Simulation supported POD curves for automated ultrasonic testing of pipeline girth welds

Abstract

A probability of detection (POD) curve relates the detectability of a flaw to its size. It plays an important role in the qualification process of nondestructive testing (NDT) methods since it gathers the influence of all the parameters that can alter the detectability of the flaw and, therefore, gives a measure of the performance of the NDT method (in terms of detection capabilities). POD curves were before exclusively obtained thru expensive and time consuming experimental campaigns. Simulation based POD calculations have recently been introduced in the NDT community. The determination of POD curves based on the simulation of the inspection method is presented in the case of the automated ultrasonic (AUT) inspection of girth welds using the zonal discrimination approach. The methodology to obtain these curves is divided into different steps that are derived from the ASTM standard practices and Det Norske Veritas (DNV) recommendations for these AUT inspection procedures using hit/miss analysis. The simulations and the computation of the POD curves are performed using the software CIVA developed by the CEA-LIST.