A bellows sealed plug valve includes a valve body having an inlet passage and an outlet passage,Plug Valves a valve chamber between the inlet and outlet passages. A valve plug has substantially the same shape as the valve chamber and is rotatably disposed therein. A shaft is movable linearly in response to a signal from a valve actuator. A bellows is sealingly disposed between the valve chamber and the valve actuator and means are located between the bellows and the valve plug for converting linear movement of the shaft connected to the valve actuator to rotational movement of the plug. Various means are disclosed including helical thread mechanism,API Cast Steel Valves clevis mechanism and rack and pinion mechanism, all for converting linear motion to rotational motion. In a bellows sealed plug valve including a valve body having an inlet passage and an outlet passage, a valve chamber between said inlet and outlet passages, BALL VALVESa valve plug having substantially the same shape as said valve chamber and being rotatably disposed therein, said valve plug having a flow passage disposed therethrough, said flow passage disposed such that with said valve plug in a first position said flow passage is in alignment with said inlet and said outlet passages and provides fluid communication therebetween, and with said valve plug in a second position said flow passage is out of alignment with said inlet and outlet passages and said valve plug interrupts fluid communication therebetween, a shaft connected to a valve actuator movable linearly in response to a signal from said valve actuator, wherein the improvement comprises: a cap assembly, an operator shaft passing through said cap assembly, a bellows cooperating with said operator shaft and said cap assembly to prevent fluids from passing between said bellows and said operator shaft and to form a primary sealing assembly isolating said valve chamber from the atmosphere, a secondary sealing means and a spring retainer encircling said operator shaft, a return position spring encircling said operator shaft and positioned between said secondary sealing means and said spring retainer, a pinion extending from said valve plug and in contact with said operator shaft; said operator shaft is adapted at one end to form a rack and interact with said pinion, whereby the linear movement of said operator shaft results in the rotational movement of said pinion and said valve plug connected thereto; and said cap assembly includes a cap, and a valve housing, and wherein said bellows cooperates with said cap assembly at a point along said valve housing and said operator shaft thereby effecting a fluid tight seal to prevent fluids from passing between said bellows and said operator shaft and said valve housing and said bellows.

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