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ASME VIII-1 Nozzle Spacing Clash

Sajjad2164

Sajjad2164

Mechanical
Joined
Dec 22, 2015
Messages
56
Location
CA
I'm designing a vertical distribution tank under ASME Section VIII, Division 1, and encountered UG-42 clashes in PV Elite due to tightly spaced outlet nozzles (see attached image).

PV Elite flags several “Diameter Limit Clashes”, where the centerline distance between nozzles (e.g., N7 & N8 ~546 mm) is less than the sum of reinforcement limit radii (~602 mm).

I'm exploring:
  • Applying UG-42(c) using an assumed large opening
  • Justifying via Appendix 1-7 or elastic FEA
Has anyone resolved similar multi-nozzle spacing issues while staying within Division 1? Would appreciate insights or best practices.
2025-06-03_16-58-36.png
 
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I would not be using individual reinforcing plates on each nozzle. I would use a thickened insert (try 2 times tshell) or perhaps a full thickened ring though I'm not sure where the large nozzle on the far side is.

I have never used PV Elite so I don't know how to specify an insert like this or if this will remove the warning message. If it doesn't you should be able to provide hand calculations that show the UG-42 rules are followed.
 
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Just ignore the warning from PV Elite. We dealt with close nozzle spacing almost in every project, with only 2"-3" gap between flanges. You can use thicker re-pad (not thicker than 1.5 x shell thickness and 2" minimum width, our own practice), or thicker nozzle, local thicker shell, integral reinforcement, etc., too many ways as long as area reinforcement met and keep weld toes of re-pads from fouling (every engineering firm has their own guideline how far away)
 
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You can't just ignore the warning....UG-42 is there for a reason.
 
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I haven't run PVE in a loooong time but I believe the user could enter a limit value for reinforcement. In this case the max limit would be equal to the nozzle C-C distance.

As to reinforcing itself I would not pad each nozzle. Too much :)

Regards

Mike
 
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You can modify the limits of reinforcement in PVElite.

1748998743755.png

However, if you have that kind of spacing, you'll still have to consider multiple openings and overlapping local stress due to piping external loads if applicable. You can increase the thickness of the shell course where the nozzle is located rather than applying individual reinforcing plates.
 
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See UG-42: you have to limit the diameter of reinforcement of each clashing nozzle and the software will re-calculate the area required for nozzles reinforcement acc. to UG-37.
 
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