I'm using pvelite for a quick analysis of a steam circuit, made by two collector pipes connected together by an array of vertical pipes.
I'm modeling half circuit because it is symmetric; I'm using a shell component for the collector, nozzle components for the array of vertical interconnecting pipes.
I'd like to check what happens to the collectors thickness if I increase the design pressure.

PvElite output is warning me about the interference between the nozzle components that model the array.
I would like to override this warning, because according to UG-53 I have imposed a user defined joint efficiency to take into account the weakness caused by the array on the distributor shell.

So, here are my questions:
1) first of all, do you see any mistake in my approach (imposing the joint efficiency as per UG-53, modeling the vertical pipes as nozzle components, etc..)
2) can UG-53 be included in the analysis, or can the output refer to UG-53 to justify the nozzle interference warning?

I hope everything is (more or less) clear.
Thank you

Federico

One more question.
If I insert a user defined Joint Efficiency, pvelite is warning me that J.E. is out of range (I have to set it to 0.41).
Don't you think that it should be useful to let the user input a low joint efficency (even lower than the minimum listed in UW-12), in order to allow the check of UG-53 requirements?

At the moment I'm considering 0.45 to run the analysis, and MAWP is definitely higher than the disegn pressure, so I'm confident that for my application the design is suitable.
But it would be nice to have the possibility to run these analyses without any workaround.

Hello Federico

If I understand you correctly, you basically have a header with a lot of closely positioned branch pipes. Strictly speaking, this is a piping system and ASME Section VIII, Division 1 is perhaps not the best tool for performing the analysis. However, ASME treats nozzles and ligament efficiencies (UG-53) completely separately. If the nozzles are fully reinforced, that should cater for the stresses in the branch.

If you choose to apply a ligament efficiency, I feel that is a good conservative approach. I would like to know if any other members of the forum have any thoughts on the matter.

There is no harm and you are not violating the rules of the code by lowering the joint efficiency.

Yes, that's the problem I'm analysing.
I basically have chosen ASME because this heating system will be inserted in a (not stamped) ASME vessel.
I also wanted to perform a quick check and, why not, to understand how to implement UG-53 in pvelite models.

I think if you are analyzing nozzles and applying UG-53 then you may be double dipping.

The nozzle spacing criterion and the reinforcement check is trying to account for weakness in the shell due to nozzle.

In my opinion you should do one or the other.