Experimental Study on the Quantitative Relationship between the Non-contact Magnetic Signal and Detection Height of Ferromagnetic Pipelines

Abstract

The non-contact magnetic detection technology has good application prospects in the detection of buried steel pipelines. However, the variation of non-contact magnetic signal and measured height is unknown. The application of the technology in pipeline burial inspection is restricted. Therefore, this article conducts non-contact magnetic signal experimental testing on full-size steel pipelines. The collection method, pipe diameter, internal pressure, measurement height, and the non-contact magnetic signal are quantitatively analyzed. And the propagation factor f G was defined to quantify the degree of influence of measurement height on the non-contact magnetic signal. The results indicate that when the measurement height increases from 0.1 m to 2.0 m, the variation amplitude of the magnetic gradient modulus obtained by the parallel acquisition method is the largest, with a change rate of - 0.35. The amplitude and linear rate of change of the propagation factor f G increase with the pipe diameter and internal pressure. The amplitude and linear rate of change of the propagation factor f G increase with the pipe diameter and internal pressure. In the range of pipe diameters from 355.6 mm to 1016 mm, the amplitude of f G variation is 0.53, and the rate of change is 0.26. Furthermore, the amplitude of f G change due to a unit increase in internal pressure is 0.022, with a corresponding rate of change of 0.0114.