Experimental Investigation of Net-Section-Collapse Criterion for Circumferentially Cracked Cylinders Subjected to Torsional Moment

When a crack-like-flaw is detected in piping during in-service inspection, the limit load criterion given in the codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Section XI can be applied to evaluate the structural integrity of the piping. However, in-service piping is generally subjected to combined tensile, bending, and torsional loading, and a methodology to evaluate the limit moment for torsion has not yet been established because of inadequate experimental validation. In this study, fracture tests were conducted for circumferentially cracked cylinders subjected to torsional moment. The experimental maximum moments were compared with the limit moments, which were evaluated on the basis of the net-section-collapse criterion for torsional moment. The maximum moments can be conservatively predicted by the net-section-collapse criterion.