Ultrasonic Thickness Inspection of Oil Pipeline Based on Marginal Spectrum of Hilbert-Huang Transform

摘要

Measurement of pipeline wall thickness is one of the main contents of nondestructive inspection on offshore oil pipeline. A novel approach based on the marginal spectrum of the Hilbert-Huang transform is proposed for ultrasonic echo signal processing. The demodulated ultrasonic echo signal contains the thickness information of pipeline wall, which is an approximately periodic signal. The marginal spectrum is obtained by applying Hilbert-Huang transform to the ultrasonic echo signal. It effectively reveals the information of wall thickness of pipeline. The relation between the main frequency and the wall thickness of pipeline is established to calculate the wall thickness. The validity and the robustness of the proposed method are shown by signals collected by ultrasonic pipeline intelligent gage.