Fracture estimation method for pipe with multiple circumferential surface flaws subjected to bending

Li, Y.* ; Sugino, Hideharu*; Hasegawa, Kunio*; Onizawa, Kunio ; Doi, Hiroaki*; Ebisawa, Katsumi*

When a flaw is detected in a stainless steel pipe during in-service inspection, the limit load criterion given in the standards 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 integrity of the pipe. However, in the present standards, the limit load criterion is only provided for the case of single flaw, although multiple flaws such as stress corrosion cracking have been detected in the same circumferential cross section in a pipe. In this paper, a fracture estimation method is proposed based on the limit load criterion for multiple independent circumferential surface flaws with arbitrary number and distribution, to evaluate the integrity of the pipe in a rational way. Several numerical examples are given to show the validity of this method.