The delivery to Bladt Industries A/S, an international steel contractor specializing in large-scale and highly complex steel structures, was completed in July 2019. Development of the offshore wind farm is ongoing and is expected to be in operation in the first half of 2020.
The customer required corrosion resistant studs to fasten the WTG external platform to each of the 23 wind turbine foundations. The studs would have to be maintenance free throughout the 27-year design life of the turbines – which conventional carbon steel bolts would simply not be capable of.
The studs require a high degree of corrosion resistance as they are situated within the ‘atmospheric zone’ where they will be affected by saltwater that might cause corrosion problems when salt particles dry on the studs.
Studs with very high tensile strength were also required to maintain the integrity of the WTG external platform throughout the turbine’s lifespan.
The BUMAX solution
The project design team opted for BUMAX® SDX 109 studs, nuts and washers that ensure a maintenance free solution over the project’s design life.
“Using BUMAX SDX 109 studs provides the design team with peace of mind that they can rely on to last the entire 27-year design lifespan of the foundations,” explains Søren Bøgh, Bladt Project Manager on the Northwester 2 Project. “The project designer stressed the importance of selecting premium stainless steel studs that can cope with the harsh off-shore environment.”
“Our BUMAX® Super Duplex 109 studs offer exceptional corrosion resistance to the harsh salt water environment they will be subjected to,” claims Torben Sten, Business Development Manager at BUMAX. “As far as I know, we were also the only supplier that was able to offer strain hardened property class 10.9 – which is also essential for this kind of application.”
BUMAX worked closely with the customer to meet an extremely tight delivery deadline. The normal production schedule for this kind of custom-made fastener was reduced by several weeks to avoid potentially costly delays to the wind turbine project.
“We had good cooperation with BUMAX with very good weekly follow-up meetings during the manufacture of the studs,” says Bøgh. “They delivered on time despite a tight schedule.”
The BUMAX® studs will realize cost savings for the customer through lower maintenance costs and less turbine downtime.
The low maintenance requirements will reduce the need for offshore wind turbine maintenance teams to conduct potentially dangerous stud replacement tasks.