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Feedwater Systems Reliability Users Group Annual Meeting

January 20-23, 2014

Feedwater Pump Thrust Bearing FailurePresented By: Kurt J. Weis

Rotating Equipment Repair, Inc.

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Pump Specifics

• Pump Mfg: Delaval• Pump Model: 1BSX1524• Discharge Pressure: 1700 FT• Flow: 14500 GPM• Speed: 4234 RPM

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SummarySeptember 2006: Pump was last overhauledSeptember 2007: Pump speed was increased 1000 rpm because of companion pump failure. Thrust bearing temperature increased significantly and alarmed. Pump was brought back to normal speed but thrust bearing temperature remained higher than normal.November 2008: Pump started experiencing higher vibration levelsFebruary 2009: Vibration level hit a warning limit of 0.325In/sec. It was decided to replace the outboard journal bearing and thrust bearing at the next opportunity.March 2009: The pump was tripped due to high thrust bearing temperature. The outboard bearing housing was disassembled. The outboard side of the thrust bearing was completely destroyed. The outboard bearing journal and thrust bearing were replaced and the pump was returned to service with still elevated thrust bearing temperature and vibration levels.

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Summary Continued

A corrective action report was written. With help from the thrust bearing manufacturer is was determined that the 0.188” diameter oil inlet orifice was only allowing 3.5GPM to the thrust bearing. The required flow rate is 5.0GPM. It was decided to increase the inlet supply pressure from 14psig to 18.5psig. This lowered the thrust bearing temperature and allowed the unit to make it to the refueling outage.During the outage the oil path within the bearing housing was milled wider to increase the amount of oil to the thrust bearing. September 2009: The pump was started coming out of the outage. The thrust bearing drain temperature had decreased 16°F compare to pre-outage.December 2009: The thrust bearing fails again.

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Summary Continued

Pump failure is highly visible to plant management.The following consultants were brought in:Pump OEMBearing OEMIndependent Engineering FirmIndependent Hydraulics EngineerRotating Equipment Repair

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Causes Considered

• Insufficient Oil Supply• Thrust Loading due to Pipe Stress• Thrust Loading due to Pump

Thermal Growth• Foreign Material in Oil Supply• Foreign Material in Water Supply• Impeller to Diffuser Misalignment

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