Methods Of Multi-channel Ultrasonic Automatic Testing For Thick-wall Steel Pipes

Thick-walled steel pipes are widely used in industrial fields,playing a role in manufacturing,construction,transportation,exploration and so on in all walks of life.However,in the process of production,the loose organization and slag of the material make the steel pipe have defects such as foldings,cracks and delaminations that reduce the quality of the steel pipe.That make the steel pipe difficult to play the due role,causing security risks.So it is very important to make the research for the defect defection of the thick steel pipe.In this paper,to solve the ultrasonic testing technical problems in the steel pipe whose thickness-to-diameter ratio is greater than 0.3,using the way of analyses of the detection principle and practice verification to test area defects,longitudinal defects and the transverse defects of the steel pipe in helical scanning method.By choosing the manual probe frame,using the big conical head tips,ventilation of the multi-channel ultrasonic transceiver device,replacing the original warning light and other ways,hardware devices are optimized and detection function become better.According to its module division,the testing software can achieve the waveform display,defect scanning,data management and other functions.The area defects of the steel pipe are very small.So it is very difficult to test them in a high speed.That makes area defects become the key to limit the detection efficiency.This paper optimizes parameters and uses four probes to test area defects.Using the sum of the area defects' effective detection width of the four probes to replace the focal spot diameter of the probe,which satisfies the demand of the scanning coverage.Improving the detection efficiency and defects detection rate by optimizing the pitch and other parameters.The steel pipes containing the longitudinal and transverse defects are also tested a lot and the testing results are good.For the steel pipe containing periodic structure,in order to make the longitudinal defects and periodic structure distinguished and avoid interference of the periodic structure's signals.Compiling the display module of developed view and using imaging technology of developed view to show the scanning results clearly.So the longitudinal defects and the periodic structure can be distinguished.And the area defects and transverse defects are also scanned in the developed view to make researches.