Gas Vent Pipe Type “B” was installed backwards

[cassandra_hollow@]

Gas Vent Pipe Type “B” was installed backwards. The pipe that leads to the furnace cannot the changed and has the male end. What they had done was cut the end off one section of pipe, making two female ends. This is where it was leaking so off I went to change it out. Can I install the entire pipe system backwards if not what are my other **

Thanks
CC