The example below shows how little is needed for the loads on the nozzles to be exceeded. The installation temperature is 15C, and the design temperature is 30C. Code B31.3. With such a small temperature difference, which caused thermal elongation of only 1 mm, if the nozzles of two tanks were connected rigidly with a straight DN 100 pipe without any self-compensation, the forces and moments on these nozzles would be exceeded by about 150%.
From this case, it is recommended to never connect to the nozzles with a straight section that is supported on one side by another nozzle or a fixed point. The sketch below shows just such a connection between the nozzles marked as two yellow collars.
Here is a model of part of the installation. These are the nozzles at the bottom of the tanks at the end of their conical parts.
The stress results are shown below and are as accurate as possible.
The deformation results are shown below and do not raise any particular doubts.
Finally, the results of exceedances at the nozzles.
