I've seen recovery tank pressure as high as 450psi, running dual TR-21's with no after cooler, so recommend staying with something capable of those pressures in case something goes wrong, goes wrong, goes wrong...............
You will never get there with a sanitary spool, not because the wrapper isn't thick enough, but because of the deflection an the ends, which bow the lid up off the gasket.
Even if you had special spun hemispherical heads made for lids, the clamping system isn't strong enough for those pressures.
Our 50# refrigerant recovery tank is rated at 350 PSI, so burst is probably around 1000 psi.
It would be easy to manufacture the tanks using a welded wrapper and spun heads, but with it comes the liability of manufacturing a pressure vessel, so much insurance premium would be added to the cost, as would ASTME certification.
You would also have to solution anneal them afterwards to retain the corrosion properties in the weld zone, or use a low carbon grade of a higher chromium grade of stainless, adding more cost.
We aren't happy with water accumulating in the carbon steel tanks, so are looking for an already made stainless tank, which might be drawn into service.
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