Stress intensity factors of rectangular circumferential surface cracks on the inside of a pipe under arbitrary loading

Circumferentially directed surface cracks on the inside of pipes play an important role in nearly all pipe systems loaded by internal pressure, by thermal loads or seismically. This paper presents an approximate weight function solution to calculate the stress intensity factors at the deepest point and at the surface points of such cracks under arbitrary loading. The stress intensity factors for the standard loading cases of pure axial tension and linear varying stress against the pipe wall are given as a function of crack depth and crack length. A comparison with the solution for the semi–elliptical surface crack in a plate is shown. The results are valid for (thickness/inner pipe radius) = 0.1.