Determination of the Parameters of Stress-Corrosion Cracks of the Main Gas Pipeline Based on the Results of Eddy Current Control

Abstract

In order to increase the accuracy of estimating the depth of stress-corrosion cracks in the main gas pipeline from the measured signal of the overhead eddy-current transducer, a mathematical recognition method based on the regularization method is proposed. Analytical expressions are obtained for the smoothing function and the optimal regularization parameter, which makes it possible to obtain stable estimates of the depth of stress-corrosion cracks in the main gas pipeline. In the absence of spatial resolution of a group of stress-corrosion cracks based on the signal of an overhead eddy-current transducer, a mathematical model of a group of cracks with the same depths and a constant interval is proposed. The procedure for determining the values of the parameters used in the regularization parameter of the smoothing functional is described. Based on the analysis of eddy-current transducer signals by the regularization method obtained on artificial models of stress-corrosion cracks in the main gas pipeline, it is shown that the average relative error in estimating the depth of a group of identical cracks does not exceed 8.5 %. It is shown that the estimate of the depth of a continuity defect obtained by recognizing a group of unequal cracks is close to the average value of this parameter established for a group of cracks, while the average relative error in estimating the average depth of a group of unequal cracks does not exceed 8 %.