A finite element stress analysis of an internal head with externally loaded pipe clips was performed using a 3D model, and taking advantage of quarter symmetry.

Mechanical loads used in the structural analysis included:

Weight + dead load
Bending moment and shear load due to wind
Platform clip loads
Various combinations of internal pressure/vacuum in the upper and lower chambers

Each case was simulated individually, and compared to ASME Code allowable stress values, using the methodology of ASME Section VIII, Division 2 Mandatory Appendix 4. Stress intensity for one of the load cases is shown below.