The Digital Magnetic Nondestructive Testing Technique and Its Applications
Nondestructive Testing (NDT) plays an important role in the prevention of failure. So, NDT techniques are widely used in processing, manufacturing and in-service inspection. As a conventional nondestructive testing method, magnetic particle inspection is widely used in industries. During the magnetic particle inspection, magnetic particle is the sensor measuring flux leakage due to defects in ferric materials. It is difficult to store the test results. So if the magnetic sensors such as the hall element, sensing coil, are adopted to measure the magnetic field, the electrical signals can be obtained and transformed to the digital signal by the A/D converter. And then they can be stored in computer and analyzed by the signal processing software. This is the digital magnetic nondestructive testing. In this paper, we focus the discussion on the magnetic NDT technique, particularly, on the employment of the digital technology into the magnetic NDT. The basic content of the digital magnetic NDT is described, which includes magnetic testing technique, analog preprocessing and digital signal processing techniques. Producing and measuring the magnetic field signal are the two basic parts of the digital magnetic NDT. The signal analysis and processing is the core of this inspection technology. The crucial characteristic of this technology is the synthesis of the new material, new element, new principle and information processing based on the computer. The importance of the digital technology is emphasized in the magnetic testing. Then the two primary types of digital magnetic NDT equipments are developed in order to meet the diverse requirements of different fields. One is the portable equipments used in the testing of sucker rods, oil pipes and coiled tubes at the well sites. The other is the fixed digital magnetic NDT unit capable of inspecting new and used oil country tubular goods. The testing unit mentioned above can detect the cracks with 0.3mm deep, the through-hole with 1.6mm diameter and the corrosion with 2~4％ wall-thickness loss.
nondestructive testing magnetic flux leakage oil country tubular goods sucker rod magnetic field sensor
WU Xinjun XU Jiang KANG Yihua
School of Mechanical Science and Engineering Huazhong University of Science and Technology, Wuhan, 430074, P.R. China
国际会议
北京
英文
2007-08-05（万方平台首次上网日期，不代表论文的发表时间）