Liquid Penetrant Testing.

(P.T.)

Liquid Penetrant Testing (P.T) is a method of Non-Destructive Testing that is widely used on non-porous materials for the detection of discontinuities open to the surface of the material.

Alternate names may include: 

Dye penetrant inspection (DPI)

Liquid penetrant inspection (LPI)

Penetrant testing (PT)

Brief overview of the procedure:

Test objects are coated with a visible of fluorescent highly penetrating dye solution.

After adequate penetration time is allowed, the excess penetrant on the surface of the component is carefully removed, involving techniques that allow retention of penetrant that may have penetrated subsequent discontinuities.

A developer is applied, the developer aids in drawing out the penetrant from any flaws so that an indication of the flaw becomes visible.

The inspection is performed under ultra-violet or white light depending on the type of penetrant dye that is selected.