Experimental study on the probe dynamic behaviour of feeler pigs in detecting internal corrosion in oil and gas pipelines

•The trajectory of the probe swept across the concave surface 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.

Leakages are the major cause of in-service natural gas and oil pipeline accidents, and many factors, such as corrosion, can lead to leakages. The feeler pig is one of the most typical contact-testing tools in oil and gas pipelines. In this paper, the probe dynamic behaviour of the feeler pig in detecting internal corrosion has been investigated using a handmade inspecting system. The dynamic characteristics of the probe are different in the uphill section and the downhill section, and the trajectory of the probe is asymmetric. A bouncing phenomenon was found in the outlet region of the corrosion. The experimental results indicated that both the speed and the spring pre-tightening elastic force are closely related to the inspection precision. The research in this paper provides guidance for studying the inspection precision of the feeler pig.