By the reliability D is meant the probability of taking correct decisions in estimating the article (product) quality [2]. Ordinarily, the point estimate of the reliability on the basis of the alternative criterion is used [2–4]. In this case, it is recommended to compare the testing method under investigation with a standard method. As the latter, it is recommended to open the welded joints. The reliability matrix is used (see table). For the statistical testing of long welded joints, as a
product unit, it is necessary to use an element (a fragment of the joint) which can individually be tested, repaired, and tested once again. The recommended length of the element is 40 mm [3].