spherical tank

The circumferential stress, also known as tangential stress, in a tank or pipe can be determined by applying the concept of fluid pressure against curved surfaces. The wall of a tank or pipe carrying fluid under pressure is subjected to tensile forces across its longitudinal and transverse sections.
 

Problem 134
The wall thickness of a 4-ft-diameter spherical tank is 5/16 inch. Calculate the allowable internal pressure if the stress is limited to 8000 psi.