Status Analysis of API 5L Seamless Steel Pipe
Date:2018-04-04 View:1005 Tag:Status Analysis of API 5L Seamless Steel Pipe
API 5L seamless steel pipe is characterized by its large diameter and relatively thick wall thickness. Therefore, according to this feature, full use of ultrasonic eddy current detection and internal and secondary surface detection functions are combined to achieve a “no blind spot” test. By adopting the “steel tube rotation and detection probe forward combination”, it not only solves the problem of detection of the title, but also solves the space that occupies a narrow space.
Therefore, the detection of seamless steel tubes at home and abroad generally uses magnetic flux leakage detection or water pressure detection. In China, there is a poor performance of the seamless magnetic flux leakage testing equipment. Once used, it needs to be imported. Imported magnetic flux leakage testing equipment is expensive, and it is difficult for most domestic enterprises to accept; the hydraulic pressure test is inefficient and labor intensity is high, especially when the operator's responsibility is not high, and the hydraulic pressure test name actually exists. It can be seen that the inspection of large-caliber seamless steel tubes has become an urgent problem to be solved in the metallurgical steel pipe industry.
Sink ultrasonic flaw detection is using steel spiral forward, ultrasonic probe fixed. The characteristics of the thickness of the coupling layer are fully coupled to the steel pipe through the sink and the bottom, ensuring the same effect. However, due to the main detection of internal defects on the surface and in the presence of blind subsurface defects, resulting in undetectable, coupled with the use of spiral type, 12m-long steel tubes require 30m space and other defects, affecting the detection method and promotion of steel. s Choice.
The circumferential surface of the steel pipe surface is detected by coil eddy currents. When detecting the eddy current through the coil, the larger the diameter of the detected pipe, the larger the area of the coil detection coil, and the lower the signal to noise ratio. It is for this reason that the eddy current testing standard, which uses coil eddy current testing, has a foreign economic scale of no more than 140 mm. In addition, through the type test of seamless steel tubes, there is a certain degree of difficulty in the magnetization and demagnetization of steel.
At present, China's metallurgical industry, the detection of high-pressure boiler seamless steel pipe is mainly focused on the following specifications φ160mm, and most of the traditional through the coil eddy current testing or independent tank ultrasonic testing methods. More than φ160mm seamless steel pipe adopts the traditional eddy current test method and has many titles. It is also not allowed by national standards. If independent ultrasonic testing is used, there is a certain depth of mechanism for ultrasonic detection of blind spots, which does not guarantee the reliability of the overall test results.