Which technique is not acceptable for removing oil or grease prior to testing?

The technique of brushing the surface with a power wire brush is not acceptable for removing oil or grease prior to testing because it can introduce fine scratches or surface contaminants that may impact the results of the magnetic particle inspection. The method could also lead to the removal of small surface features that are important for detecting discontinuities.

In contrast, washing with a solvent and using a vapor degreasing method are effective ways to remove contaminants without altering the surface integrity. Dusting with chalk or talc and wiping may also be acceptable, although it’s not typically the first choice for oil or grease removal. Proper surface preparation is crucial in magnetic particle inspection, as contamination can obstruct the visibility of defects and lead to inaccurate inspection results. Therefore, maintaining surface quality while ensuring cleanliness is a priority, which validates why the use of a power wire brush is inappropriate in this context.