Alstom Train Services, the British-based maintenance, overhaul and technical support division of Alstom Transport, expects by the middle of this year to be able to offer a wheel and axle inspection service using electro-magnectic array technology. The planned Electro-Magnetic Metal Fatigue & Crack Inspection Service (EMMFaCIS) would be based on a worldwide licensing agreement which Alstom Train Services signed in 1998 with NEWT International Ltd for use of the Lizard EMA system.

Developed for inspection of underwater structures in the oil and gas industry, EMA uses the flow of ’current sheets’ to detect cracks and other defects in metal components. A probe is passed over the surface of the component to measure the length and depth of the defect, with the lift-off or distance between the probe and the surface also recorded so that the effect of dirt or other coatings can be taken into account. The defect can be presented by means of separate length, depth and lift-off traces, or as an inverted three-dimensional image.

Capable of detecting cracks 5mm long and 0·1mm deep looking through non-conductive coatings up to 15 mm thick, Lizard is seen as offering considerable performance and cost advantages over other non-destructive testing technologies, requiring no surface cleaning and able to cope with complex surface geometry. Flexible software allows an inspection database to be created, with thresholds set for corrective action.

Alstom believes that EMA would allow a wheel or axle to be inspected in 30 sec in a workshop environment or within 5 min in the depot using hand-held or motorised probes. As well as developing EMMFaCIS as a mobile service, the company is looking to use EMA in maintaining Alstom trains for London Undergound’s Jubilee and Northern lines, Great North Eastern Railway and the Virgin West Coast fleet through its new subsidiary West Coast Traincare Ltd.

Alstom Train Services Ltd, Reader Enquiry Number 142