RING CRANES Ӏ APPLICATION REPORT
Procurement and Construction (EPC) contractors and other companies involved in the market have to present cost-efficient solutions in order to succeed in tendering.”
Another major change in the
market, has been the growth in the size and capacity of the turbines. Augustyns says in Rotterdam, the Netherlands, a 15MW turbine is currently being tested. “Five years ago, you would see 5 MW turbines everywhere; this turbine has triple that capacity. At the moment, most of the jobs have models of 7 MW.” Commenting on the trend
towards bigger turbines, Lefevre says: “Offshore wind turbines have increased in height and weight drastically in the past decade, with turbines moving slowly towards 15 MW capacity and nacelles getting close to 1,000t. Also, with larger foundations (jackets and monopiles) required to support these machines, onshore logistics is greatly impacted with stronger equipment needed to manage marshalling ports for both foundations and wind turbine generator (WTG) packages.”
RING CRANES “Currently for typical 10MW WTG marshalling hub scopes, where only towers have to be assembled and stacked at the marshalling
Mammoet-Giant, a joint venture between Mammoet and Giant Heavy Machinery Services, has
upended the upper block of the first locally fabricated jacket of a wind turbine in Taiwan. The PTC 200-DS ring crane and a Liebherr LR 1750 crawler crane were used to lift the 257t upper block. After the upending operation, the upper block was placed on custom designed supports and the 25m height structure was then transported by 24 axle-lines of SPMT to the next location for further assembly process.
harbour before installation vessel load out, medium-sized crawler cranes are required (up to 1,350t capacity). With the 12/15MW turbines slowly being implemented, larger crawler cranes will have to be mobilized for tower pre- assembly (up to 1,600t),” adds Lefevre. Sarens is currently using a 1600t Demag CC 9800 at a fabrication yard in France, to lift the upper part of jackets and place it on top of the lower parts. “We have reached a point that
even cranes of this capacity are being used well above 75% of their capacity. I believe that currently there is a market for crawler cranes of the highest capacity (3,000t) or ring cranes,” Augustyns comments. A few years ago, the company
performed a tandem lift of a 1,022t jacket in Methil, Scotland, using two Demag crawlers, a CC9800 and a CC8800-1. For jackets of similar size at the Smulders Projects jacket yard in Newcastle, one of the Sarens Giant Cranes (SGCs) was deployed for the load-out and assembly operations. The SGC-120—with a 130m main boom and maximum capacity of 3,200t—was used to handle 28 jackets destined for the Beatrice Offshore Windfarm. Augustyns says this solution offered more flexibility and was less
complex compared to tandem lifts. He clarifies that the use of a ring crane is more suitable for projects with long duration, because of the high mobilisation, assembly and disassembly costs. For example, the SGC-120 remained at the Smulders Projects jacket yard in Newcastle for five years.
One of Mammoet’s ring cranes, the PTC 200-DS, is assisting Sing Da Marine Structure Corporation—a marine engineering subsidiary of China Steel Corporation—with the assembly of jackets. “Jackets are typically assembled
in two halves: lower and upper. Both sections are upended and then the upper piece is lifted onto the lower piece. The complete jackets are then lifted in one complete piece and loaded onto vessels. Depending on the project, the vessels will deliver to an intermediate marshaling yard or they will go directly to the installation point offshore,” says Lefevre. “The ring crane is selected
for lifting capacity at height and at reach. The heights of offshore wind jackets are reaching 90m plus, and weights are exceeding 2,000t. Upending and assembling activities in this jacket class can be executed with the largest crawler cranes on the market (3,000t), but the pure reach needed to lift out onto vessels is only possible with the load moment capacity offered by our largest ring cranes. Load-in and load-out via this method is faster and more efficient than alternative methods.” By the third quarter of 2021,
three of Mammoet’s largest PTC cranes will be assembled on quaysides serving offshore wind projects. “If someone had said this would be the case ten years ago when these cranes were first commissioned, it would have seemed comical. This is a clear
34 CRANES TODAY
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