Threaded Closure Design of High Pressure Vessel

'75,000 psi . . . no experience' stay away, stay far away.

...[Inference: no design standards available either] and make sure other CR4 readers stay away too.

thank you for advice,

actually, this amount of pressure is normal in High pressure food processing, we usually apply between 200-700MPa (30,000~100,000 Psi) for some processes. so we need high pressure vessels to contain such pressure.

If you really have no choice but to design it, get a custom design from the manufacturer that currently sells the ones used in you factory, that if a threaded design is feasible; ask them.

Yes, there are some companies manufacturing the same kind of vessels with threaded closures. It is feasible. Check the following site:

https://www.highpressure.com/products/reactors-pressure-vessels/series-r-reactors-o-ring-closure/
You can help me to contact them.

Thank you

Trying to design something like this without experience is playing with fire.

Please rethink this. Too many people have been injured and/or killed doing something like this.

If you have to get yourself involved in this work, consider the Autoclave HP fittings which are suitable up to 100,000psi.

But I'd strongly suggest if you're not familiar with designing this sort of equipment at these pressures that you employ someone else who is.

Thank you, it was helpful

Caution is certainly required, but I understand that sometimes one has to design at the edge of one's knowledge. You should not need advice on the basic calculations for stress calculations - if you do, then stop immediately, and employ some one who does.

This wouldn't be a school assignment would it !

If you do have a general professional understanding of the design issues involved, then you'll need to get a better understanding of the more subtle aspects, including safety related ones, by talking to a manufacturer of similar equipment, by carefully reverse engineering the work of others and by interpretation as required from a pressure vessels code. FE analysis would also be useful.

I gather your work will involved high pressures with "water", rather than with "gas" so the safety issues are not so severe and slightly lower safety factors may be considered for this reason. The basic calculations are quite simple, but the proper assessment of safety factors and metallurgical issues might not be.

I'd also be including calculations that showed how big the impact (pun intended) of vessel failure might be, and physical stress testing post manufacture if the item was to be used near personnel.

I agree, basic calculations are quite simple but safety should be first. I will consider that.

I suppose just to complete those basic calculations and give it to an expert local manufacturer. I've done most of the work but the closure is the issue now.

closure diameter, no. of threads, cross sectional area and the force acting on the closure.

I found number of manufacturer of vessels with such closure, but no calculations or design guide, just products for sale:

http://www.highpressure.com/products/reactors-pressure-vessels/series-r-reactors-o-ring-closure/

I hope you can help me on that

Interrupted screw.

The pressure you quote is around 5000 bars water pressure. You mention a 4" internal diamter. while you say that this is "normal" within the food industry, it nevertheless falls within the area of (high) pressure vessels. There are laws governing the design, construction, inspection & operation of presssure vessels. Do note that it would be illegal for someone to design such a vessel without the necessary qualifications and certification in Pressure Vessels. It is extremely dangerous to say the least. I have worked with water pressure of 300 bars and with gas pressure of 25 bars (small reactors).

Before you proceed with anything, check whether you are not breaking the law. The 4" is quite large. This certainly falls within the range of pressure vessels and the appropriate laws come into play here.

I once worked with a reactor of 6 mm I.D. (around 1/4") and this was to attain pressure of 25 bars. This was only a lab scale device. We found it very difficult to even achieve a sealed pressure of 25 bars with our limited machining resources. If you are not a mechanical engineer and Pr. Eng. as well as certification in Pressure Vessel Design & Inspection, you would be breaking the law by attemnpting this design task.

If you had obtained the said unit from a supplier, then you should not be fiddling with the equipment without their professional input.

Extremely Dangerous ! Advice : Stay away from it !

I didn't know this information, I've no intention to break any lows. In fact, my work is just to complete a basic calculations and equations and main shape dimensions and give it to local manufacturer who are expert in pressure vessel design and inspection.

I just want to perfect my side of work

Just remember ignorance of a law is no excuse when it comes to breaking it. There are numerous laws that have to do with construction and with fabrication. These may vary from country to country. But you will find that those relating to pressure vessels usually follow codes that refer to ASME, etc.

Organizations will usually screen technical staff for the certifications, proffessional bodies required for specific jobs. Coded Welders are required in fabrication of pressure vessels. The inspectors of these also require special papers. The designers (usually mechanical engineers) will require certification for pressure vessel design. This is much like a drivers license for differnt levels of vehicles.

If it is that you do manage to work out the rough dimensions of the pressure vessel, what would you do with these figures? And there are formulae available. The sizes have little value on their own. Do note that the Pr. Eng., the certifications etc, apply even more so to structural engineers. They generally have to sign off designs for manufacture or fabrication. To do this they need papers over and above the relevant degree certificate.

Do also note that a pressure vessel goes together with a whole range of complex, well thought out system of piping and instrumentation. This itself requires another detailed process analysis - methods such as Hazop Study, Fault Tree analysis are used to scrutinize the (process) design on paper. For this you will need a team of engineering people : process, control and mechanical engineering.

Your best bet would be to contact suppliers of the particular food industry device you are looking at. Your supervisor should not be assigning you tasks that you are ill-qualified to carry out.

What type of food industry device requires such an astronomical pressure anyway?

ASME section VIII for the design of pressure vessels

ASME section II ferrous materials for pressure vessels

http://www.google.com/url?sa=t&rct=j&q=asme%20section%20viii&source=web&cd=1&ved=0CEkQFjAA&url=https%3A%2F%2Fwww.asme.org%2Fproducts%2Fbooks%2Fguidebook-for-the-design-of-asme-section-viii-pres&ei=_wjcUeHMCvir4AOcqID4Cw&usg=AFQjCNFgybFdA-hhgYKZnvaL5IgzP2XpFw

Follow the rules, do the work and you probably won't kill anyone. ASME boiler and pressure vessel codes provide all of the information required to produce a minimally acceptable design. Experience and the latest current knowledge can produce a superior design.

Actually, designing a small vessel for 75,000 psi is not that difficult. Making it structurally sound is very possible. I've done designs that were 60 ksi rated with 90 ksi proof pressures, but I had total control over form and function. The really tricky part becomes the part you call "threaded enclosure", this can be very problematic depending on what you mean by threaded enclosure. If threads or fasteners are holding this device together, deflections are critical. That said; the really tough part of this is sealing it.

A water leak at 75,000 psi (or 112,500 psi proof pressure) will cut like a knife through anything it hits, including fingers, arms, legs, etc. This is truly the dangerous part. As others have said, if you've never done this, find someone who has. I could design this, but I won't as there are far too many unknowns here and I'm not willing to coach someone through it. You have one chance, get professional help. I'd search online looking for ASME coded fabricators and start asking questions. They may not want to do this either, but they may know who will.

Trust me, you do not want to hurt someone with this.

Good Luck.

You are above some of the latest waterjet cutting equipment pressures but the threaded devices they use for high pressure lines may answer the question re threaded connections. With these pressures I would not get involved under most or any circumstances. Also the lines are quite small about 6 MM OD and the wall thickness is very thick. Anything over a garden hose pressure 65 PSI can be dangerous if used incorrectly.

The basic principles of the Occupational Safety and Health Administration (OSHA) 29CFR1910, Process Safety Management (PSM) 29CFR1910.119 are very good guidelines for an endeavor such as this. Although they may not be directly applicable they should be reviewed to provide a good source of the methodology for designing, start-up and operation of this type of project.

One of the most important parts of them is there philosophy of, if it is or could be a risk: 1) change the procedure to a safer one; 2) change the equipment/process/procedure to eliminate the problem (engineer it out); and 3) If you can't make it absolutely safe don't do it!

All it takes is a hole at 0.0000133 in² (that's 13 millionth of an square inch) to lift a one pound weight off it! If someone makes a miscalculation or fabrication error, even in the lower pressures of pressure testing this is akin to a small atomic bomb! This makes a Claymore Mine seem like a nothing!

Get some experienced and extremely knowledgeable help before you even get to the "thinking about" stage.

Good Luck, Old Salt