There are a few exceptions divers should be aware of Luxfer aluminum tanks manufactured before June of 1986 are of an inferior Aluminum alloy and should be avoided. Even with the EddiCurrent test that was designed to find flaws in the neck as they begin to develop it is just safer, easier and less expensive to avoid these tanks. Steel tanks that are never exposed to moist fills will not rust from the inside out so you could say that the life of your tank is highly dependent on the quality of the fills you receive. Steel tanks are available in both high and low pressure types using low pressure tanks makes it highly unlikely to get short fills and more likely to get regular overfills. Overfills can shorten the useful life of any tank and "may" be hazardous. Using Low pressure steels above their rated pressure may be useful for particular dive profiles.