Status Analysis of API 5L Seamless Steel Pipe
Date:2018-04-12 View:946 Tag:Status Analysis of API 5L Seamless Steel Pipe
The characteristics of API 5L seamless steel pipe are large diameter and thick wall thickness, so the "no blind spot" detection is realized by the combination of ultrasonic testing eddy current and internal and external surface detection function according to this characteristic. By using the "steel pipe rotation to detect the positive combination of probes", we not only solve the problem of heading detection, but also solve the space occupied by reducing the space.
Therefore, magnetic flux leakage testing or water pressure testing is usually used for seamless steel pipe inspection at home and abroad. In China, the production of seamless magnetic flux leakage testing equipment has no good performance. Once it is used, it needs to be imported. Imported magnetic flux leakage testing equipment is expensive, most of the domestic enterprises are difficult to accept, and the hydraulic test efficiency is low, the labor intensity is big, especially when the operator's responsibility is not high, the hydraulic test is only nominal. Obviously, the realization of large caliber seamless steel pipe inspection has become an urgent problem for metallurgical steel pipe industry.
The ultrasonic inspection of the sink is made of steel screw and ultrasonic probe. The thickness of the coupling layer is completely coupled to the bottom of the steel pipe to ensure the same thickness. However, because of the main detection of surface defects and subsurface defects, there is a blind spot, which can not be detected, and the spiral type is used, and the 12m long steel pipe needs 30m space and other defects, which affects the selection and popularization of the steel inspection method.
The circumferential surface of the surface of the steel tube is measured through the direct eddy current. When using straight through eddy current testing, the larger the diameter of the detected pipe, the larger the coil area of the circle will be, and the lower the signal-to-noise ratio. It is for this reason that eddy current testing standard adopts cross flow eddy current testing, and its external economic scale should not exceed 140mm. Besides, it is difficult to detect seamless tubes by type, magnetization and demagnetization.
At present, the testing of seamless steel tubes in high pressure boiler in China's metallurgical industry is mainly concentrated on the following specifications (160mm), and most of the traditional direct through eddy current testing or single vertical tank ultrasonic testing methods. For the seamless steel pipe above 160mm, there are many terms to be detected by the traditional through eddy method, which is also not allowed by the national standard. If independent ultrasonic testing is adopted, there is a blind spot of ultrasonic detection mechanism in depth, which can not guarantee the reliability of the whole detection result.