Principles of use of ball valves:1. For main oil and natural gas pipelines that need to be cleaned and buried underground, ball valves with full-bore and fully-welded structures should be selected; for those buried on the ground, ball valves with full-bore welded connections or flange connections should be selected ; Branch pipe, choose flange connection, welding connection, full bore or reduced bore ball valve. Non-metallic materials that resist pressure release and burst should be selected for nominal pressures above PN100 (CL600).
Since the ball valve usually uses rubber, nylon and polytetrafluoroethylene as the material of the seat seal, its operating temperature is limited by the material of the seat seal. The cut-off effect of the ball valve is accomplished by pressing the metal ball against the plastic valve seat under the action of the medium (floating ball valve). Under the action of a certain contact pressure, the valve seat sealing ring undergoes elastic-plastic deformation in local areas.
The advantages of ball valves are: 1. Has the lowest flow resistance (actually equivalent to only a section of round pipe of the same nominal size). 2. It can be reliably used in corrosive media and low-boiling liquids because it does not get stuck during operation (when there is no lubricant).
The ball valve is evolved from a cock. Its opening and closing part is a sphere, and the sphere is rotated 90o around the axis of the valve stem to achieve the purpose of opening and closing. The ball valve is mainly used to cut off, distribute and change the flow direction of the medium on the pipeline. The ball valve designed with V-shaped opening also has a good flow adjustment function.