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.