What is Liquid Penetrant Testing?

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, each dependent 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 is vital, otherwise indications could be obscured
  
• 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.