Hello, Assume that we have a pipe flowing with air of around 80 degrees F surrounded by air of approximately 140 degrees F. The pipe can be made out of three materials: Aluminum, Mild-Steel, and Stainless Steel. What material would it be best to use for the pipe in order for the air flowing through the pipe not to get heated as much (provided that wall thickness is the same)? In case I didn't make myself clear, http://www.ivdstudios.com/Misc/Turbo_pipe_question.png [Broken] of what I am talking about. For reference, thermal conductivity of aluminum is around 230 degrees. Thermal conductivity of mild-steel is around 50 degrees, and the thermal conductivity of stainless steel is around 15 degrees. I have no clue on how to interpret those numbers. :uhh: My confusion rises because, even though I think mild-steel won't heat up as fast, it will heat up more than aluminum over time overall and will thus pass more heat. Thank you in advance for your input. :) P.S. To those wondering, this question is in regards to the intercooler piping on a turbo'd car. I know it won't make a whole lot of difference, but this debate has been going on for way too long within the turbo community.