Before a propane tank may be refilled, the DOT requires that it be inspected by our staff. A propane cylinder may not be refilled if it is corroded; dented; bulging; damaged on valves, footings or valve protection; damaged from fire or misuse; leaking; missing an overfilling device; out of date. Out-of-date tanks may not be refilled and may only be requalified at a registered DOT facility.