Stresses at openings in the torispherical end closure of a pressure vessel
In the design of torispherical heads for cylindrical pressure vessels, it would often be desirable to position openings or branch connections in the vicinity of the toroidal portion of the shell, but from strength considerations it is normal practice to avoid doing so. An 18 inch inside-diameter model vessel of this type, with a nominal inside toroidal radius of 1.25 in was used for making strain and hence stress measurements in the shell due to internal pressure. Four unreinforced openings of 3 inch diameter were placed at different positions in the torispherical end and an elastic stress distribution for the shell around each opening was obtained. Distributions of elastic stresses in the shell were compared for the different opening positions with those in the unpierced shell in the toroidal region. Plastic deformations were measured in an over-pressure test and a plastic limit pressure was estimated.