Orifice valves controls the volume of gas through the valve into the production conduit. These valves are used for continuous injection of gas. They are fitted mostly at the bottom of the wells. Since they do not have charged bellows and stem configuration they remain in open condition and allow the free passage of injection gas into the production tubing. These valves have an integral robust reverse flow check valve at the bottom to prevent production fluid backflow. The reverse flow check valves have elastomeric primary seal and metal to metal secondary seal to prevent tubing to casing communication. Reverse flow check valves are rated to 5000 psi differential pressure.