I can't tell you what that stuff is but I watched a 120 gallon tank being
set and filled.
The LP service guy painted the fittings for the regulator to the LP tank
with something that was gooey like Permatex non-hardening (not Permatex
though). He used teflon tape at his brass nipples to mate with the copper
line.
If you decide to use anything to assist the seal, use it cautiously; you
don't want anything traveling into your regulator or to your gas outlet
orifices.
I can see that a light application of shellac might give a better seal
............... but could cause problems removing fittings for service at
a later date.
Simple grease might help reform non perfect flares for a better fit.

Stan Wilder

On Sat, 19 Oct 2002 20:04:12 -0700 Bill Davidson <wdavidson@THEGRID.NET>
writes:
> I've got my new propane tank bolted to the under side...
> And I have cut and bent and flared tubing ends...
> ready to connect the tubing and tighten the flare nuts...
>
> but a question...
>
> I noticed that when I took the flare nuts apart there was a dark
> colored
> greasy like substance on the threads... and maybe on the flared ends
> of the
> tubing... Originally I though that might be old propane decomposed
> into
> sludge... but now I'm wondering if the previous installer put a dab
> of axel
> grease on the flares.... perhaps it assures a better seal???
> Anybody know what that black stuff is on the flare ends?
>
> thanks,
>
> Bill Davidson
>
>

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