When Seaway Heavy Lifting was asked to support the installation of 84 new wind turbines off the coast of Scotland, tight deadlines and a focus on safety meant that lashing chains made with Dyneema® were the only choice for transportation.
Lightweight lashing chains made with Dyneema® offer increased benefits for health, safety and quality, while reducing overall costs. For the Beatrice Offshore Windfarm, Seaway Heavy Lifting (SHL) used Green Pin Tycan® chains made with Dyneema® – supplied by Van Beest B.V. – to move the foundation piles to the site more efficiently.
Beatrice, a 588 Megawatt offshore wind farm being built in Scotland’s Outer Moray Firth, comprises 84 wind turbines on pre-piled jacket substructures. Once in operation, the power generated will be collected on two offshore transmission modules via 33 kV array cables and associated equipment. The wind farm, once fully operational, will provide energy equivalent to the needs of approximately 470,000 homes.
On Beatrice, SHL worked with seabed-to-surface engineering company Subsea 7. SHL jointly managed, designed, engineered, fabricated, and installed the jacket foundations and array cables for the 84 wind turbines, and transported and installed the offshore transmission modules, which included 336 piles for the jackets.
The challenge was the tight timetable. The piles were to be transported on barges from three locations, one in Germany and two in the Netherlands, to the Beatrice site. Once in the field, the piles, weighing around 150mT each, would be installed by SHL’s impressive heavy lift vessel, the Stanislav Yudin.
Lashing the piles securely for their journey would require chains or strips measuring 16m long with a minimum breaking load (MBL) of 20 tonnes (t). Made of steel, each chain would weigh 64kg. This in turn would need a crane to position the chains over the barges. And this would take more time than was available.
The solution was to use lightweight lashing chains made with Dyneema®, a choice SHL says it found easy to make as it was already familiar with Dyneema® in its heavy lifting slings and tow lines. Instead of 64kg, each 16m Green Pin Tycan® chain would weigh just 10.2kg at the required MBL of 20t. This would enable the crew to simply throw the synthetic lashing chains over the piles, from one side of the barge to the other, and without a crane. Using synthetic lashing chains with Dyneema® offered further handling benefits, too: “Another reason we never considered steel chains was because they tend to slide off the piles and fall deep into the barge,” explains SHL Installation Engineer Wouter Boot. “Recovering them eats up more time and money.”
The shift to Green Pin Tycan® chains means SHL is now using Dyneema® fiber technology for three different applications: heavy lift slings made with Dyneema®, which have a breaking strength between 500t and 3000t each; tow lines with Dyneema®; and now, the synthetic lashing chains with Dyneema® for heavy duty lashing. “We do not want to use steel equipment anymore for lashing and lifting,” says Frits van Dorst, SHL Project Engineer, while Dirk-Jan Mattaar, SHL Principal Engineer, adds: “We prefer to use only fiber-based lightweight equipment for this.”
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