What is a common limitation on prod spacing of less than 76.2 mm (3 in.) during magnetic particle testing?

In magnetic particle testing, prod spacing refers to the distance between the conductive prods that are used to create an electrical current in the test material. When the spacing between the prods is less than 76.2 mm (3 in.), one of the common limitations is that the particles tend to bend around the prod instead of being attracted directly to the area of interest.

This bending effect occurs because the magnetic field generated by the prods can create non-uniformities in the magnetic flux. As a result, the magnetizing field is less effective in drawing particles to potential defects located in the material. Instead, the magnetic particles may be deflected away, leading to a lack of accumulation at critical areas, which can ultimately result in missed defects.

Understanding this limitation is crucial for ensuring effective magnetic particle testing. Proper management of prod spacing helps maintain the integrity of the testing process and assures that any defects present can be properly identified.