The magnetic traces are used to show defects in the ferromagnetic material and its products.
The magnetic particle inspection method can detect the exposed surface, and can not directly observe the small defects with the naked eye or with the aid of a magnifying glass. It can also detect the unexposed surface, but the near-surface defects buried a few millimeters below the surface.
The principle of flaw detection is that when the ferromagnetic steel tube is fully magnetized, the magnetic lines of force in the tube wall are blocked by defects at or near the surface, the magnetic lines of force at the defect are distorted, and a part of the magnetic lines leak out of the inner and outer surfaces of the steel tube. Leakage of the magnetic field.
An electromagnetic detection method that uses a detecting element to detect a leakage magnetic field to detect a defect, that is, a magnetic flux leakage test. When a detecting element located on the surface of the steel pipe and moving relative to the steel pipe picks up a leakage magnetic field and converts it into a defective electrical signal, a signal reflecting the defect is obtained through the probe, thereby determining the defect. The sensitivity of the flaw detection is the highest on the outer surface of the steel pipe and decreases from the outer surface to the inner surface as the wall thickness increases.
When the defect direction is perpendicular to the direction of the magnetic field line, the leakage magnetic field strength of the defect is the largest, and the detection sensitivity is also the highest. As the defect trend is skewed, the strength of the leakage magnetic field gradually decreases until the two directions are consistent, and the leakage magnetic field strength is close to zero. Therefore, when a longitudinal and lateral flaw detection device is used, it is not sensitive to the oblique defect reaction, and a blind angle region is easily formed.
Number of channels
F60~F168mm drill pipe
10％ corrosion pit
0-360 °step1 °
Drill pipe detection method
Drill pipe does not move, probe car forward and backward
The internal and external surface
100%15、detection blind zone：£100mm（drill pipe body）
F3.2mm through-hole(8 hole calibration)
Detection blind zone
£100mm（drill pipe body）
Position resolution accuracy
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