Magnetic Particle Testing

Magnetic particle testing (MT) detects surface and near-surface discontinuities in ferromagnetic materials by inducing a magnetic field and applying fine ferromagnetic particles to the surface. Where a crack or void interrupts the magnetic field, a flux leakage occurs that attracts the particles and forms a visible indication.

Arc Inspection Services performs both wet and dry MT using AC yokes, DC prods, and coil magnetization techniques. Fluorescent wet MT under UV (black) light provides the highest sensitivity for fine surface cracks and is commonly specified for critical components such as lifting lugs, hook blocks, and crane structures.

MT is faster and more sensitive to surface cracks than penetrant testing on ferrous materials, making it the preferred method for weld toe cracking, grinding cracks, and heat-affected zone (HAZ) hydrogen cracking. It is widely specified for in-service inspection of lifting equipment, pressure vessels, and structural welds.