What are the stability and critical pressure of externally pressurized vessels? Are there stability issues with pressure vessels?

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What are the stability and critical pressure of externally pressurized vessels? Are there stability issues with pressure vessels? For a shell subjected to external pressure loads, when these loads increase to a certain level, the shell suddenly loses its original shape or develops wrinkles; once the load is removed, the shell cannot return to its original state. This phenomenon is known as buckling or instability of a shell under external pressure. Essentially, the internal wall stress shifts suddenly from a pure compressive stress state before instability to a primarily bending stress state at the time of instability. The minimum external pressure at which a container loses stability is called the critical pressure pr; the higher this value, the greater the container’s resistance to instability. For thin-walled containers, as long as there is compressive stress within the wall, stability can be achieved first. Stability issues are not limited to vessels under external pressure; vessels under internal pressure can also have stability problems sometimes. For example, vertical pressure vessels subjected to axial compressive stresses due to weight loads and wind moments, pressure heads with localized compressive stresses, as well as the saddles of horizontal pressure vessels, all present stability issues.