Acoustic emission monitoring of corrosion in steel pipes using Lamb-type helical waves

Abstract

This paper is concerned with the monitoring of corrosion in steel pipelines using the acoustic emission (AE) technique. Large uniform corrosion in pipes causes significant wall-thickness loss, and the intensity of the AE activity is correlated with the severity of the corrosion. A new approach for considering the helical propagation of corrosion-related AE events is proposed. Specifically, it is suggested that a longer portion of conventional AE hit is considered to account for multiple arrivals of Lamb-type modes traveling helically in the circumference of the pipe known as helical guided waves (HGW). Using the recorded amplitude of these events, a qualitative corrosion monitoring approach is proposed using the b-value analysis. An accelerated corrosion test on a steel pipe instrumented with a network of AE sensors is carried out to validate the proposed approach. Moreover, a numerical study is performed to evaluate the energy variation of HGW during the corrosion process. Both experimental and numerical results suggest that helical Lamb-type AE has the potential to be utilized for corrosion monitoring.