i did just that years ago for a small compressor i built
just a detail about safety that i had been warned about
apparently LP and some components of natural gas will dissolve into the steel of the tank, just a few microns into imperfections
if the tank was recently used, even if you 100 percent flush the tank out with air, leaving it sit for a short period or even overnight can produce an explosive mix of gases freshly released from the steel
so don't make that mistake if you want to weld or braze on the tank
do a fresh air flush immediately before and during any hot work
basically treat it as you would a car gas tank and you will be fine
-s
