I've been to a few shops in New England that will no longer fill tanks over xx years in age, steel or aluminum -- regardless of hydro/visual status.
I'm not one to put anyone at risk, but having a few older tanks (oldest Scott AAA), a nice AL 50 my wife used to use and my 80 CU FT USD, along with an interest in the steel 72's that periodically become available, just wondering what you all do?
My first "new tank" USD, Luxfer 10-85 stands in my office with 1000 PSI remaining as a decoration and used to check regs and pressure gauges from time to time. It's honestly seen relatively few fills in it's long life (32 years) to be standing in the corner.