Shut-off trim including spring loaded check valve

A valve for regulating the flow of a fluid, the valve comprising:

• a housing which includes an interior plug chamber, inflow and outflow passages which fluidly communicate with the plug chamber, and a seating surface disposed between the plug chamber and the outflow passage;
• a reciprocally movable valve stem which extends into the plug chamber;
• and
• a shut-off trim disposed within the plug chamber between the inflow and outflow passages, the shut-off trim comprising:
• a main pilot plug having a bore extending axially therethrough, the main, pilot plug defining a main sealing surface, and a plug seating surface which is disposed within the bore thereof;
• and
• a check valve assembly disposed within the bore of the main pilot plug and comprising an auxiliary plug which is disposed within the bore of the main pilot plug and movably attached to the stem, the auxiliary plug defining an auxiliary sealing surface;
• the shut-off trim being reciprocally movable between a closed position wherein the main sealing surface of the main pilot plug is sealed against the seating surface of the housing and the auxiliary sealing surface of the auxiliary plug is sealed against the plug seating surface of the main pilot plug, and an open position wherein the main sealing surface of the main pilot plug is separated from the seating surface of the housing and the auxiliary sealing surface of the auxiliary plug is separated from the plug seating surface of the main pilot plug, the shut-off trim being configured such that the separation of the auxiliary sealing surface of the auxiliary plug from the plug seating surface occurs prior to the separation of the main sealing surface from the seating surface as the shut off trim moves from the closed position toward the open position.

A valve for regulating the flow of a fluid, the valve comprising:

• a housing which includes an interior plug chamber, inflow and outflow passages which fluidly communicate with the plug chamber, and a seating surface disposed between the plug chamber and the outflow passage;
• a reciprocally movable valve stem which extends into the plug chamber;
• and
• a shut-off trim disposed within the plug chamber between the inflow and outflow passages, the shut-off trim comprising:
• a main pilot plug having a bore extending axially therethrough, the main pilot plug defining a main sealing surface, and a plug seating surface which is disposed within the bore thereof;
• and
• a check valve assembly disposed within the bore of the main pilot plug and comprising an auxiliary plug which is disposed within the bore of the main pilot plug and movably attached to the stem by a pin which is movable concurrently with the stem, the auxiliary plug defining an auxiliary sealing surface;
• the shut-off trim being reciprocally movable between a closed position wherein the main sealing surface of the main pilot plug is sealed against the seating surface of the housing and the auxiliary sealing surface of the auxiliary plug is sealed against the plug seating surface of the main pilot plug, and an open position wherein the main sealing surface of the main pilot plug is separated from the seating surface of the housing and the auxiliary sealing surface of the auxiliary plug is separated from the plug seating surface of the main pilot plug.