A method for estimating the shape and size of internal corrosion of pipes using the echo height of ultrasonic pulses

摘要

PROBLEM TO BE SOLVED: To estimate size independent from the shape and the size of corrosion in ultrasonic inspection method for inspecting corrosion on the pipe inner surface, and to performing pipe deterioration diagnosis in a short time, with high accuracy and at a low cost by utilizing a probe sold at a market. SOLUTION: The maximal value of the defect echo height is searched on measurement data by an ultrasonic probe, to thereby estimate the corrosion center position. Ultrasonic echo data are sampled at equal intervals in a grid- like shape, and data of artificial corrosion simulating erosion, pitting and crevice corrosion as typical three kinds of local corrosion shapes are prepared. Erosion is classified from two echo heights, namely, the defect echo height and the multiecho height, by threshold processing. In addition, spread of the defect echo height is classified by the threshold processing, and pitting and crevice corrosion are classified from the difference of spread of the corrosion.