Nozzle Design on Flat-Sided Vessels

[jmb39]

I'm looking for a method to determine the allowable external forces & moments for nozzles on flat-sided vessels analogous to the methos for cylindrical vessels in the Pressure Vessel Handbook (Megyesy) [13th Ed., pp 153-158].

I considered using the Megyesy cylinder method, driving the vessel diameter to infinity to simulate the flatness, but I thought that there might be a simpler, and more reliable approach.

 

[vesselguy]

Yes, there is a more reliable method and it is called FEA if you really want to know the numbers.

No, there is no closed form plug-in the number formula to do what you want to do and that's why FEA is really the only choice for this case.

If you have a flat sided vessel, then I highly doubt you have a pressure vessel. More like you have a bin, which is an atmospheric tank. If so, then you can just put some reinformcent gussets on the nozzle to stiffen up the joint if you really have to since this is no longer a Code equipment. I had done that a few times on rectangular bins which were used a lot in mining and copper refining and it works fine.

 

[jmb39]

My main concern is being able to help my customer tell his piping engineer what the allowables are for the nozzles. Normally, our policy is to say "zero" allowable loads on our nozzles - the piping must be fully supported with flex connections to prevent loading on our nozzles. Unfortunately, "zero" throws a wrench in my customer's piping design program, so I'm forced to provide some number with which to work.

This is a internally reinforced & externally stiffened horizontally oriented process equipment with a decidedly net exteral pressure.

Thanks for the insight, though. Any more thoughts?

 

[vesselguy]

Yes, I know what you have to do. I've been there and done that so many times. On the EPC side, we just want the fabricator to dream up some allowable loads to offload to the piping guy so we can get him off our back. But, realistically, an experienced vessel engineer knows the fabricator can not give him "max allowable nozzle loads" due some obvious reasons, especially for a nozzle on a flat plate. Just explain to him the reality, or you can dream up some number using Roake and Young handbook's formulas for a circular plug on a flat plate. Anyone who is really serious about checking nozzle load on an equipment would ask the fabricator's engineer to provide the flexibility and give that to his piping engineer to use in Ceasear and then give the resulting loads to the fabricator to check. Allowable nozzle load is just load of cr&$ to fill standards (sadly I have to that soon).