In order to keep the couplers on you need to have the pipes beaded. If you dont then they are going to blow off. Welding the pipes together is a foolish idea becuase the motor does flex in the cradle and the piping needs to be able to do the same.

I have run 30psi on standard couplers and t-bolt clamps without any leaking. I beaded my pipes with a TIG welder so the beads might be consider slightly larger than those of a Bead roller.

Terry