Research On Ultrasonic-based Welding Defect Detection Equipment For Stainless Steel Pipes

Thin-walled austenitic stainless steel welded pipe is widely used in many fields such as petroleum,chemical industry,automobile,nuclear power and energy because of its relatively simple production process and low cost.With the continuous increase of application fields,the quality requirements of welded pipes are also getting higher and higher,especially for welded pipes used in the field of nuclear power,all-round inspection of their welds and base metals is required.At present,electromagnetic detection technology is widely used in online and offline flaw detection of small-diameter stainless steel welded pipes,but limited by the skin effect of eddy current flaw detection,it is difficult to find defects on the inner wall of welded pipes,and it is difficult to meet the high-precision flaw detection requirements of welded pipes for nuclear power.Ultrasonic flaw detection technology has the advantages of strong penetration,low pollution and high sensitivity,and is widely used in industrial flaw detection.Because the stress of the thin-walled welded pipe weld(forming stress and welding stress)is easily distorted,coupled with the interference of the ultrasonic signal of the welded structure,ultrasonic flaw detection is seldom used in online or offline automatic flaw detection of thin-walled stainless steel welded pipes at the current stage.Combined with the current actual situation,this subject researches and develops the online ultrasonic automatic detection technology and equipment suitable for thin-walled austenitic stainless steel welded pipes,which will greatly supplement and improve the flaw detection technology of thin-walled stainless steel welded pipes.Improve the product quality of stainless steel welded pipes for nuclear power.,with high research value and commercial value.In this study,the ultrasonic on-line detection technology of stainless steel welded pipe was introduced in detail from three aspects: theory,technical design and experiment.The first chapter introduces the commonly used nondestructive testing methods and the development and research status of ultrasonic flaw detection equipment;the second chapter focuses on the introduction of ultrasonic and ultrasonic critical refraction longitudinal waves,which are the theoretical basis for ultrasonic on-line flaw detection of thin-walled stainless steel pipes;In theory,a detection scheme is designed,combined with the characteristics of the detection object and the on-site environment,the detection method and detection probe are selected,and the framework of the ultrasonic online detection system is constructed.Mechanical structure and inspection software.The mechanical structure mainly includes three parts: coupling water tank,floating detection mechanism and probe calibration mechanism.The detection software has the functions of ultrasonic pulse signal waveform display,scanning result display,parameter adjustment,data storage,defect alarm,etc.Chapter 5 Design-based ultrasonic online inspection system for welded pipes and experimental detection of artificial defect samples.The experimental results show that the ultrasonic critical refraction longitudinal wave can effectively distinguish the inner and outer wall defects of the thin-walled welded pipe,and the detection accuracy is high.The floating ultrasonic flaw detection equipment designed in this project has perfect functions and reliable operation,and meets the requirements of ultrasonic online automatic flaw detection of thin-walled stainless steel welded pipes.The ultrasonic flaw detection technology and flaw detection equipment developed in this project can realize all-round detection of the base metal and weld seam of thin-walled austenitic stainless steel welded pipes,which indicates that the application of ultrasonic flaw detection technology in the field of welded pipe flaw detection has broad prospects.Strong engineering value.