Ball valves are very widely used for isolation service. They are a derivative of Plug valves having a ball shaped closure and are particularly suited to on/off control with low pressure drop. The seat matching the ball is circular and therefore the seating stress is uniform and it is usual for ball valves to have soft seats which will conform readily to the surface of the ball. Isolation is achieved by the ball rotating 90 degrees in the pipeline. Ball valves are available with various actuator options including, but not limited to Lever, Gear, Electric, Pneumatic or Hydraulic Actuator and Spring return lever or Dead mans handle.