Liquid Penetrant Testing

Liquid penetrant testing (PT) detects surface-breaking discontinuities by applying a penetrant liquid that is drawn into open flaws by capillary action. After a dwell time, the excess penetrant is removed and a developer is applied, drawing the trapped penetrant back to the surface as a visible indication.

Arc Inspection Services offers both visible dye penetrant (red/white system) and fluorescent penetrant testing under UV light. Fluorescent PT provides higher sensitivity and is preferred for aerospace, precision machining, and critical pressure boundary components. Visible PT is ideal for field conditions where UV illumination is impractical.

PT is the method of choice for austenitic stainless steels, aluminum, titanium, and other non-ferrous alloys that cannot be inspected by magnetic particle testing. It is widely used for weld inspection in food, pharmaceutical, petrochemical, and power generation applications where material cleanliness standards are strict.