 A 3-way plug valve could also be designed to shift flow between ports 1 and 2, 2 and 3, or 1 and 3, and possibly even connect all three ports together.The flow-directing possibilities in multi-port plug valves are similar to the possibilities in corresponding multi-port ball valves or corresponding multi-port valves with a rotor.An additional possibility in plug valves is to have one port on one side of the plug valve and two ports on the other side, with two diagonal and parallel fluid pathways inside the plug.