Fatigue crack growth and fracture studies on straight pipes with circumferential surface notch

Fracture behaviour of piping components used in pressurised heavy water reactors of nuclear power plants are of great importance to ensure safety and integrity against the extreme load conditions. Fracture mechanics approach predicts crack growth behaviour under normal operating conditions and failure load under accidental conditions. Leak-Before-Break concept is used to investigate the structural integrity of the piping components. Experimental investigations were carried out on straight pipes to study their fatigue and fracture behaviour under bending. Fatigue tests were conducted on 406 mm outer diameter straight pipes to study the crack growth with various notch configurations. Fracture tests were also conducted on the pipes, which were tested in fatigue, under monotonic loading for their fracture resistance. A new database on fatigue life of large size carbon steel pipes has been created which will be very useful for integrity assessment of power plant structures. The details of the studies are presented in this paper.