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Dye Penetrant Inspection (DPI)

Dye Penetrant Inspection (DPI)

Dye Penetrant Inspection (DPI)

Dye Penetrant Testing (DPT) or Liquid Penetrant testing is the most common NDT technique used to detect surface-breaking discontinuities.

This non-destructive testing technique, also known as dye penetrant testing is a cost-effective method to locate is discontinuities in the test specimen it is a viable option when the surface to be tested requires a high amount of sensitivity. This method is commonly used to detect discontinuities that are open to the surface like undercut, porosity, LOP, LOF, cracks, etc. DPT can be applied to all ferrous, non-ferrous, and all non-porous materials.
It is commonly used to detect defects in the manufacturing process. ANDT works with all industry sectors including, power generation, aerospace, petrochemical and oil and gas, construction, marine applications we can provide dye penetrant inspection (DPT) on-site at our customer’s premises or at our highly modern laboratories.

The method is also useful for testing on-site as it is portable (usually due to spray canisters) and when applying certain techniques such as visible method contrast there is no need for additional resources such as electricity, water, or ultraviolet light source. This makes it highly convenient for inspecting surface discontinuities.
The tested item is first cleaned before the penetrant is applied, penetrant can be applied in a variety of ways like dipping, spraying, or brushing. The penetrant is given time to soak into any defects, the penetration time (dwell time) dependent on the chosen penetrant and customer requirement.
Afterward, the excess penetrant is removed and the component is dried depending on the process used. Then a developer is applied. The developer helps to draw the penetrant out of the flaw and onto the surface to form a visible indication this retrieval of penetrant back to the surface from the crack is known as Blotting action. A visual inspection is then performed under ultraviolet or white light, depending on the type of penetrant used.
Classification of penetrants is by their sensitivity levels and content when selecting a penetrant, factors such as environment under which the test is to be performed, surface finish, size of defects sought, chemical stability, flash point, and the size to the part are considered.

Our Quality Assurance techniques for dye penetrant inspection include:

  • Visible solvent removable

  • Water washable

  • Post emulsifiable

ANDT’s well-qualified personnel hold a minimum of Level II in ASNT and are highly experienced in performing dye penetrant inspection.  
By choosing ANDT for dye penetrant inspection, round-the-clock testing as well as a regional collection and delivery service, reliable inspection. We can provide the inspection service that will ensure your products or equipment is fit for purpose and meets national and international standards, as well as our highly train manpower, are also best in class for inspection or training in today’s highly regulated markets.


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