Stamped somewhere on your tank, or on a plate attached to the tank, should be the date it was manufactured.   Years ago, when I worked propane as a summer student, we would not fill exposed vehicle tanks which were more than X-years old unless they had been re-certified within the last 5-years.

Luckily the tanks on our Westies are not that big and, while not under tremendous pressure, they are under enough to cause some real damage when they fail - I've only seen regulators and valves being blown out as a result of their insertion points in the tank deteriorating (threads), but have heard of the ends of under vehicle tanks being ripped open as the result of one or more pin-sized holes from rust.

When I bought the Hyena last year ('88 WBX), I had the tank pressure tested, and I tested all lines and fittings, before using it.

On 06-Oct-2015, at 11:45, Nick Feickert wrote:

> Ok. I've been reading a lot in the archives on options for the tank. My
> plan was to remove all the fittings, refinish the tank with POR-15 and
> fresh white paint, replace the regulator, shut off valve, and maybe the
> fill valve. Bleeder valve looks good as does the fill valve but I noticed
> that the rubber gasket in the inside end has a small gap in it. Anyway, I
> see the new tanks offered by GW, BD, Van Cafe all have the additional
> relief valve that the OEM tanks don't have. So let's get down to the brass
> tacks (pun intended). Is the only real issue here the cost of a new tank?
> Can a refurbished LP tank be just a good and complaint and a new one?(or
> at least be grandfathered in) Do you still have issues with stations not
> wanting to fill a NEW tank? I seems to me that the OEM tanks work just
> fine as long as all the components are in good working order....so let's
> hear from you!!! Do I refurbish or replace???
> 
> Peace,  Nick