American Locomotive
Well-known member
My go to now is Loctite 567. It's expensive, but it works extremely well. It's only downside is that it does behave as a bit of a thread-locker. They say it has "low disassembly strength", but I found that anything over 1.5" NPT or so will require some heat (not a lot, maybe 120-130 degrees) to break it free with a reasonable sized wrench.
Of course in many applications, holding the fitting still is desirable.
Of course in many applications, holding the fitting still is desirable.