Review of Literature on Probability of Detection for Liquid Penetrant Nondestructive Testing

A review of the published literature on the reliability of liquid penetrant testing (LPT) identified twelve major probability of detection (POD) studies conducted between 1968 and 2009. Based on these studies, significant variability in performance is inferred between different implementations of the post-emulsifiable LPT process. This report presents statistical inferences for the defect size expected to be detected with 90% POD by most implementations of post-emulsifiable LPT, based on the published data. The reliably-detectable defect size of aNDI = 3 mm currently specified for the Royal Australian Air Force general procedure for post-emulsifiable LPT is consistent with estimates of the average performance of LPT demonstrated in the literature.