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NDT Inspection on a Mechanical System Component

TWI undertook a NDT (non-destructive testing) inspection, on-site in France. Technicians used 3 NDT methods, MPI (magnetic particle inspection), UT (ultrasonic testing) and PAUT (phased array ultrasonic testing), to inspect a component within a mechanical system.

A TWI member company contacted TWI requesting a NDT inspection on a component within a mechanical system. The component suffered from a handling incident during transportation, prior to installation. The company wanted to ensure that the component was free from defects and that it had not become damaged.


  • To carry out an inspection on the four rims of the component
  • To use a visual inspection to identify any indications of defects
  • To use MPI to identify any surface-breaking flaws
  • To use UT and PAUT to detect the presence of any sub-surface defects
  • To confirm that the component is fit-for-service
The set-up for UT inspection.
The set-up for UT inspection.


The technicians carried out a visual inspection of the surface of the component, looking for any indications of cracks, laps, seams, folds or other damage. No visual indications were found, so the technicians proceeded to prepare the component for UT inspection. The aim of the UT was to inspect the component and identify any defects between the rim and wheel core boundary. Initially, a 0 degree normal beam probe was used, over a 50mm grid to detect lamination type flaws.

The UT found no defect indications, so the technicians decided to use a PAUT 45 degree shear wave probe. This provided 100% surface coverage, in both directions. No defect indications were detected, however the technique was able to detect several geometric signals giving confidence that the inspection would be capable of detecting both volumetric and favourable planar defects, if they had been present. Therefore, the UT/PAUT inspection ruled out any sub-surface flaws.


The combination of NDT methods (visual, MPI, UT and PAUT) confirmed that there were no defects within the component, enabling it to be used as originally intended.

The set-up for MPI inspection.
The set-up for MPI inspection.
Avatar Yanick Bocage Project Leader - Non-Destructive Testing

Yanick is a project leader in the non-destructive testing (NDT) section at TWI, working principally on designing models, such as calibration blocks, wedges, components, probes, animations and simulations. He also creates and assembles new tools, using components from a wide variety of suppliers, as well as delivering on-site weld inspections, utilising NDT methods.

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