Quality inspection for Seamless steel pipe
Seamless steel pipe quality inspection
Quality inspection is a very important part of the seamless steel pipe production process. High-quality seamless steel pipes must pass a rigorous inspection process. Here are five methods for quality inspection of seamless steel tubes.
1, Ultrasonic testing
The non-destructive inspection method for the flaws in the seamless steel tubes was examined by using the effect of the difference in the acoustic properties of the seamless steel tubes and their internal defects on the propagation of the ultrasonic waves, and was represented by the symbol UT.
2, eddy current testing
A flaw detection method that uses the principle of electromagnetic induction to detect flaws on the surface and near surfaces of seamless steel tubes and is represented by the symbol ET.
It is a more powerful tool for rapid detection of bulk. Therefore, even not limited to large-caliber thermal expansion seamless steel tubes, it has become an indispensable means for all kinds of steel inspection. The automatic eddy current detection method is mainly applied to a point probe detection method for the quality inspection of a steel pipe and a method for detecting a probe through a probe.
The former method uses point probes to detect the longitudinal defects of steel tubes at high speed. The detection speed is determined by the number of probes and the rotation speed. Generally speaking, the detection speed is relatively slow. The latter detects the transverse defects of the steel tubes through the probe. This method is simple and the detection speed is high. Fast (usually up to 60m/min). In addition, due to the extremely sensitive pair of through holes in the eddy current testing method, the main method of the relevant standard is to replace the pipeline hydrostatic test.
3, magnetic flux leakage testing
The surface of the seamless steel tube is magnetized, and the leakage magnetic field of the defect is picked up to form the electrical signal of the defect. The non-destructive inspection method for finding the defect is represented by the symbol LT.
4, magnetic particle inspection
A magnetic flux flaw detection method, a method of non-destructive inspection using a phenomenon in which a leakage magnetic field of a ferromagnetic material is generated in a strong magnetic field and adsorbs magnetic powder, is represented by the symbol MT.
Magnetic flux leakage flaw detection is performed by applying a magnetic field to a seamless steel tube to make it magnetized (globally magnetized or partially magnetized). A magnetic flux escapes the surface of a seamless steel tube at the surface and near surface defects of a seamless steel tube to form a leakage magnetic field. In the presence of the magnetic powder applied on the surface of the seamless steel pipe, an aggregated magnetic mark can be formed and the presence of defects can be exhibited. Magnetic particle detection methods are widely used, mainly to detect defects on the surface or near surface of seamless steel tubes.
5, ray detection
A flaw detection method using rays to penetrate an object to detect defects inside the object is indicated by the symbol RT.
The main application of ray detection is to detect the macroscopic geometric defects (detection) inside the seamless steel tube. The radiography method is the most basic and most widely used ray detection method. Ray detection is suitable for most types of steel pipes. Radiographic inspection of the seamless structure of the internal structure of the seamless steel pipe can generate visual images, qualitative and quantitative accuracy, test results recorded directly, and long-term preservation.
Ultrasonic detection and ray detection are mainly used for the detection of flaws inside seamless steel tubes. Magnetic particle detection, penetration detection, and eddy current testing are mainly used to detect the surface and near-surface defects of seamless steel tubes.
Of course, in order to verify the mechanical properties of the seamless steel pipe meet the requirements of the standard, we should carefully prepare the test sample of the mechanical properties of the seamless steel pipe. Mechanical properties tests include tensile strength, yield strength, elongation, impact energy, and so on. Process performance tests include crush test, flaring test, hydrostatic test, curl test, cold bend test, and perforation test. These test items are based on different standards and different uses of seamless steel tubes.
In short, in order to obtain high-quality seamless steel tubes, we must carry out rigorous testing of multiple methods and steps for each seamless steel tube.
