Magnetic Particle Test is a form of non-destructive testing for aerial devices. It involves magnetizing the device and applying metal particles to reveal flaws. How are imperfections detected?

• A. Imperfect areas attract the metal particles to the flaw.
• B. Visual inspection only.
• C. Hydrostatic pressure testing.
• D. Ultrasonic testing.

Answer: (A)

In magnetic particle testing, imperfections are detected because magnetizing the part creates a magnetic field that leaks at flaws. Surface and near-surface defects disturb the magnetic circuit, producing a leakage field. When metal particles are applied, they are drawn to these leakage areas and gather at the flaw, forming a visible indication that shows where the defect resides. This adherence of particles to the flaw is what makes the imperfection detectable.

Other methods shown in the options operate differently: visual inspection alone cannot reveal subsurface flaws; hydrostatic pressure testing checks for leaks under pressure but doesn’t produce surface particle indications; ultrasonic testing uses sound waves to image internal features rather than attracting particles.