Plumbing advice re: reliability of pvc unions

[The Guy]

Originally Posted by Madreefer

That's how I tightened one a long time ago and I broke the bond where it was glued on. But I did'nt use primer. As for the o-ring seal i've never had a problem. It's actually a good idea to use unions on external return pumps in case your pump or pump seal goes, much easier than having to cut your plumbing.

I guess me being an HVAC mechanic by trade I forget and assume people would use a hold back on the stationary glued part of the union, also some O-ring lube is good idea on unions.
Hey Bill your new DT looks awesome!