Psi rating for radient floor heat panel test???

Lamp Wick and a good pipe dope. If the threads on the pipe are cut incorrectly you can have leaks. Threaded joints done properly do not leak
When I pressure check piping usually I isolate just the piping section
Years ago I did a chill water line job. When the piping got down to 3 inch the contractor decided he didn't want to use weld fittings and he hired a guy to cut and thread pipe
He called me sometime later in a panic. They had leaks everywhere. I went out there and found every threaded joint this guy did was bad, fittings were bottoming out.
He wanted to know if I could run a bead around each leaking joint and I told him no. The fittings were malleable and I wasn't doing that. I had him order all new weld fittings and some more pipe and redid the entire job