Identification of defects in HDPE piping thermal fusion welds based on microwave inspection and true density measurement

In this paper, defects often found in the thermal fusion welds of high-density polyethylene (HDPE) piping were identified by microwave scan inspection and true density tests. The sound thermal fusion welds without defects were inspected by microwave scan technique. The obtained microwave interference pattern and the scan image produced were taken as the evaluation standard. Then the thermal fusion welds containing different defects were inspected and the resultant scan images were different from the standard image of the sound weld. In addition, true density tests were performed for the defect-containing welds to provide supplementary evidences. The results of microwave inspection and true density tests demonstrate that some common defects in thermal fusion welds of HDPE piping can be detected and identified using the microwave scan method in combination with the true density measurement.