Analytical Limit Loads for Tube Sections With Circumferential Degradation

The fracture mechanics evaluation of tubes and pipes with circumferential degradation typically requires that the plastic limit load capacity be evaluated under a combination of axial force and bending moment loading. Most available analytical solutions are thin-wall approximations and may not work well for heavy-wall applications. The present paper derives an analytical limit load for a cylindrical pipe or tube with a partial circumferential, partial through-wall flaw and its bounding cases (through wall partial circumferential and uniform circumferential part-throughwall flaw). The solution is not in closed form, but can be easily solved with available mathematical software like MathCAD. The obtained limit loads for a steam generator tube are compared to those from simplified analytical solutions. The effect of tube supports on the limit load of a tube with non-axisymmetric flaw is discussed with a simplified model.