Self sealing gate valve

Abstract

.Iadd.A gate valve structure having a slab gate member and a pair of opposed seat assemblies on opposite sides of the gate member. The seat assemblies loosely fit in recesses in the housing and the dimensions of the gate member, seat assemblies and housing recesses are such that there is controlled interference between all sealing surfaces on assembly. An emergency sealant system provides emergency sealant to the face of the seat assemblies. .Iaddend.

What we claim is: 
     
       1. A through conduit gate valve comprised of a housing with a bore therethrough, a valve chamber intersecting said bore, a reciprocating slab gate member located in said valve chamber, said gate member provided with a passage alignable with the bore in the open position and a solid portion to cover said bore in the closed position, facing annular recesses surrounding said bore, each recess having an end wall intersecting the bore, an annular wall coaxial with the bore, one side open to the bore and one end open to the valve chamber, a seat member in each of said recesses, each seat member formed of an annular ring having a lesser outer diameter than the annular wall of its recess whereby each seat member loosely fits into its recess, each seat member provided with a passage aligned with the bore, the axial length of each seat member being greater than the axial length of its recess whereby a portion of each seat member protrudes into the valve chamber to form a sealing face for co-operation with a face of the gate member, each sealing face provided with an annular groove, a deformable plastic sealing member positioned in said annular groove, said deformable plastic sealing member extending beyond the plane of the sealing face to form an annular ring of sealing contact area, each seat member having an axially outward face which opposes the end wall of its recess, the radially outer corner of said axially outward face provided with a rectangular notch which together with the corner formed by the end wall and the annular wall of the recess forms a rectangular chamber, a resilient O-ring positioned in said chamber forming a seal between the seat member and its recess, said O-ring having an initial outer diameter approximating the outer diameter of the seat member and a thickness substantially less than the radial depth of the chamber and greater than the axial length of the chamber, the gate member, sealing surfaces of the seat member and the distance between the end walls of the recesses being so proportioned that there is a slight interference between all sealing surfaces on assembly, the seat member having an annular groove about its periphery axially inward of the corner notch, said groove being generally rectangular in shape, a resilient O-ring positioned in said annular peripheral groove, the thickness of said O-ring being such that it is greater than the radial depth of the groove and less than the axial length of the groove, said seat member provided with a second annular groove about its periphery, said second groove positioned between the first annular peripheral groove and corner notch, the sealing face of the seat member provided with an annular groove of greater diameter than the deformable plastic sealing member, a number of spaced passages connecting the annular groove of the sealing face with the second annular peripheral groove, the housing provided with a passage having one end communicating with the second annular peripheral groove and the other end provided with a lubricant fitting to permit the introduction of sealant to the sealing face of the sealing member, the O-ring defining a restraining chamber whereby the sealant introduced through the fitting is directed into the second annular peripheral groove, passage and sealing face annular groove, the differential in the areas of the restraining chamber being such that there is a resultant force tending to force the upstream seat forward to more intimate contact with the gate, the reactive force of the sealant against the gate being of a lesser magnitude than the force tending to move the seat forward. 
     
     
       2. A through conduit gate valve comprised of a housing with a bore therethrough, a valve chamber intersecting said bore, a reciprocating slab gate member located in said valve chamber, said gate member provided with a passage alignable with the bore in the open position and a solid portion to cover said bore in the closed position, facing annular recesses surrounding said bore, each recess having an end wall intersecting the bore, an annular wall coaxial with the bore, one side open to the bore and one end open to the valve chamber, a seat member in each of said recesses, each seat member formed of an annular ring having a lesser out diameter than the annular wall of its recess whereby each seat member loosely fits into its recess, each seat member provided with a passage aligned with the bore, the axial length of each seat member being greater than the axial length of its recess whereby a portion of each seat member protrudes into the valve chamber to form a sealing face for cooperation with a face of the gate member, each sealing face provided with an annular groove, a deformable plastic sealing member extending beyond the plane of the sealing face to form an annular ring of sealing contact area, each seat member having an axially outward face which opposes the end wall of its recess, the radially outer corner of said axially outward face provided with a notch which together with the corner formed by the end wall and the annular wall of the recess forms a chamber, a resilient O-ring positioned in said chamber forming a seal between the seat member and its recess, said O-ring having an initial outer diameter approximating the outer diameter of the seat member and a thickness greater than the axial length of the chamber, the gate member, sealing surfaces of the seat member and the distance between the end walls of the recesses being so proportioned that there is a slight interference between all sealing surfaces on assembly, the seat member having an annular groove about its periphery axially inward of the corner notch, a resilient O-ring positioned in said annular peripheral groove to form a seal between the peripheral wall of the seat member and the annular wall of the recess, said seat member provided with a second annular groove about its periphery, said second groove positioned between the first annular peripheral groove and corner notch, the sealing face of the seat member provided with an annular groove of greater diameter than the deformable plastic sealing member, a number of passages connecting the annular groove of the sealing face with the second annular peripheral groove, the housing provided with a passage having one end communicating with the scond annular peripheral groove and the other end provided with a lubricant fitting to permit the introduction of sealant to the sealing face of the sealing member, the O-rings defining a restraining chamber whereby the sealant introduced through the fitting is directed into the second annular peripheral groove, passage and sealing face annular groove, the differential in the areas of the restraining chamber being such that there is a resultant force tending to force the upstream seat forward to more intimately contact with the gate and the reactive force of the sealant against the gate being of a lesser magnitude than the force tending to move the seat forward. 
     
     
       3. A through conduit gate valve comprised of a housing with a bore therethrough, a valve chamber intersecting said bore, a reciprocating slab gate member located in said valve chamber, said gate member provided with a passage alignable with the bore in the open position and a solid portion to cover said bore in the closed position, facing annular recesses surrounding said bore, each recess having an end wall intersecting the bore, an annular wall coaxial with the bore, one side open to the bore and one end open to the valve chamber, a seat member in each of said recesses, each seat member formed of an annular ring having a lesser outer diameter than the annular wall of its recess whereby each seat member loosely fits into its recess, each seat member provided with a passage aligned with the bore, the axial length of each seat member being greater than the axial length of its recess whereby a portion of each seat member protrudes into the valve chamber to form a sealing face for co-operation with a face of the gate member, each sealing face provided with an annular groove, a deformable plastic sealing member positioned in said annular groove, said deformable plastic sealing member extending beyond the plane of the sealing face to form an annular ring of sealing contact area, each seat member having an axially outward face which opposes the end wall of its recess, the radially outer corner of said axially outward face provided with a notch which together with the corner formed by the end wall and the annular wall of the recess forms a chamber, a resilient O-ring positioned in said chamber forming a seal between the seat member and its recess, said O-ring having an initial outer diameter approximating the outer diameter of the seat member and a thickness greater than the axial length of the chamber, the seat member having an annular groove about its periphery axially inward of the corner notch, a resilient O-ring positioned in said annular peripheral groove to form a seal between the peripheral wall of the seat member and the annular wall of the recess, said seat member provided with a second annular groove about its periphery, said second groove positioned between the first annular peripheral groove and corner notch, the sealing face of the seat member provided with an annular groove of greater diameter than the deforming plastic sealing member, a number of passages connecting the annular groove of the sealing face with the second annular peripheral groove, the housing provided with a passage having one end communicating with the second annular peripheral groove and the other end provided with a lubricant fitting to permit the introduction of sealant to the sealing face of the sealing member, the O-rings defining a restraining chamber whereby the sealant introduced through the fitting is directed into the second annular peripheral groove, passage and sealing face annular groove, the differential in the areas of the restraining chamber being such that there is a resultant force tending to force the upstream seat forward to more intimately contact with the gate and the reactive force of the sealant against the gate not being of a lesser magnitude than the force tending to move the seat forward. 
     
     
       4. A through conduit gate valve comprised of a housing with a bore therethrough, a valve chamber intersecting said bore, a reciprocating slab gate member located in said valve chamber, said gate member provided with a passage alignable with the bore in the open position and a solid portion to cover said bore in the closed position, facing annular recesses surrounding said bore, each recess having an end wall intersecting the bore, an annular wall coaxial with the bore, one side open to the bore and one end open to the valve chamber, a seat member in each of said recesses, each seat member formed of an annular ring having a lesser outer diameter than the annular wall of its recess whereby each seat member loosely fit into its recess, each seat member provided with a passage aligned with the bore, the axial length of each seat member being greater than the axial length of its recess whereby a portion of each seat member protrudes into the valve chamber to form a sealing face for co-operation with a face of the gate member, each sealing face provided with an annular groove, a deformable plastic sealing member positioned in said annular groove, said deformable plastic sealing member extending beyond the plane of the sealing face to form an annular ring of sealing contact area, each seat member having an axially outward face which opposes the end wall of its recess, the radially outer corner of said axially outward face provided with a notch which together with the corner formed by the end wall and the annular wall of the recess forms a chamber, a resilient O-ring positioned in said chamber forming a seal between the seat member an its recess, said O-ring having an initial outer diameter approximating the outer diameter of the seat member and a thickness greater than the axial length of the chamber, the seat member having an annular groove about its periphery axially inward of the corner notch, a resilient O-ring positioned in said annular peripheral groove to form a seal between the peripheral wall of the seat member and the annular wall of the recess, said seat member provided with a second annular groove about its periphery, said second groove positioned between the first annular peripheral groove and corner notch, the sealing face of the seat member provided with an annular groove of greater diameter than the deformable plastic sealing member, a number of passages connecting the annular groove of the sealing face with the second annular peripheral groove, the housing provided with a passage having one end communicating with the second annular peripheral groove and the other end provided with a lubricant fitting to permit the introduction of sealant to the sealing face of the sealing member, the O-rings defining a restraining chamber whereby the sealant introduced through the fitting is directed into the second annular peripheral groove, passage and sealing face annular groove, the sealant system being so proportioned that the forces developed by sealant being injected are such that there is a resultant force tending to move the seat out of its pocket into an intimate contact with the gate maintaining the gap between the sealing faces of the seat and gate at a minimum. 
     
     
       5. A valve comprised of a housing with a bore therethrough, a valve chamber intersecting said bore, a valve member located in said valve chamber, said valve member provided with a passage alignable with the bore in the open position and a solid portion to cover said bore in the closed position, facing annular recesses surrounding said bore, each recess having an end wall intersecting the bore, an annular wall coaxial with the bore, one side open to the bore and one end open to the valve chamber, a seat member in each of said recess, each seat member formed of an annular ring having a lesser outer diameter than the annular wall of its recess whereby each seat member loosely fits into its recess, each seat member provided with a passage aligned with the bore, a portion of each seat member forming a sealing face for co-operation with a face of the valve member, each sealing face provided with an annular groove, a deformable plastic sealing member positioned in said annular groove, said deformable plastic sealing member extending beyond the plane of the sealing face to form an annular ring of sealing contact area, each seat member having an axially outward face which opposes the end wall of its recess, the radially outer corner of said axially outward face provided with a notch which together with the corner formed by the end wall and the annular wall of the recess forms a chamber, a resilient O-ring positioned in said chamber forming a seal between the seat member and its recess, said O-ring having an outer diameter approximating the outer diameter of the seat member and a thickness greater than the axial length of the chamber, the valve member, sealing surfaces of the seat members and the distance between the end walls of the recesses being so proportioned that there is a slight interference between all sealing surfaces on assembly, the seat member having an annular groove about its periphery axially inward of the corner notch, said groove being generally rectangular in shape, a resilient O-ring positioned in said annular groove, the thickness of said O-ring being such that it is greater than the radial depth of the groove and less than the axial length of the groove, said seat member provided with a second annular groove about its periphery, said second groove positioned between the first annular groove and corner notch, the sealing face of the seat member provided with an annular groove of greater diameter than the deformable plastic sealing member, a passage connecting the annular groove of the sealing face with the second annular peripheral groove, the housing provided with a passage having one end communicating with the second annular peripheral groove and the other end provided with a lubricant fitting to permit the introduction of sealant to the sealing face of the sealing member, the O-ring defining a restraining chamber whereby the sealant introduced through the fitting is directed into the annular groove passage and sealing face annular groove, the differential in the areas of the restraining chamber being such that there is a resultant force tending to force the upstream seat forward to move into intimate contact with the valve member and the reactive force of the sealant against the valve member being of lesser magnitude than the force tending to move the seat forward. 
     
     
       6. A through conduit gate valve comprised of a housing with a bore therethrough, a valve chamber intersecting said bore, a reciprocating slab gate member located in said valve chamber, said gate member provided with a passage alignable with the bore in the open position and a solid portion to cover said bore in the closed position, facing annular recesses surrounding said bore, each recess having an end wall intersecting the bore, an annular wall coaxial with the bore, one side open to the bore and one end open to the valve chamber, a seat member in each of said recesses, each seat member formed of an annular hub portion having a lesser outer diameter than the annular wall of its recess whereby each seat member loosely fits into its recess, each seat member provided with a passage aligned with the bore, the axial length of the hub portion being slightly greater than the axial length of the recess, each seat member having a flange portion provided with a front face which protrudes into the valve chamber to form a sealing face for co-operation with a face of the gate member, and a rear face which contacts the wall surrounding the recess, each sealing face provided with an annular groove, a deformable plastic sealing member positioned in said annular groove, said deformable plastic sealing member extending beyond the plane of the sealing face to form an annular ring of sealing contact area, the hub portion of each seat member having an axially outward face which opposes the end wall of its recess, the radially outer corner of said axially outward face provided with a rectangular notch which together with the corner formed by the end wall and the annular wall of the recess forms a rectangular chamber, a resilient O-ring positioned in said chamber forming a seal between the seat member and its recess, said O-ring having an initial outer diameter approximating the outer diameter of the seat member and a thickness greater than the axial length of the chamber, the gate member, sealing surfaces of the seat member and the distance between the end walls of the recesses being so proportioned that there is a slight interference between all sealing surfaces on assembly, an annular groove in the rear face of the hub portion, said groove being generally rectangular in shape, a resilient O-ring positioned in said annular groove, the thickness of said O-ring being such that it is greater than the axial depth of the groove and less than the radial length of the groove, said seat member provided with a second annular groove in the rear face of the hub portion, said second groove being radially inward of the first annular groove, the sealing face of the seat member provided with an annular groove of greater diameter than the deformable plastic sealing member, several passages connecting the annular groove of the sealing face with the second annular peripheral groove, the housing provided with a passage having one end communicating with the second annular peripheral groove and the other end provided with a lubricant fitting to permit the introduction of sealant to the sealing face of the sealing member, the O-ring defining a restraining chamber whereby the sealant introduced through the fitting is directed into the annular groove passage and through the passage into several sealing face annular grooves, the sealant system being so proportioned that the forces developed by the sealant being injected are such that there is a resultant force tending to move the seat out of its pocket into intimate contact with the gate maintaining the gap between the sealing faces of the seat and gate at a minimum. 
     
     
       7. A through conduit gate valve comprised of a housing with a bore therethrough, a valve chamber intersecting said bore, a reciprocating slab gate member located in said valve chamber, said gate member provided with a passage alignable with the bore in the open position and a solid portion to cover said bore in the closed position, facing annular recesses surrounding said bore, each recess having an end wall intersecting the bore, an annular wall coaxial with the bore, one side open to the bore and one end open to the valve chamber, a seat member in each of said recesses, each seat member formed of an annular ring having a lesser outer diameter than the annular wall of its recess whereby each seat member loosely fits into its recess, each seat member provided with a passage aligned with the bore, the axial length of each seat member being greater than the axial length of its recess whereby a portion of each seat member protrudes into the valve chamber to form a sealing face for co-operation with a face of the gate member, each sealing face provided with an annular groove, a deformable plastic sealing member positioned in said annular groove, said deformable plastic sealing member extending beyond the plane of the sealing face to form an annular ring of sealing contact area, each seat member having an axially outward face which opposes the end wall of its recess, the radially outer corner of said axially outward face provided with a rectangular notch which together with the corner formed by the end wall and the annular wall of the recess forms a rectangular chamber, a resilient O-ring positioned in said chamber forming a seal between the seat member and its recess, said O-ring having an initial outer diameter approximating the outer diameter of the seat member and a thickness substantially less than the radial depth of the chamber and greater than the axial length of the chamber, the gate member, sealing surfaces of the seat member and the distance between the end walls of the recesses being so proportioned that there is a slight interference between all sealing surfaces on assembly. .Iadd. 8. A through conduit gate valve comprised of a housing with a bore therethrough, a valve chamber intersecting said bore, a reciprocating slab gate valve member located in said valve chamber, said gate member provided with a passage alignable with the bore in the open position and a solid portion to cover said bore in the closed position, facing annular recesses surrounding said bore, each recess having an end wall intersecting the bore, an annular wall coaxial with the bore, one side open to the bore and one end open to the valve chamber, a seat member in each of said recesses to form an upstream seat member and a downstream seat member, each seat member formed of an annular ring having a lesser outer diameter than the annular wall of its recess whereby each seat member loosely fits into its recess, each seat member provided with a passage aligned with the bore, the axial length of each seat member being greater than the axial length of its recess whereby a portion of each seat member protrudes into the valve chamber to form a sealing face for cooperation with a face of the gate member, each sealing face provided with an annular groove, a deformable plastic sealing member positioned in said annular groove, said deformable plastic sealing member extending beyond the plane of the sealing face to form an annular ring of sealing contact area for sealing contact with the gate member, each seat member having an axially outward face which opposes the end wall of its recess, the radially outer corner of said axially outward face provided with a rectangular notch which together with the corner formed by the end wall and the annular wall of the recess forms a rectangular chamber, a resilient O-ring consisting solely of a stretchable elastomeric material positioned in said rectangular chamber forming a seal between the seat member and its recess, said O-ring having an initial outer diameter approximating the outer diameter of the seat member and a thickness substantially less than the radial depth of the chamber and greater than the axial length of the chamber such that the O-rings are initially deformed axially upon assembly to provide the force for initially causing said sealing contact between the sealing members and said gate member; the gate member, sealing surfaces of the seat member and the distance between the end walls of the recesses being so proportioned that there is a slight interference between all sealing surfaces on assembly, each seat member having the outward face thereof spaced from the opposed end wall of the associated recess on assembly and being exposed to and responsive to fluid pressure from both the bore and the valve chamber for floating back and forth movement of the seat members with respect to the gate member and the housing thereby to provide fluid pressure actuated seat members, said upstream seat member and its associated plastic sealing member upon the reaching of an excessive fluid pressure in the valve chamber being moved out of sealing contact with the gate member to relieve the excess fluid pressure in the body chamber to the bore, said O-ring being stretched radially outwardly into sealing engagement with the annular wall of the associated recess when the fluid pressure in the bore is greater than the fluid pressure in the valve chamber. .Iaddend.