Abstract
Acousto-ultrasonic technique that combined ultrasonic and acoustic emission tests was used to evaluate the corrosion damage of pipe in this study. The experimental equipment was established to improve the corrosion process of carbon steel pipe. The internal conditions of the carbon steel pipe were under 473K temperature and 10Mpa pressure, and acousto-ultrasonic technique was used to inspect the degree of corrosion. Ultrasonic bulk waves are limited by poor time resolution when used in the measurement of corrosion depth in thin wall structures because the corroded surfaces cause unclear echo signal edges. Therefore, in this study, the ultrasonic guided waves were generated in the pipe due to its thickness, and mode conversion of the guided wave is subsequently occurred due to the implications of the corrosion on the pipe. To analyze only the mode for evaluation of the corrosion has a limitation because of the variation of defects by corrosion. In order to overcome this problem the analysis by many parameters can be possible by using the acoustic emission technique. In this study, the corroded pipe for a period of time (three and six months) was tested by acousto-ultrasonic technique, and AE parametric features were compared. The features of energy, count, rise time and amplitude were useful to measure the degree of corrosion inside the carbon steel pipe under 473K temperatures and 10Mpa pressures.
