Dye Penetrant Testing

Dye Penetrant Inspection (DPI) / Liquid Penetrant Inspection (LPI) / Fluorescent Penetrant Inspection (FPI)

Dye Penetrant Inspection, also known as Penetrant Testing (PT), Liquid Penetrant Inspection (LPI) or Fluorescent Penetrant Inspection (FPI). It is a method that is used to reveal surface breaking flaws by bleed out of a coloured or fluorescent dye from the flaw. Dye Penetrant Inspection can be used on almost any non-porous material.

The technique of Dye Penetrant Inspection is based on the ability of a liquid to be drawn into a clean surface-braking flaw by capillary action. After a period of penetration time, excess surface penetrant is removed and a developer applied. This draws the penetrant from the flaw to reveal its presence. Colour contrast penetrant requires good white light while fluorescents need to be used in darkened conditions with an ultraviolet light (also known as Black Light).

It is essential that the material is carefully cleaned first, otherwise, the Dye Penetrant Inspection penetrant will not be able to enter the defect. If surface penetrant is not fully removed, misleading indications will result.

Dye Penetrant Inspection (DPI) Facilities

InCon have designated Bays for DPI testing at our Test House and specialise in fast turnaround of items in for a test, often on a ‘while you wait for’ basis if need be. Items are returned back to Clients in the same clean state as we receive them in.

DPI testing is also a very simple test which is easily carried out on site, our Technicians are all dual qualified in PCN / ASNT and produce computerised reports on site at the time of a test. DPI Testing is normally carried out in conjunction with other NDT methods to produce a comprehensive Inspection Service.

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