I mean, it's just metal. As long as you make sure it is empty this is perfectly safe. Once a propane tank has reached the end of it's life as a propane tank it

I mean, it's just metal. As long as you make sure it is empty this is perfectly safe. Once a propane tank has reached the end of it's life as a propane tank it is completely reasonable to re-purpose them. You just have to be safe. Welders do this all the time. The scent they put in is actually somewhat flammable too. You take the valve out, leave it inverted, clean clean it out with soapy water, etc. It is a non-trivial process, but propane tanks are good steel.