Portable magnetic flux leakage inspection system for detecting corrosion damage in pre-stressed concrete poles

© Fraunhofer IZFP
BetoFlux in field

For decades, pre-stressed concrete poles have been used on a wide scale in transport infrastructures to support railway and tram overhead lines among other things. The combination of static and dynamic loads and corrosive chemical environments makes ferromagnetic pre-stressed steels susceptible to stress corrosion cracking. This mainly affects the exposed area of the poles where animal excrements, road salt and leakage currents promote corrosion.

In the recent past, there have been accidents of concrete poles buckling and shattering for no apparent reason. Upon examining the damage, indications of stress corrosion cracking were found. Because of the outer concrete shell corrosion is visible to the naked eye but at an advanced stage. Existing inspection methods cause mechanical stresses to the poles, which can lead to further damage. Fraunhofer IZFP’s scientists developed the portable manual inspection system BetoFlux basing on magnetic flux leakage technique.