PRINCIPLE
Magnetic Particle testing is a surface inspection applicable to magnetic materials such as carbon steel. This NDT method is based on inducing a magnetic field in parts and then looking for leakage magnetic field caused by surface discontinuities. During MT testing, a magnetic field is applied and magnetic particles sprayed (wet) or dusted and floated (dry particles). An accumulation of magnetic particles is an indication of potential discontinuity.
EQUIPMENT
The two requirements for conducting magnetic particle testing are: (a) method of magnetization of the part and (b) selection of the magnetic media. Magnetization methods include coils to produce longitudinal magnetization, passing current directly through the part to produce circular magnetization, and yokes, etc. Magnetic mediums include fine high permeability particles coated with visible or fluorescent dyes. Particles can be dry powder or in a wet suspension. Other auxiliary equipment includes pie gauge, shims, Gauss meter and a 10 lb weight to test AC yokes.
APPLICATIONS
Applications include inspection of welds, pipes, shafts, turbines, forgings, etc.
INDUSTRY CODES
ASTM E709, ASME V Article 7
TRAINING
MT Level II (includes Level I), Duration – 24 hours
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