The reason propane tanks are required to be re-certified every 10 years is they corrode and rust inside. What you see on the outside is sometimes worse on the inside. If you take it to a propane company, they can safely remove the propane from the tank and probably exchange it for a tank that has been re-certified. I have seen what happens in a propane gas ignition. The person had terrible flash burns and lived for about 4 days before passing away. Not worth the risk.