An experimental evaluation of the probe dynamics as a probe pig inspects internal convex defects in oil and gas pipelines

•The trajectory of the probe swept across the convex defect is asymmetrical.•With increasing speed, a bouncing phenomenon appears in the exit region.•The larger of the speed, the larger of the bouncing amplitude.•The larger of spring pre-tightening forces, the smaller of the bouncing amplitude.•The probe dynamics differ in the uphill and downhill sections.

The periodic pigging of oil and gas pipelines for dewatering, cleaning and inspection has become a standard industry procedure. The probe pig is the most typical tool for contact-testing in oil and gas pipelines. The dynamic behavior of the probe as it inspects convex defects has been investigated using a home-built inspection system. The probe dynamics differed in the uphill and downhill sections, and the trajectory of the probe was asymmetrical. A bouncing phenomenon was found in the exit region of the convex defect. The experimental results indicated that both the speed and the spring pre-tightening elastic force are closely related to the inspection precision. This study provides a reference for analyzing probe dynamic behavior and improving its inspection precision.

Graphical abstractThe speed and spring pre-tightening force are closely related to the inspection precision and dynamic behavior of a probe pig during the probe’s sweep across concave defects during the pipeline pigging process. For an ideal concave defect, the trajectory of the probe’s sweep is asymmetrical, and with increasing speed, a bouncing phenomenon appears in the exit region of the convex defect.Figure optionsDownload full-size imageDownload as PowerPoint slide