Penetrant Testing (PT)

Any invisible surface-connected discontinuities such as cracks, pores, incomplete fusion of joints on almost all kind of materials can be detected by means of naked eyes. Liquid penetrant is applied on surface of materials to penetrate surface-connected discontinuities, and then absorbed by applying a developer to reveal the discontinuities. The developer shows line marks on cracks and round marks on pores.


Closed defects (surface-disconnected discontinuities) cannot be detected by this method. Not applicable to porous and uncleaned materials.


Application processes respectively, (1) Pre-cleaning, (2) Application of penetrant, (3) Waiting for penetration, (4) Removal of exceeding penetrant with inter-cleaning, (5) Development, (6) Inspection, (7) Evaluation and report preparation, (8) Final-cleaning.



  • TS EN ISO 3452-X: Non-destructive testing – Penetrant testing.
  • TS EN ISO 3059: Non-destructive testing – Penetrant testing and magnetic particle testing – Viewing conditions.
  • TS EN 10228-2: Non-destructive testing of steel forgings – Part 2: Penetrant testing.
  • TS EN ISO 23277: Non-destructive testing of welds – Penetrant testing – Acceptance levels.
  • TS EN ISO 10893-4: Non-destructive testing of steel tubes – Part 4: Liquid penetrant inspection of seamless and welded steel tubes for the detection of surface imperfections.
  • TS EN 1371-1: Founding – Liquid penetrant testing- Part 1: Sand, gravity die and low pressure die castings.
  • TS EN 1371-2: Founding – Liquid penetrant testing – Part 2: Investment castings.