Magnetic Flux Leakage Detection Technology Of Small Diameter Pipeline Based On 3D Magnetic Sensor

Urban transportation gas pipeline is an energy transportation tool for urban industrial production and social life,which is closely related to urban safety.Once the leakage of urban transportation gas pipeline causes explosion,it will cause a great impact on urban industrial production,social life and life and property.In order to prevent the occurrence of urban gas pipeline transportation accidents,it is of great significance to carry out pipeline defect detection to ensure the economic and social stability of the city.The detection of urban gas transmission pipelines is mainly based on detection of buried pipelines.Pipeline magnetic flux leakage internal detection method is generally adopted,and fluid drive detection device is used for detection operation.At present,magnetic flux leakage internal detection of pipeline is widely used in the detection of large diameter long distance oil and gas pipeline.However,in the detection of small diameter of urban transportation gas pipeline,the detection is difficult due to the problems of heavy weight,large structure and small pipe diameter of the detection device.In order to realize the internal magnetic flux leakage detection of small diameter pipelines,this paper adopts the internal magnetic flux leakage detection method of pipelines based on three dimensional magnetic sensors to solve the problems of small diameter pipelines,heavy weight and large structure of detection devices.The main work of this research is summarized as follows:First of all,the magnetic flux leakage detection system of small diameter pipeline is designed and implemented.According to the actual demand of small diameter pipeline,the overall scheme design is carried out on the basis of analysis demand.The magnetic flux leakage detection system for small diameter pipelines includes a hardware part and a software part.In the hardware part,in order to overcome the difficulty of magnetic flux leakage internal detection of small diameter pipeline,three dimensional magnetic sensor is used to detect magnetic flux leakage,and wheel bridge type steel brush free structure is given to make the detection device light and simple in structure;in the software part,in order to meet the function of magnetic flux leakage internal detection of small diameter pipeline,the detection program of three dimensional magnetic sensor and the software of magnetic flux leakage detection system for small diameter pipeline are developed.Secondly,the method of complete ensemble empirical mode complete ensemble empirical mode(CEEMDAN)is used to analyze the magnetic flux leakage detection signal of small diameter pipeline to eliminate signal interference.The CEEMDAN method is introduced to decompose magnetic flux leakage detection signal from high frequency to low frequency to obtain interference signal and useful signal.Then,the correlation coefficient method and the energy value method are combined to select useful signal,and magnetic flux leakage interference signal can be removed by reconstructing the useful signalFinally,the defect contour imaging of magnetic flux leakage detection of small diameter pipeline is realized.Using simulation analysis,the simulation model of small diameter pipeline is established,the magnetic flux leakage detection signal is extracted,and the characteristics of three dimensional magnetic flux leakage signal are analyzed in detail.Based on the three dimensional magnetic flux leakage detection data,the three dimensional magnetic flux leakage signal graph is drawn,from which defect contour imaging characteristic information is obtained.Then,the data segmentation recognition method is used to identify each magnetic flux leakage signal to pick up the defect contour area.Combined with the threshold segmentation method,the typical defect,irregular shape defect and crack groove defect contour imaging of small diameter pipeline magnetic flux leakage is completed.The experimental results show that the magnetic flux leakage defect profile imaging method presented in this paper can qualitatively and quantitatively analyze the defects.