Magnetic Particle Testing
Detect surface and near-surface discontinuities in ferromagnetic materials with high sensitivity.
Overview
Magnetic Particle Testing (MT) is a fast, highly sensitive method for detecting surface and near-surface discontinuities in ferromagnetic materials. By inducing a magnetic field and applying fine ferrous particles, MT reveals flux leakage at defects with striking visual clarity — often catching cracks that PT can miss in painted or thinly coated surfaces.
How the method works
When a ferromagnetic part is magnetised, any discontinuity transverse to the magnetic field creates a leakage flux at the surface. Iron particles — wet or dry, visible or fluorescent — accumulate at these leakage zones and form a clear visual indication of the defect.
MT is uniquely effective at finding sub-surface defects up to ~3 mm deep, including lack of fusion in welds, fatigue cracks under coatings, and forging laps. Yoke, prod, and coil techniques each suit different geometries and access conditions.
Because MT is fast and minimally invasive, it is widely used for in-service inspection of structural welds, lifting gear, and rotating equipment where downtime must be minimised.
Why AUTRESONUS for MT
- Certified Level II MT inspectors with deep experience on weld and structural assets.
- Full range of techniques available: AC/DC yokes, prods, coils, wet fluorescent, and dry visible.
- Calibrated UV-A lamps and reference blocks verified before every campaign.
- Integrated MT + PT + VT inspection programmes for complete surface coverage.
- Proven track record on lifting gear certification and statutory inspection regimes.
Key Benefits
- High sensitivity to surface and shallow sub-surface defects
- Fast inspection cycles — ideal for production environments
- Effective on weld toes, HAZ, and fatigue-prone areas
- Minimal surface preparation required
- Works through thin coatings (typically up to 50 μm)
- Fluorescent wet MT delivers exceptional contrast under UV-A
Our Inspection Process
- 1
Surface prep
Light cleaning to remove loose scale, rust, and heavy contamination.
- 2
Magnetisation
Apply field via yoke, prod, or coil — direction selected to suit expected flaw orientation.
- 3
Particle application
Apply wet fluorescent or dry visible particles while field is active.
- 4
Inspection
Examine under white light or UV-A at code-required intensity; mark indications.
- 5
Demagnetisation & report
Demagnetise component, document findings with photos and accept/reject.
Applications
- Structural and pressure-retaining welds
- Crankshafts, drive shafts, and rotating components
- Lifting equipment, crane hooks, and shackles
- Forgings, castings, and billets
- Pipeline weld inspections in the field
- Subsea and offshore structural assets
Codes & Standards
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