Port expansion
18 March 2008
Nine Atlas Copco barge-mounted air compressors are being used as part of the US$ 183 million project to upgrade Qingdao Port, on the Shandong Peninsula, in China. The aim is to raise the port's capacity to 320 million tonnes of cargo-or 12 million twenty foot equivalent units (TEU)-per year by 2010.
Building the necessary deep water berths involves underwater drilling inside the harbour, without damaging existing submerged structures. the work also involves drilling into different materials, which requires versatile compressors, and of course the machines must be up to working in a tough marine environment.
The machines chosen were five XRHS 485s and four XAHS 416s, providing a free air delivery of 28.8 m3/minute and 25 m3/minute at 20 and 17 bar pressure respectively. All nine compressors are mounted on two barges to ensure easy manoeuvrability around the harbour to the drill site locations.
“We have been using Atlas Copco compressors for over five years. there have been no major malfunctions and the utilisation hours have reached as high as 98%,” said Wei Zhuangji, manager of contractor New Harbor Engineering Company's equipment maintenance department.
New Harbor Engineering's contract called for more than 700000 drill meters to be carried out generally drilling 3 m into the seabed to increase the depth to 15 m. the seabed rock was predominantly hard granite and drilling was done using a 165 mm diameter drill bit and a 219 mm casing.
“Unlike onshore drilling additional factors to be considered include the ‘bounce’ of the barges due to the 2 to 4 m high sea swells and the fast currents,” said Mr. Wei Zhuangji adding, “We also had to contend with 15 m of bending casings below the water surface.”
Blasting was carried out using waterproof emulsified dynamite with between 4 to 8 kg per hole metre. When drilling and blasting close to jetties and walls the contractor performed controlled blasting with reduced explosive and segment explosion. Seismographic procedures were also undertaken on the jetties.
