The Design Of An Automatic Ultrasonic Testing Scanner With Feedback For Pipeline Weld

The industrial pipeline is the basic equipment of modern industry. Under the harshworking conditions, kinds of defects are hidden in the girth welds. In order to guarantee thesecurity and reliability of the in-service pipeline, the pipeline girth weld needs to be inspected.The traditional manual inspection techniques has been gradually replaced by the modernautomatic ultrasonic testing because of its high efficiency, low probability of missing defects,and excellent scanning repeatability. With the rapidly increasing of industry develop in ourcountry, the requirement of testing equipment is also raised by the enterprise. In order toimprove the applicability, reduce the cost and break the monopoly of the scanning device, it isnecessary to design an ultrasonic testing scanner which comes up to the industry standard ofour country.This paper did research on the mechanical structure and control system of the girth weldsultrasonic testing scanner based on the applied base class research project of China SpecialEquipment Inspection and Research Institute:“Research on the automatic ultrasonic testingscanners for pipeline”. The main contents of this paper are as follows:(1) Established overall design scheme and scanning process of ultrasonic testingscanning device according to the technical requirement of the device. Research and designhave been done on the technology of the mechanical structure of scanning device andsoftware diagram of control system.(2) Researched on the technology of the static model of the scanner to make sure that theadsorption of scanning device is reliable and dependable. Deduced the magnetic force formulaof magnetic wheel at random position. Worked on minimum torque of the motor whenscanning device is running.(3) Based on the traditional structure of magnetic wheel, analyzed how adsorption forceis affected by guide wheel thickness, steel plate thickness, magnetic permeability andmagnetic force separately on ANSYS. And therefore the better cost performance one has beendesigned. (4) In order to prevent the device from deviating the preset orbit in complex environmenton the tube wall, offset correction has been added to the scanner, as well manual andautomatic correction manner. If the scanner deflected substantially, the wireless controller canbe used to correct by man. Otherwise, the linear CCD sends the real-time offset to themicrochip, and then the speed of the motors will be modified until the offset reduces to anacceptable error. The control algorithm of PID is used in the microchip to make sure thesignals sent to motors could lead to correct the offset accurately and timely. Simulating ofmotor’s speed before and after the correction and experiments of testing defects of girth weldshave been done.