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Module 7. Maintenance practices

Which of the following NDT methods requires that the surface of the test piece is cleaned down to bare metal?

  • Eddy Current.
  • Magnetic Particle.
  • Dye-penetrant.

Explanation

Dye penetrant relies on the dye entering surface-breaking defects, so the test surface must be cleaned down to bare metal with no paint, plating or coating that could bridge over and hide the openings. Eddy current and magnetic particle can tolerate thin coatings and do not require removal down to bare metal in the same way.

keithanddave asking:

Why is this not eddy current?

Community Comments (2)

T
trap2307 Posts: 43 21.05.2013 / 19:13
Hello!
Because Eddy current method is only for detecting internal cracks of material. But before using the Dye-penetrant method, the surface should be cleaned.
B
bragithor Posts: 1 27.04.2015 / 14:39
The removal of paint is not always required in Dye-Penetrant testing

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