The advanced version of the proven plunger valve is designed as flow optimized inlet and outlet valve for piggable pipelines. The piggable main line is connected to the valve's housing. The vertically arranged piston is designed in a way that in the closed position a smooth, piggable passage is produced. The new protected seal concept facilitates a slim, pipeline optimized design and switching of the piston whilst the valve is pressurized. The complete valve unit with all seals can be replaced without having to dismount the valve. Thus, the plunger valve can be quickly used again.