NDT - Non-Destructive Testing

Impressive Welding offers a non destructive testing service to compliment our versatile metal fabrication shop. We have the facility to carry out MPI and DYE PEN testing on components and provide all the necessary documentation to PCN Level 2 for peace of mind. 

Providing a range of Non destructive testing services we can carry out on-site or in-house, including;

  • Inspections of pipe-work
  • Pressure vessels
  • Structural steelwork
  • Castings
  • Forgings
  • Fabrications
  • Precision machined components
  • Sub-sea assemblies

Our multi-disciplined NDT technicians are committed to quality and are trained to PCN Level 2 standards offering the following processes:

  • MPI (Magnetic Particle Inspection)
  • DPI (Dye Penetrant Inspection)


This test is used for detecting cracks in metals like cast iron and steel which can be magnetised. For carrying out the test the casting is magnetised and then fine particles of iron or steel are spread on its surface. Presence, of a crack or void in the casting, results in interruption of the magnetic field and leakage of magnetic flux at the place of the crack. 

The particles of iron or steel spread on the casting surface are held by this leaking flux giving a visual indication of the nature and extent of crack. Very small cracks or voids at or near the surface which may not even be detected by radiography are easily revealed by this method. Advantages of MPI;

  • Can find both surface and near sub-surface defects
  • Can discover defects quickly
  • Any defects are visible on the surface of the part
  • More complex components can be inspected this way


This method also is used for detecting very small surface cracks and has the advantage over the magnetic particle method that it can be used for any material. The parts to be tested are either dipped into or covered with a penetrant testing liquid which has very good wetting and penetrating ability. The liquid is drawn into the cracks or voids by capillary action. 

After the penetrant has been applied to the surface to be tested extra penetrant is wiped off the surface is dried and a developer applied to it. This developer helps in drawing out the penetrant so that it becomes visible on the surface. The penetrant liquids often contain materials which fluoresce under ultraviolet light or a die to indicate their presence.

Advantages of using this method;

  • It will show small surface flaws
  • Can be used where MPI cannot
  • Can test large components quickly
  • Testing involving spray cans is very portable and efficient

If you require any further information on NDT or would like a quotation please don’t hesitate to call our sales team today on 0191 414 1066 or Email: sales@impressivewelding.co.uk for further information.

Do not hesitate to contact us on 0191 414 8901 or email sales@impressltd.co.uk for more information on how we can help you with your requirements.