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Seamless steel pipes commonly used NDT methods

Oct 26, 2016

Conventional non-destructive testing methods: radiography, magnetic particle (or MFL) testing, penetration testing, ultrasonic testing and Eddy current testing.

1 seamless steel tube radiographic testing (RT)

One of the earliest methods of non-destructive testing, is widely used in metal and non-metal materials and products for internal defects testing, at least more than 50-year history. It has incomparable advantages, namely test defects, reliability and intuitiveness, radiographic and will be used for defect analysis and as a quality document archive. But this way there are more complex, higher-cost disadvantage, and should pay attention to radiation protection.

2 seamless steel tube magnetic particle testing (MT) or magnetic flux leakage testing (EMI)

The detection principle is based on the ferromagnetic material is magnetized in a magnetic field, the discontinuity of the materials or products (defect), magnetic flux leakage, magnet powder adsorption (or detected by detector) was revealed (or displayed on the instrument). This method can only be used for ferromagnetic materials or surface or near-surface defects testing of products.

3 seamless steel tube penetration test (PT)

Includes fluorescent, colored in two ways. Because of its simple, convenient operation, is for lack of magnetic particle inspection test effective methods for surface defects. It is mainly used for inspection of surface defects of non-magnetic material.

Principles of fluoroscopy are checked products will be immersed in a fluorescent liquid, due to capillary phenomenon of seamless steel tubes, filled with fluorescent liquid in the defect, get rid of the liquid on the surface, due to light-induced effects, liquid fluorescent under ultraviolet light revealed defects.

Dye penetrant inspection of the theory and principles of fluoroscopy is similar. Is no need for special equipment, just use defects Imaging powder adsorption in liquid coloring in manifest suction surface defects.

4 seamless steel pipe ultrasonic testing (UT)

This method is the use of ultrasonic vibration to find materials or parts inside (or surface) defects. Depending on the ultrasonic vibration method can be divided into CW and pulsed wave; according to the different modes of vibration and propagation can be divided into p-wave and s-wave and surface waves and lamb waves 4 form in the workpiece spread; according to the different sound transmission and reception conditions, and can be divided into single probe and probe.

5 seamless steel tube for Eddy current testing (ET)

Eddy current detection of alternating magnetic field produces the same frequency of the Eddy current in the metal, using the Eddy-current the size relationship between the resistivity of metallic materials and to detect defects. When surface defects (cracks), the resistivity will increase the presence of defects, associated with Eddy-current is reduced accordingly, small change after enlargement of the Eddy current instruments indicated, will be able to show the existence and size of defects.