Dye-penetrant inspection, also referred to as liquid penetrate inspection or penetrant testing, is a widely-applied and low-cost inspection method to check surface-breaking defects in all non-porous materials.
A form of Non-Destructive Testing (NDT), dye-penetrant inspection is based on capillary action. This means that low surface tension fluid is allowed to penetrate into clean and dry surface-breaking discontinuities. The penetrant is applied to the test component by means of dipping, spraying, or brushing.
After adequate penetration time has been allowed for, the excess penetrant is removed and a developer applied to draw the penetrant out of the flaw. This makes any hairline cracks visible to the naked eye. The inspection process itself is carried out under ultraviolet or white light, depending on whether the dye used is fluorescent or non-fluorescent.
Rope-access specialist Skyriders has been honing its NDT expertise since 2002, having received the stamp-of-approval from Eskom to conduct this specialist service at its power-station fleet. NDT forms part of a holistic Wear Failure System that forms part of Eskom’s maintenance and repair programme.
This ranges from visual inspection through to ultrasonic wall-thickness measurement and dye-penetrant or magnetic particle testing, to name a few. “All of these inspection methods are aimed at determining the current condition and any defects in the various components,” Skyriders Marketing Manager Mike Zinn explains.
Dye-penetrant inspection, in particular, was recently showcased at a major project for a large fertiliser plant in the Free State. Here a large structure with ancillary attachments had to be inspected thoroughly.
Skyriders worked as sub-contractor to SSA Acoustic & Specialised Inspections (Pty) Ltd. on this project. SSASI has specialised in delivering proven acoustic emission monitoring methodologies to their specific target market.
“The highly-specialised nature of the inspection work at height necessitated such collaboration,” Zinn explains. Skyriders focuses on providing its customers with complete solutions for all of their inspection and maintenance and repair needs.