Design Of Automatic Inspection System For Pipeline Girth Weld TOFD Detection

Pipeline known as the great arteries of the modern industry and the people life, which has great importance to safeguard national energy security and to protect the economic construction and the life of the people. Because of the impact of human factors or in the course of the operation by the media,pressure and other factors, the butt weld, as the most vulnerable place of pipeline, may appear different degrees of defects in the process of installation and welding, which affect the safe in operation of pipeline. In order to ensure the in-service pipeline operation safely, stably and effectively, it is necessary to carry out nondestructive inspection on a regular basis.The traditional manual nondestructive testing has been the main means of industrial pipeline inspection in the past few years. With the improvement of industrial automation, automatic nondestructive testing has become a research hotspot. In many of the nondestructive testing, ultrasonic testing has become the main technology for automatic nondestructive testing because of its own characteristics. As the advantages of high detection efficiency, good repeatability and so on, automatic ultrasonic testing is becoming more and more popular.Based on the engineering application research project of Chinese Special Equipment Inspection and Research Institute - Manufacture of feedback pipeline automatic scanning device, using the diffraction time difference method (TOFD) ultrasonic testing technology, we designed the automatic scanning device. The scanner equipped with TOFD probe to detect the pipe girth weld in service automation. The main research work is as follows:(1) The paper analyzed the research status of pipeline girth weld automatic scanning system at home and abroad; compared the advantages and disadvantages of several types of structure automatic scanner. Aiming at the shortcomings of the existing automatic scanners, such as complex structure,large volume and inflexible, we designed an automatic scanning device with more flexible, convenient, small and exquisite. The scanner uses magnetic wheel adsorption type car structure, compared with the existing automatic scanning device, we added a CCD to realize automatic tracking function, and at the same time, using the automatic rectification and wireless control, made it easy to operate.(2) Completed the design of mechanical structure and key components of the scanner.(3) Through the design of the main controller module, CCD acquisition module, motor drive module, wireless remote control module and power conversion module, we completed the circuit schematic. Finally, fabricated the PCB board and welded the relevant components to complete the design and production of the whole hardware circuit system.(4) Planned the control process of the scanner, realized CCD tracking control and PWM motor control through the programming with using black line extraction algorithm and PID control algorithm. Established the motor model to simulate the performance of the motor, and established the Simulink model of the system in the Matlab software to simulate the performance of the entire control system, the simulation response curve satisfies the requirements of fast response time and stable operation.(5) Experiments were carried out in the laboratory environment and the industrial field, which verified the requirements of the automatic scanning machine to meet the requirements of the industrial field test.