Research On In-line Detection Technology Of Electromagnetic Ultrasonic Pipe

Oil and gas are important energy substances.As the main way of oil and gas transportation,pipeline transportation will produce corrosion,cracks and other defects after long-term use,leading to oil and gas leakage,and serious accidents will occur,endangering social security.Therefore,it is of great significance to ensure the safe operation of pipelines.Electromagnetic ultrasonic testing has the advantages of no couplant,strong acceptance to high temperature environment and wide detection range.It is an effective means of pipeline inspection.In this paper,the electromagnetic ultrasonic pipeline inspection technology is studied.The basic theory of electromagnetic ultrasound,magnetostrictive effect,guided wave formation mechanism and related concepts are studied.The relations among the physical quantities of static magnetic field,eddy current field and force field based on Lorentz force and magnetostrictive force are derived.The waveforms excited by different combinations of magnets and coils are studied.In order to complete the detection of corrosion defects and circumferential and axial crack defects in one pipeline inspection,the number of magnets can be reduced and the inspection effect can be improved while multi-channel inspection.In this paper,a multi-channel body and a conductive body electromagnetic ultrasonic transducer are designed,and a combined magnet is designed as the bias magnetic field.The magnetic field strength of the combined magnet in the test piece is simulated and analyzed by COMSOL software and compared with the traditional magnet structure.The simulation model is established and the thickness measurement model of the spiral coil placed under the magnetic pole and the guided wave model of the turn-back coil placed between the two magnetic poles are analyzed.The effect of converter conversion efficiency.The hardware circuit used by the electromagnetic ultrasonic pipeline inspection prototype and other accessories required for pipeline inspection are designed and introduced,and the corresponding software system is designed to complete the processing,storage and analysis of the detection signal.In order to verify the detection effect of the designed body and guide electromagnetic ultrasonic transducer,an experimental platform was built to conduct experimental verification of the body and guide electromagnetic ultrasonic transducer,and to analyze the difference in conversion efficiency between it and the common transducer structure.And verify its ability to detect defects.The results show that the signal-to-noise ratio of the echo amplitude of the bulk-conductor integrated transducer is improved by 20% compared with the traditional transducer.Capable of detecting crack defects over 1 mm in width and corrosion defects over2 mm in width.Finally,an electromagnetic ultrasonic pipeline inspection prototype for pipelines is built,which can complete the detection of axial and circumferential crack defects and the thickness of corrosion defects through the host computer software.