A detection system for pipeline direction based on shielded geomagnetic field

• The characteristic of the geomagnetic field inside the oil pipeline is discussed.
• An algorithm based on shielded geomagnetic field for detecting the pipeline direction is proposed.
• The pipeline direction inspection system is introduced in this paper.
• We verified the inspection method by several experiments.

An oil pipeline direction inspector is presented in this paper. The oil propels the enclosed spherical detector moving inside the pipeline. According to field needs, many kinds of sensors can be added to the system besides the core navigation module. We calculate the pipeline direction using the magnetic field inside the pipeline, combining with other mileage measurement methods, to calculate the three-dimensional position eventually. The relationship between the trend of pipeline and the magnetic field is analyzed based on the magneto static shielding theory. Through many repeated experiments inside the underground piping system, the analysis of collected experimental data shows that although the pipeline is made from ferromagnetic material, the magnetic field still exists inside the pipeline. There is a certain mathematical relationship between the magnetic field and the pipeline direction, and this could be used to inspect the direction of the pipeline. A series of trial in buried pipelines have been done, showing that the system is of good accuracy and reliability.