Multiple Opening Reinforcement Help

[HPM3]

Hello,

I have two nozzle openings in a torispherical head. Both 3.94" ID, centers spaced 6.5" apart. If I consider these openings individually, there is adequate strength in the shell, nozzle & welds, that no additional reinforcement is required. I think I understand the rules of UG-42a regarding these openings if I was using an actual re-pad, but I'm not clear on what to do when there's already enough strength in the nozzle, shell & welds. The "limits of reinforcement" of these openings overlap but since there is no repad or additional reinforcing element for the individual openings, does it matter? If the combined reinforcement areas in the shell, nozzle & weld, for both fittings is greater than the sum of the areas required for each opening - am I good to go with no additional reinforcement?

Thanks for your help.

HPM

 

[SnTMan]

HPM3, first, the fact that you have no reinforcement pad makes no difference as to application of UG-42. Reinforcement is a term applied to any excess thickness not required for pressure and other loadings.

A simple way to interpret UG-42(a) is that it requires the limits of reinforcement to be restriced to half of the distance between nozzle centerlines, for equal diameter nozzles. In your case, the limits of reinforcement for each nozzle would be 6.5 inch diameter, or 6.5 / 2 = 3.25 inch each side of the opening centerline. If the limits permitted by UG-41 are applied, these limits overlap and the common area is counted for each opening, which UG-42(a) does not permit.

Most software will allow restriction of the limits of reinforcement.

Any added reinforcing element, such as a pad is subject to the same limits of reinforcement, i.e., any material outside the limits may not be considered as contributing.

Regards,

Mike