Repair of a Francis turbine
Our Turbine Refurbishment and Testing Workshop in Martigny repaired a Francis turbine for Groupe E. A delicate operation.
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Location: The Montbovon hydroelectric power station is located on the Sarine River in the Gruyère region, at the end of the Lessoc reservoir. It turbines the water retained upstream by the Rossinière dam. |
Of all the water turbines, the Francis turbine is undoubtedly the one that requires the most specialised expertise to refurbish. Such expertise is available at our central workshops in Martigny, in particular our specialist recently renamed RRC workshop that focuses on the refurbishment of turbines and controls.
Groupe E recently entrusted us with the repair of a Francis turbine from the Montbovon power station: non-conforming indications suggested the need for a welding intervention. This is a delicate operation that requires expertise and dexterity, as the mechanical tolerances were already at their minimum. It was vital that the critical dimensions were preserved during the welding and grinding work.
Deformation had to be avoided
In consultation with the customer’s engineers, and in order to avoid any deformation, we therefore decided to deploy a specific welding procedure that required no subsequent heat treatment. A real challenge requiring expertise and synchronisation! But the engineers and welding specialists in our workshops rose to the challenge.
In the end, the final work was carried out in the presence of the customer, marking the end of a project completed on schedule. Thank you to Groupe E for the excellent cooperation and putting its faith in us!
The operation, step by step
Francis turbine: ext. Ø 1835 mm, height 843 mm, 15 blades, weight 3091 kg.
Welding / Areas presenting non-conforming indications are carefully prepared and welded in accordance with the established procedure.
Grinding / After welding, the welded areas are ground together to ensure a uniform surface.
Machining / The mechanical parts of the turbine are machined with minimal material removal so as to retain the original dimensions.
Non-destructive testing / This is performed to detect any defects that require correction and to ensure the quality of the repairs.
Balancing / The static balancing of the turbine is checked to ensure optimum operation.
