Upcycling well pressure tank?

I recently had to replace a quite large (approx 80 gallon) well pressure tank due to leaky bladder.  (Which, at my age, I probably shouldn't make fun of. ;) )

Anyway, I'm wondering what things I could do with the old one now? It seems a waste to just haul it off for scrap.

It's large, thick steel, so my first thought is if I could figure out how to do a hydrostatic test I could convert it into an air tank?
Or chop it in half for animal feed/water trough?
Or somehow make a stand and use it as a water tower for when the power goes out?
Or, maybe a storage tank for farm fuel?
Other ideas?

Also, that last one brings up another question.  What to do (if anything) about the old rubber bladder inside?  Do you think I should toss some sticks in there and try to burn it out?  Just leave it?  ...?

Good question. The proof pressure should be known from the manufacturer, and would be the same for air as for water. My pressure tanks are thinner than my compressor tank, so I bet there is a fair difference in the proof pressure, but 90psig should be fine (common enough in municipal water systems and air tools). I would not burn it, that would change the temper of the steel and void expectation of pressure performance. If the bladder leaks, let it leak, it won't hurt an air accumulator tank if you use it for that (might even sing to you through its rubbery lips :-)). If you have a small shop compressor, parallelling it into the output air might be handy. But do check the proof pressure, and keep the compressor cutoff below it...

Other than that, a tank is a tank, except when it's upside down. You do any biodiesel or chem reactor stuff?

Best,
Mark

Cut off one end and use it as the barrel on a RMH?

I've seen people use old tanks to make cement mixers. It would be basically the same thing to make a mixer for cob, or a sand muller for metal casting. I have a vague memory of someone making one with some sort of 'plow' and cannonball(s) to churn and mash green sand. There are lots of videos online of various designs.

How about a "pre-heating" tank for your regular hot water tank? Use solar power to heat it?

If the bladder is flexible & will come out, you could maybe use it as a small pond liner.

I would never toss a pressure tank -- what a great resource! Rainwater tank, rocket stove, livestock troughs, etc. etc.

But before you get out the angle grinder ... Just because the air bladder has failed doesn't mean it is useless as a pressure tank. My previous property had an old but large pressure tank that never had an air bladder at all. Every year I would drain the tank, hit it with compressed air and pressurize it to about 30 psi. This reset the air "spring" at the top of the tank and it was good for another year. The only drawback is that the water turbulence slowly entrains the air and pulls it out of the tank; hence the need for an annual refresh.