I defined a global mesh size of 50 mm using the standard mesh component in the project tree. Then I defined an edge sizing on each of the outer surfaces of the shell like this:

From the inside of the shell:

From the outside of the shell:

I think the sudden change in stress (especially as seen from the inside) is a bit strange. The results are displayed as unaveraged.

Here is the plot of the peak stress vs the element edge length:

The large value only were found in only a couple of small elements. I think this value can be disregarded.