PVC will blow up, so I've been told. I think I can show a pic.
http://i1156.photobucket.com/albums/p561/45Aber/garage017_zps03c15447.jpg
Of black iron pipe not deadly PVC.
I bet the lapping compound would work. I might not have got it tight enough standing on a ladder but it felt tight. I'll try some pipe dope on the mating surfaces. I bought Blue Monster non hardening, it's white though.
The soap is bubbling at the threaded side of the union.
I got half of my air pipe system on the wall. 30' of 3/4" with two up and over work drops and a straight drain drop in 1/2" black iron. I've got a union in the middle of the 3/4" and unions for each 1/2" drop. I put 175 psi to it and had leaks at the water filter and the 1/2" union. I expected...
My old compressor was a Sears oil less with a 26 gal tank. I could go thru it and set its regulator at 150. It ran at 175 psi but the pump fried, no oil!
I have a new IR TS4N5 setting in the corner of my shop and plan to use 1/2" black iron pipe along 30' of the side wall. The pipe is rated at 150 psi but the compressor puts out 175 psi. Do I need a regulator right at the compressor to keep pressure at 150? I plan to have three drops, one for air...