Tough welding questions on one of the UK's biggest overseas construction jobs have prompted Cleveland Structural Engineering to call TWI for technical support. The Darlington based Industrial Member is charged with construction of the decks, and the trusses between the decks, of the new Tsing Ma suspension bridge in Hong Kong.
The two tier 2km long structure will carry cars, trucks, buses and rail traffic from Hong Kong mainland to Lantau Island and the new airport, but welding this 48000t steel structure was far from straightforward. 'TWI gave us technical support on the choice of welding process to be used between the trough and the deckplate' said Cleveland's Harold Dewsnap. 'The specification requires 80% minimum penetration between the trough and the deck.'
To achieve the required standard Cleveland carried out extensive procedural trials in submerged arc welding to determine four critical parameters; amperage, arc voltage, speed and torch angle. 'To meet the fabrication programme we had to invest in a new machine, mainly designed by Cleveland, which can make six welds at a time. The result of all this is that we are now producing 20 panels a week.'