Doing Battle with the Heavy Weights

Last year saw one of the biggest alternative lifting projects ever on a giant regasification terminal offshore Italy. Assembled in huge modules in Spain, this terminal is set to serve huge tankers bringing in liquified natural gas, largely from Ras Laffan in Qatar. It was towed to its final position in August 2008 and when online later in the year, it will process 8bn cubic metres of gas, which represents 10% of Italy’s annual demand.

The assembled structure is immense and measures about 188m long, 88m wide and 48m high. It is installed in 30m deep water and in the bottom are two steel LNG tanks, total capacity 250,000 cubic metres, surrounded by a double concrete wall. In total, it weighs 290,000 and is ballasted with sand and gravel. As well as the main working block it also has two moorings for LNG ships and accommodation for 63 people.

The plant is owned by consortium Adriatic LNG, which includes Exxon Mobil (45%), Qatar Petroleum (45%) and Edison (10%). The general contractor of the €200m, three-year project was Aker Solutions, with civil construction contractor Acciona responsible for site preparation and gravity base structure construction, Fagioli for heavy haul and heavy lift, and mechanical contractor Dragados.

Once the concrete shell was finished, it was Fagioli’s job to offloaded the steel tank sections, weighing up to 1,600 tons each and drive them down a ramp with an 8% incline into the basin, into the GBS via another steel ramp. Because the tanks float above the GBS floor, Fagioli installed 60 strand jacks on to the concrete roof, and suspended each section into position for nearly a month for final welding. But this was just the start of the job.

Structural strength

Once the insides of the terminal were finished, Fagioli was responsible for offloading, transporting and installing 11 modules, six pre-assembled units and 100 other non-modular units on the top of the gravity base structure.

Fagioli director of operations and project management Paolo Cremonini says that the main issue was not weight or centre of gravity definition but the structural strength of the module during the transportation. “In fact, the actual SPMT configuration had to be defined not only according to module weight, centre of gravity and dimensions, but also to respect the strength of the module structure, verifying that the loads imposed by the SPMT’s bed were acceptable in any phase of transport and installation operations. And this required a great, deep and continuous interface with the client,” he says.

There were two ways for lifting these loads onto the structure, which was 40 metres from the edge of the basin wall, and almost 25 metres high. First, Fagioli re-hired two 750 ton Liebherr LR 1750 crawler cranes for the smaller single lifts, and for larger tandem lifts. One crane came from Austrian firm Felbermayr (in luffing jib configuration with ballast wagon), another from Sarens of Belgium. It lifted four topside modules, six pre-assembled units and 100 other structures with the
crawlers.

Too heavy

The largest modular units were simply too heavy for even the large crawlers. For this job, Fagioli had to design and install an elevator. On the basin wall side, it set up two or three 30 metre-high lifting towers (depending on the lift) with two strand jacks mounted on top (600 ton or 750 ton capacity).

In addition, a further pair of strand jacks hang, upside down, from their anchor blocks on steel beams protruding from the GBS support. Each strand jack holds up one end of a 40m-long, 3.6 metre wide and 2.2 metre high horizontal beam that spans the gap between the GBS and quay wall.

The intricacy of the operation is so great that each beam has been specially designed to be used in divers machinery and lifting operations. Each is a modular construction, but each has pin connections for ease of assembly and transport by road or ship. The box sections were designed to resist twisting forces that might otherwise have required transverse supports. Fagioli had four beams on site. On top of the beams twelve 600 ton capacity skid shoes rolled the modules from the quay on to the elevator, and then to final position on top of the GBS.

The elevator’s biggest load was the vaporisation module, a 4,800 ton behemoth that measured 75m long, 31.5m wide and 28.4m tall. In another first, Fagioli used its elevator systems to move and replace the Baosteel Shanghai furnace in one piece. It will be used again for assembly operations of the offshore platform Scarabeo 8 for Fincantieri Palermo, in Italy.

To comply with Exxon Mobil requirements, Fagioli staff worked to project-specific general procedures (there were more than 40), scenario-based risk assessments, and regular audits. Even minor lifting or moving operations required a safe job analysis and a toolbox talk. Site contractors operated a near miss reporting programme.

Representatives of every level of the construction project (client, main contractor and subcontractors) attended weekly site safety meetings. The planning and preparation seems to have paid off; during 22 months of site operations and 180,000 hours, Fagioli employees only suffered a couple of injuries, requiring no more than first aid treatment.

On such a major job, the lack of injuries and such a successful result showed the value of Fagioli’s forward planning and the level of professionalism that is vital when carrying out work of this size. The sheer weight of the modules meant that the level of innovation needed to design even the most basic equipment was a task in itself. A job well done means that the degasification terminal is gearing up for business and is one to watch in the coming months.

A version of this article first appeared in our sister publication Cranes Today.