In this paper, the surface crack problem in a cylinder subjected to internal pressure is solved. The analysis is based on the body force method, but it is different from the conventional body force method in the following point. That is, the body forces to be distributed continuously on the assumed boundaries in an infinite body are approximated by some discrete point forces acting on the outside of the assumed boundaries. By using this method combined with the resultant force boundary conditions, solutions with high accuracy are obtained.

For rectangular cross-sectional ring headers, the authors’ theoretical stress analysis is presented to agree with actual stresses by measurement with strain gages. Therefore, this analytical method is applicable for similar rectangular cross-sectional ring headers. When the aspect ratio (length of two cylinders/radius difference between two cylinders) is more than three, moments originating at the end of finite long cylinders and tangential stresses on the half-length of both cylinders are almost the same as values from infinitely long cylinders. Regarding the welds between flat cover plates and cylinders, cover plate designs can be remarkably thinner by changing the weld shape, that is, by using T-joint weld with a single-bevel groove, than compared to Type (i) in PG-31 of ASME Code.