Magnetic Particle Testing

Magnetic Particle Testing (MT)

Magnetic Particle Testing

Magnetic particle testing, or MT, is a very sensitive, nondestructive testing method used on rigid materials like iron, cobalt, nickel and their alloys. It’s one of the fastest, most cost-efficient ways to ensure that critical elements like pipes or pipe welds are safe and ready to be used.

Minuscule cracks or discontinuities lead to fatigue – and, eventually, to failure of the part. MT can detect even the smallest surface cracks, and certain subsurface issues, as well. That’s helped make this method of inspection the industry standard.


Any ferrous metal object that is magnetized becomes surrounded by an invisible magnetic field. If there is a crack or hole in the object, that magnetic field is disrupted. During magnetic particle testing, metal shavings are applied to the object, and they are attracted to these disruptions.

As they cluster around a crack, or “flux leakage field,” these shavings provide a visible indication of the flaw’s size and shape. Particles are chosen in order to best contrast with the color or darkness of the metal being tested. If there are no flaws, the shavings remain evenly distributed across the magnetic field.

MT is used in two variants: wet and dry. Wet MT allows the metal shavings to move more freely over surfaces. Dry MT is especially practical when testing pipes where high temperatures prevent using liquid.


Magnetic particle testing provides real-time results, and equipment portability makes it ideal for field inspections. That’s why a number of different industries now use MT to determine the fitness of a component. Examples include the petrochemical, structural steel, power-generation, automotive and aerospace industries.

This process is useful when underwater inspections are required, including structures like offshore oil wells and submerged pipelines. MT is also employed as an inspection method on fasteners, automotive parts, castings, weldments and forgings, among other components.


Are you in need of magnetic particle testing? USINDT’s mobile darkrooms bring any needed materials to you as part of a full suite of testing, inspection and certification services for the construction, manufacturing, power generation, oil and gas, aviation and infrastructure sectors.