Low cycle fatigue crack growth and ductile fracture under dynamic/cyclic loadings for Japanese carbon steel piping: Part I--Experimental study

To evaluate the structural integrity of power plant piping during earthquakes, dynamic fracture strength of 4-inch carbon steel pipes with circumferential defect's were examined. Pipes were subjected to monotonic and alternate bending loads at room temperature. In monotonic loading tests, the maximum load to failure increased slightly with loading rate. The number of cycles to failure can be expressed by the ratio of load amplitude to plastic collapse load. Since the load ratio is independent of length and configuration but does not depend on whether a defect is partly or entirely through the pipe wall, it is useful for estimating the strength of piping subjected to seismic loads