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Liquid Penetrant Testing
One of the most effective methods to reveal surface-breaking cracks and flaws in almost any type of material.
What it is
Liquid penetrant testing is one of the best methods for detecting surface-breaking discontinuities in ferrous and non-ferrous metals, aluminium, alloys, ceramics, glass and some plastics.
The method is based on capillary action: thanks to its low surface tension, the liquid enters extremely small openings. It is also used to detect leaks in pipes, tanks and welded joints.
How the test works
- CleaningThe surface is cleaned and dried, removing oil, paint and dirt that could block openings.
- Penetrant applicationThe liquid is applied to the area to be inspected.
- Dwell timeThe liquid is given time to enter the discontinuities by capillary action.
- Excess removalPenetrant left on the surface is carefully removed.
- DevelopmentThe developer is applied and draws out the trapped liquid, revealing the flaws.
- Evaluation and final cleaningIndications are evaluated and recorded, and the part is cleaned.
Where we apply it
- Propellers and naval components
- Welded joints
- Cast, forged and machined parts
- Non-magnetic materials such as stainless steel and aluminium
- Leak detection in pipes and tanks
What it detects
- Surface-breaking cracks
- Surface porosity
- Laps and folds
- Surface-breaking lack of fusion
Advantages
- Works on almost all non-porous materials
- Simple, portable and low cost
- Indications visible directly on the part
- Handles complex geometries
Limitations and precautions
- Only detects surface-breaking flaws
- Requires thorough cleaning before and after the test
- Not suitable for porous materials
Frequently asked questions
Does liquid penetrant testing work on stainless steel and aluminium?
Yes. Unlike magnetic particle testing, it does not require a magnetic material, so it is widely used on stainless steel, aluminium and other alloys.
Does the test damage the part?
No. It is a non-destructive test: after inspection the part is cleaned and remains fit for use.
Shall we inspect your equipment?
On site, in the workshop or at your supplier, with a technical report at the end.