There are many kinds of quality inspection methods for large-diameter seamless pipes, and physical methods are also the most common inspection methods. Physical inspection is a method of using some physical changes to carry out measurement or inspection. The inspection of the internal defects of raw materials or large-diameter seamless steel pipes is generally carried out by non-destructive testing. At that time, non-destructive testing included magnetic testing, ultrasonic testing, non-destructive testing, penetration testing, etc.
Magnetic inspection
Magnetic flaw detection can only detect the defects of the surface and near-surface layers of magnetic large-diameter seamless steel pipes, and only qualitative analysis can be made for the defects, and the characteristics and depth of the defects are only possible based on work experience. Magnetic inspection is to detect defects by using the magnetic flux leakage generated by large-diameter seamless steel pipes that are magnetized by electromagnetic fields. According to the different ways of accurately measuring magnetic flux leakage, it can be divided into magnetic particle inspection method, induction coil method and magnetic description method. During this period, magnetic particle inspection method is the most widely used.
Infiltration inspection
Penetration inspection is to use some physical characteristics such as liquid water permeability to detect and show defects, including coloring inspection and fluorescent flaw detection, which can be used to inspect the surface defects of ferromagnetic materials and non-ferromagnetic materials.
NDT
Non-destructive testing is a flaw detection method that uses the characteristics of radiation penetrating chemical substances and attenuation coefficients in chemical substances to find defects. According to the radiation used in flaw detection, it can be divided into three types: X-ray flaw detection, gamma non-destructive testing, and high-energy non-destructive testing. Because of the different ways of presenting defects, each NDT is divided into hydrolysis method, display screen observation, photographic method and industrial TV method. Radiation inspection is mainly used to inspect the defects such as cracks, lack of penetration, blow holes, and welding flashes inside the welding of large-diameter seamless steel pipes.
Ultrasonic flaw detector
Ultrasound can be used to check internal defects because of the reflection surface generated on the pages of different materials in the transmission of metal materials and its uniform materials. Ultrasound can check the defects of all welding materials and all positions, and can find the direction of defects more comfortably, but it is difficult to recognize the characteristics, appearance and size of defects. Therefore, ultrasonic flaw detectors for large-diameter seamless steel pipes are often used in conjunction with radiographic inspections.