Mechanical Engineering - Engineering Materials - Discussion

The correct answer is superficial defects.

The dye penetrant method, also known as liquid penetrant testing (LPT), is a non-destructive testing technique used to detect superficial defects on the surface of materials. It involves applying a coloured dye to the surface, allowing it to penetrate into any surface-breaking defects, and then wiping off the excess dye. The defects are then revealed by applying a developer, which draws out the trapped dye.

Dye penetrant testing is commonly used to detect:

- Surface cracks
- Porosity
- Pinholes
- Seams
- Other superficial defects

It is not typically used to detect:
- Core defects (internal defects)
- Temporary defects (defects that are not permanent)
- Subsurface defects (defects below the surface)

Other non-destructive testing methods, such as radiography, ultrasonic testing, or magnetic particle testing, may be used to detect internal or subsurface defects.

Dye penetrant inspection (DP), also called liquid penetrate inspection (LPI) or penetrant testing (PT), is a widely applied and low-cost inspection method used to check surface-breaking defects in all non-porous materials (metals, plastics, or ceramics).

THANKS, @Shashi Kant.

Actually DP Test used for welding test of different type of vessel plate for checking crack & blow holes at welded joints.

Procedure: First clean welded area, use Dye (red colour solvent PP-15) rest Penetrant time 10 min. Than after clean using cleaner (PC-21) and finally use developer (white colour solvent PD-31) for results. If there is any crack and blow holes occurs shown visible red colour.

If there is no blow holes and any crack shown welding is good.

Before dye penetrant is applied on the surface of specimen, it is cleaned by removing dust on the surface. Then the dye penetrant is applied on the surface of specimen. Then excess penetrant is removed. Then the developer is applied on the surface of specimen. If there is any defect on the surface, penetrant gets accumulated at the defect& defect is located.

How to locate surface defects?