What is one of the main benefits of using liquid penetrant testing?

One of the main benefits of using liquid penetrant testing is its speed and cost-effectiveness. This method allows for a quick inspection process since it involves applying a liquid penetrant to the surface of the material, allowing it to seep into any cracks or defects. After a designated dwell time, the excess penetrant is wiped away, and a developer is applied to draw out the penetrant from the flaws, which are then visible as indications. This straightforward procedure can be performed relatively quickly compared to other non-destructive testing methods. Additionally, since the equipment and materials needed for liquid penetrant testing are generally low-cost and easy to obtain, it presents a cost-effective solution for detecting surface defects in various materials.

The other options highlight aspects that do not align with the significant benefits of liquid penetrant testing. For instance, there's no limitation to only non-metal surfaces; liquid penetrant testing can indeed be applied to both metals and other materials. Also, while it doesn’t require sophisticated equipment, more complex non-destructive testing techniques may demand advanced tools and settings. Additionally, the method is particularly effective for detecting surface flaws rather than deep internal ones, as because it relies on access to the surface of the material.