Magnetic Particle Inspection (MPI)

Magnetic Particle Inspection (MPI) is a fast, reliable and cost-effective NDT method for detecting surface-breaking and near-surface defects in ferromagnetic materials. QMS Asset Integrity delivers NATA-accredited MPI services using AC magnetic flow techniques across a wide range of industrial assets.

MPI is essential for weld toe cracking detection, fatigue crack identification on structural members, and quality verification during fabrication. Our technicians are experienced across the oil and gas, marine, mining, and manufacturing sectors, performing both workshop and field inspections to support your asset integrity programme.

The method is particularly valuable during shutdown inspections and turnarounds where rapid, reliable surface inspection of critical welds and components is required.

MPI works by inducing a magnetic field in the ferromagnetic test piece using an electromagnet, yoke, or prods. If a surface or near-surface discontinuity is present, it disrupts the magnetic flux and creates a leakage field at the surface. Fine ferromagnetic particles - applied as a dry powder or in a liquid suspension - are attracted to this leakage field, forming a visible indication that reveals the size, shape and orientation of the defect.

QMS uses AC magnetic flow techniques, which are optimal for detecting surface-breaking defects. Inspections can be performed under white light (visible contrast particles) or UV-A light (fluorescent particles) for enhanced sensitivity.