Various defects in the manufacturing process of precision welded pipes can generally be found in the production through flattening, flaring or hydrostatic testing, but there are also some defects, especially internal defects, which are difficult to find and judge by visual inspection, but may be found in Appears during use or during cold working. Therefore, it is necessary to set up non-destructive testing on the production line to find the defects of the product in time. From the perspective of high production efficiency of the welded pipe unit, batch low-quality welded pipes can be avoided, and the quality of the finished product at the factory and the quality of the subsequent cold processing can also be guaranteed.

There are many methods for non-destructive testing of steel pipes. The most commonly used for welding precision steel pipes are ultrasonic, eddy current or magnetic leakage detection. Eddy current flaw detection is suitable for surface defects of metallic materials and defects near the surface; magnetic flux leakage detection is used for surface defects and internal defects of a certain depth. Ultrasonic flaw detection can find slender defects, the top of the weld is not welded through, the hidden cracks and the cracks in the heat affected zone of the center of the weld can be correctly found and determined. Through non-destructive testing, it is detected that the welded seam of the welded pipe has not been welded through, has not melted, contained slag, bubbles, shrinkage cracks, and has longitudinal and longitudinal strips and delaminations on the inner and outer surfaces.

There are two levels of non-destructive testing. The first level is on-line testing, which is placed in the sizing section, and is used to monitor the quality of welds. The second level is non-destructive testing of finished steel pipes, which requires testing of the entire pipe to ensure product quality.