Research and application of internal crack detection technology in pipeline based on balanced electromagnetic technology
In order to solve the problem of online detection and evaluation of pipeline cracks,based on the technical principle of balanced electromagnetic detection,the simulation model of electromagnetic field and crack on pipeline surface was established,the balanced electromagnetic internal testing system for 1 219 pipeline was designed and developed,and the standard pipe sample with crack was fabricated and the pulling test was carried out.The simulation results show that the electromagnetic field distortion caused by pipeline crack will cause the amplitude and phase changes of the voltage signal in the balanced electromagnetic sensor,and the phase law of the signal generated by the crack at different angles is different.For the axial crack,the crack length is positively correlated with the peak-valley distance of voltage signal.For circumferential cracks,crack length is related to the number of probes that detect voltage signals and the probe spacing.The amplitude of induced voltage signal is related to the crack shape and location such as crack angle,burial depth and crack depth.All angle cracks within the threshold can be identified and quantified effectively through the above features.Through the pulling test and comparative analysis of the prefabricated crack-containing standard pipe,it is verified that the balanced electromagnetic internal detection system has good detection performance at the detection speed of 2 m/s.The crack detection rate and quantization accuracy of the pipe body and girth-weld cracks basically meet the expected performance requirements,and the crack detection rate within the lower threshold of low speed can reach 91.67%.Under the condition of 90%confidence,the quantization accuracy of girth weld crack length is less than±10 mm,and the depth accuracy is less than±3 mm.The research results can provide a new solution for pipeline girth weld crack detection.
balanced electromagnetic technologypipe crackinternal detectionpulling test
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