Dye Penetrant Inspection

NATA Accredited Dye Penetrant Inspection

Dye penetrant inspection is a non-destructive surface test method designed to aid the visual inspection of surface breaking discontinuities. Parts being inspected using this method first need to be thoroughly cleaned to remove any surface grease, oil, paint, scale or other contaminants which may mask any surface breaking discontinuities.

Once the surface has been thoroughly cleaned and dried, the penetrant material is applied by spraying, brushing, or immersing the part in a penetrant bath. The penetrant is left on the surface for a sufficient time to allow as much penetrant as possible to be drawn into any discontinuities breaking the part surface. The excess penetrant is then removed from the surface of the sample while removing as little penetrant as possible from any discontinuity.

Depending on the penetrant system used, this step may involve cleaning with a solvent, direct rinsing with water, or first treating the part with an emulsifier and then rinsing with water. A thin layer of developer is then applied to the sample to draw penetrant trapped in flaws back to the surface where it will be visible. Developers come in a variety of forms that may be applied by dusting (dry powdered), dipping, or spraying (wet developers).

The developer is allowed to stand on the part surface for a period of time sufficient to permit the extraction of the trapped penetrant out of any surface flaws. This development time is usually a minimum of 10 minutes. Significantly longer times may be necessary for tight discontinuities. Primary Applications:

  • Inspection of material after grinding for the detection of cracks or remaining corrosion.
  • Inspection of non-magnetic/non-metallic materials e.g. SS316, plastics etc
  • Inspection of large or batch components.

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