Failure Analysis of Pneumatic motor in Tilt Drive of Steel Making Vessels

This paper investigates the failure of a pneumatic motor within the emergency tilt drive system of an LD Vessel, a critical component in steelmaking. The incident, which occurred during trial operations, was characterized by excessive RPM that led to significant mechanical damage to the motor and its centrifugal brake mechanism. Root cause analysis identified uncontrolled acceleration as the primary culprit, directly linked to the malfunction of the centrifugal brake system, which is designed to regulate motor shaft RPM. Key findings included a fragmented speed limiter housing, a deformed speed limiter element, and severely worn components within the centrifugal brake (liners, springs, flyweights). Furthermore, damaged and dislocated bearings were observed, attributed to inaccessible lubrication points, alongside wear on gear teeth. The failure was concluded to be a cascading event of mechanical faults, exacerbated by insufficient braking during vessel reversal, a critical absence of scheduled maintenance for the centrifugal brake, and inherent design flaws hindering lubrication access. This incident emphasizes the urgent need for integrating condition-based maintenance practices, ensuring designs that facilitate accessibility for lubrication, and rigorously enforcing operational guidelines to bolster equipment reliability and safety. Recommendations include the mandatory installation of centrifugal brake assemblies on all emergency drive gearboxes, restricting pneumatic tilt drive operation when brakes are not present, and formally incorporating centrifugal brakes into maintenance schedules with detailed plans for inspection and condition-based replacement. Keywords: Centrifugal Brake, Pneumatic Motor