To celebrate making it over $80 of Google AdSense revenue (only took 2 years) I placed a copper pipe (Type K) part catalog on this website. The sizes where taken from this website.
To get the pipes to be included in your catalog, place the three files from the other website in the following folder:
Vista: C:\ProgramData\Autodesk\C3D 2008\enu\Pipes Catalog\US Imperial Pipes\Circular Pipes
XP: C:\Documents and Settings\All Users\Application Data\Autodesk\C3D 2008\enu\Pipes Catalog\US Imperial Pipes\Circular Pipes
Once copied over, go to the Pipes menu, Part Builder and click on the catalog regen button. The copper pipe should then be available to add to a parts list, although it may not show up after clicking the button. If it doesn't show up click the folder with check mark button and try again.
I'm looking for sponsors for other pipe sizes. Send me an email at firstname.lastname@example.org if you are interested.