Magnetic Particle Testing (MT)

Trusted Detection for Ferromagnetic Materials

Magnetic Particle Testing (MT) is one of the most reliable and widely used non-destructive testing methods for detecting surface-breaking and shallow subsurface discontinuities in ferromagnetic materials such as carbon steel, low-alloy steel, and iron. The principle is straightforward yet highly effective: a magnetic field is induced in the test component, and finely milled ferromagnetic particles are applied to the surface. Where a crack, lap, seam, or other discontinuity interrupts the magnetic flux flow, the particles accumulate at the leakage field, forming a visible indication that maps the defect location, length, and orientation.

At Oil and Gas Plant Engineer Consultants, our certified MT technicians perform magnetic particle inspections across refineries, petrochemical plants, power stations, and fabrication workshops throughout South Africa. Whether you require pre-service weld acceptance testing during construction or in-service crack detection during a turnaround shutdown, our team delivers accurate, code-compliant results with rapid turnaround times.

MT is particularly valued in the oil and gas industry for its ability to inspect large weld lengths quickly and economically. It excels at detecting fatigue cracks, hydrogen-induced cracking, stress corrosion cracking, and grinding cracks in pressure-containing components — defect types that are critical to structural integrity and operational safety. Combined with its minimal surface preparation requirements and portability, MT remains indispensable for field and shop inspections alike.

• ASME V & BS EN ISO 17638 compliant procedures
• AC and DC magnetisation techniques available
• Wet fluorescent and dry powder methods
• Detects surface and shallow subsurface flaws

Why Choose MT Over Other Surface Methods?

When it comes to surface inspection of ferromagnetic materials, magnetic particle testing offers distinct advantages over liquid penetrant testing (PT) and visual inspection. While PT can detect surface-breaking flaws on any non-porous material, MT goes further by also revealing shallow subsurface discontinuities — defects that lie just beneath the surface and would be invisible to penetrant methods. This makes MT the superior choice for detecting inclusions, cold shuts, and hydrogen cracks that initiate below the surface.

MT is also significantly faster than PT. There is no dwell time required for penetrant to seep into flaws, no developer application wait, and no multi-stage cleaning process. A skilled MT technician using a yoke can inspect metres of weld per hour with immediate visual results. This speed advantage translates directly into reduced inspection costs and shorter shutdown durations — critical factors during plant turnarounds where every hour of downtime carries substantial financial impact.

Additionally, MT is less sensitive to surface condition than PT. Components with slightly rough surfaces, light mill scale, or thin paint coatings can still be effectively inspected using MT, whereas PT demands thoroughly cleaned and degreased surfaces. For in-service inspections in demanding industrial environments, this practical advantage makes MT the go-to method for ferromagnetic components across the oil and gas, petrochemical, and power generation sectors in South Africa.