Magnetic Particle Inspection

MPI Weld Defect

This is a common method used for the inspection of ferromagnetic materials at a relatively low cost and is ideal for detecting surface and near surface flaws.

The process uses an induced magnetic field within the component under test and magnetic iron filing particles in a suspension liquid. The suspension is usually delivered using an aerosol can.

Two methods of MPI used by IIS are as follows:

Colour Contrast:  Using a white background paint to aid the contrast of flaws being detected. This is performed under normal white light conditions and is a very widely used technique on weldments.

Fluorescent: This test is the most sensitive. The technique eliminates the use of contrast paint and is mainly used for machined components in the oil and gas, nuclear, defence and aerospace sectors. Inspection is performed under a UVA lamp in a darkened environment.

  • The fluorescent particles will fluoresce green-yellow when exposed to ultraviolet light which is the peak colour sensitivity of the eye.
  • In both cases the surface conditions are required to be satisfactory prior to inspection. Paints and coatings are to be removed and the surface must be free from oil, grease, rust, scale or anything that might impede the test..

Contact Details
Unit 22, E-Net Park
Mill Road Industrial Estate
West Lothian
EH49 7SF

TEL: 01506 844944


Opening Hours
Monday:           08:00 - 16:30
Tuesday:          08:00 - 16:30
Wednesday:     08:00 - 16:30
Thursday:         08:00 - 16:30
Friday:              08:00 - 13:30
Saturday:          Closed
Sunday:            Closed