Research Of High Temperature Pipe Ultrasonic Corrosion Monitoring Technology

Ultrasonic testing technology is widely used in nondestructive testing from all walksof life, due to good directionality, measurement results, accurate and the advantages ofsimple operation. For years, experts and scholars at home and abroad were committed tothe research of ultrasonic testing technology, that makes ultrasonic detection technologybecoming one of the most mature and widely used nondestructive testing technology. Atpresent, for chemical pipelines in service online monitoring, the ultrasonic thicknessmeasurement technology is the main method.The paper aims at the phenomenon of high temperature chemical metal pipeline wallthinning, due to corrosion. The principle of ultrasonic corrosion detection technology isstudied, and the ultrasonic pulse reflection method thickness method is used to realize thefixed-point periodic monitoring of pipeline corrosion. The concrete design scheme ofUltrasonic pipeline corrosion monitoring system is put forward, the works principle of hightemperature pipeline corrosion monitoring system is explained. Generally, the workingtemperature of chemical transport pipelines is above350℃, ultrasonic detectiontechnology is used for high temperature chemical pipeline corrosion monitoring, ultrasonicprobe direct contacting with the, and measuring point temperature will damage the probeof the piezoelectric properties. To solve the thermal damage problem of probes, the bufferrod is used as temperature buffer. Material properties, geometry and structure parametersof buffer rods are important factors that influence the buffer rod top temperature and tailingsignals. In order to minimize the buffer rod top temperature and suppress trailing signals,finite element thermal simulation analysis and experimental analysis are used for bufferrods.By ANSYS finite element thermal analysis, the different sizes of cylindrical bufferrod are simulated, the nodal temperatures are got, the influence that the length and radiuschanges of cylindrical buffer rods to the top temperature are analyzed. The introduction ofthe probe test structure, when the ultrasonic propagates in the buffer rod, trailing signalsappear. Further study of ultrasonic propagation characteristics and analyze the reasons that cause trailing signals. For tailing signals generation principle, there are two methods ofsuppressing trailing signals: shortening the lengths or increasing the radiuses of buffer rods;changing the shape of buffer rods, to break the condition of waveform conversion, byultrasound contrast experiments, the possibility of suppression trailing signal method isstudied.The CTS-26A ultrasonic flaw detector is used, the pitch-catch technique ultrasonicmeasurement method is used, launching the same frequency and amplitude of ultrasonic torespective cyindrical, single taper and double taper buffer rods, comparative analysis of theecho signal. The experimental results show that both measures are effect to suppresstrailing signal, can effectively extract the measuring signal, and meet the requirements ofhigh temperature pipeline corrosion monitoring.