Reliability assessment method for pressure piping containing circumferential defects based on fuzzy probability

Randomness of the assessment parameters and fuzzy failure areas both exist in the reliability assessment of pressure piping containing circumferential defects. The use of fuzzy sets is considered in this context. It is pointed out that the failure probability of pressure piping containing circumferential defects is in fact a fuzzy failure probability, and a method to compute the fuzzy failure probability of pressure piping is proposed. Numerical examples that consider the fuzzy failure areas of pressure piping can have an effect on reliability estimation of pressure piping containing defects, and different assessment results can sometimes be obtained. Compared with the conventional reliability estimation method, which neglects the existence of fuzzy failure areas, the method proposed in this paper provides a more complete assessment of pressure piping containing defects.