A major utility company had a Foster Wheeler 60 DF horizontal split case circulating water pump that required repair. They decided to complete the refurbishment during a 14-day unit outage by using the Hydro South service center. The plant had a spare impeller, shaft, and shaft sleeves in inventory. The availability of spare parts usually facilitates an efficient and trouble-free repair. Unfortunately, it was discovered that the parts available were not properly designed for use in the existing pump.
Before the pump was pulled for the outage, the spare parts were sent to the Hydro South facility for inspection. This is where the first problem was discovered- the threaded shaft and shaft sleeves were designed for the incorrect rotation. If they had been installed as-is, the rotation of the pump would have resulted in displacement of the sleeves. The plant elected to modify the parts to prevent the sleeves from backing off during operation. Hydro South accomplished this by drilling and tapping the sleeves for set screws and dimpling the shaft.