A Novel ACFM Probe With Flexible Sensor Array for Pipe Cracks Inspection

Pipes are important components for well drilling, production, and transportation in petroleum industry. However, due to factors such as vibration, corrosion, fatigue damage, etc., pipes are prone to cracks. This paper presents a novel ACFM probe with flexible sensor array for the inspection of inner and outer cracks in pipes with different diameters. The simulation model of the ACFM probe with flexible sensor array is established by the finite element method. The influences of the crack length and the lift-off on the distance between the Bz peaks and troughs are analyzed respectively. The relationship between the offset distance of the crack from the pickup coil center and the detection sensitivity is studied. The probe made by flexible PCB and the testing system are developed. The experiments are carried out. The results of experiments and simulations show that the probe with flexible sensor array can detect inner and outer surface cracks for pipes with different diameters, and both circumferential and axial cracks can be identified. The distance between the Bz peaks and troughs can measure the crack length. When the crack is offset from the center of the pickup coil, the adjacent pickup coil can compensate for the detection sensitivity.