As the ball valve usually uses rubber, nylon polytetrafluoroethylene as the seat sealing ring material, its service temperature is limited by the seat sealing ring material. The cut-off function of the ball valve is completed by the mutual compression between the metal ball the plastic valve seat under the action of the medium (floating ball ball valve). Under the action of certain contact pressure, the elastic-plastic deformation of the valve seat sealing ring occurs locally. This deformation can compensate the manufacturing accuracy surface roughness of the ball, ensure the sealing performance of the ball valve.

　　Since the valve seat sealing ring of ball valve is usually made of plastic, the fire resistance fire prevention of ball valve should be considered when selecting the structure performance of ball valve, especially in petroleum, chemical, metallurgical other departments, especially when using ball valve in flammable explosive medium equipment pipeline system.

　　In general, ball valve is recommended in the pipeline system with double position adjustment, strict sealing performance, mud, wear, necking channel, rapid opening closing action (1 / 4 turn opening closing), high pressure cut-off (large pressure difference), low noise, cavitation gasification, small leakage to the atmosphere, small operating torque small fluid resistance.

　　Ball valve is also suitable for light structure, low pressure cut-off (small pressure difference), corrosive media in the pipeline system. Ball valve can also be used in low temperature (cryogenic) equipment pipeline system. In the oxygen pipeline system of metallurgical industry, it is necessary to use the ball valve with strict degreasing treatment. When the main pipeline in oil gas pipelines needs to be buried underground, full diameter welded ball valve is needed. When regulating performance is required, special structure ball valve with V-shaped opening shall be selected. In the petroleum, petrochemical, chemical, electric power, urban construction, the working temperature of the pipeline system above 200 degrees