3angles Non Destructive Testing
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Magnetic Particle Testing
Magnetic Particle Testing (MT) is a nondestructive testing method of revealing surface and subsurface discontinuities in magnetizable materials. This is accomplished by inducing a magnetic field in a ferromagnetic material and then applying the surface with iron particles (either dry or suspended in a liquid). Surface and near-surface flaws disrupt the flow of the magnetic field within the part and force some of the field to leak out at the surface. Iron particles are attracted and concentrated at sites of the magnetic flux leakages. This produces a visible indication of defects on the surface of the material.
An example where 3angles uses magnetic particle testing is for the inspection of steam turbine rotors. The turbine rotor is magnetized by performing a 'head shot' to be able to detect indications in the axial direction. Depending on the size of the rotor we will utilize one of our mobile power units with a capability to generate up to 10,000 AMPS direct current. The inspection of the tangential direction is accomplished by longitudinal magnetization using a 3-turn coil. Other components where we typically perform MT are diaphragms, casings, shells and certain valve parts.
We also perform Magnetic Particle Testing on our wet bench unit which has the capability to magnetize parts using up to 5,000 AMPS DC. This unit is mostly used for the inspection of new machined parts and components. The unit has a set-up to perform a head shot as well as using a 5-turn coil to magnetize parts.
MT indication on blade dovetail
MT wet-bench for in-house inspections