Problem 2: The spherical gas tank is fabricated by bolting together two hemispherical thin shells. If the 8-m (inner diameter) tank is to be designed to withstand a pressure of 2 MPa, determine the minimum wall thickness of the tank and the minimum number of 25-mm diameter bolts that must be used to seal it. The tank and the bolts are made from material having an allowable normal stress of 150 MPa and 250 MPa, respectively. (Answers t = 26.7 mm and n = 820 bolts).