Pipe rating evaluation in vacuum oven

[cames]

Hi,
At my job, We are trying to buy a vacuum oven (link at bottom), the issue is that since it doesn’t have name plate (its really old).
Without a nameplate, it becomes a safety issue since we don’t know what pressures we can safely operate at. The oven has shelfs with piping
that act as heat exchangers.

The water is pumped into the pipes through a pump in a closed loop, the water pressure coming into the pipes of the vaccuum oven would come in at 25psi

How would i evaluate the piping to know it can safely operate at 25psi?
Another option, could I install a pressure regulator to keep the incoming water below below 15 psi, so it doesn't have to be to follow ASME Section VIII, Div 1?

https://www.aaronequipment.com/usedequipment/dryers-drying-equipment/vacuum-shelf/51996008

 

[LittleInch]

Given that this operates at a negative pressure, I'm not at all certain that it classifies as a pressure vessel. If you add a PRV to relieve at say 5 or 10 psig for the main enclosure, then you should be good for any leakage of water inside the box without calling it a pressure vessel

The piping and shelfs etc look to me like simple piping so why not pressure test them in water to 1.5 x max working pressure? pump it up, inspect it and leave it for an hour in a temp controlled location and observe any pressure drop.

At that pressure you could go to 2 x 25 psi without any issue if you want to really prove the system.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[cames]

Thanks for the reply LittleInch

The vacuum negative pressure would operate at 12psi so it would fall outside of Pages from ASME Section VIII, Div 1 minimum pressure requirement of 15 psi, so i am good on that end.

was thinking also, what if i install a pressure regulating valve for the incoming well water and set it to below 15 also, would this make it fall outside of ASME Section VIII, Div 1 as well?

 

[Rputvin]

I'm used to working with vacuum furnaces. They have continuously circulating water in the jackets and lids, none of which are ASME vessels. A low pressure relief valve on the outlet (~5-15psig) ensure the water system doesn't pressurize those items, most of which are too thin to hold much more than 15psi regardless.

Some of the more open furnace manufacturers install pressure reducing valves on the inlet on the order of 15psig and run everything parallel, others will take 45psig at the inlet and flow through their power supplies and other passages that can handle pressure, and put their low-pressure non-code vessels at the tail end of their series chain of devices to reduce pressure in the vessels to below 15psig.

Since you need to operate at low pressure in your 'vessel' you need to be careful about how the water system incorporates this into the loop. Backpressure needs to be as close to 0psig as possible in order to allow other aspects of the system to float in the 0-15psig range without popping your relief.