I'd try hammering in a torx bit or another tool that is close to the
same shape. I've heard of people having good luck with that JB Cold
Weld - I have two tubes but haven't used it yet myself.

I'd be real nervous about welding on a fuel tank that may have fumes
even though the gas is old.

On Fri, 06 Feb 2004 18:52:39 -0600, wrote:

Got an old Case loader that's been sitting for a long time.
It has two heavy steel gas tanks welded to the frame. At the bottom of
each tank is a drain; a socket head pipe plug.
Pulled the the first plug with a hex socket,it came out easy.
Along with a quantity of rust, sludge, and old gas.
Went to pull the second plug, and hex won't fit. Someone
has munged the recessed hex trying to get the plug out, instead of a 3/8
hex it is now roughly a 3/8 square.
Tried to turn it with a 3/8 adapter, but there is just a little bit too
much clearance around the adapter.
Any ideas of how to get this plug out other than drilling it?
Might some kind of epoxy/liquid metal hold the adapter enough to get it
out?