The large lifting yoke used by Eltronic for offshore operations is a heavyweight steel construction. So heavy that its weight was becoming a problem for Eltronic's customer. Eltronic Heavy Industries therefore teamed up with Fiberline to find a lighter solution made of GRP composite instead of steel.
"We simply had to reduce the weight," explains Kenneth H. Svinth, CEO at Eltronic Heavy Industries, describing the problem and its solution. The lifting yoke is used for installing individual blades on offshore wind turbines, and Eltronic's customer – a major offshore wind turbine producer – wished to switch to using a faster and smaller crane for the task. This could only be done by reducing the weight of the yoke. Eltronic therefore contacted Fiberline Composites to discuss a solution using GRP profiles, which in direct comparison with steel weighs only about 25%.
It was an essential requirement that the new GRP construction should be every bit as safe to work with as the steel original. Much of the manual work takes place at a height of eight metres, and Eltronic guarantees that the turbine blades, which are 75 metres long and weigh 25 tonnes, can be lifted into place in wind speeds as high as 14 m/s. "We found that GRP is just as reliable a material as steel," says Kenneth H. Svinth, referring to the extensive documentation which exists for profiles and gratings from Fiberline.
Another aspect, which although not a direct requirement from Eltronic has subsequently proved to be a major advantage, is the durability of GRP. "Visually, steel degrades rapidly in the harsh offshore environment, says Kenneth H. Svinth, "but this is not the case with GRP composite, which looks the same whether it has been at sea for two days or two years.”
To date, the collaboration between Eltronic Heavy Industries and Fiberline Composites has resulted in five GRP platforms.
Eltronic's platform measures 15 x 6m, weighs a total of 3 tonnes and incorporates 205m of GRP profiles and 107 m2 of GRP gratings. All joined together using 2,500 acid-resistant, stainless steel bolts. The large construction was delivered to Eltronic on two road transporters.
Eltronics platform måler 15 x 6 meter og har en samlet vægt på 3 tons
Eltronics Heavy Industries develops and supplies equipment for transporting, installing and servicing both onshore and offshore wind turbines.
For further details, see www.eltronic-hi.com
Weight and durability
The use of GRP profiles in offshore constructions is becoming increasingly commonplace. Above all because GRP is non-corrosive and considerably lighter than e.g. steel. In direct comparison with steel, GRP weighs around 25%. When the total GRP volume is taken into account, Fiberline's customers usually end up with a weight saving of about 50%.