What is penetrant testing (PT)?
Dye Penetrant Inspection (DPI) is widely used to detect surface breaking flaws. This non-destructive testing technique, also known as liquid penetrant inspection (LPI), is a cost-effective method used to locate surface breaking flaws such as cracks, porosity, laps, seams and other surface discontinuities.
The test works by applying a visible dye to the surface and letting it sit for several minutes to penetrate cracks and imperfections.
Then excess dye is cleaned away and a developer is applied to pull remaining dye from the crack and highlight areas of concern.
The developer dries into a white powder, and red indications will appear on the surface where the penetrant has gone into a cavity or crack.
How to do the dye penetrant?
| Here are the steps for a dye penetrant test: | ||
| Step 1 | Clean | Coat the part to be inspected with cleaner or remover. Allow the cleaner to dissolve dirt or film. Wipe dry with a clean cloth. Repeat if necessary. |
| Step 2 | Apply penetrant | Spray or brush the part to be inspected with penetrant. Allow the penetrant to remain on the part for 10-30 minutes. |
| Step 3 | Clean way excess dye | Excess dye is cleaned away. |
| Step 4 | Apply developer | A developer is applied to pull remaining dye from the crack to highlight areas of concern. |
Dye penetrant testing is commonly used to inspect the surfaces of non-porous assets made out of ceramics, plastics, and metals, such as welds, castings, forgings, plates, bars, and pipes.
Advantages of dye penetrant inspection include:
- Large areas and large volumes of parts/materials can be inspected rapidly and at low cost.
- Parts with complex geometric shapes are routinely inspected.
- Indications are produced directly on the surface of the part and constitute a visual representation of the flaw.
Baoding Guokun, is a professional casting factory, mainly produding and exporting various metal castings in steel, iron, aluminum, bronze, etc. So the standard we used for PT is EN 1371-1, This European Standard specifies a liquid penetrant testing method for castings produced in conventional sand moulds, by gravity and low-pressure die casting, except for investment castings and high-pressure die castings.
This European Standard applies to all cast metals, except copper-tin and/or copper-tin-lead alloy castings, where copper is the major constituent.
I listed some standards as follows:
