Status Analysis of API 5L Seamless Steel Pipe

API 5L seamless tube is characterized by a large diameter, wall thickness is relatively thick, so according to this feature make full use of ultrasonic detection of eddy current and internal and secondary surface detection features combined to achieve "no blind spot" testing. Through the use of "steel pipe rotation, detection probe forward combination", not only solve the problem of detecting the title, but also solve the space occupied by narrowing the space.

Therefore, at home and abroad for the seamless pipe testing, the general use of magnetic flux leakage test or water pressure. In China, there is no good performance for the seamless magnetic flux leakage detection equipment produced, once the use of that need to import. Imported magnetic flux leakage testing equipment is expensive, the majority of domestic enterprises difficult to accept; and water pressure test efficiency is low, labor-intensive, especially when the operator responsibility is not high, the water pressure test in name only. Can be seen, to achieve large-diameter seamless steel pipe inspection has become a metallurgical steel pipe industry to be solved.

Sink ultrasonic testing is the use of steel spiral forward, ultrasonic probe fixed. Through the sink and the bottom of the steel pipe was fully coupled to the characteristics of the coupling layer thickness to ensure the same. But because the main detection of internal defects on the surface of the surface and sub-surface defects in the existence of blind spots, resulting in undetectable, coupled with the use of spiral-type, for 12m long steel pipe needs space 30m and other deficiencies, has affected the choice of steel detection methods and Promotion.

The through-coil eddy current detects a circumferential surface of the steel pipe surface. In the use of through-coil eddy current inspection, the greater the diameter of the pipe being detected, the greater the area of the coil to detect the circle, the lower the signal to noise ratio. It is for this reason, eddy current testing standards, the use of through-coil eddy current testing, the size of its foreign economy shall not exceed 140mm. In addition, the seamless pipe through the type of testing, the magnetization and demagnetization of steel and so there is a certain degree of difficulty.

At present, China's metallurgical industry for high-pressure boiler seamless steel pipe testing mainly concentrated in the following specifications φ160mm, and most of the traditional through-coil eddy current testing or independent tank ultrasonic testing method. For more than φ160mm seamless steel pipe using the traditional through-type eddy current method for testing, there are a lot of title, but also the national standards are not allowed. Such as the use of independent ultrasonic testing, the existence of a certain depth of the ultrasonic detection mechanism of the blind spot, can not guarantee the reliability of the overall test results.