Study On Key Techniques Of Automatic Testing And Measurement System For Tubing

Tubing is widely used in oil, chemicals, mechanical and boiler industry. With the view of improving products'quality, and reducing the number of industrial accidents, enhancing the economic efficiency, it is of great significance to design a nondestructive testing system for tubing.After analyzing the status of non-destructive testing methods and systems at home and abroad, the author develops a magnetic flux leakage (MFL) testing system for Multi-sized pipe according to the requirements of the tubing users and producers, which can detect transversal and longitudinal flaws and measure the wall thickness and length of the tubing.Two motion modes: straightaway mode and spiral mode are used to transmit the tubing. In comparison with the two modes, the spiral motion mode are selected and the method of calculating its'key parameters is proposed. The transversal magnetization is studied and the two-coil open magnetization is proved more suitable for the system. Bar-like transversal probe and its'installation machine are designed which can be used for testing multi-sized tubing and make its'operation easier and its'costs lower.Wall thickness and length must be measured according to the improved API testing standards for tubing quality. Consequently the magnetic measurement of wall thickness is introduced and the axial magnetization and circumferential magnetization are used together in practice to measure the wall thickness, which can take an online, high-speed, continuous and accurate measurement of the wall thickness. A simple method of measuring the tubing length is studied and it can meet the requirements of low precision length measurement.The testing application is development according the testing requirements and the algorithm for the measurement of length and wall thickness is mainly discussed. Further more, the application of the MFL testing system is provided, including installation, use, operation, experiment etc. It has been proved to be of high sensitivity, high signal-to-noise ratio, good repeatability and stability by practical application.