Piping components such as tees and elbows used in the primary heat transport system of power plants undergo stress fluctuations due to operational and extreme loading conditions. Crack initiation and through-thickness lives of piping components are of primary concern in the justification of Leak Before Break methodology for the design of piping components. Two full-scale carbon steel (SA333 Gr.6) elbows of 406 mm outer diameter were tested under constant amplitude cyclic loading. Crack initiation and crack growth were monitored using NDT equipment. The fatigue tests on the two elbows show that the inner surface of the elbows at the crown points is the vulnerable location for the occurrence of fatigue cracks. It was also observed that more than one crack grows simultaneously at the crown point of the elbows.
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