Sealing Fuel tank AN fittings

[Daniel S.]

Moring all-
As I'm about to embark on the jouney of the fuel tank internals, Im wondering if it is acceptable to put a SMALL fillet around the external joint of the vent tube where it enters the AN fitting & the back side if the AN nut (after torquing the fitting)? Same with the standard fuel pick up fitting. I've seen a few folks having issues with these not sealing properly. I do have a good quality flaring tool but it does seems to leave a slight ridge on the back side of the flare... Ive searched high and low to find a text book answer to see if this was an acceptable practice but have come up empty handed. I do know that Vans seals the internal threads of their flop tube fittings with proseal. What's the general oppinion here? I'm sure Walt can produce a documented answer

Thanks all!

[JonJay]

I would not want to cover up a compromised fitting with sealant. I would want to know it was leaking and fix it. Proseal would just hide the issue, maybe permanently, but I want to see my fittings and put a wrench to them at every CI.
So, I didn't, nor would I, use any kind of sealant on a flared fitting body.
But, that is just me and I am always keeping an open mind.

[JonJay]

After I wrote the above, I realized you can't see the fittings on the inside of the tank. But again, I didn't goop over those either.

[Walt]

Using proseal to ensure fittings don't come lose inside a tank (like Van's does) is fine but I have no ref material to back this up.

It should absolutely not be used in an attempt to seal a leaking or poorly constructed joint. You need to be 100% confident in your flares and assembly process and not use proseal as a back up to a poor connection.

Sealing fuel tanks on the outside is a 'band-aid' approach to tank sealing, seal the fittings with a bead around the perimeter on the inside or don't bother.