Weeping fuel fitting...sealant?

kawabunga

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Upon recently completing my build, the final step was to put fuel in it and fire it up. I discovered that my fuel hose barb fitting has a slight weep at the threads from the tank bung.
I used a weld in bung, 1/4" NPT, and I'm using a 90º elbow 1/4" fuel fitting. Because it's a 90º bend, it has to be fitted in a specific direction. I had the bung placed in the tank properly prior to welding but the heat must have distorted things a bit and my placement was thrown off. I used a 1/4" NPT tap to try and get myself a little more turn to get the fitting in the proper direction, which that worked, but now I have a very slight weep of fuel from it. I cannot go any further in because of both direction of the fitting and clearance issues.
Has anyone used some kind of sealant on fuel fitting/tank bung threads before? All I have at the moment is teflon tape for my air tools, but I don't think that plays well with fuel.
Any suggestions?
 
I'll betcha if you were to wind cotton thread into the pipe threads before assembly that cotton thread would be enough to seal it ? Some petcock gaskets are fibrous. That's my thinking. And it's cheap and easy to try
;)
 
Teflon tape is fine. They make "gas" specific Teflon tape. but it's the same stuff just thicker and colored yellow so it's easy to see in the tool box. And the "gas" is natural gas.
 
Machine, the bung and fitting do not have a mating surface other than the threads used to assemble, so I don't think there's a way to get a gasket in-between them.
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Gary, I'll give the tape a shot. I was afraid that fuel would eat it up and end up leaking anyway.
 
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Yes, you have to use pipe sealant or teflon tape. This is what I use -- actually I often use it and teflon tape together. Anyways, there is not a single "correct" orientation for threaded fittings. With sealant, they will seal anywhere within a 360 degree or greater tightening arc. Or more. An important added function of the sealant is that it acts as lubricant, allowing the fitting to be further screwed in than if sealant wasn't used and preventing galling. And, another important added function is that it prevents galvanic corrosion that occurs when dissimilar metals are in contact with each other.
There really isn't very much pressure in a tank. With good sealant, the fittings usually don't have to be crazy-tight to seal.
 
Permatex fuel resistant gasket & flange sealant. Worked on my petcock screws. Part number 85420.
 
Machine, the bung and fitting do not have a mating surface other than the threads used to assemble, so I don't think there's a way to get a gasket in-between them.
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Gary, I'll give the tape a shot. I was afraid that fuel would eat it up and end up leaking anyway.

Hi kawabunga,
Teflon thread tape. it's proof against anything except Gamma radiation, works at way above boiling point
AND it'll allow you to set your elbow to the angle you want.
 
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