and
a secondary static seal spaced axially apart and functionally independent from the primary static seal and positioned to redundantly seal the static leak path; and
wherein the secondary dynamic seal and the secondary static seal each include a seal ring having:
a chevron profile defining a first leg 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 to opposing annular surfaces: and
a stand off having a first end and a second end, wherein the first end is positioned on a supportive shoulder and the second end inserts into the interior radius defined in the apex of the chevron profile to support the chevron profile on the stand off; and

wherein the seal ring of the secondary dynamic seal and the secondary static seal each comprise 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.

2. The valve of claim 1 , wherein the primary dynamic seal comprises a metal to metal seal formed by an outer diameter tapered portion of the packing ring sealingly engaging an outer diameter of the valve stem.

3. The valve of claim 1 , wherein the primary static seal comprises a metal to metal seal formed by an inner diameter tapered portion of the packing ring sealingly engaging an inner diameter of the valve body.

4. The valve of claim 1 , further comprising a plurality of bumps circumferentially spaced apart on the back ring, defining a plurality of fluid channels through which a fluid can vent past a sealing surface of the seal ring.

5. The valve of claim 1 , further comprising a packer retainer ring releasably connected to the valve body, the packer retainer ring engaging a surface of the packing ring, transferring axial load on the packing ring to the valve body.

6. The valve of claim 5 , further comprising a static retainer ring seal sealing between the packer retainer ring and the valve body, and a dynamic retainer seal sealing between the packer retainer ring and the valve stem.

7. The valve of claim 1 , further comprising:
a port extending radially through the valve body; and
a check valve sealing between the packing ring and the valve body, the check valve positioned to allow a fluid in a space between the packing ring and the valve body to escape out of the port, but preventing the fluid from entering through the port to the space between the packing ring and the valve body.

8. The valve of claim 7 , wherein the check valve comprises:
two annular check seal rings, each check seal ring having a chevron profile defining a first leg 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 to opposing annular surfaces;
a back ring associated with each check seal ring and 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; and
a check seal stand off having a first end and a second end, wherein the first end inserts into the interior radius of one of the check seal rings and the second end inserts into the interior radius of the other of the check seal rings, to support each of the check seal rings on the check seal stand off.

9. A valve stem packing assembly for sealing a valve stem to a valve body having a body cavity, the packing assembly comprising:
a packing ring circumscribing the valve stem within a stem opening extending axially through the valve body;
a primary dynamic seal positioned to seal a dynamic leak path between the packing ring and the valve stem, wherein the primary dynamic seal comprises a metal to metal seal formed by an outer diameter tapered portion of the packing ring sealingly engaging an outer diameter of the valve stem;
a unitary secondary dynamic seal spaced axially apart and functionally independent from the primary dynamic seal and positioned to redundantly seal the dynamic leak path;
a primary static seal positioned to seal a static leak path between the packing ring and the valve body, wherein the primary static seal comprises a metal to metal seal formed by an inner diameter tapered portion of the packing ring sealingly engaging an inner diameter of the valve body;
a secondary static seal spaced axially apart and functionally independent from the primary static seal and positioned to redundantly seal the static leak path; and
wherein the secondary dynamic seal and the secondary static seal each include:
an annular seal stand off having a first end and a second end;
a seal ring having a chevron profile positioned on the seal stand off so that the second end of the seal stand off inserts into the chevron profile wherein the seal ring defines a first leg and a second leg extending from an apex of the chevron profile radially outward, the first and second legs sealing to opposing annular surfaces of the valve stem and the valve body;
wherein the first end of the seal stand off has a substantially flat portion positioned on a supportive shoulder of one of the packing assembly and the valve body, and the second end of the seal stand off is in operative engagement with the chevron profile; and

a check valve sealing between the packing ring and the valve body, the check valve positioned to allow a fluid in a space between the packing ring and the valve body to escape out of a port that extends radially through the valve body, but preventing the fluid from entering through the port to the space between the packing ring and the valve body, the check valve comprising:
two annular check seal rings, each check seal ring having a chevron profile defining a first leg 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 to opposing annular surfaces;
a back ring associated with each check seal ring and 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; and
a check seal stand off having a first end and a second end, wherein the first end inserts into the interior rad

Assignees

• Vetco Gray Inc
• Vetco Gray Llc

Inventors

• Hunter Rick C

Classifications

• F16K39/04

  for sliding valves · CPC title

• F16K3/0227 Primary

  Packings · CPC title

• F16J15/3212 Primary

  with metal springs · CPC title

• F16J15/3236

  with at least one lip for each surface, e.g. U-cup packings · CPC title

• F16K41/08

  with at least one ring provided with axially-protruding peripheral closing-lip · CPC title