Did you know that ultrasonic testers can be used to check the thickness of enclosed rusty wrought iron box-sections?
The technique has been used to check plate thicknesses remaining on Brunel’s Swivel Bridge, built in 1849 in Bristol City Docks. It carried road traffic over the entrance lock of the Floating Harbour, but could rotate to allow ship to pass. It is now derelict, but a restoration project is under way, led by NHIG Council member Geoff Wallis and a team of volunteers.
Repeatable results were obtained using an ultrasonic 2 Mhz array with water-based gel coupling agent. The instrument needed to be calibrated on wrought iron, as the pre-programmed settings for steel and cast iron gave incorrect readings. For further information see www.brunelsotherbridge.org.uk or contact Geoff on firstname.lastname@example.org