Magnetic particles testing is performed using typically an electromagnetic yoke and a spray solution of iron particles in a solvent. The technique is suitable for surface breaking defects only and the surface prior to the inspection needs to be prepared by grinding/removing any coating, unlike the ACFM method.
In order to increase the optical contrast during the inspection depending on the inspection being performed either white light or fluorescent liquids are used. Depending on the method used either white light or UV light is used.
Magnetic particle testing is used to inspect various materials at different levels of the manufacturing process to determine if they are fit for use. It is also used to test materials that are in service to determine if they are fit to continue in service.
Testing is performed according to ASTM E1444, ASME V-7, ISO 9934.