Hi, this technique was first proposed by Undseth in the old "How i Did it forum". But seeing as that's gone now and it's a great technique I will post it again here. Once again this was posted first by Undseth not me!
First create a curve that has the profile that you want your pipe/tube to be.
Then create a nurbs circle that has the radius that your pipe is to be. (Both of these can be created anywhere in the scene)
Now select the circle , then select the curve, then go to surfaces>>extrude>>options.
Select the options shown below and hit extrude. You should have a lovely little pipe that you can modify by modifying the original curve (as see in the pic attached.
Hope this technique is useful to you guys. Post questions about it in this thread and I'll try to help you out.
Technical Director - Framestore
Currently working on: Your Highness