Ball valve takes ball with circular hole as opening and closing element. The ball is driven by valve stem to rotate 90°around valve stem to perform opening and closing. The valve is used to cut off or switch on the medium within pipeline, and widely used in petroleum refining, long-distance transportation pipeline, chemical, paper making, pharmaceutical, water conservancy, electric power, municipal and steel, etc. Special consideration is made to strength, safety, resistance to harsh environment during design. It's suitable for various corrosive and non-corrosive mediums. Different materials may be selected for transportation of water, steam, oil, natural gas, nitric acid, acetic acid, oxidant and urea. Ball valve has compact structure and reliable sealing. Its sealing surface and spherical surface are closed normally which make it resistant to flush erosion by the medium, and easy to operate and repair.