Five nondestructive testing of UT RT MT PT ET

Nondestructive testing is widely used in the field of industry. The technology does not destroy parts or materials, can be detected on site directly with high efficiency. At present, the most common non-destructive testing there are five kinds:

• UT (Ultrasonic Testing)
• RT (Radiographic Testing)
• MT (Magnetic Particle Testing)
• PT (Penetrant Testing)
• ET (Eddy Current Testing)

Ultrasonic testing for butt welding 90 degree elbow

UT (Ultrasonic Testing)

In a certain speed and direction,this mechanical wave can transmit in the material. And it will produce reflection when it encounters a heterogeneous interface with different acoustic impedance. Heterogeneous interface could be a defect or a bottom surface of the object being measured. This reflective phenomenon can be used for ultrasonic flaw detection.

RT (Radiographic Testing)

This is the most basic and prevalent NDT method.

1 X-ray characteristic: X-ray is a photon. Its electromagnetic wave are short, the wavelength of 10~10cm.

2.The principle of X-ray image formation is: the difference between the characteristics of X-ray and the density and thickness of the parts.

penetrant testing or dye penetrant inspection or liquid penetrant inspection for large caliber elbow weld

MT (Magnetic Particle Testing)

Magnetic particle detection can only detect the surface of ferromagnetic materials or near-surface defects. Because the magnetic traces are accumulated on the detected surface, so can visually display the discontinuous shape, position and size. It also can determine the general attribute.

The sensitivity of magnetic particle detection can reach 0.1μm by the discontinuous width. With multiple magnetization methods, the size and geometrical shape of workpiece nearly can not effect the magnetic particle detection. What’s more, it can detect defects in all directions of the workpiece.

It suits the Nondestructive testing for Stainless Steel Fittings especially.

PT (Penetrate Testing)

The basic working principle of Penetration detection:

Capillary action of liquid.

Luminescence phenomenon of solid dyes under certain conditions.

Therefore, Penetration detection is to check if there is coated dye penetrates the surface of the workpiece. If there is a defect, the traces of the penetrate will appear under a certain light source. It detects the appearance and distribution of defects.

ET (Eddy Current Testing)

Place coil with alternating current on the metal plate or pipe. At the same time, an alternating magnetic field is generated in and around the coil. Then the specimen produced a vortex-like induction alternating current, known as Eddy Current.

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