Magnetic Particle Testing

How magnetic particle inspection works

When a ferromagnetic component is magnetised, a surface or near-surface crack disrupts the magnetic flux and creates a small leakage field at the surface. Fine magnetic particles applied to the area migrate to this leakage field, forming a visible indication that outlines the crack. Fluorescent particles under ultraviolet light further increase sensitivity.

The method is particularly effective on welds, where fatigue cracks typically initiate at the toe and root, and on highly-stressed members where surface-breaking defects are the first sign of trouble.

• High sensitivity to surface and near-surface cracks in steel
• Fast coverage of welds and structural members
• Fluorescent option for enhanced detectability
• Reliable on the ferromagnetic materials common to cranes and EWPs

Where we apply it

Magnetic particle inspection is a primary NDT method in the five- and ten-year major inspection, applied to safety-critical welds and members. It is also used in failure investigation to confirm and delineate cracking, and in structural assessment of machines with uncertain history.

Reporting

Indications are located, photographed and reported against the acceptance criteria. Where a crack affects fitness for service, the finding drives the recommended repair or the wider engineering conclusion.