17MW Deriaz Hydro Turbine - Re-machining and Complex Runner Chamber Reprofiling

17MW Deriaz turbine was suffering from severe cavitation in the runner chamber area after many years of operation Metalock set up a 12metre long x 250mm diameter boring bar to pre-determined datums provided by the customer.

From this setting Metalock checked

• The level and flatness of the top cover locating flange.
• The flatness and parallelism of the bottom cover locating faces.
• The diameters size and run-outs on the radial faces of the top cover locating flange.
• The wear, concentricity and run-out/ovality of the runner chamber profile in relation to the top cover locating flange.
• Re-machined the 3.635m diameter top cover locating flange was machined to achieve a level and flat face.
• Re-machined the upper and lower weld preparations and sighting groove into the existing old runner chamber and the old runner chamber was cut out and removed.
• Re-machine the 3-metre diameter, 262mm wide rotor brake track which was badly scored.
• Re-machine to clean up the outer 3-metre diameter flange on the spiral inlet pipe.
• Re-machine the lower cheek-plate face to bring it level and parallel to the top cover locating flange.
• Re-machined 24 x guide vane lower bush housings. Re-machined 24 x guide vane lower bush housings.