Reliability and sensitivity of visible liquid penetrant NDT for inspection of welded components

Welding, as an approach to join components, is used extensively by various industries. Generating several types of defects is one of the major weaknesses of the technique. Thus, inspection to detect the defects is normally considered as a stage of welding procedure. One of the main categories of the defects is surface cracks, which are found by nondestructive testing methods. However, visible liquid penetrant as a technique to reveal this kind of flaws is broadly used, the method capabilities in defect detection of welded components have not been comprehensively studied. In this paper, utilizing reliability and sensitivity concepts of nondestructive testing, its abilities in detecting of surface crack of welded joints are investigated. The results of the paper illustrate that the detection and missing rates are 52 % and 48 %. In addition, taking into account 95 % degree of confidence, probability of detection for defects with length equal to 3.73 mm is 90 %.