Relation between Risk-Informed In-Service Inspection and Inspection Qualification

The paper describes the results of a project set up to investigate approaches to quantifying the confidence associated with inspection qualification. Three approaches to quantify the inspection capability based on inspection qualification were considered in pilot studies. These approaches were a direct judgement method, and a Bayesian approach including a weighting and scoring of various parts of the evidence presented in the technical justification, and an approach based on the relationship between POD and margin of detection. The pilot studies resulted in a set of recommendations related to the quantification of inspection qualification. Particular attention was paid to the development of guidance to support the application of the Bayesian model that combines and quantifies the "soft" evidence from a technical justification with the "hard" evidence obtained from practical trials. Besides the application of the quantification approaches, the project also illustrated how, if defect growth can be modelled, it is possible to link inspection qualification results, risk reduction and inspection interval.