Since ball valves usually use rubber, nylon and polytetrafluoroethylene as the sealing ring materials for the valve seat, the operating temperature of the ball valve is limited by the material of the valve seat sealing ring. The closing function of the ball valve is accomplished by the metal ball pressing against the plastic valve seat under the action of the medium (for floating ball valves). Under the action of a certain contact pressure, local areas of the valve seat sealing ring undergo elastic-plastic deformation. This deformation can compensate for the manufacturing accuracy and surface roughness of the ball, ensuring the sealing performance of the ball valve. 

Also, since the sealing rings of ball valves are usually made of plastic, when choosing the structure and performance of the ball valve, it is necessary to consider its fire resistance and fire prevention capabilities. Especially in the petroleum, chemical, and metallurgical industries, when using ball valves in equipment and pipeline systems with flammable and explosive media, greater attention should be paid to fire resistance and fire prevention. 

Generally, in pipeline systems where two-position regulation is required, strict sealing performance is needed, there is mud, wear, constricted channels, rapid opening and closing action (1/4 turn for opening and closing), high-pressure cutoff (with large pressure difference), low noise, cavitation and vaporization phenomena, small leakage to the atmosphere, small operating torque, and low fluid resistance, it is recommended to use ball valves. 

Ball valves are also suitable for pipe systems with lightweight structures, low-pressure stop valves (with small pressure difference), and corrosive media. They can also be used in low-temperature (cryogenic) devices and pipeline systems. In oxygen pipeline systems in the metallurgical industry, ball valves that have undergone strict degreasing treatment must be used. When the main pipelines in oil and gas pipelines need to be buried underground, full-diameter welded ball valves must be used. When it is required to have regulating performance, special structures with V-shaped openings must be selected. In pipeline systems with working temperatures above 200 degrees in the petroleum, petrochemical, chemical, power, and urban construction industries,