i work at a plumbing supply store too..
if you mean DWV waste pipe... then i wouldnt use it, it will sag, and get brittle, not to mention its designed for a 2/3 drainage system.. ie, 2/3 of the pipe is the maximum flow that should be run thru it, thus having no pressure.
PVC pressure pipe is alot stronger, and expensive, but still isnt designed for heat...
as 66 skyline gt said, ABS pipe is probably one of the safest bets, or a piping system called dizayn/aquaplast, these are both designed to take a decent amount of pressure and heat, but definte values im not 100% sure on.
let us know how the results go... if you find some kind of plumbing pipe that will do the job fine, i may be able to get some good deals for SAU