Liquid Penetrant Testing is one of the most common surface crack detection in regular use. The Dy-Mark Flawchek Crack Detection System makes use of the Colour Contrast method for detecting fine cracks, flaws and surface discontinuities in welded metalwork. The process for applying the Colour Contrast method is as follows:
The first step is to ensure that the surface being tested is clean and free from all contamination e.g. grease, oil, rust and paint. Spray the test area with the Dy-Mark Flawchek Cleaner, wipe the surface with a cloth and allow the area to dry thoroughly.
In the second stage of the process, a penetrating liquid is applied to the surface of the weld to be tested. After Dy-Mark Flawchek Penetrant has been applied, it must then be allowed to “dwell” for at least 10 minutes. The “dwell” time is a predetermined soak period that allows for the adequate penetration of the liquid penetrant into any surface breaking discontinuities. Allow excess Penetrant to drain and wipe over the test area with a cloth.
The third step is to remove any excess Penetrant with a liquid solvent. With Dy-Mark Flawchek Remover, wipe surface to remove excess Penetrant and allow the area to dry thoroughly.
The final stage in the surface crack detection process is the application of a developer to draw out any penetrant left behind within any surface discontinuities. Using Dy-Mark Flawchek Developer, spray a light coat over the area to be inspected – avoid leaving a heavy film. The Developer should be left to dry and then the area inspected for flaws after 2-3 minutes. If very fine flaws are suspected, the parts should be re-inspected after 20 minutes.
