What are the differences in the failure modes of internal pressure cylinders and external pressure cylinders? In which parts of pressure vessels can stability problems occur? Why?

Brick-throwing, stress applied, failure modes, duration of failure, shape of failure; external pressure vessels, compressive stress, instability failure, sudden occurrence, over a certain time period; flattening; internal pressure vessels, tensile stress, strength failure, gradual degradation over time, yielding deformation or fracture. In multi-chamber vessels, when the pressure difference between adjacent chambers is too large, the chamber walls are prone to instability failure.

What was said upstairs is very detailed; there’s nothing to add

This post was last edited by SDHZZXM on 2016-1-21 at 10:53. In ellipsoidal heads subjected to internal pressure, circumferential compressive stresses occur at the bottom edge of the head due to the rounding effect, which may lead to circumferential instability of the head.

Internal pressure instability also occurs at the large and small ends of the conical shell.

1. Differences in failure modes of pressure vessels under internal and external pressures: Internal pressure often leads to failures related to strength and toughness, while external pressure usually results in circumferential instability. However, thick-walled cylinders can also experience strength failure under external pressure. 2. Local instability can occur in pressure vessels due to the supports (saddles, lugs, legs, skirts, etc.), at the corners of elliptical heads, and at the junctions where convex heads meet the shell. However, this instability is different from the instability of the shell under external pressure; it is not a circumferential instability, but rather a flattening caused by insufficient local stiffness. Furthermore, it should be noted in particular that under internal pressure, the shell is prone to circumferential instability at the junction where the large end of the conical head meets the shell ； At the junction of the small end with the housing, circumferential instability is likely to occur at the small end. This is why the connection between the large and small ends of a conical shell under internal pressure requires reinforced design. For a detailed analysis of the principle, refer to the reinforcement principle at the junction between the tank roof and the tank wall in vaulted or conical top tanks. The above has no source; it is merely personal understanding. Different opinions are welcome, and discussions are encouraged.