ABSTRACT
NJHPS has largest Desilting Complex, longest HRT & deepest Surge Shaft in the world. River Satluj carries heavy sediment load. To exclude sediments, Desilting Chambers have been provided. Each chamber is connected to SFT by 3 conduits. Free flow D-shaped SFT carries silted water back to river. 24 slide gates are provided for flushing out silt. Silted water strikes embedded parts of SFT Gates with high velocity and erodes them necessitating repair and maintenance. Same was earlier repaired by manual welding and grinding method. Due to space limitation, verticality & plainness of seal/guide faces were not achieved. This resulted in leakage from the gates and influenced generation. This paper describes techniques used earlier and reasons for their being unsuccessful. Further details of welding technique, in-situ machining of gate grooves, reduction in leakage, generation rise & financial gains is discussed. Specific emphasis is given to equipment and procedure of in-situ machining.
