2019, 03 March |
DOI: 10.14489/td.2019.03.pp.004-013
Badalyan V. G. Abstract. For assessing the reliability of testing results obtained using the ultrasonic non-destructive testing (UT) it is need to be taken into account not only the probability of flaws detection, but also the probability of missing them and fixing false flaws. For these purposes, ROC analysis of testing data is often used, which reflects the mutual dependence of the number of false and the number of correctly found flaws. The ROC analysis was performed according to the UT of 24 of welded joints of austenitic pipelines with a diameter of 325x15, containing 61 real cracks; as a result, ROC-charts and ROC-curves are constructed. The coordinates of the occurrence, the length and height of cracks are determined by means of metallographic studies. The effectiveness of the use of ultrasonic flaw characterization (UFC) and conventional flaw detection at ultrasonic inspection is considered. In UFC, the flaw parameters (length, height) are determined by focused acoustic images; in traditional flaw detection – according to the amplitude of the signal from the flaw. The ROC diagram additionally presents the inspection results corresponding to individual groups of operators (three groups each on the UT by the AUGUR system and the traditional flaw detector). Analysis of the ROC diagrams showed that the methods of UFC are more effective than the method of traditional flaw detection, and the variation of the values of the Youden index for certain groups of operators is much smaller when using the methods of ultrasonic flaw detection. According to UFC data, ROC curves are constructed depending on the height of flaws. The reliability of the inspection of flaws of different heights for the methods of UFC has been evaluated. Building in practice such graphs based on the results of traditional ultrasonic flaw detection in most cases is not possible. This is due to the fact that the corresponding ROC curves are plotted depending on the amplitude of the signal from the flaw, and the height of the flaws weakly correlate with the amplitude of the signal. It was demonstrated how the ROC curves provide additional information for optimizing the methods of ultrasonic testing by increasing the signal-to-noise ratio, choosing conditions for maximizing the Youden index. Keywords: ultrasonic flaw characterization, AUGUR, reliability of the testing, Receiver Operating Characteristics
V. G. Badalyan (Co Ltd “Scientific Production Center of Nondestructive Ultrasonic Testing “ECHO+”, Moscow, Russia) E-mail: Данный адрес e-mail защищен от спам-ботов, Вам необходимо включить Javascript для его просмотра.
1. Berens A. P. (2000). Probability of detection (PoD) analysis for the advanced retirement for cause (RFC). Engine structural integrity program (ENSIP) nondestructive evaluation (NDE) system development, Vol. 1. PoD analysis. Final report. AFRL-ML-WP-TR-2001-4010.
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