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Axial Nozzle offset in elliptical heads

Axial Nozzle offset in elliptical heads

Axial Nozzle offset in elliptical heads

(OP)
My question is related to axial nozzle offsets in elliptical heads for heat exchangers. A senior engineer at work told me you cannot offset a nozzle by more that 80% of the shell diameter.  Anyone heard of a similar rule. I would like to read/learn more about it.

Thanks in advance.

RE: Axial Nozzle offset in elliptical heads

Per UG-37 when and opening and its reinforcement in an ellipsoidal head are located within a circle that is 80% of shell diameter, the thickness to compensate is not the minimum thickness of the head, but the thickness of a sphere with a radius specified by code: this results in less reinforcement required.
There is however no prohibition of putting the opening outside that circle.

prex

http://www.xcalcs.com
Online tools for structural design

RE: Axial Nozzle offset in elliptical heads

No prohibition for putting nozzles outside the 80% limit as noted above.  Maybe a company's particular specification however.  I'd find out which from the so-called "senior" engineer.

Brian

RE: Axial Nozzle offset in elliptical heads

This is a requirement in the British Pressure Vessel Code - PD5500 and is normal practise in Europe and amongst most major clients.

RE: Axial Nozzle offset in elliptical heads

I am sorry... I do not understand

What, exactly, is meant by an "axial nozzle offset" ?

How do you measure or dimension this ?

  

RE: Axial Nozzle offset in elliptical heads

prex, my interpretation has been that there are no specific requirements in the Code when the nozzle and its reinforcement fall outside the 80% limit, i.e. is is a U-2 (g) design, therefore I tend to avoid placing nozzles out there.

It is your practice to use the minimum head thickness per UG-32(d) in your reinforcement calculations, rather than the thickness of a sphere as per UG-37? Nobody kicks about it?

Anybody else use this technique? It would be very useful.

Thanks in advance.

MJCronin, it is a nozzle with its axis aligned with the vessel long axis and parallel to it, off centerline.

Regards,

Mike

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