Sec. VIII Div. 2, Part 5.4 Buckling

[LS_SMS]

Folks, I am looking at 2023 ASME Sec. VIII, Div. 2, Part 5.4.2 for the Method A Buckling Analysis. I plan to use the ANSYS eigenvalue buckling solver to perform the work. Here are some excerpts from the code...

This method is intended for use on independent individual components (e.g., heads, cylinders, and cones) assessed in isolation.

Separate eigenvalues shall be extracted for each component in the assembly, λ_component,k.

If assessing multiple components simultaneously in one assembly, each component’s loads shall be multiplied by its dominating eigenvalue, β_{b component,k} = λ_component,k.

I see a common theme about "assessing individual components." If I have a simple pressure vessel, one cylinder with two hemispherical heads, how do I assess all three of those components in isolation? I'm confused on how one would do this in FEA software. In FEA, I would normally model all three together so that the load path through the structure was accurately captured. And if the vessel has nozzles and appurtenances, it seems like this procedure could get pretty agonizing with a slew of separate components. I'm curious to hear some feedback.