Liquid Penetrant Testing (PT)

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Penetrant Testing (PT) inspection services

MISTRAS’ Penetrant Testing (PT) inspection services find surface-breaking discontinuities on relatively smooth, nonporous surfaces.

Penetrant Testing (PT) – also known as liquid penetrant inspection (LPI) or dye penetrant testing – is based on the properties of surface wetting and capillary action, which causes a liquid to rise when confined to a small opening. After applying the penetrant and wiping away the excess, the penetrant that rises to the surface can indicate surface-breaking anomalies.

MISTRAS' PT services are widely applicable to identify discontinuities in a variety of assets given its ease of use and minimal equipment requirements. Our technicians perform PT on assets in a variety of industries, with a wide range of shapes, sizes, and materials, including:

  • Metals
  • Composites
  • Glass
  • Ceramics
  • Rubber
  • Plastics

MISTRAS uses multiples forms of penetrant inspections to find defects in rolled products, castings, forgings, and welds:

  • Solvent-Removable: useful for small, localized areas
  • Water-Wash Removable: used for rough, uneven, and large surface areas.
  • Wet Fluorescent: sensitive to smaller flaws than other LPI methods

Our certified PT inspection technicians select the penetrant method based on sensitivity levels, job and site conditions, and other variables.

Penetrant Testing (PT) Inspection Applications

Penetrant testing is a popular non-destructive testing (NDT) technique because of its low cost and flexibility.

In PT, assets do not have to be disassembled or removed from the facility for inspection, making the inspection process quick and efficient.

MISTRAS utilizes PT inspections in the field and in the lab for assets in the oil & gas, aerospace, power generation, infrastructure, and manufacturing industries.

Traditional visual inspection (VT) can miss small defects that are not yet visible to the naked eye. However, even the smallest leaks, cracks, and other flaws can waste costly resources, adding up to huge losses for your facility.

PT identifies both visible and seemingly invisible discontinuities, giving you important information for repair and maintenance planning. Though not the most advanced NDT technique, PT inspection can be used as a tool to identify the presence of defects that require more in-depth analysis and quantification.

MISTRAS uses penetrant testing to inspect:

  • Rolled Products: Anomalies, such as cracks, seams, or laminations
  • Castings: Cold shuts, hot tears, porosity, blow holes, or shrinkage
  • Forgings: Cracks, laps, or external bursts
  • Welds: Cracks, porosity, undercut, overlap, lack of fusion, or lack of penetration

Penetrant Testing (PT) Inspection Benefits

The main advantages of penetrant testing include:

  • Relatively easy to use
  • Highly-sensitive to small discontinuities
  • Applications for a wide range of material types
  • Large areas or large volumes of parts/material can be inspected rapidly and at low cost
  • Parts with complex geometries can be inspected easily
  • When using visible dye penetrants, indications are produced directly on the surface of the part, providing an immediate visual indication of the anomaly
  • Aerosol spray cans can make equipment very portable

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