how do I get my NPT connections to not leak

[ericm979]

How do you make NPT connections that don't leak? Too many of the ones I added recently leak. I have been using permatex liquid PTFE sealer.

 

[teg]

I'm wondering that too... I'm guessing that I tighten mine way too much... Anyone else?

 

[4570Man]

The only ones I’ve found that don’t leak I torqued the crap out of. If for some reason the rotation is limited it’s pretty much guaranteed to leak.

 

[KYErik]

It sounds counter intuitive, but it is possible to over tighten these fittings and distort the threads. Its better to tighten them just a little snug, then tighten just a little more at a time if they happen to leak.

 

[tomplum]

When you get those stubborn ones, use Permatex #1 Form a gasket in the tube.

 

[4570Man]

That’s opposite of my experience. Anything that’s not about as tight as you can get it with a regular wrench leaks.

 

[Oldpath05]

I thought this was Teflon Tape was for or am I on the wrong page again.

 

[/pine]

You can eliminate relying on thread sealant by switching to NPTF and using NPSM female fittings...all mechanical...stouter than JIC...!

 

[4570Man]

I’ve had better luck with the white liquid thread sealer. As in Teflon tape fails every time when oil is in the picture in my experience.

 

[downsizingnow48]

If it is hydraulic, I use Loctite 545. If it is water, I use Rectorseal #5. If it is gas, I use gas rated Teflon tape and sometimes Rectorseal as well. Never had any of these leak if the fitting is properly tightened.

The fitting could be too tight or too loose, it will leak either way. I always get them just about as tight as possible, but it is possible to over tighten. Also these days some fittings are poor quality and might not seal at all. I got some of those one time at a big box store.