There are many kinds of quality inspection methods for LSAW pipe, among which the physical method is also the most commonly used inspection method, and the physical inspection is the method of using some physical phenomena for determination or inspection. Material or welded pipe internal defects in the inspection, are generally used non-destructive flaw detection methods. The current non-destructive testing has a magnetic flaw detection, ultrasonic flaw detection, ray detection, infiltration detection.
Magnetic inspection
Magnetic flaw detection can only find defects on the surface and near surface of the magnetic welded pipe, and the defects can only be quantitatively analyzed, and the nature and depth of the defects can only be estimated empirically. Magnetic inspection is the use of magnetic field magnetization of ferromagnetic welded pipe produced by the magnetic leakage to find defects. According to the different methods of measuring magnetic leakage, it can be divided into magnetic powder method, magnetic induction method and magnetic recording method, in which the magnetic powder method is the most widely used.
Penetration test
Penetration test is to use the permeability of certain liquids and other physical properties to find and show defects, including coloring test and fluorescence detection of two kinds, can be used to check the ferromagnetic and non-ferromagnetic material surface defects.
Radiation flaw detection
Ray flaw detection is the use of radiation can penetrate the material and in the material has the characteristic of attenuation to find defects of a flaw detection method. According to the different rays used in flaw detection, can be divided into X-ray flaw detection, γ-ray flaw detection, high-energy ray flaw detection. As it shows the defects of different methods, each ray detection are divided into ionization method, fluorescent screen observation method, photographic method and industrial television method. Radiographic inspection is mainly used to test the welded pipe weld internal cracks, unwelded, porosity, slag and other defects.
Ultrasonic flaw detection
Ultrasonic waves in the metal and other uniform media propagation, due to the interface in different media will produce reflection, so it can be used for internal defects inspection. Ultrasonic can test any weldment material, any part of the defects, and can be more sensitive to find the location of the defects, but the nature of the defects, shape and size is more difficult to determine. Therefore, ultrasonic flaw detection of straight seam welded pipe is often used in conjunction with ray inspection.
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