I would definatly check for any gas left! I suggest a MATCH dropped in the valve! if it is full we won't have to worry about the tank desposal then! lol. otherwise like others said, try sell or call local propane co;s for disposal. that would make one heck of a yard roller or even a black top steam roller after all the fittings are removed and welded up. lol.
I don't think the tank will ABSORB any propane as it will vaporize and disapate, if the valves are left open for a while. they COAT the insides with the liquid propane just to keep rust off it, as it (propane) is an oil type product and rust preventer. there should be 0 OX in side unless the valves are left open, then they will rust inside and be useless as a propane tank anylonger. would make one heck of a nice BBQ pit though. cut the sides for doors, and such but moving it you would need it's own wheels for sure. let us know when the PIG ROAST is. /forums/images/graemlins/smile.gif
Mark M