I think what Stressguy81 mentioned is WRC 107, and Ricahrd answer for that is for WRC 297, so it is clear now that the intrepretation for CAESAR II help facilty Quote above is for WRC 107 we can considered the vertical vessel as spherical as in Case 1 that stressguy81 give and as in WRC 107, so that the cosie directional can be orthogonal, but for WRC 297 i think it can't be applied since it only for Cylinder-cylinder intersections, so for this case there is to option:
1. Considered itas spherical and do the WRC 107 analysis in CAESAR II.
2. Or you can use FE Pipe to get the flexibility and input it back to CAESAR II.
Thanks.