Babcock Marine was looking for a way to remove a massive refueling crane from their Devonport dockyard. The 1,450-ton, 125 meter long steel structure was built in the 70’s to replace fuel rods in nuclear submarines. But a new gantry system had made the crane obsolete. Instead of taking the crane apart piece by piece, Mammoet suggested removing it whole and demolishing it elsewhere; a solution that saved thousands of man-hours and kept the yard open for business.
Minimizing disruption by thinking big.
Babcock Marine had been told that demolishing the old hammerhead crane on site was the only way to get rid of it – an approach that would have meant slowly deconstructing the crane from both sides in order to keep the gigantic framework in balance. And besides requiring a significant amount of hours worked at dangerous heights, the offices beneath the crane would have had to be vacated for months on end. Two collateral consequences Babcock Marine wasn’t very keen on. But with Mammoet’s plan, they wouldn’t have to worry about either.
Removing the crane in one piece reduced downtime and improved safety.Babcock Marine, Plymouth UK
Mammoet proposed removing the crane in one piece. Commissioned to do the job, Mammoet brought in 2,000 tons of equipment, including gantry beams, skid shoes, MSG towers, strand jacks and four mobile cranes. In perfect weather conditions, Mammoet jacked up the 1,450-ton crane and skidded it across the beams. Using strand jacks, the crane was then lowered onto a barge 40 meters below. From there, the largest dockside crane in Western Europe was tugged to its final disassembly location.
Sept 24 2008 Installing the gantry beams
Sept 27 2008 Forty meters to go to the barge below
Sept 28 2008 Working round the clock
Sept 29 2008 Transportation to the disassembly location
Within twenty hours, the crane was taken down. Less than one tenth of the previously proposed man-hours were required to get the job done, and total downtime for the dock was greatly reduced. The nearby offices only had to be evacuated for short periods during crane lifts over the buildings, avoiding the need for long-term relocation of several hundred workers.
By having a big plan, Mammoet managed to make the impact on Babcock’s operations relatively small while ensuring the safety of the crew involved.