Models on reliability of non-destructive testing

The reliability of ultrasonic inspections has been studied in e.g. international PISC (Programme for the Inspection of Steel Components) exercises. These exercises have produced a large amount of information on the effect of various factors on the reliability of inspections. The information obtained from reliability experiments are used to model the dependency of flaw detection probability on various factors and to evaluate the performance of inspection equipment, including the sizing accuracy. The information from experiments is utilised in a most effective way when mathematical models are applied. Here, some statistical models for reliability of non-destructive tests are introduced. In order to demonstrate the use of inspection reliability models, they have been applied to the inspection results of intergranular stress corrosion cracking (IGSCC) type flaws in PISC III exercise (PISC 1995). The models are applied to both flaw detection frequency data of all inspection teams and to flaw sizing data of one participating team