Because the pulse repetition frequency of pipeline ultrasonic inner inspection is very high

the echo data amount generated is very large

automatic acquisition of wall thickness information is the core problem. At the same time

the working condition of the actual pipeline is very complex

the useful echo signal is mixed with varied noise and uncertain disturbance

which requires the automatic wall thickness conversion algorithm with a strong adaptability. But the accuracy of second-order statistics method commonly used for the automatic wall thickness conversion is lower

the misdiagnosis rate and the miss rate is higher

and so on. Aiming at this problem

the echo signal was processed using 1.5-dimension spectrum of higher-order statistics. And according to the frequency range of wall thickness and the periodic characteristics of spectral lines

the spectrum data were intercepted and transformed again

and the improved 1.5-dimension spectrum was obtained. The transit time of the wall thickness was acquired

and then the wall thickness was obtained. Experimental results show that the inspection precision of the algorithm is very high and much better than the second-order statistics method

which is suitable for the corrosion inner inspection on long-distance oil pipeline.