Dye Penetration Test

A Dye Penetration Test, or otherwise known as Dye Penetrant Test, “PT” or Liquid Penetration Test; is one of the most basic Non Destructive Examinations (NDE) or tests that can be performed on a completed weld.  A visual look at a completed weld may not tell if there are defects in a weld.  By performing a dye penetration test, one is able to visually observe imperfections on a welding more easily.  It involves pouring a liquid dye over a weld and letting it seep into any tiny crevice that is present.  The liquid is then washed away and a spray (called a “developer”) is then applied over the weld.  When the developer dries, it pulls out the dye within the crevice and the defect can then be seen where the dye comes out.  However, this method can only detect surface flaws and will not tell you the condition of the weld below the surface.  For that, you will need to use other tests like the Radiography Test or the Ultrasonic Test.  The advantage of this test is that is is cheap and easy to perform.

This short video shows from YouTube shows how a Dye Penetration Test is done.