A Quantitative Analysis Method for Pipeline Defect Inspection Based on Infrared Thermal Imaging

Abstract

A method of infrared thermography image processing for pipeline defect inspection is presented in this paper. It can be used to quantitatively analyze the surface defect type, area, and detect location on the inner wall of pipelines. Firstly, in order to resolve the problem of obtaining the infrared thermal image, a special infrared thermal imaging device based on eddy current heating is designed, which may be used to obtain the thermal image of the inner pipe wall defect with less distortion and calibrating the image from pixel to real dimension, while it being carried by inspection robot into pipelines. Then, an algorithm, which can identify the defect shape in the image and obtain associated parameters of the defect, is developed. And a calibration method to convert pixel unit into actual size is given, which is helpful to determine the area and location of defect. The experimental examples show that the given method is available. Using the method together with the proposed infrared imaging device, which can be installed in the pipeline inspection robot, the task of nondestructive testing for the surface defect on the inner wall of the pipelines may be realized.