With the progress of science and technology and rapid development, pipeline transportation is more and more strict. Also slowly found the shortcomings of the old structure, as well as the owners (users) put forward suggestions combined with the manufacturer's structural improvement. Also slowly appeared the ball valve, DIB, dib-2 and other functions of the structure. Because people did not have more awareness of DIB before, the SPE valve seat of DBB was pressurized into DBB, and the valve seat of DPE in DIB was pressed tightly to seal the ball. When the pipeline was repaired, DBB ball valve was used in the upstream, and the pressure in the middle chamber was too high to release the pressure to the downstream, resulting in accidents such as environmental pollution or casualties. Dib-2 is one side of the SPE seat and the other side of the DPE valve seat. Note that the SPE valve seat must be installed upstream during the installation, so that the SPE seat will automatically relieve the pressure to the upstream when the pressure in the middle chamber increases. Therefore, the safety of DIB ball valve is beyond doubt.