The radon pipe that vents radon gas from a building is a very important component of a radon abatement system. The radon mitigation pipe system must be completely sealed so that this cancer causing gas isn't forced back into the home. Henceforth typical air venting ducts are not used. The most commonly used material is PVC pipe like that used for drain and vent pipe for plumbing. Although the specifications allow for schedule 20 PVC, I would strongly recommend using schedule 40 which is much stronger and less apt to crack or break open. Schedule 40 pipe also insulates better and is thus quieter. When radon is suctioned from below the home concentrations can easily reach into the hundreds of pCi/L or even thousands. Simple stated you don't want this pipe to get a hole in it.
Another reason for using plastic pipe is because there will be condensation created. So the radon pipe will have to be sloped to drain the water back into the soil. If improper slope isn't maintained a build up of water in the vent will create unwanted noise and could reduce or even stop the air flow.
I recently repaired a do-it-yourself system that was installed with galvanized 6" round duct(very leaky). Before the homeowner project started the level was 14pCi/L and afterward the level had climbed to 41pCi/L!
Another important aspect of the radon piping installation is that it must vent 12" above a roof of the building, not highest roof or above the peak is required. Also the pipe must be at least 10 feet from any windows or skylights that can be opened, this can be disregarded if the pipe is 2' above the opening. A common bad practice is to install a pipe out the side of the house like you would vent a furnace or a dryer vent. This would allow the possibility of the radon reentering through the sill plate or open windows.
A properly installed system must have the fan installed outside of the living space. A garage, attic or the side of the home would be appropriate for fan placement.