Limit load of throughwall cracked elbows: comparison of test results with theoretical predictions

Integrity assessment of piping components with postulated cracks is very important for safe and reliable operation of power plants. Pipe bends or elbows are among the very important piping components in any power plant. The existing equations of limit load of elbows have various shortcomings. Additionally, there is only limited test data on elbows in open literature. A comprehensive experimental and analytical programe has been undertaken at Reactor Safety Division (RSD) of Bhabha Atomic Research Centre (BARC) to conduct fracture tests on throughwall cracked elbows and to also propose new limit load equations for a throughwall cracked elbows. The prediction from these newly proposed limit load equations agreed well with the test results. The present paper describes the elbow test specimens, the test setup, the test results and provides a description of the elastic-plastic finite-element analysis. The newly proposed collapse moment equations for throughwall circumferentially cracked elbows are presented and a comparison of test results with theoretical predictions is made to validate the equations.