Dye penetrant inspection (DPI)
IRISNDT can provide both PCN and ASNT qualified technicians to carry out dye penetrant inspection using either the fluorescent, colour contrast, water washable, solvent based or submerged technique in one of our purpose built laboratories throughout the UK or at the client’s premises throughout Europe.
Dye penetrant inspection (DPI) is a widely applied inspection method used to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). The penetrant may be applied to all non-ferrous materials and ferrous materials, although for ferrous components magnetic-particle inspection is often used instead for its subsurface detection capability. LPI is used to detect casting, forging and welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks on in-service components.
The main advantages of DPI are the speed of the test and the low cost. Disadvantages include the detection of only surface flaws, skin irritation, and the inspection should be on a smooth clean surface where excessive penetrant can be removed prior to being developed. Conducting the test on rough surfaces, such-as as-welded welds, will make it difficult to remove any excessive penetrant and could result in false indications. Water-washable penetrant should be considered here if no other option is available.