This type of inspection is used to identify forging, casting and welding surface defects. Such defects includes hairline cracks, surface porosity, leaks in new products, and service induced fatigue cracks. Liquid Penetrant Testing (PT) is a non-destructive testing method used to locate surface breaking discontinuities in non-porous materials, this method may be applied to ferrous and non-ferrous materials. However, for ferrous material components magnetic particle inspection is usually preferred.

 

Application DPT: 

1. Welds and weld overlays, castings and forgings, valves and their components, machined parts, pressure vessels, clad vessel linings, and structural steel.

2. New fabrication weld inspection.

3. Code compliant inspection.

4. ASME Section V for pressure vessels.

5. ASME B31.1 and B31.3 for piping

6. API 1104 for pipelines.

7. In-service welds.

8. Ferrous and non-ferrous components.

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Advantages:

1. High visibility of indications because of contrast.

2. Low cast and fast results.

Field Ready.

4. Highly portable tools can be used in most locations.

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Limitations:

1. Can only detect surface flaws.

2. Conducting the test on rough surfaces, such as fabricated welds, will make it difficult to remove any excessive penetrant and could result in false indications.

3. Penetrants are limited by temperature and special penetrants can be used for higher temperature ranges.

4. Test material must be relatively non-porous.

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Below are some pictures of inspection jobs conducted by Qualtech NDE: