ASME VIII, Div 2 Part 5 Design By Analysis Method

[engpes]

I have an oblong nozzle with complex geometry. It will require an ASME VIII, Div 2 Part 5 FEA analysis. For construction reasons, a repad will be more practical for the application.

My question is as follows:

1.) Can stresses be linearized through the vessel wall and repad combined in order to categorize them?
2.) Should the stresses be linearized through the shell and repad independently? (not sure how this would work)

The repad would be about 4 inches wide and 1/2" thick. It would be welded to the nozzle neck via bevel weld and fillet welded around the perimeter.

Thank you in advance.

 

[TGS4]

Make sure that your r/t ratios fit within the limits of applicability of an elastic analysis (see 5.2.1.3). Otherwise, I would choose option 1).

The linearization may be simple, but categorization for an oblong nozzle may be more difficult. I would follow the advice of 5.2.1.2 and apply the elastic-plastic analysis method for demonstrating Protection Against Plastic Collapse. And don't forget about the other failure modes, too: Local Failure, Buckling, and Ratcheting (and Fatigue if in cyclic service).

 

[engpes]

Yes it does meet the r/t ratio requirement for elastic analysis and yes I am checking all of the failure methods.