Caster roll failure prevention – Prognosis & diagnosis through monitoring system of machine cooling water circuit

Abstract

Rourkela Steel Plant has two slab casters having soft water circuit for machine cooling. Each caster segments comprises of solid forged steel rolls with water-cooling hole in guide roll. Failure of these rolls due to thermal fatigue restricts the efficiency of continuous casting operation. The main reason for roll breakage due to thermal fatigue is the reduced volume of water through the internal cooling hole and allowing rolls operating temperature to increase. The magnitude of thermal stress is influenced by the external and internal roll cooling efficiency since it controls the magnitude of ΔT. Impairment of internal cooling efficiency can lead to development of fire cracks of the bore surface and finally leading to roll failure. To prevent the caster roll failure due to thermal fatigue as a sequel to impairment of internal water cooling efficiency, the need was to install a system for real time measurement of water flow, pressure and temperature of inlet and outlet water through these segments. A system for real-time measurement of these parameters was installed in the caster segment of Steel Melting Shop- Rourkela Steel Plant for prognosis and diagnosis of the impairment of the internal cooling water circuit. Through the various dashboards, it was possible to monitoring the inlet – outlet water flow rate, pressure difference and differential temperature. Diagnosis of the causes of the rise in differential temperature was made possible through the water flow rate and pressure indications in the dash board. Through the monitoring system for machine cooling water circuit it was possible to reduce the caster roll failure due to thermal fatigue through proper diagnosis and prognosis. The monitoring systems for machine cooling water circuit has been effectively used for preventing the failure of caster rolls due to reduced thermal stresses and improve the machine availability.