Analysis and Design of Ellipsoidal Pressure Vessel Heads

The paper describes the development of design rules for 2:1 Ellipsoidal Heads. Elastic, elasto-plastic, and limit analysis results are evaluated to determine the lowest failure mode, including buckling under internal pressure. The numerical values of the failure pressure are compared with ASME Code requirements. It is shown that the code rules are overly conservative for thick heads and are unsafe for very thin heads used in low-pressure applications. A simple design formula is developed, based on rational safety factors, in a form adaptable for a pressure vessel code. The need for further work toward improved failure mode analysis is discussed.