Liquid Penetrant Testing (PT)

Liquid Penetrant uses the property of capillary action to find surface breaking discontinuities in a variety of materials. Penetrant testing uses a low viscosity liquid (penetrant) that is applied to the surface of a test piece. Liquid Penetrant Inspection uses this capillary action to allow the penetrant to enter into fissures and voids that are open to the surface. After a dwelling time the excess penetrant is removed, any remaining penetrant in the voids will flow back out exposing the indication. There are a variety of techniques included in liquid penetrant testing available depending on the type of inspection and the type of flaws a technician is aiming to find.

Advantages of Liquid Penetrant Testing Techniques:

  • Ease of use
  • Can be used on a variety of material types
  • Part geometry does not affect test
  • Very portable

Disadvantages of Liquid Penetrant Testing Techniques:

  • Good for surface indications only
  • Requires a very clean part
  • Careful cleaning of part important so indications don’t get covered
  • Post-test clean-up can be a chore
  • Possible misinterpretation of flaws

It is highly recommended that proper training in the liquid penetrant method be received and Texas NDT Academy is the place for that cutting edge learning. This method is one of the core elements of TXNDT. Some of the other courses offered are Magnetic Particle Testing, Ultrasonic Testing and Visual Inspection.