I've spent the past 5 days putting together all my rigid copper pipe for my shop air. Whew! There are over 300 solder joints.

Only two (found so far) soldered leaks and they were biggies and easy to find and repair. I've found three screw connector leaks that teflon tape will not seal, but they are to aluminum (drier and regulators) and steel (blast cabinet). I will try pipe dope instead of tape tomorrow. Without the unions, I could not be redoing these easily.

But... All 8 of my unions leak seriously! The faces all look good and clean on the easily accessed ones... I have tried polishing the faces, and the seating ring appears to go all the way around. I have read that you can over tighten them. I've tried putting everything I "have" on them with 14" wrenches after trying lower pressure to tighten them. Other statements are "tighten them with 2 foot cheaters". I think I could break them that way! I have not tried pipe dope or tape on the faces, which some say "can" work.

The big compressor is here, but not wired yet, so I am charging (for leak testing) with my small one. It will drop from 100 psi to 0 in an hour or so.

Any ideas?

Thanks,

David