High pressure stem packing for gate valves

In a valve having a valve body presenting a fluid flow passage therethrough, a valve member mounted in the body for reciprocating movement between an open position and a closed position, a valve stem connected to the valve member to move same between the open and closed positions in response to axial reciprocation of the stem, and a valve bonnet mounted to the body and receiving the valve stem, an improved packing assembly comprising:

• a plurality of packing rings arranged about the valve stem in a stack and contacting the stem and bonnet in sealing relation;
• a pair of anti-extrusion rings arranged about the valve stem at opposite ends of the stack of packing rings to sandwich the packing rings between the anti-extrusion rings, said anti-extrusion rings contacting the stem and bonnet and being formed of a harder substance than said packing rings to impede extrusion of the packing rings along the stem and bonnet;
• and
• a pair of packing retainer rings between which said anti-extrusion rings and packing rings are sandwiched, one retainer ring having a surface facing inwardly towards the fluid flow passage, said retainer rings being mounted for movement toward one another under the influence of fluid pressure in the flow passage acting on said inwardly facing surface of said one retainer ring to thereby squeeze said packing rings against the valve stem and bonnet for increased sealing force with said anti-extrusion rings acting to impede extrusion of the packing rings between the valve stem and bonnet.

A packing structure for sealing a movable shaft to a housing presenting a fluid flow passage which is exposed to a high pressure fluid therethrough, said packing structure comprising:

• a plurality of packing rings mounted about the shaft in sealing contact with the shaft and the housing;
• a pair of retainer rings between which said packing rings are located with one retainer ring having an inwardly facing surface upon which the fluid pressure in the flow passage acts to urge said one retainer ring outwardly toward the other retainer ring, thereby squeezing said packing rings against the shaft and the housing to increase the sealing effect of said packing rings as the fluid pressure acting on said one retainer ring increases;
• each retainer ring having a beveled inside edge adjacent the shaft and a beveled outside edge adjacent the housing;
• and
• a metal chamfer ring disposed against each beveled edge of each said retainer ring between said retainer ring and the adjacent said packing ring, each said metal chamfer ring having a cam surface thereon contacted by said corresponding beveled edge in a manner to force said metal chamfer rings against the shaft and the housing by camming action upon outward movement of said one retainer ring toward said other retainer ring in response to the fluid pressure from the flow passage, whereby extrusion of said packing rings along the shaft and the housing is substantially prevented by said metal chamfer rings, the effectiveness of said metal chamfer rings in preventing extrusion of said packing rings increases with increased fluid pressure from the flow passage.

In a high pressure valve having a valve body presenting a fluid flow passage therethrough, a valve member mounted for movement between an open position and a closed position relative to the flow passage, and a movable valve stem connected with the valve member to effect movement thereof between the open and closed positions, the improvement comprising:

• a bonnet on the valve body receiving the valve stem and defining an annular space about the stem terminating in a shoulder facing generally inwardly towards the flow passage;
• a plurality of packing rings in said annular space arranged about the valve stem to effect a seal therewith and with the bonnet;
• a pair of retainer rings between which said packing rings are located with one retainer ring disposed against said shoulder, other of said packing rings having a surface facing inwardly towards the valve body and upon which the fluid pressure in the flow passage acts to urge the other retainer ring outwardly toward said one retainer ring, thereby squeezing the packing rings against the valve stem and bonnet to increase the sealing effect of the packing rings as the fluid pressure acting on the other retainer ring increases;
• each retainer ring having a beveled inside edge adjacent the valve stem and a beveled outside edge adjacent the bonnet;
• and
• a metal chamfer ring disposed against each beveled edge of each retainer ring between the retainer ring and the adjacent packing ring, each metal chamfer ring having a cam surface thereon contacted by the corresponding beveled edge in a manner to force the metal chamfer rings against the stem and bonnet by camming action upon outward movement of said other retainer ring toward said one retainer ring in response to the fluid pressure from the flow passage, whereby extrusion of the packing rings along the stem and bonnet is substantially prevented by the metal chamfer rings, the effectiveness of the metal chamfer rings in preventing extrusion of the packing rings increases with increased fluid pressure from the flow passage.

A gate valve comprising:

• a valve body having a valve chamber and a fluid flow passage;
• a gate mounted in the valve chamber for movement between an open position and a closed position relative to the flow passage;
• a valve stem carrying the gate between the open and closed positions in response to axial reciprocation of the stem;
• a bonnet assembly mounted to the valve body and having a bore in which said valve stem is received for axial reciprocation, said bonnet assembly defining an annular space in said bore around the valve stem and a shoulder facing generally toward the valve chamber at an outer end of said annular space;
• a pair of packing retainer rings positioned in said annular space with one retainer ring disposed against said shoulder, the other retainer ring having a surface facing inwardly towards the valve body and upon which the fluid pressure in said valve chamber acts to urge said other retainer ring toward said one retainer ring, each retainer ring having a beveled inside edge adjacent the valve stem and a beveled outside edge adjacent the bonnet assembly;
• a plurality of packing rings sandwiched between the retainer rings in sealing relation with the valve stem and bonnet assembly, said packing rings being squeezed against the stem and bonnet assembly when said other retainer ring is urged toward said one retainer ring;
• and
• a rigid chamfer ring positioned against each beveled edge of each retainer ring between the retainer ring and the adjacent packing ring, each chamfer ring having a cam surface thereon engaged by the corresponding beveled edge in camming fashion to force the chamfer rings against the valve stem and bonnet assembly in response to movement of said other retainer ring toward said one retainer ring, whereby said chamfer rings impede extrusion of said packing rings between the valve stem and chamfer rings and between the bonnet assembly and chamfer rings.

A gate valve comprising:

• a valve body having a valve chamber and a fluid flow passage;
• a gate mounted in the valve chamber for movement between an open position and a closed position relative to the flow passage;
• a valve stem carrying the gate between the open and closed positions in response to axial reciprocation of the stem;
• a bonnet assembly mounted to the valve body and having a bore in which said valve stem is received for axial reciprocation, said bonnet assembly defining an annular space in said bore around the valve stem and a shoulder facing generally toward the valve chamber at an outer end of said annular space;
• a pair of packing retainer rings positioned in said annular space with one retainer ring disposed against said shoulder and the fluid pressure in said valve chamber acting to urge the other retainer ring toward said one retainer ring, each retainer ring having a beveled inside edge adjacent the valve stem and a beveled outside edge adjacent the bonnet assembly;
• a plurality of packing rings sandwiched between the retainer rings in sealing relation with the valve stem and bonnet assembly, said packing rings being squeezed against the stem and bonnet assembly when said other retainer ring is urged toward said one retainer ring;
• a rigid chamfer ring positioned against each beveled edge of each retainer ring between the retainer ring and the adjacent packing ring, each chamfer ring having a cam surface thereon engaged by the corresponding beveled edge in camming fashion to force the chamfer rings against the valve stem and bonnet assembly in response to movement of said other retainer ring toward said one retainer ring, whereby said chamfer rings impede extrusion of said packing rings between the valve stem and chamfer rings and between the bonnet assembly and chamfer rings;
• a plurality of aligned openings in said retainer rings and packing rings, and a plurality of pins in the respective openings, at least one of said pins has a threaded connection with said other retainer ring, a beveled edge around each opening of each retainer ring confronting the adjacent packing ring;
• an annular metal gasket positioned against each beveled edge of each retainer ring between the retainer ring and the adjacent packing ring, each gasket having a chamfer which is engaged by the corresponding beveled edge in camming fashion to urge the gaskets against the pins upon movement of said other retainer ring toward said one retainer ring, whereby extrusion of said packing rings between said pins and gaskets is impeded;
• at least one metal ring mounted in the bonnet assembly in sealing contact with the valve stem at a location inwardly of said other retainer ring, said metal ring scraping foreign material from the valve stem upon axial reciprocation of the stem;
• a sealant passage in the bonnet assembly located outwardly of said metal ring for injecting sealant against the valve stem;
• and
• a groove in the valve stem extending past said metal ring to provide communication between the sealant passage and valve chamber when said gate is in the closed position, thereby permitting application of sealant through said passage to the valve chamber in the closed position of the gate.