B3 metal seated ball valves are specially designed according to actual working services or customer's requirement. It can be used in adverse working services and can meet the bad working services requirement such as high temperature, high pressure, strong corrosion and medium with grain, etc. This series of ball valves can use two type of structure of trunnion mounted or floating ball, the seat is grinded after accurately machined along with the matched ball and forms tight contact with the ball through spring loading to reach to initial seal, the contact between seat and ball is much more tight under the medium pressure at working status with safe reliable seal, long life cycle and easy operation. This kind of valve is widely used in the industries of petrochemical, papermaking, sewage treatment, mines, ocean platform, etc.