6. Summary

The chapter delves into the stress analysis and failure modes of ellipsoidal heads, highlighting their superior stress distribution and ease of fabrication. It covers the design and fabrication methods outlined in various pressure vessel codes and standards, including ASME VIII-1 and VIII-2. Notably, the chapter presents an in-depth investigation into buckling and plastic collapse through experiments and nonlinear finite element methods, providing new formulas for predicting these failure modes. Additionally, it discusses the control of fabrication quality, including shape deviation, forming strain, and forming temperature, offering innovative methods for evaluating and enhancing the quality of ellipsoidal heads. The chapter concludes with a new failure mechanism-based design method that addresses the limitations of current design rules, providing a more accurate and economical approach.