Paradigm Shift in the Holistic Evaluation of the Reliability of NDE Systems

Abstract

The aim of this publication is to provide an overview of new methodologies for evaluating the reliability of NDE systems in accordance with the specific requirements of industrial applications. After a review of the substantive issues of the previous decades, the go forward guidance is concluded. For high safety demands a quantitative POD (Probability of Detection) created from hit/miss experiments or signal response analysis and ROC (Receiver Operating Characteristics) are typically created. The modular reliability model distinguishes between the pure physical-technical influence, industrial application factors, and human factors. It helps to learn which factors can be determined by modeling and by open or blind trials. A new paradigm is offered to consider the POD or reliability of the system as a function of the configuration of input variables and is used for optimization rather than for a final judgement. New approaches are considered dealing with real defects in a realistic environment, affordable but precisely like the Bayesian approach or model assisted methods. Among the influencing parameters, human factors are of high importance. A systematic psychological approach helps to find out where the bottlenecks are and shows possibilities for improvement.

Structural reliability assessment of cracked pipes: The role of probability of detection data

“…These curves, for a given inspection scenario (including the geometry and the material of the component), are extremely specific. In principle, these curves depend on the following variables: The type of technique and the inherent capability of the NDT detection equipment. The application factors. Human factors related to the staff who perform the inspection. For the assessment of the effectiveness of different UT inspection teams, Simonen and Woo proposed three different POD ( a ) curves used for ferritic steel pipes. These curves were called the “Poor team”, Equation , the “Good team” (GT), Equation , and the “Advanced team” (AT), Equation and correspond to the performance achieved by different teams of inspectors.…”

“…These curves, for a given inspection scenario (including the geometry and the material of the component), are extremely specific. In principle, these curves depend on the following variables: [21][22][23][24] a. The type of technique and the inherent capability of the NDT detection equipment.…”

Conclusions of the 6th European American Workshop on reliability of NDE

“…AP and HF can be covered only partly (see Fig. 2 for the Modular reliability model [3]). Could maybe a performance demonstration predict the field POD?…”

“…physical reasoning by ENIQ). The main achievement of the first Workshop was the conceptual model [2] (later referred to as Modular Reliability Model [3] in terms of the reliability formula which simply says that the total reliability of an NDE system is composed of the intrinsic capability, IC (which stands for the physical principle behind the defect indication and its technical realization as an upper bound), the application factors, AP (describing the realistic circumstances like UT coupling, limited access, noise of the surrounding …) and the human factors, HF, present in each application. While imperfect-e.g.…”

A human factors perspective on the use of automated aids in the evaluation of NDT data

“…Next to the intrinsic capability, application, and organizational factors, human factors are considered to be one of the major contributors to the reliability of NDT [1]. If the NDT system is highly reliable, and the inspection is applied under optimal conditions; human factors are most likely to be blamed for something going wrong.…”