Plug valve for reduced leakage

A plug valve, said plug valve comprising:

• a valve housing, said housing having a flow passage therethrough, said housing having an internal way system;
• a valve plug, said valve plug being rotatably fitted within said valve housing across said flow passage for controlling fluid flow;
• an actuating stem, said stem having at least two side portions, said stem having shoulder, said shoulder extending radially outward from and separating said side portions, said stem being operatively connected to said plug, said stem being operatively fitted into a female recess in said plug, said stem being at least partially housed within said housing, said stem having a greater clearance with said plug when said passageway is not correspondence with said bore, said clearance providing for the prevention of internal leakage past said plug when said plug is in the closed position;
• an external sealing member, said sealing member being circumferentially disposed about said stem proximal to an axially adjacent section with respect to said shoulder on the opposite said thereof with respect to the said valve plug, said sealing member being located in said internal way system such that said sealing member compressingly and sealingly interacts with said shoulder whenever said shoulder is urged axially away from said plug by fluid pressure;
• a first chamber, said chamber being at least partially defined by the end of said plug interacting with said stem, said valve housing and the side of said stem shoulder opposite said external sealing member, said first chamber being responsive to fluid pressure for compressing and sealing interaction with said shoulder whenever said shoulder is urged axially away from said valve plug, said first chamber having a buffering media;
• means for controlling the pressure of said fluid irrespective of fluid pressure in said flow passage;
• means for permitting the axial movement of said stem in response to fluid pressure in said first chamber to compressingly and sealingly interact with said shoulder and said external sealing member;
• a second chamber, said second chamber being partially defined by the end of said plug distile to said stem, said valve plug having a surface area exposure to said second fluid chamber which is greated than the corresponding surface exposure of the end of said plug interacting with said stem to said first chamber, said second chamber having a buffering media;
• and
• means for providing fluid communication between said first chamber and said second chamber.

A plug valve, said plug valve comprising:

• a valve housing, said housing having an internal bore extending therethrough, said bore defining a fluid flow passage, said housing having a concentric cylindrical dome;
• a valve plug, said plug having a passageway therein, said plug being rotatably fitted within said housing, said plug extending across said flow passage such that fluid flow is controlled through said flow passage, said plug having a femalw recess, said female recess being located on the upper surface of said plug;
• a first sealing member, said member being in the form of a liner, said member circumscribing the periphery of said plug, said member being apertured in correspondence with said passageway through said plug, said member being positioned between said plug and said housing;
• an actuating stem, said stem having at least two side portions, said stem having a shoulder, said should extending radially outward from and separating said side portions, said stem being operatively connected to said plug, said stem being fitted into said female recess in said plug, said stem being at least partially housing within said concentric cylindrical dome of said housing, said stem having a greater clearance with said plug when said plug passageway is not in correspondence with said housing bore, said clearance providing for the prevention of internal leakage past said plug when said plug is in the closed position;
• an upper fluid chamber, said chamber being defined by said upper surface of said plug, said lower surface of said dome, said first sealing member, said lower most side portion of said actuating stem and said lower side of said shoulder;
• means for providing bearing surfaces for said actuating stem, said means having an upper and a lower portion, said upper portion extending above the periphery of said actuating stem to the top of said dome;
• a second sealing member, said member being disposed between said upper and said lower portions of said means for providing bearing surfaces for said actuating stem.

A plug valve, said plug valve comprising:

• a valve housing, said housing having an internal bore extending therethrough, said bore defining a fluid flow passage, said housing having a concentric cylindrical dome;
• a valve plug, said plug having a passageway therein, said plug being rotatably fitted within said housing, said plug extending across said flow passage such that fluid flow is controlled through said flow passage, said plug having a female recess, said female recess being located on the upper surface of said plug;
• a first sealing member, said member being in the form of a liner, said member circumscribing the periphery of said plug, said member being apertured in correspondence with said passageway through said plug, said member being positioned between said plug and said housing;
• an actuating stem, said stem having at least two side portions, said stem having a shoulder, said shoulder extending radially outward from and separating said side portions, said stem being operatively fitted into said female recess in said plug, said stem being at least partially housed within said concentric cylindrical dome of said housing, said stem having a greater clearance with said plug when said passageway is not in correspondence with said bore;
• an upper fluid chamber, said chamber being defined by said upper surface of said plug, said lower surface of said dome, said first sealing member, said lower most side portion of said actuating stem and said lower side of said shoulder;
• means for providing bearing surfaces for said actuating stem, said means having an upper and a lower portion, said upper portion extending above the periphery of said actuating stem to the top of said dome;
• a second sealing member, said member being disposed between said upper and said lower portions of said means for providing bearing surfaces for said actuating stem;
• means for urging said plug upward relative to said housing, said means for urging further comprising:
• an opening, said opening located in the bottom portion of said housing, said opening having at least two concentric counter bores, said second counter bore having a smaller diameter than said first counter bore;
• means for covering said opening;
• a tightening bolt, said bolt being centrally located relative to said opening, said bolt being adjustably fitted within said means for covering;
• a thrust washer;
• a first diaphragm, said first diaphragm being fitted about said first counter bore;
• and
• a second diaphragm, said second diaphragm being disposed immediately about said first diaphragm, said second diaphragm being fitted about said second smaller counter bore.