A ball valve is normally a quarter-turn valve where a machined, hollowed-out ball can be turned in an outer casing to the open position for full flow or to the closed position to obstruct flow within a pipeline. There are other designs that allow the flow to be mixed or diverted to particular pipe directions. The general body types for ball valves are single body or 1 piece, split body ( 2 or 3 pieces), side and top entry trunnion mounted and welded. With trunnion-mounted ball valves, the anchoring of the ball absorbs the thrust from the line pressure preventing excess friction between the ball and seats. At full working pressure, the operating torque for the pneumatic or electric actuators is comparatively low.

These can be actuated manually by levers, handwheels, using compressed air in pneumatic actuators, or electrically. Most ball valves are of the floating seat design because of cost and weight considerations. For the food industry, sanitary ball valves need to be used where they are in contact with food ingredients.