Active infrared thermography for defect detection of polyethylene pipes

We present defect detection of polyethylene (PE) pipes by using active infrared thermography technique. A finite element model was built to mimic the transient heat transfer in PE pipes, in which constant heat flux boundary condition was applied to the inner surface of the PE pipes. Various defects with different diameters and depths were simulated in PE pipes and they would affect the thermal distributions from which the relation between thermal images and defect sizes and locations would be established. An electrical heating bar, as the novel thermal excitation source, was employed in active infrared thermography experimental system. The finite element simulation results are well agreed with the one obtained from the infrared imaging experiments and it demonstrated that finite element numerical method can be an effective method to analyze infrared imaging. Furthermore, defects in heat fusion joints of PE pipes were fabricated and detected by the developed active infrared thermography. The experiment showed that active infrared thermography based on an electrical heating bar could provide a novel tool for nondestructive evaluation of PE pipes.