Bumax Provides Maintenance-Free Fasteners to Marine Turbine

Swedish specialist fastener maker Bumax (Åshammar, Sweden) has supplied premium stainless steel fasteners to a pilot hydropower project in France. The company reports 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 that provides Europe with reliable renewable energy.

Bumax 88 fasteners were used on the 1 MW HydroQuest (Meylan, France) 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 30 m 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 reportedly showed that they had maintained their properties.

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. Bumax says the 316L grade stainless steel has is well suited for demanding marine applications and provides durable and maintenance-free fastener solutions.

The tidal turbine prototype was designed by HydroQuest, 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, enabling for the avoidance of costs and potentially dangerous procedures.

Following the pilot project at Paimpol Bréhat, HydroQuest is integrating Bumax 88 bolts in the design of its of tidal turbine. 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.