Nozzle offsets

[mizzoueng]

So I am a winnozl user (only program we have) and I have a tangential nozzle on a 64" ID vessel. Winnozl says that I cannot do this according to WRC 107 as Rm/2=16.08" and my center to center distance is 30.08".

But somehow the manufacturer (who uses compress) says its okay per WRC 107 when using compress. I don't have a copy of WRC 107 in front of me now, but I don't understand how COMPRESS reads the bulletin differently.

Has anyone ever ran into this before?

 

[TomBarsh]

For a given shell diameter, the stresses in the shell per WRC-107 will be function of the size of the "footprint" the attachment makes on the shell. Given the same shell and same loads, a smaller footprint will produce higher stresses in the shell, and vice versa.

WRC-107 does not provide rules for "obround", etc, footprints produced by a non-radial nozzle, such as the tangential nozzle you describe. Consequently, the WRC-107 analysis is not applicable to this type of nozzle but might be used to obtain a coarse idea of an upper bound for the stresses.

For non-radial nozzles COMPRESS conservatively uses the nozzle diameter as the characteristic dimension in the WRC-107 analysis, rather than the longer chord formed by the nozzle opening. But from that point onward, the analysis follows WRC-107 method, including the limitations on geometric parameters.

COMPRESS provides a finite element analysis of nozzles as a standard feature. I suggest that you ask your vendor to perform this analysis in lieu of the WRC-107 analysis for this nozzle.





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