Study of the Coating Thicknesses Effect to the Length of the Indication via Magnetic Particle Testing

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Parvinee Angboonta
Paisan Thongson
Prajak Angboonta

Abstract

This research aims to study the coating thicknesses on specimen effecting to the magnetic particle testing. The main studies variables are the coating thickness which study the three coating types, 1. White contrast coating, 2. Color coating, and 3. Lacquer coating. The research testes with the NA – 16 notch defect test bar of the wide size, the length size and the depth size 0.0060-inch, 0.0625-inch, and 0.0200-inch respectively. The experiment was conducted for indications on both uncoated test specimen and coated test specimen. The experiment tests the coated test specimen that has a low thickness until the thickness where a clear indication cannot be displayed. This research uses a ac – yoke for magnetizing the coated test specimen while spraying the fluorescent magnetic powder on the desired location to inspect. The images are recorded via a microscope at 30X magnification under UV – A light in a dark room.


The experimental results found that the thickness of the 3 types of coatings affected the amount of magnetic field intensity generated on the specimens of different coating thicknesses. The thickness of the coating that has the greatest and the least effect on the magnetic field strength are the white coating., the lacquer and the color coating respectively. The values of three coated types thickness affect the magnetic field strength are 61.19 µm, 73.63 µm, and 83.56 µm respectively. The coating thickness is acceptable when the length of the indication on the coated surface is at least 50% of the length of the corresponding indication prior to coating according to the Section V of ASME Code.

Article Details

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Research Article

References

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