Rail Head Crack Detection
Magnetic particle inspection reveals cracks at and just beneath the surface of ferromagnetic material. The rail is magnetised and fine magnetic particles are applied; where a crack interrupts the magnetic field, the particles gather along it and the defect becomes directly visible as a sharp line. It is one of the most sensitive methods available for surface-breaking cracks in steel.
Why rail head crack detection matters
Cracks in the rail head begin small and grow under repeated wheel loading. Caught early, the response is grinding or planned replacement of a section; missed, the same defect can develop into a transverse break under traffic. Magnetic particle inspection is fast, requires no complex instrumentation, and shows the crack itself rather than an instrument reading — which makes it well suited to examining a specific location where damage is suspected.
What it detects
Where it is applied
- ●Rail head and running surface examination
- ●Rail ends and bolted joints
- ●Locations flagged by earlier inspection
- ●Post-grinding verification
DELIVERED USING MAGNETIC PARTICLE (MT)
Applicable Standards
SANS 3577-3, ASTM E709
Professional Equipment
Magnaflux Yokes, UV Lamps, Fluorescent Particle Systems
Common questions
Why is this used on rail rather than dye penetrant?
Rail is ferromagnetic steel, which is exactly what magnetic particle inspection is designed for, and it is both faster and more sensitive on that material — including for cracks that are very tight or slightly sub-surface. Dye penetrant is the method for non-magnetic materials.
Will the inspection damage or mark the rail?
No. The rail is magnetised temporarily and the particles are removed afterwards. Nothing is cut, drilled or permanently altered.
Can it find defects deep inside the rail?
No — it is a surface and near-surface method. For defects within the body of the rail head, ultrasonic testing is the appropriate technique, and the two are often used together.
Where we deliver it
MPIA Services is based in Durban (also known as eMkhomazi), KwaZulu-Natal, and carries out rail head crack detection on site across all nine South African provinces. Mobile field units travel to the asset, so the work happens in place — on live rail corridors, in yards and depots, and at industrial sites — rather than requiring components to be sent away. See where we work.
Need rail head crack detection?
Tell us the asset, the standard you need to satisfy and where the work is. We will come back with scope, timing and a quotation.
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