Reduction in diversion due to coil break in CRNO grades of coils

• Diversion due to coil break in CRNO coils showed a sharp increase during Jan–May’12.
• Systematic study that was carried out to analyze the reasons for high diversion due to coil break in CRNO steel.
• The major contributor to coil breaks was found to be the condition of bridle rolls and misalignment in coilers of annealing and slitter line.
• Introduction of various measures led to reduction in coil break generation from a level of 30% to less than 2%.

Diversion due to coil break in cold rolled non oriented (CRNO) grades of coils showed an increasing trend during Jan–May’12 at Silicon Steel Mill (SSM), Rourkela Steel Plant (RSP). Coil break increased from a level of less than 1% during to a level of 30% in May’12. Samples from hot rolled coils and finished coils were taken and detailed metallurgical investigation was carried out to ascertain the genesis of such defects. Further studies were carried out in the processing lines and material flow was tracked from steel making to final product. The probable reasons were identified and corrective measures were taken leading to reduction in diversion due to coil break less than 2%.