At a run-of-river Hydropower Station in France, the spillway on a Kaplan turbine was repaired and protected in situ with a combination of epoxy composite and coating systems. Despite three flooding events occurring during the repair procedure, the application team was able to overcome this, successfully repairing the spillway and protecting it against future erosion and corrosion damage for the long term.
Approximately 40 Sq Metres (430.6 Sq Ft) of Corrosion Damage on Spillway
The Hydropower Station was experiencing generalised erosion and corrosion, covering approximately 40 sq metres (430.6 sq ft) on one of its spillways with 15mm (0.6 in) metal loss recorded in some areas. This was caused by continuous exposure to high-velocity water, turbulence and abrasive particles. An intervention was required in order to rebuild the damaged profiles, restore hydraulic geometry and provide long-term protection against further wear in this challenging environment.
The Plant produces almost two billion kWh of electricity per year — enough to supply roughly 815,000 households with electricity annually. Given the critical role the plant plays in providing renewable energy to the local area, it was imperative that the application was carried out promptly, with minimum downtime being incurred.
Specification of Epoxy Repair Composite and Protective Coating
Following an inspection by Authorised Belzona Distributor, Protecmo, a combination of epoxy coating and composite systems were specified.
For the severely corroded and eroded areas, Belzona 1311 (Ceramic Metal) was chosen. This is a 100%-solids, ceramic-filled epoxy repair composite, specifically designed to repair metal surfaces subjected to high levels of erosion and corrosion. Following a successful erosion resistance test carried out by the Client, the epoxy coating, Belzona 1331, was further specified. This system will provide outstanding erosion and corrosion resistance under immersed conditions, such as those found in the aqueous environment of the spillway.
As this polymeric technology is cold curing, this helps to mitigate the health and safety concerns that can otherwise arise when hot work is involved.
Application Team Adapt to Unexpected Flooding
Firstly, a fully sealed containment airlock was installed; incorporating air treatment, dust extraction and vacuum recovery systems to ensure safe and controlled working conditions.
All surfaces were then grit-blasted using corundum abrasive to provide a surface compliant with Sa 2.5 cleanliness in accordance with ISO 8501-1. Unfortunately, three flooding events occurred during the surface preparation stage. In order to adapt to these unforeseen events, the team had to grit-blast the substrate three times.
In areas with material losses of up to 15 mm (0.6 in), custom-made formers were used to apply the two-part system, Belzona 1311 (Ceramic Metal). This technique ensured that the substrate could be accurately restored to its original hydraulic profile.
The two-part epoxy coating, Belzona 1331, was then applied in two coats of approximately 300 µm (11.8 mil) each, achieving a minimum total dry film thickness of 600 µm (23.6 mil).
Throughout the application process, careful control of material impregnation, overcoating intervals and curing times and conditions was maintained to ensure the long-term durability of the repair.
Spillway Protected Against Future Erosion and Corrosion Damage
The combination of Belzona systems, combined with an efficient and adaptive application carried out by Protecmo’s team, ensured that the spillway was successfully repaired and protected against future damage with minimum downtime being incurred. In turn, by prolonging the lifespan of this critical hydropower asset, this supports the Hydropower Station’s contribution to renewable energy generation.
About Protecmo
Established in 1983, Protecmo is the Authorised Distributor of Belzona epoxy repair composites and high-performance protective coatings across the South of France. Its coverage includes key locations such as Toulouse, Montpellier, Nice, Bordeaux, Grenoble and Lyon, among others. Through Belzona’s Product Plus service, Protecmo provides responsive, local support — including 24-hour technical assistance and on-site application guidance.
Frequently Asked Questions
How quickly can spillway repairs be completed?
Project timelines depend on the size of the damaged area, environmental conditions and curing times. However, in-situ composite repairs are typically much faster than full component replacement or welded rebuilds.
How long can an epoxy composite and coating repair last in a hydropower environment?
When properly specified, surface-prepared and applied under controlled conditions, high-performance epoxy composites and coatings can provide long-term protection for many years. Longevity depends on operating conditions, water velocity, abrasion levels and adherence to recommended maintenance inspections.
How much does it cost to repair a spillway at a hydro plant?
The cost to repair a spillway at a hydro plant varies depending on the extent of erosion and corrosion, the size of the damaged area, site accessibility and downtime requirements, so an on-site assessment is essential for an accurate estimate. To receive a tailored quotation and technical guidance, contact your local Belzona representative using the Belzona Distributor Finder: https://www.belzona.com/en/distributor-finder.aspx
Where can I find more information about surface preparation standards?
For more information about surface preparation standards, please refer to the following blog post: A Guide to ISO and SSPC/NACE Surface Preparation Standards
Learn More
Contact Your Local Distributor to Learn More About Belzona Solutions for Hydropower
Chloe Hirst is the Senior Copywriter at Belzona Limited and is based in Harrogate, England. She gained a Bachelor’s Degree (with Hons.) in Media and Communications (specialising in Journalism) at Goldsmiths College, University of London. Chloe regularly writes case studies and thought leadership content featuring a variety of different industries, with a special focus on the renewables sector. In both 2023 and 2024, she won the Best Manufacturing Content Creation Specialist (UK) Award as part of Acquisition International’s Influential Businesswoman Awards.
