Penetrant Testing – PT

NDTCause & Effect: Corrosion in Piping. Read more ... » Penetrant Testing (PT) is a very cost-effective method for locating surface anomalies in all non-porous materials. PT is utilized, in most cases, to detect welding, casting, and forging defects, such as cracks, leaks, and fatigue in test objects.

There are three major components to this testing method, including a cleaner, penetrant dye, and a developer, usually all applied via aerosol can. This step-by-step process includes: pre-cleaning of the surface, application of penetrant material (brushing, spraying, or dipping), dwell time to allow penetrant to fill any potential anomalies, penetrant removal, application of developer, inspection/evaluation, and a post clean of the penetrant processing material from the test object. NDT penetrant testing methods offered by Steel City NDT include:

  • Dye Penetrant Inspection (DPI)
  • Fluorescent Penetrant Inspection

Crack found utilizing Dye Penetrant method


NDT penetrant testing started in the 1890’s as the Oil and Whiting method. The oil was used as the penetrant and the whiting was a chalk dust suspended in alcohol used as the developer. The Oil and Whiting method was used by the railroad industry to detect large cracks in the components of the railway. The main advantage of this testing method is that it can be used on mostly any material, and the results will appear directly on the surface of the test object. This can be used on ferrous materials; however, it is mainly used on nonferrous materials, such as aluminum, titanium, and magnesium.

To learn more about our NDT penetrant testing services, contact us today: 1.855.638.2489.