Student question: Routing pipe

I have an exercise (so it is not a real life situation) where I have to draw a pipe coming from the top of a tower to a fin-fan. On the middle of the way I have a reboiler. I can route this pipe over the reboiler, under the reboiler or around the reboiler.
In my simple mind I think route the pipe over the reboiler is not a good idea because may cause problems when the reboiler need some maintainance. Go around the reboiler it is ok but is the longest way, I mean, more pipe, more money.
So the best solution is take the pipe under the reboiler.
Am I right?
Is there any rule(s) I have to follow to route a pipe?

Thank you.