I'm working with 3/4" brass fittings, which seem pretty robust.
Some plumbing fittings should be only finger-tight. My friend said I should use 2 wrenches to make these as tight as I can, and then some.
How tight should I make them?
EDIT: I am plumbing water, but I'd like to learn to plumb gas, too.
Best Answer
Leakage path through NPT threads occurs between the very peaks of one thread and the very valley of the opposing thread. No matter how tight you make NPT threads, a leakage path still exists. It is the function of the sealant to block the path between the male and female thread.
This is most helpful!
Most screwed piping is tightened until it feels "right" and the fitting is pointing in the desired direction. What the experienced mechanic is often "feeling" is how the fitting is getting tight. Screw it into until it starts to seat. Then up the force a little by yanking. If each yank gives less movement, you probably have a sound joint. If the movement stops suddenly, you have probably bottomed out. The experienced plumber knows when to stop before he damages the fitting or boss. Caution is advised, tapered pipe fittings into an aluminum boss as excessive torque can crack the boss. This is especially true when using Teflon tape because the low friction of Teflon makes it easy to over-tighten.