Liquid Penetrant Testing – PT

Liquid Penetrant Testing (PT) 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.  PT is a non-destructive examination method used to locate surface breaking discontinuities in non-porous materials (metals, plastics, or ceramics).  This method may be applied to ferrous and non-ferrous materials, although for ferrous components magnetic-particle inspection is often used instead for its subsurface detection capability.


  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. CSA Z662 for pipelines
  7. In-service welds
  8. Ferrous and non-ferrous components


  1. High visibility of indications
  2. Low cost and fast results
  3. Field Ready
    – Highly portable tools can be used in most locations
    – Can operate with battery power as well as supplied power when available


  1. Can only detect surface flaws
  2. Conducting the test on rough surfaces, such as 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 generally operate best in the range of 4 °C to 52 °C (40 °F to 125 °F). Special procedure and penetrants can be used for temperatures outside this range but these must be qualified by a procedure test
  4. Test material must be relatively non-porous