What is a “false indication” in LPT?

A “false indication” in Liquid Penetrant Testing (LPT) refers to an indication that is not related to a genuine defect within the material but is instead caused by surface conditions that can mislead an inspector. This phenomenon occurs when surface irregularities, such as scratches, inclusions, or contaminants like oil or dust, interact with the penetrant material in a way that produces a signal resembling a defect. This can lead to incorrect conclusions being drawn regarding the integrity of the tested component.

Therefore, identifying and understanding false indications is crucial for accurate testing results in LPT. It highlights the importance of surface preparation and cleanliness before testing, as well as the need for trained personnel to differentiate between genuine defects and those caused by surface irregularities or contaminants.