API 5L seamless tube is characterized by large diameter and thick wall thickness. Therefore, according to this feature, we can make full use of the combination of ultrasonic eddy current and internal and external surface detection functions to achieve "no blind spot" detection. By using "steel tube rotation, probe forward combination", not only the problem of detection title is solved, but also the space occupied by reducing space is solved.


Therefore, magnetic flux leakage testing or water pressure testing are generally used for seamless pipe testing at home and abroad. In China, the seamless magnetic flux leakage testing equipment produced does not have good performance, once used, it needs to be imported. Imported magnetic flux leakage testing equipment is expensive, which is unacceptable to most domestic enterprises. Moreover, hydraulic test is inefficient and labor intensive. Especially when the operator's responsibility is not high, hydraulic test is nominally the only one. It can be seen that the inspection of large diameter seamless steel pipe has become an urgent problem to be solved in the metallurgical steel pipe industry.


The ultrasonic detection of flume is carried out by steel spiral and the ultrasonic probe is fixed. The thickness of the coupling layer is guaranteed to be the same through the complete coupling between the tank and the bottom of the steel tube.  However, due to the main detection of surface and internal surface defects, whether there are blind spots, leading to undetectable, coupled with spiral use, for 12 m long steel pipe needs 30 m space and other shortcomings, affecting the selection and promotion of steel testing methods.


The circumferential surface of the steel pipe surface is inspected by eddy current through the coil. When using through coil eddy current inspection, the bigger the diameter of the detected pipeline, the bigger the coil area of the detection circle, and the lower the signal-to-noise ratio. It is for this reason that the eddy current testing standard adopts the eddy current testing through the coil, and its external economic size should not exceed 140 mm. In addition, it is difficult to magnetize and demagnetize seamless tubes through type tests.


At present, the seamless steel tube inspection for high pressure boilers in China's metallurgical industry mainly concentrates on the following specifications, i.e. 160mm, and most of the traditional eddy current inspection through coils or independent groove ultrasonic inspection methods. For seamless steel pipes over 160mm, the traditional straight-through eddy current method has many titles, which are not allowed by the national standards. If the independent ultrasonic testing is used, there is a certain depth of blind spot in the ultrasonic testing mechanism, which can not guarantee the reliability of the overall testing results.