The in-pipe localization is a challenging task, particularly in underground buried pipelines, due to the blockage of GPS signals and the infeasibility of installing additional sensors on the already constructed multitude of networks of pipelines. This paper proposes a novel localization system that capitalizes on the detection of welds that are regularly positioned within a pipeline, via electromagnetic sensors mounted on a traveling device inside a pipeline. The welds are present as a result of joining each pair of pipe segments, known as spools, which are manufactured of a standardized length. The localization is achieved by means of recording the timestamp whenever a weld is detected, whereby the average velocity and travelled distance of the moving device can then be determined from two consecutive readings. The estimated average velocity and travelled distance obtained from the detection of welds are combined with the acceleration and angular velocity readings obtained from an inertial measurement unit to determine the location of the travelling device. The proposed system is designed to provide higher accuracy at lower computational complexity and hardware costs when compared to other existing systems, which often require both in-pipe and out-of-pipe interactions. Furthermore, the proposed system is designed attachable to and/or integrate-able with standard pipeline intervention gadgets (PIGs), robots, or other widely used intervention and inspection tools.

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