Evaluation of tests of pipes with circumferential cracks based on the limit load concept

Circumferentially cracked pipes of an austentic stainless steel were tested in four-point bending. The test results are evaluated using the plastic limit load concept. A simple equation is derived for the limit moment of an ovalized pipe. The test results agree only qualitatively with the limit moments predicted which tend to be non-conservative because the hardening effects are not taken into account properly. The CEGB-R6 approach is shown to give conservative estimates of the maximum moment observed.