Research On The Above Ground Marking Technology Of Pipeline Inspection Based On Magnetic-Flux Leakage Theory

Many long distance oil-Pipelines have come into the old period in our country.Pipelines' leaks caused by corrosion incessantly threaten humans' life, propertyand living environment. The Magnetic-Flux Leakage Theory is a popular methodinspecting the pipelines' corrosion. The system of pipeline inspection basedMagnetic-Flux Leakage Theory includes three parts: the MFL-PIG, the AboveGround Marking (AGM) system, and the Data Analysis system.Now, CNPTC (China North Pipeline Technology Company) is developing thehigh resolving power MFL pipeline inspection system. AGM system researched inthis text is the part of this inspection system. The AGM system is the locating partof the pipeline inspection based on the magnetic-flux leakage theory. It plays animportant role in locating the pipeline's corrosion.In the first, this text introduces the significance and methods of the pipelineinspection, the Magnetic-Flux Leakage Theory, and the work principle of theAGM system. The characteristics of MFL signal are analyzed. And then, a newdesign project of the high resolving power AGM system is presented. Comparedwith other products, the new AGM has creative structure and optimized softwareand hardware, so it is more portable, more reliable and more sensitive.The Above Ground Marker and the Standard Clock Source are two essentialdevices of the AGM system. This paper describes their structure design, thehardware circuit design of signal collection, data processing, data memory, timerecording, lithium battery charging and discharging, data communication,keyboard and display. Also, the software of AGM system is summarized in thistext. In addition, it is involved that selection and design of the Crystal Oscillators,as a key component of this system. Their performance is checked up by inspectionexperiments. Finally, reliability, resolving power and performance of the AGMsystem are validated by a lot of experiments.