Relationships Between the Proportional Law and the Charts Used in ASME VIII-1 and EN13445-3 for Designing Shells and Tubes Under External Pressure

Shells and tubes usually fail in the form of buckling under external pressure. Charts are used in the design of shells and tubes in the standards of ASME VIII-1 and EN13445-3 and these simplify the calculation process, while the proportional law is a more effective and simple method. In this paper, the relationships between the proportional law and the charts used in the standards were researched; finite element method (FEM) was used to compare the accuracies of the proportional law and the charts. It was theoretically proved that the proportional law and the charts were using essentially the same method to calculate the critical buckling pressure; they were different forms of the same dimensionless tension stress–strain curves. The simulation results showed that the proportional law and the charts had effectively equal accuracies in calculated critical buckling pressures. Therefore, the proportional law can be a candidate method included in the standards for the design of shells and tubes under external pressure.