On Fri, 27 Sep 2013 04:55:06 -0700, bob haller wrote:

the OP will find a must inspec date stamped into the tank,
after that no propane supplier will legally be able to fill it....

Large tanks will outlast all of us, and then some; so I
seriously doubt there is an "expiration date" on them.

I dont know how they inspect such large tanks

When I first called the propane company years ago, they
said I had to pay for an inspection before they would fill it
(since I told them it was my tank).

I wasn't home at the time the inspector did his work, so I
don't know what he did, but, he reconnected the tank and
shut off and tagged the kitchen grill because it was missing
an element (which I subsequently replaced).

I suspect (but need to confirm) that these large tanks won't
be filled if they don't meet regulations, which the propane
company has under control.

So I suspect inspection isn't a problem for the homewowner
for these large aboveground tanks.