A vessel is to be designed to withstand an internal pressure of 10 MPag (1450 psig) at 250°C. The tangentto-tangent length (z) of the vessel is 15 m, and the inside diameter (D_i) is 1.52 m. The vessel is designed to have 2:1 elliptical heads and will be made of grade 316 stainless steel. Estimate the thickness of the shell and heads and the mass of the vessel. Use a corrosion allowance of 3.175 mm (1/8-in) and a joint efficiency of 0.85.