Dear Naderi,

In my opinion, properly reinforced openings (manways) that will not be subject to external forces and moments do not require this effect to be considered. It would seem reasonable to conclude that since there are not normally problems with such designs, the inclusion of pressure thrust on manways would not be necessary.

There is an article on this subject in a back issue of COADE's Mechanical Engineering Newsletter. You can find it on our website. As always, gather as much information as possible so that you can make an informed decision.