DBB Ball Valve combine two in-line isolation valves into a single body with an additional ball valve used to drain or vent trapped fluid between the two obturators to ensure highest level of safety in double isolation and bleed service. Using a double block and bleed valve versus two separate valves saves weight and space on the piping layout and ensures a significant reduction of potential leakage to the atmosphere, minimizing any hazardous risk when transferring liquids or gas.