High temperature GC valves are made of Nitronic 60, with a rotor made of a polyimide/PTFE/carbon composite designated Valcon T. Valves are rated for 300 psi gas at 330 or 350°C, depending on the bore size.
Valves can be actuated manually or automated with pneumatic or electric actuators. GC valves usually require a standoff - an extension between the valve and actuator which allows the valve to be mounted in the heated zone while the actuator or handle remains outside at ambient temperature. Standoffs are available in lengths of 2", 3" 4", and 6".