Dye Penetration Testing

Dye Penetrant Testing

Langley Alloys can offer dye penetrant inspection (‘dye pen’) by our team of experienced operators. It is a relatively low-cost method to check for surface defects in a variety of components. Also known as liquid penetrate inspection due to the use of a liquid dye to highlight surface features, it is usually applied to castings or forgings where there is the potential for manufacturing defects to exist. However, Langley Alloys has also undertaken dye pen testing on machined components, forged fittings and seamless tubes in accordance with precise customer specifications.

‘Dye pen’ inspection exploits capillary action, whereby a liquid is drawn in to small breaks or cracks that may exist in the surface. Firstly, the dye is applied to the clean surface of the item, by brush, spray or immersion. It is allowed to sit for a period of time, typically up to 30 minutes, before excess dye is removed. A second solution, called the developer, is then applied in our case by aerosol spray. Again, it is left to ‘develop’ as it absorbs the liquid dye that has been held in any surface breaks and thereby highlights their location and approximate size. Visual inspection is carried out in a well-lit space usually, although UV light may be used for certain dyes to increase the resolution.

Langley Alloys undertakes dye penetrant inspection in-house, within our main warehouse. That way we can offer a responsive service, adding negligible time to the processing of our customer orders. In addition, it is more cost-effective than relying upon third-party inspectors who will also incur significant travel costs and time. When combined with ultrasonic testing (UT), which identifies internal defects and features, it allows us to provide greater security of a products quality covering a wide range of product forms and sources.

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