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Liquid Penetrant Testing

Detecting Flaws on Non-porous Surfaces

Liquid penetrant inspectionLiquid penetrant testing, also known as liquid penetrant inspection, dye penetrant testing, penetrant testing or LPI, is reliable for detecting surface-breaking flaws in materials with a non-porous surface such as metals, plastics, glass and ceramics. This method relies on a fluorescent or visible dye penetrant seeping into a flaw such as a lap, seam, fracture or crack to form a surface indication that can be evaluated under special lighting.

Penetrant Testing to Meet Your Requirements

Laboratory Testing Inc. is PRI Nadcap accredited for liquid penetrant inspection and provides a certified test report with each order. Both Fluorescent and Visible Dye Penetrant Testing are provided.

  • Orders are processed with the highest quality Magnaflux testing materials.
  • Water-washable and post-emulsifiable fluorescent penetrants in sensitivity levels 2, 3 and 4 are available to meet your specification or application.
  • NDT technicians are certified to meet industry requirements:
    • Liquid penetrant testing stationsASNT SNT-TC-1A
    • NAS410
    • MIL-STD-2132
    • Pratt & Whitney PWA-NDTQ
  • Products up to 25 ft. in length can be tested.

Test Methods/Specifications

  • ASTM E1417
  • MIL-STD-6866
  • MIL-STD-271
  • MIL-STD-2132

The Liquid Penetrant Testing Process

Before performing a liquid penetrant test, the surface of the test material must be thoroughly cleaned to remove any contaminants that could prevent the penetrant from entering flaws. Etching may be required if mechanical operations such as machining, sanding, or grit blasting have been performed on the item.

A fluorescent or red visible dye penetrant is applied to the cleaned test material, then it is left on the surface for a sufficient time to allow penetrant to seep into a defect. After this dwell time has elapsed, the excess penetrant is removed from the surface. Next, a thin layer of developer is applied to the item to assist in drawing penetrant trapped in flaws back to the surface where it will be visible as indications. The test item is viewed under special lighting so any indications can be evaluated according to the liquid penetrant testing specification or customer requirements. When performing fluorescent penetrant testing, indications must be viewed under darkened conditions with a high-intensity UV lamp.

LTI’s equipment includes three large liquid penetrant testing dip tanks, a 25 ft. dwell tank for pipe, tubing, bar, etc. and a large testing room with three high-intensity black lights.

LTI Capabilities

  • Dye Penetrants – Magnaflux brand
    • Visible dye
    • Fluorescent – water-washable and post-emulsifiable penetrants in sensitivity levels 2, 3 and 4
  • Products Tested – metals and other non-porous materials
  • Size Availability – ability to test materials up to 25 feet long
  • Certified NDT Level 2 and Level 3 Inspectors – evaluate all test results