Samson, provider of performance cordage, and Endenburg BV, Samson’s Master Fabricating Distributor in Europe, has provided Seaway Heavy Lifting (SHL) with the first very large diameter synthetic rope slings certified by Lloyd’s for offshore installations. The two lifting systems, made from 144-mm diameter AmSteel-Blue, Samson’s rope made with 100% Dyneema high modulus polyethylene fiber, are currently assisting in the installation of 140 turbine foundation monopiles as a part of the North Sea’s Greater Gabbard project, the largest wind farm currently under construction.
SHL anticipated that synthetic slings would reduce potential damage to the monopiles during their transfer from the supply barge to the deck of the installation vessel in rough seas. Each monopile weights from 519 to 676 metric tons. SHL chose to use braided rope slings over traditional woven round slings because strengths of up to 4,457 metric tons could be achieved, and because these slings have a removable jacket they are easy to inspect, repair, and splice on site. Another factor in SHL’s decision to use rope slings was that they could be fabricated in longer continuous lengths than round slings.
The very large diameter rope was manufactured at Samson’s Lafayette, La., plant. Subsequent break testing confirmed that the rope exceeded the strengths required for the job. Endenberg then fabricated the slings and grommets, with all weight-bearing points protected by chafe gear. Upon delivery, these became the first very large diameter synthetic rope slings certified by Lloyd’s for multiple uses in offshore installations.
By the end of February 2010, 67 of the 140 turbine foundation monopiles had been installed. Of the two lifting systems fabricated, the first is still in use and shows no sign of wear according to Endenberg's master splicer, who has conducted two inspections. These inspections included removing the jacket and closely examining the entire line for wear and damage. Lloyd’s also proof loaded the line and recertified it for continued use. Through this process, it was determined that the original set of slings could be used for the remainder of the installations, with the second set held as backup.