Penetrant Testing is a non–destructive method for finding discontinuities that are open to the surface of solid and essentially non-porous materials. Indications of flaws can be found regardless of the size, configuration, internal structure, or chemical composition of work piece being tested and regardless of flaw orientation. Liquid penetrant can seep into (and be drawn into) various types of minute surface openings (reportedly, as fine as 4micro inch in width) by capillary action. Because of this, the process is well suited for the detection of all types of surface cracks, laps, porosity, shrinkage areas, lamination and similar discontinuities in casting, forgings, welds and other product forms. Dye penetrant inspection is used extensively for the testing of wrought and cast products of ferrous and non-ferrous metals, powder metallurgy parts, and ceramics and glass objects.

In practice, the liquid penetrant inspection process is relatively simple. Equipment generally is simpler and less costly than that for most other NDT methods .When used on ferromagnetic steels, in some instances, the sensitivity of liquid penetrant test is better than that of magnetic particle testing.


The major limitation of liquid penetrant testing is that, it can detect only imperfections that are open to the surface. Another factor that may inhibit the effectiveness of liquid penetrant testing is the surface roughness of the object being tested .Rough or porous surfaces are likely to produce false indication.

Liquid penetrant testing depends mainly on a liquid's effectively wetting the surface of a solid work piece of specimen, flowing over the migrating into cavities that are open to the surface.Closely related to wetting ability is the phenomenon of capillary rise or depression.

The liquid penetrant testing requires at least five steps:

  1. Surface preparation.
  2. Application of penetrant.
  3. Removed of Excess penetrant.
  4. Application of Developer.
  5. Observation and Reporting.

Liquid dye Penetrant inspection 

  1. Specialized stationery type penetrant inspection equipments for Aerospace NDT applications.
  2. Modern testing equipments perfectly equipped with various sensitivity penetrants and Water washable, post Emulsifiable penetrants for high sensitivity applications.
  3. High intensity black light kits for fluorescent inspection and demagnetizing equipments
  4. Liquid penetrant testing professionals are qualified and certified to PT Level I, II as per ASNT recommended practice SNT-TC-1A .
  5. Experienced in house ASNT NDT Level III consultants and experts for providing techniques establishment, procedure preparation, approval and consultancy services.
  6. ASNT NDT Level III trainers for conducting in house or external NDT Level I & II training and certification courses on Liquid dye penetrant testing and other NDT inspection methods. Read more about Liquid Penetrant Testing Personnel Certifications.
  7. Penetrant Testing Level 2 certified professionals to provide Liquid Penetrant testing services across India
  8. Sales and Supply of Dye penetrant inspection (DPT), penetrants, cleaners, solvents, developers and other consumables and accessories. Read more about sales of Liquid Penetrant inspectionchemicals and consumables

Penetrant Testing (PT) Images

Visible Penetrant