Pressure vessel integrity in the presence of defects: The probabilistic prediction in spite of scarce data

A closed-form solution is presented for the probability of fast fracture of a pressure vessel in the presence of crack-like defects. The defect distributions are characterized by the total number of defects and the concentrations and lower threshold values of exponential size distributions. The effect of ultrasonic inspection on defect occurrence is taken into account. The structure of the failure probability is examined, and it is shown what types of defect distributions may be admitted in order to keep the likelihood of failure reasonably remote. Remarkably specific conclusions can be drawn given the limited data available. (orig.)