A novel pipeline defect detection system with enhanced magnetic moment and focused probe using spatial distance algorithm

Harmonic magnetic field detection for pipes has the merits of penetration and sensitivity. However, issues like the probe’s shape, limited data characterisation, and poor targeting restrict the detection distance. To address this, a novel defect detection system using targeted magnetic moment enhancement and targeted magnetic field focusing probe and its spatial distance algorithm is proposed to detect in-service steel pipe damage. The excitation coil structure is designed to increase the effective detection distance and focus the diffuse magnetic field. A full bridge balanced differential circuit control steategy, separate from the detection end, is adopted to extend datacharacterisation. Also, a spatial distance harmonic inner product correlation layer resolution matching tracking algorithm is proposed to alleviate the problem of the insufficiently targeted characterisation of detection data using harmonic signals under real acquisition conditions. Experiments on 20# steel pipes demonstratethat the system can discriminate the defect severity and achieve full wall thickness detection. It shows advantages in enhancing detection height andidentification clarity, especially useful for pipes with ultra-thick claddings or larger burial depths in extreme conditions, thus providing a new approach for practical engineering detection.