Mechanical Looseness in Steam Turbine-Driven Fan

This case study details the identification and resolution of mechanical looseness in a steam turbine-driven forced draft fan. The objective was to improve asset reliability and facilitate early fault detection through ad hoc vibration analysis using the Machine Sentry® platform. Following reports of excessive operational noise, the engineering team requested an immediate vibration survey, which fell outside the routine monitoring schedule. The analysis indicated significant changes in vibration readings, suggesting potential gear or bearing defects. Immediate action was taken to remove the asset from service for inspection, revealing that a loose retaining nut had caused axial float, leading to turbine blade contact and damage. Repairs were conducted, and post-repair analysis confirmed that vibration levels returned to acceptable limits, preventing further mechanical issues. This intervention was crucial in avoiding catastrophic damage to the gearbox and minimizing downtime and repair costs associated with a potential boiler outage.