Psi rating for radient floor heat panel test???

^^^Dope it and tape it and go.
Threads ain't what they used to be. Check the country of origin of the fittings as a hint. Inspect threads closely before assembling, and chase them if there's any doubt- make sure they're clean when you start! You wouldn't believe (well, maybe you would!) some of the crappy factory thread jobs I've seen. When chasing, make sure you're not cutting any new threads, just clean them up. You don't want to mess with the taper depths of the pipe threads too much.