Thread sealant on fuel line

What’s the best sealant to use for a portable poly fuel tank and then comes fuel water separator with npt fittings ? Currently have Permatex ptfe on the water separator but looking at redoing everything. I have some Permatex aviation but don’t know if it’s safe on the poly.

What are you trying to seal?? What on the tank i mean..

Sorry. Want to seal the fitting for the tank.

Look at your permatex and it should say what not to ise it on....why not use your ptfe thats on everything else? You can use any sealer thats safe for gas applications...id use what you already have on the tank.

Pic of the fitting your talking about?

That’s what I was wondering. The ptfe doesn’t list gasoline specifically. It’s a brass fitting going on the fuel tanks plastic threads.

That permatex aviation you have should work fine....any sealer should work on those..or use some plumbers tape...the teflon stuff

I recently used TFE (not PTFE) paste on my fuel line to gaso tank fitting. It says it is OK to use with gases and liquids including fuels. That is all I know about it.

I would have liked to use teflon tape as I have a lot of it around. I was just afraid it would not hold up to gasoline. Where was this thread when I needed it! haha.

If ya use something too slippery as sealant careful not to overtighten. When possible I install a clamp..either hose or a pex clamp over the outside of the plastic female fitting if there is room.


I use the yellow NG approved thread tape now.

The plastic threads will form to the brass threads. No sealant needed. Just don't over tighten.

maintenanceguy said:

The plastic threads will form to the brass threads. No sealant needed. Just don't over tighten.

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I agree ^^^ there is no pressure at the joint so no reason to over think it.

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GYPSY400 said:

maintenanceguy said:

The plastic threads will form to the brass threads. No sealant needed. Just don't over tighten.

Click to expand...

I agree ^^^ there is no pressure at the joint so no reason to over think it.

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Would the pressure caused by the EPA fuel caps be an issue? I think they are supposed to vent after 5 psi.

LDUBS said:

GYPSY400 said:

maintenanceguy said:

The plastic threads will form to the brass threads. No sealant needed. Just don't over tighten.

Click to expand...

I agree ^^^ there is no pressure at the joint so no reason to over think it.

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Click to expand...

Would the pressure caused by the EPA fuel caps be an issue? I think they are supposed to vent after 5 psi.

Click to expand...

I use a little bit of Teflon tape on mine, but I'm not sure its really necessary. Hasn't leaked in 10 years.

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My local Ace hires a lot of retired tradesmen who know what they are talking about. I needed to pick up a street elbow for my new gaso tank so headed over with the fuel line fitting in hand. Old guy in the plumbing dept reached in a drawer and handed me the fitting. I asked can I use teflon tape. He says yep the pink kind. And sure enough right on the pack it says good for petroleum and other fuels.

Anyway, made me think of this thread.

old....er tradesman lol!

There is a thread paste called Gasoila that is awesome for pipe thread hydraulic, fuel, and oil fittings.

It is non-hardening, and won't hurt anything if it gets into the system that it's used on.