Quality inspection method of straight seam welded pipe

Quality inspection method of straight seam welded pipe

There are many methods for quality inspection of straight seam welded pipes, among which physical methods are also the most commonly used inspection methods. Physical inspection is a method that uses some physical phenomena to measure or inspect. The inspection of internal defects in materials or straight seam welded pipes generally uses non-destructive testing methods. Current non-destructive testing includes magnetic testing, ultrasonic testing, radiographic testing, penetrant testing, etc.

Magnetic inspection
Magnetic flaw detection can only detect surface and near-surface defects of magnetic straight seam welded pipes, and can only quantitatively analyze the defects. The nature and depth of the defects can only be estimated based on experience. Magnetic inspection uses the magnetic flux leakage generated by the magnetic field to magnetize the ferromagnetic straight seam welded pipe to find defects. According to the different methods of measuring magnetic flux leakage, it can be divided into magnetic particle method, magnetic induction method and magnetic recording method. Among them, the magnetic particle method is the most widely used.

Penetration inspection
Penetrant inspection uses physical properties such as the permeability of certain liquids to discover and display defects, including coloring inspection and fluorescence inspection, which can be used to inspect defects on the surface of ferromagnetic and non-ferromagnetic materials.

Radiographic inspection
Radiographic flaw detection is a flaw detection method that uses the characteristics of rays to penetrate materials and attenuate in materials to find defects. According to the different rays used for flaw detection, it can be divided into three types: X-ray flaw detection, gamma ray flaw detection, and high-energy ray flaw detection. Due to different methods of displaying defects, each type of radiographic flaw detection is divided into ionization method, fluorescent screen observation method, photography method and industrial television method. Radiographic inspection is mainly used to inspect defects such as cracks, incomplete penetration, pores, and slag inclusions inside the weld of straight seam welded pipes.

Ultrasonic flaw detection
When ultrasonic waves propagate in metals and other uniform media, they will be reflected at the interfaces of different media, so they can be used to inspect internal defects. Ultrasound can detect defects in any weldment material and any part, and can more sensitively find the location of defects, but it is difficult to determine the nature, shape and size of defects. Therefore, ultrasonic flaw detection of straight seam welded pipes is often used in conjunction with radiographic inspection.
Standard control