Why control the roundness of the shell?

What if there is no requirement for the butt joint between that cylinder and the head or another section of the cylinder? Moreover, the amount of misalignment cannot exceed the allowed limits.

First, internal pressure needs to be controlled, as the calculation formulas are derived based on the diameter formula and the model is cylindrical in shape; this is also done to reduce edge misalignment and stress concentration. Second, external pressure even more needs to be controlled, because the calculation formulas require higher precision when dealing with non-circular shapes. If you look at the specific derivation process, it will become clear!

The pressure test pressure for containers designed according to GB150 is not sufficient to cause the containers to undergo overall plastic deformation; therefore, applying pressure is ineffective. Furthermore, if no control is exercised, how can the misalignment amount of Class B welds be ensured?

In addition to model calculations and the amount of misalignment, another factor in controlling the roundness of the shell is the need to control the geometric dimensions after the assembly of the internal and external components. If the roundness of the shell is not controlled, the pressure applied to the container as it becomes round after the assembly of these components will result in very high local stresses.

1. As required by the design, the calculation of the cylinder’s thickness should first be carried out in accordance with the methods used by Zhongjing Company; if the cylinder is elliptical, the thickness calculated in this way will actually be insufficient； 2. Requirements for cylinder welding: Generally, cylinders need to be joined end-to-end, or they may be equipped with end caps. If the cylinder is not circular, it will cause problems with joining them together ； 3. Due to manufacturing requirements, some containers are equipped with process nozzles, welding gaskets, and the like. If the roundness of the cylinder is out of spec, it can cause the nozzles to be misaligned, preventing the gaskets from fitting properly against the cylinder, among other subsequent problems ； At the same time, for equipment with internal components, such as heat exchangers, it can also lead to difficulties in installing the baffle assemblies ；

1. As required by the design, the calculation of the cylinder’s thickness should first be carried out in accordance with the methods used by Zhongjing Company; if the cylinder is elliptical, the thickness calculated in this way will actually be insufficient； 2. Requirements for cylinder welding: Generally, cylinders need to be joined end-to-end, or they may be equipped with end caps. If the cylinder is not circular, it will cause problems with joining them together ； 3. Due to manufacturing requirements, some containers are equipped with process nozzles, welding gaskets, and the like. If the roundness of the cylinder is out of spec, it can cause the nozzles to be misaligned, preventing the gaskets from fitting properly against the cylinder, among other subsequent problems ； At the same time, for equipment with internal components, such as heat exchangers, it can also lead to difficulties in installing the baffle assemblies ；

If the ellipticity of the internal pressure is not controlled, it not only prevents connection with the head but also affects the stress distribution. As for external pressure, the ellipticity should be controlled even more, since the safety factor of containers under external pressure is highly dependent on ellipticity.