For purposes where the absolute tightness is required.
Bray and Orton produce triple eccentric butterfly valves, which are kept at closing position with torque as globe valves and wedge gate valves. The advantage of a triple eccentric valve is unresponsiveness for temperature fluctuations, the valve can be easily opened regardless of the line temperature.
Butterfly valves, ball valves, knife gate valves, pneumatic actuators
100% tight triple eccentric valves