Hi JTE - thanks for the reply. It's actually closer to a thread spool. The pressure on the flanges is created by the wound thread, which is why it's highest near the barrel and lowest at the edge. Sorry I wasn't clear.
I actually figured this out since I wrote, but thanks again for looking...
I'm analyzing a spool, and would like to load the flange with a pressure starting at 70 psi, reducing to 0 psi at the end of the flange. Is it possible to use a polar coordinate system to define the load? If not, does anyone have any idea what the cartesian equation would look like?