Hydro Electric Power Station, North Wales. Following the isolation and removal of the valve body an inspection of the mating flanges was carried out and wear was identified.
Metalock set up a 150mm diameter boring bar which is set up between the 2 mating flanges of a large NRV (non return valve) and pre machined the bores to provide a good surface for in situ welding repairs. When the welding and NDT (non-destructive testing) was complete the boring bar was re-set and then the bore were re-machined back to the original sizes.
Flange faces being machined to accommodate a new Main Inlet Valve. The Up stream side was machined internally and externally to allow a Stainless Steel overlay to be applied to the existing inlet pipe. This was then machined to drawing size to allow fitting of the replacement valves. The downstream Flange was also machined to the correct gap using the same machine.