Industrial Accident: overspeed event on an 8000Hp steam turbine driving a 6MW generator at a co-generation facility. The turbine control panel and safety system both detected the overspeed condition but were unable to stop the runaway turbine. The independent Emergency Stop system was also ineffective due to a failed steam stop valve.
The building was evacuated at 6000 RPM, slightlly below the turbine's normal operating speed. The equipment came apart less than 60 seconds later at an estimated 11,000 RPM. The overspeed resulted in total destruction of the electrical generator and associated power equipment.
The accident occurred during a maintenance operation that did not incorporate adequate lockout-tagout (LOTO) procedures. A forensic investigation and analysis identified the design, installation, and operational aspects of the independent control and safety systems that jointly contributed to the multi-million dollar disaster.
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