Seat and trunnion assemblies for rotary valves

A plug valve comprising:

• a. a valve body having a valve chamber and inlet and outlet flow passages disposed in fluid communication with said valve chamber;
• b. a plug member rotatably disposed within said valve chamber and having a flow passage extending through it for alignment with said inlet and outlet passages in the open position of said valve;
• c. means for imparting rotation to said plug member between the open and closed positions thereof;
• d. a seat recess formed in said valve body about at least one of said inlet and outlet flow passages adjacent to said valve chamber, in axial alignment with said flow passage, the interior surface of said seat recess being joined to the interior surface of said flow passage by a generally radially extending shoulder surface;
• e. a seat assembly disposed in said recess and axially movable toward and away from said plug member, said seat assembly including a resilient sealing member disposed therein in sealing engagement with said plug member;
• f. means establishing a fluid-tight seal between said valve body and said seat assembly;
• g. means urging said seat assembly toward said plug member;
• h. the end of said seat assembly axially remote from said plug member terminating in a generally radially extending shoulder surface disposed adjacent to, and generally co-extensively with, said radially extending shoulder surface of said seat recess whereby the motion of said seat ring in an axial direction away from said plug member is limited;
• i. at least one fluid conduit extending through the valve body from the interior surface of said flow passage to the said radially extending shoulder surface of said seat recess, thereby providing means for fluid passage between the said surfaces;
• j. means permitting fluid passage between said valve chamber and the outlet of said conduit on said radially extending surface of said seat recess;
• k. said plug member being supported within said valve chamber by upper and lower trunnions rotatably mounted within said valve body and fixedly mounted within said plug member, the lowermost end of the lower trunnion being mounted within a generally cylindrical trunnion cap, said cap having a central protruding portion extending into a recess in the valve body adapted to receive it in closely fitting relationship, said protruding portion being provided with a generally cylindrical recess for receiving the lower end of said trunnion, said cylindrical recess being provided with an inwardly projecting portion of smaller radius than the radius of the recess, said inwardly projecting portion co-operating with a recess of equal or slightly greater depth within the lower end of said trunnion, wherein the trunnion recess subtends, at the center of the trunnion, an angle that is substantially 90.degree. greater than the angle subtended at the point by said inwardly projection portion of said cap, said cap and trunnion being mounted in interfitting relationship in such a position relative to the plug member as to limit its rotation to a range of substantially 90.degree. between the open and closed positions of the valve.

A plug valve comprising:

• a valve body having a generally spherical valve chamber and inlet and outlet flow passages of substantially circular cross-section disposed in fluid communication with said valve chamber;
• a generally spherical plug member disposed within said valve chamber and having a flow passage of substantially circular cross-section extending through it for alignment with said inlet and outlet passages in the open position of said valve;
• said plug member being supported within said valve chamber by upper and lower trunnions rotatably mounted within said valve body, each trunnion being fixedly mounted within said plug member by means of an interfitting engagement between a generally rectangular trunnion extension having a key projecting from one face thereof, said projection and key cooperatively interfitting within a correspondingly shaped depression within the plug member;
• means for imparting rotation to said plug member between the open and closed positions thereof;
• the lowermost end of the lower trunnion being mounted within a generally cylindrical trunnion cap, said cap having a central protruding portion extending into a recess in the valve body adapted to receive it in close fitting relationship, said protruding portion being provided with a generally cylindrical recess for receiving the lower end of said trunnion, said recess being provided with an inwardly projecting portion cooperating with a recess of equal or slightly greater depth within the lower end of said trunnion, wherein the trunnion recess subtends at the center of the trunnion an angle that is substantially 90.degree. greater than the angle subtended at that point by said inwardly projecting portion of said cap, said cap projection and trunnion recess being mounted in interfitting relationship in such a position relative to the plug member as to limit its rotation to a range of 90.degree. between the open and closed positions of said valve;
• generally cylindrical seat recesses formed in said valve body about said inlet and outlet flow passages adjacent said valve chamber, in axial alignment with said flow passage, the interior surface of each seat recess being joined to the interior surface of its associated flow passage by a radially extending annular planar shoulder surface;
• a seat assembly disposed in each said seat recess and axially movable toward and away from said plug member, said seat assembly comprising a seat ring, a retainer ring fitted about said seat ring attached thereto and defining therewith an annular groove having a restricted annular opening and an annular resilient face sealing member disposed within said groove and having an annular sealing portion thereof protruding through said restricted opening in sealing engagement with said plug member, said seat ring being provided with an annular recess extending axially therewithin for receiving said resilient sealing member, said recess being formed by a radially outer annular frusto-conical surface tapering inwardly away from the plug member and a radially inner annular frusto-conical surface tapering inwardly toward said plug member, said surfaces terminating in an annular radially extending planar surface substantially perpendicular to the axis of the flow passage;
• means establishing a fluid-tight seal between said valve body and said seat ring;
• means urging said seat ring toward said plug member;
• a generally frusto-conical sealing surface formed on said seat ring and adapted for sealing engagement with said plug member, an annular lip formed on the said seat ring by the intersection of said frusto-conical sealing surface and said radially inner annular frusto-conical surface of said annular recess within said seat ring;
• said retainer ring having an annular lip formed thereon co-operating with said seat ring lip to form said restricted opening at the outer extremity of said groove, a generally frusto-conical sealing surface formed on said retainer ring and disposed generally co-extensively with said sealing surface of said seat ring, said retainer ring being provided with a generally radially extending concavely curved annular surface intersecting said frusto-conical sealing surface of said retainer ring to define said annular lip, said concavely curved annular surface forming one interior surface of said annular groove;
• said annular resilient face sealing member disposed within said groove having a cross-sectional configuration generally corresponding to the cross-sectional configuration of said groove, said sealing member being provided with a convexly curved annular surface protruding through said restricted opening at the outer extremity of said groove for engagement with the plug member, said sealing member being of lesser axial length than the axial length of said groove and of greater radial thickness than the radial thickness of said groove, whereby the frusto-conical surfaces of said groove and the annular curved surface of said retainer ring maintain said sealing member under radial and axial compression, and wherein, at low pressures in the valve's normal pressure range, there is an annular space between the end of said sealing member remote from the plug member and the planar surface of said seat ring groove;
• a lubricant and sealant injection device carried by said valve body, first lubricant passage means formed in said valve body and being in fluid communication with said lubricant injection device, second lubricant passage means formed in said seat ring and being in fluid communication with said annular groove, said means establishing seals between said seat ring and said valve body defining a lubricant chamber and said first and second passages being in fluid communication with said lubricant chamber;
• the end of said seat ring remote from said plug member terminating in an annular generally radially extending surface, the radially inner portion of said seat ring shoulder surface consisting of a generally radially extending concavely curved annular surface, said seat ring shoulder surface being disposed adjacent to said radially extending annular planar shoulder surface of said seat recess which is adapted to limit the motion of the sealing assembly in an axial direction away from the plug member, said concavely curved annular surface providing a gap between said seat ring shoulder surface and said seat recess shoulder surface even when the radially outer portion of said seat ring surface abuts against said seat recess shoulder surface;
• the valve body being provided with at least twelve conduits extending through the valve body from the interior surface of the flow passage to the said seat recess shoulder surface opposite said concavely curved portion of the said corresponding generally radially extending surface of the seat ring, thereby providing means for fluid passage between the said surfaces and between said gap and the interior of said valve body,
• the area of said annular generally radially extending surface of said seat ring, and the area of the concavely curved portion thereof, as projected upon a plane perpendicular to the axis of the associated flow passage substantially exceeding the similarly projected area of said frusto-conical sealing surface of said seat ring.