Salvaging of Large Bell of D Furnace of TATA Steel

Large bell is an integral part of the top charging system of blast furnace. It ensures periodical raw material charging inside the furnace. During midterm relining of D furnace of TATA Steel, it was observed to be badly damaged while in service. The magnitude of worn out of bell wall thickness was up to 90 % against the drawing size. Because of cost and lead live (minimum 8-9 months), reconditioning of the bell of D furnace needed to be done within 2 months. Innovative ways was adopted to salvage the existing damaged large bell. The total cycle time taken to salvage was 45 days which was well within the requirement. The large bell after salvaging was assembled with large bell hopper and leak tested. The leak test observed only 25 droplets of water/minute came out from the seating area against the norms of 50 droplets/minute. The bell is in now service and has contributed to timely completion of shutdown with minimal cost.