Skirt
Tall, vertical, cylindrical pressure vessels (e.g., the
tower and reactor shown in Figure 1-4 and Figure 1-5
respectively) are typically supported by skirts. A support
skirt is a cylindrical shell section that is welded either to
the lower portion of the vessel shell or to the bottom
head (for cylindrical vessels). Skirts for spherical vessels
are welded to the vessel near the mid-plane of the shell.
The skirt is normally long enough to provide enough
flexibility so that radial thermal expansion of the shell
does not cause high thermal stresses at its junction with
the skirt