Which acceptance criteria is used during magnetic particle testing?

During magnetic particle testing (MT), the acceptance criteria are primarily visual. This method relies on the observation of the magnetic particles that accumulate at surface and near-surface discontinuities in ferromagnetic materials. The visual inspection is crucial because it allows for the identification of surface defects such as cracks, laps, seams, and other irregularities that may compromise the integrity of the material being tested.

The effectiveness of magnetic particle testing lies in the contrast between the indications created by the magnetic particles and the background of the surface being inspected. The inspector must be trained to recognize acceptable versus unacceptable indications based on established visual criteria, which may include size, type, and distribution of the defects.

Understanding that magnetic particle testing is distinctly different from other inspection methods such as radiography, X-ray, or ultrasonic testing emphasizes the importance of visual criteria, which are specifically tailored for the indications produced in this particular nondestructive testing technique.