The BUMAX premium stainless steel fastener solution has been verified by a two-year pilot project that has contributed to the development of the next generation tidal turbine, capable of providing Europe with reliable renewable energy.

Swedish specialist fastener maker BUMAX has supplied premium stainless steel fasteners to a pilot hydropower project in France, verifying that the fasteners suffered no corrosion, wear or galling after two years of operation in extreme conditions.

The BUMAX premium stainless steel fastener solution has been verified by a two-year pilot project that has contributed to the development of the next generation tidal turbine, capable of providing Europe with reliable renewable energy.
"This is extremely encouraging for the future of sustainable renewable energy solutions since wear and tear and maintenance are major challenges for power plants in extreme conditions like choppy and salty waters with strong currents," said Lars Holm, Managing Director of BUMAX. "Europe also needs to develop new sources of reliable renewable energy, which this project will lead to."
No traces of corrosion or galling
BUMAX 88 fasteners were used on the 1 MW HydroQuest tidal turbine installed off the coast of Brittany in Northwest France that began operation in April 2019. After over two years of operation at the Paimpol-Bréhat site at 30m depth, the turbine fasteners showed no traces of corrosion or galling.

Tests of the mechanical properties (both strength and ductility) of the bolts conducted by BUMAX after the pilot project showed that they had maintained their properties.

"No issues were found related to bolting during this project, and our team didn't have any issues with galling during disassembly," said Raphaël Coquet, Project Director at Hydroquest. "These lessons give us positive learnings for the long-term deployments, and we are confident to manufacture our future turbines with BUMAX bolts."

Corrosion resistance and strength in demanding applications
The BUMAX 88 grade was selected for its high molybdenum content and high pitting resistance equivalent number (PREN) that indicates a high resistance to localized pitting corrosion. The 316L grade stainless steel has an excellent track record in demanding marine applications to provide durable and maintenance-free fastener solutions.
The tidal turbine prototype was designed by HydroQuest, which is a French turbine technology developer of vertical axis turbines. The Paimpol Bréhat site is owned and operated by the energy company EDF.
The project partners wanted a maintenance-free fastener solution for tidal turbines to minimize operation costs over a lifespan of 20 years. Besides durability, the fasteners also had to be easy to install.

The corrosion resistance, high pitting resistance and high strength provided by BUMAX 88 bolts are essential for maintenance-free fasteners in corrosive saltwater marine environments. By avoiding the need to maintain or replace the bolts during the operation of the turbine, costs and potentially dangerous procedures can be avoided.

Next generation tidal turbines
Following the pilot project at Paimpol Bréhat, HydroQuest is integrating the learnings from the pilot to design the next generation of tidal turbine, which will also use BUMAX 88 bolts.
Seven of these 2.5 MW tidal turbines will be deployed at the FLOWATT project at the Raz Blanchard site off the coast of Normandy with a design lifespan of 20 years. The commissioning of FLOWATT is planned for 2025 with the construction of the tidal turbines starting in 2023.
BUMAX is a Swedish manufacturer of premium stainless steel fasteners located in the Swedish ‘steel belt'. BUMAX is known as the strongest stainless steel bolt in the world - providing optimal safety and reliability to fasteners in the most demanding of applications.