In which NDT method is a liquid penetrant employed?

Liquid Penetrant Testing specifically utilizes a liquid penetrant as a key part of its methodology. This non-destructive testing (NDT) technique involves applying a liquid that can seep into surface-breaking defects such as cracks, pores, or voids in solid materials. After allowing the penetrant to dwell for a specified amount of time, excess penetrant is removed from the surface, and a developer is applied. The developer helps draw out the trapped penetrant from the defects, creating a visible indication that can be seen under ultraviolet light or with the naked eye, depending on the type of penetrant used.

This method is particularly effective for detecting very fine cracks in non-porous materials and is widely used in various industries, including aerospace, automotive, and manufacturing. The reliance on a liquid penetrant is what distinguishes this testing method from others, which use different principles and materials to detect flaws.