I thought Teflon tape was just meant to lubricate the threads so that they can thread tighter. NPT is tapered and is an interference fit, so the further you thread the better the seal. It also prevents galling and so the thread surfaces remain smooth and less potential for gaps. Too much teflon tape can restrict how far you can thread onto the fitting and that means less thread overlap, which weakens the joint. Although 100 psi is pretty low, so I think you're fine... even if it's not done correctly.
March 7, 2017, 10:53 a.m. - ExtraSpecialandBitter
I thought Teflon tape was just meant to lubricate the threads so that they can thread tighter. NPT is tapered and is an interference fit, so the further you thread the better the seal. It also prevents galling and so the thread surfaces remain smooth and less potential for gaps. Too much teflon tape can restrict how far you can thread onto the fitting and that means less thread overlap, which weakens the joint. Although 100 psi is pretty low, so I think you're fine... even if it's not done correctly.