Leaky Unions

[Jim P]

I have two-piece fuel supply lines from the tank to selector valve and after 50 hours, both unions started seeping a little. I filled both tanks and then it sat in the sun, and as the tank heated, it did push some fuel out the vents, so there seemed to have been a little more pressure on the unions with the valve off. Other than re-building the lines, is there a way to seal the b-nut/ union? I'm tempted to just replace these with a single flex line.

Jim

[az_gila]

Originally Posted by Jim P

I have two-piece fuel supply lines from the tank to selector valve and after 50 hours, both unions started seeping a little. I filled both tanks and then it sat in the sun, and as the tank heated, it did push some fuel out the vents, so there seemed to have been a little more pressure on the unions with the valve off. Other than re-building the lines, is there a way to seal the b-nut/ union? I'm tempted to just replace these with a single flex line.

Jim

...do the trick.

http://www.aircraftspruce.com/catalo...37fittings.php

Fully certified and safe to use....

[Jim P]

Thanks Gil. I was thinking about those but wasn't sure.

[frankh]

That worked for me..

Usually the only reason a tapered union will leak (assuming you have 37 deg tapers on both parts) is that they are not tight enough or some foreign object has pitted the seat.

What i have done in the past is to use a scrap steel fitting of the right size and a little valve grinding paste to poilish the offending sealing surface.

Seals it right up, my A&P friend was impressed at least.

Be sure to remove all traces of the paste!

Frank

[Mel]

I've found that a very small drop of blue or green Lock-Tite on the flare will help the seal.