How to get 12 year old propane tanks inspected. April 02, 2014, 09:21:57 pm Yahoo Message Number: 145588Wal-Mart has there 20# ( Refilled exchange ) propane tanks on sale here in Denver for $18.92 and you get a FREE $10 gift card. That makes the price of the propane $8.92. I traded in a 3/2000 tank and CHOOSE a 7/2013 tank. Now I have a tank that is good for another 11+ years before it needs to be inspected. I need to trade off 5 more tanks but they all have some gas in them to be used up before I trade them off. All the tanks are out dated. More than 12 years old. My problem is that I no longer use propane on the grill. I switched the home grill over to natural gas off my home service. I only use the propane exchange locations to get new tanks.