Federal law: Any cylinder less than 100 lb. capacity must be recertified 12
years from date of manufacture stamped on top collar.
This certification must be performed by a propane company licensed to inspect cylinders. I have heard of charges varying from $0, if you have them refill cylinder at the same time, up to as high as $30. This charge is not regulated by law.
Beginning a couple of years ago, re-certification date is applied to a sticker which is affixed to the top collar. It will read month, date, and letter 'E'.
Cylinder must scrapped 5 years from the date beside the letter 'E'.