Indeed, it's about a Ring Stiffener and I would think something all around wouldn't have a "tip". But here PVElite operates with "Stiffener Circ Stress at Shell" and "Stiffener Circ stress at Tip" and User Guide says the Height of Section Ring is used to compute the stress at the tip of the stiffener, so here "tip" is just "extremity" (not necessary the extremity of something long and narrow). As terminology, would be or wouldn't be more precise, I guess "extremity of the section" of the stiffener would be acceptable. As point in space, should be located at horn of saddle, where the circumferential bending moment is maximum, at tip of the section- for example on the stiffener's flange assuming the stiffener is a T section ring.
How to solve the high stress at horn of saddle? Obviously, one option is to check what means to increase "a little" the thickness of shell instead to consider a stiffener. Often, to have success, this option is combined with others as making the saddle wider, wear plate longer and wider, moving the saddle closer to vessel head to help with head's inherent stiffener effect, increasing the contact angle. The stiffener option is the last one and means to check interference with welds, nozzles, pads, platforms, insulation, etc and for this reason is not preferred. In addition, for stress point of view, it is more advantageous to have an internal stiffener which in practice may be not an enthusiastic option.
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