A vacuum fractionating tower containing removable trays and having insiue diameter of 10ft and tangent length (L) of 18ft is required for design. The tower is to operate under full vacuum and 8000F conditions. The material of construction is plain carbon steel available in four (4) different shell plate thicknesses of 0.625,0.5,0.325 and 0.250 inches. Showing your calculations clearly, and evaluate the minimum shell plate thickness for designing the tower without using circumferential stiffeners at tray positions [10 marks]