Research on Identification of Welding Defects of Pipe Pile Based on Infrared Camera Method

The pile connection process of prestressed pipe piles usually uses welding. The welding process requires substantial welds, multiple passes of welding, and no holes on the surface. Under the special end plate structure of pipe piles, it is difficult to implement traditional weld detection methods such as X-ray and ultrasonic waves. Therefore, this paper proposes a method for identifying weld defects using continuous shooting with an infrared camera. First, continuous infrared photography was performed on 4 prestressed pipe piles with a diameter of 500 mm, one frame every 5 seconds, a total of 50 frames. After the weld was cooled, the penetration method was used to inspect the weld quality in the infrared shooting area, and weld defects were found in one of the inspection areas. By dividing the weld area into sub-blocks, the temperature distribution and average temperature drop characteristics of each sub-block are collected. Differences in acquisition temperatures due to local material differences and emissivity were corrected by homogenization of the temperature-time curves. The study found that there are some sub-regions in the defect area where the infrared homogenization temperature decreases rapidly. This feature is consistent with the characteristics of sporadic holes detected by the penetration method, thus verifying the feasibility of this method. The research provides a new possibility for testing the welding quality of prestressed pipe piles.