Research on eddy current-based pipeline stress detection method

Accurate assessment of the stress status in oil and gas pipelines is crucial for identifying stress anomalies and weak points, preventing potential yielding and damage. This study investigates the influence of stress on eddy current impedance in steel, proposes an eddy current-based pipeline stress detection method, verifies the effectiveness of the detection method through experiments, and studies the influence of material microstructure on the detection technique. The research results indicate that this method exhibits excellent detection performance for the stress of five types of pipeline steels: X45, X52, X65, X70, and X80. When the detection frequency is in the range of 1 kHz to 10 kHz, the eddy current detection results of pipeline steel will be approximately arranged in a straight line on the impedance plane in the order of stress from high to low. Within this frequency range, there exists an optimal correlation between impedance amplitude and the stress state of pipeline steel. As stress increases, the eddy current impedance amplitude changes in a regular cubic curve pattern. When fitting the stress of steel and the impedance amplitude using a cubic curve, the coefficient of determination of the fitted curve exceeds 0.995.