Connected Pipes

Each end of the pipe needs an Entrance. Both must have the same connected pipe ID.
Set area 0 in one end and area 1 in the other end.

Make a Path with the same ID as the entrance's "Connected Pipe ID".
Each node on the path must be placed and "Value 6" in the node numbered as below:

Image of how to place the node in each pipe with its value:

The path must be connected from one end of the pipe to the other this is just to show the placement.
You can place more nodes on the path if you need, only the first and last need the above value 6 number.
World 7-A area 2 is good for more information.

Example shapes:
Reverse L

Setting a pipe as "exit only" does work, but this is never used on connected pipes in retail.