High pressure vessel

[dMemphys]

Hello!

I'm currently working on the design of a relatively high pressure vessel: a 20cm-inside-diameter and 45-inside-height vessel containing 1000bar oxygen.

My goal, here, is to make my own idea of the beast first and to evaluate grossly its cost. Fully detailed design would be contracted afterwards to real professionals.

I was wondering if anyone could advise me on books or other ressources that would help me in my task. I was able, with the help of ASME BVPC Sec8 Div3 and a few other ressources, to dimension the cylindrical vessel, but it seems to me that vessels with a diameter ratio greater than 1.5 are rather rarely mentionned in the litterature. I really have some trouble with the design I should give to the cover and how I should take into account openings due to instrumentation inserts and windows.

So far, I'm looking at 20cm-inside-diameter and 60cm-outside-diameter (Diam ratio of 3) in Inconnel 718 (for the oxygen) which gives me, according to ASME, a rupture pressure of 8000bars (8-to-1 security factor).

Anyway, thank you for your time,

Denis Maloir

 

[ash9144]

Why not contact an industrial gas supplier and get a cylinder of oxygen?

 

[gr2vessels]

Dennis,
You don't have to invent new safety rules, just apply them as required by the code. So far you apply exaggerated safety margins and materials. All this is reflected on an exaggerated wall thickness and costs. Please note that the ASME code allowable stress include a reasonable safety margin and you don't need to double, triple that. There is no simple few page guide how to design safe pressure vessels. Just remember that the the quoting in pressure vessels can be done only by highly experienced people in dasign, manufacture and delivery of this type of equipment. Otherwise it could be a very costly exercise for you and your company. Contact someone experienced in quoting something like that. Either confess you know very little of the topic and ask for their help or ask a full quote for the equipment and pretend is yours. You might fail after the first few questions about the quote, but that's the risk of pretending.
Cheers,
gr2vessels

 

[dMemphys]

Hello gr2vessels,

You raise a valid point but you're mistaken about my intentions.

My goal is simply to have a way to have a gross idea of the dimensions of the autoclave. We intend to monitor reaction rates at high pressures and wanted to port a low pressure version of this device to a high pressure version. I was thus looking for some rules of thumb as to the impact that the operating pressure, along with our instrument inserts would have on the dimensions of the system. This is merely to have a better idea of what we will be talking about when confronting our needs to the contractor. I actually have this weird habit of documenting myself as much as possible before asking for quotes, especially in areas I know little about. It has a tendency of sparing me huge amounts of time lost in unnecessary calls, reunions and revisions of designs.

That being said, I was merely applying the KD-221 'Cylindrical Monobloc Shells under internal pressure' formula (Design pressure = 2/3 (Sy) ln(Y)) and I was told that a common practice was to work at 1/8th of the max allowable pressure, hence the huge thickness. Am I mistaken here?

Thank you for your time!

 

[TGS4]

dMemphys - I'm not sure where you heard to use 1/8th the MAP. It's just not true. As has been pointed out, the design Codes have design margins deemed sufficient by over 100 years of experience and hundreds of thousands of man-years of experience and expertise. You are certainly free to go further, but these design margins have been shown to be sufficient in and of themselves.

If you are just doing a rough sizing estimate, follow the Code to the letter.

 

[ricklts]

Denis,

You may want to contact a supplier of autoclaves or one of the specialty connection manufacturers, and let them give you a preliminary sizing estimate for your vessel. This is a (and excuse me but I can't think in metric sizings/pressures) basically a smaller vessel 8" nominal ID x 18" ID Length x 15,000 psig vessel. You did not mention temperature or the reason for selecting Inconel 718, but if another alloy is acceptable, it may be smaller or less expensive.

Rick