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Five detection methods for surface defects of thick-walled rectangular tubes
Date:2019-12-24      View(s):555      Tag:rectangular tubes

1. Eddy current detection

There are various methods of eddy current detection, such as conventional eddy current detection, far-field eddy current detection, multi-frequency eddy current detection, and pulse eddy current detection. Different types and shapes of defects on the surface of a rectangular tube can produce different types of signals. The invention has the advantages of high detection accuracy, high detection sensitivity and fast detection speed, can detect the surface and subsurface of the pipeline to be inspected, and is not affected by impurities such as oil on the surface of the rectangular pipeline to be inspected. The disadvantage is that it is easy to judge the defect-free structure as a defect, the false detection rate is high, and the detection resolution is not easy to adjust.


2. Ultrasonic inspection

When using ultrasonic waves to enter an object and encounter a defect, some sound waves will be reflected, and the transmitter and receiver can analyze the reflected wave and measure the defect very accurately. Ultrasonic inspection is often used for forgings inspection, but it is not easy to inspect complex shaped pipes. The surface of the inspected square torque tube needs to have a certain degree of finish, and a coupling agent is required to fill the gap between the probe and the surface to be inspected.


3. Magnetic particle detection

The detection principle of the magnetic particle method is to realize the magnetic field in the rectangular tube material. According to the interaction between the leakage magnetic field defect and the magnetic powder, when the surface and near surface discontinuities or defects, then the discontinuous or defective magnetic field lines A magnetic pole resulting from local deformation. Its advantages are equipment, high reliability and less intuitive investment. The disadvantages are high operating cost, defects cannot be correctly classified, and low detection speed.


4. Infrared detection

Through the high-frequency induction coil, an induced current is generated on the surface of the rectangular tube. Induced current causes more energy to be consumed in the defect area, resulting in local temperature rise. By detecting the local temperature in the infrared, the depth of the defect can be determined. Infrared inspection is generally used for the detection of planar defects, and is not suitable for the detection of uneven metal surfaces.


5. Magnetic leakage detection

The magnetic flux leakage detection method is very similar to the magnetic particle detection method, and its application range, sensitivity and reliability are stronger than the magnetic particle detection method.


The manufacturer of thick wall rectangular pipe reminds you that the surface of rectangular pipe can play a great role, which can improve the rust prevention ability of rectangular pipe. When monitoring the other party's rectangular tube, we can monitor in accordance with the above five points.

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