Hi!
I have come across a vessel having steam jacketted nozzles. The internal design pressure of the vessel is 50 Psig at 360 deg F and the design pressure of the jacket side is 80 Psig at 360 deg F. My problem is to find out the required thickness of shell due to the external presuure of 80 Psig at 360 deg F acting at jacketted nozzle locations.If I apply this external pressure throughout the length of the vessel, I am sure that I will end up with a much thicker shell than required or will have to provide much more stiffner rings than required.The question in front of me is how to analyse the shell for a localized external pressure.There may not be the requirement of additional stiffeners or increase in shell thickness if I am able to properly analyse the case.Hope someone will give me a solution.

One more question.
How to analyse a 2" dia hairpin /helical type stamcoils inside a pressure vessel, using PV Elite/Codecalc? Can I analyse the steam coil as shell subjected to external pressure = vessel design pressure and subjected to internal pressure = coil design pressure, and apply minimum thickness requiremnt of shell as per relevant ASME Sec VIII Div -1 Paragraph?