1. FSRUG Feedwater Systems Reliability Users Group (Jan 2013) San Antonio, TX SGFP Lube Oil Systems & Maintenance – No Problems Presenter: Art Washburn, P.E.

2. FSRUG

3. DISCUSSION POINTS Two Rules to Get You Home and Plant Priorities Lubrication Oil Systems – Types –Lubrication System – Static Sump –Lubrication System – Forced Feed –Grease and Oil Mist Injection Oil Ring Submergence Oil Ring Journal Surface Peripheral Velocity Limit Oil Ring – Maintenance Lubrication System – Forced Feed Forced Feed – Drain Piping Forced Feed System – Challenges Water Intrusion – Traditional Oil Deflector vs. INPRO Deflector Industry Events Source References

4. FSRUG Two Rules:

5. FSRUG Two Rules: Rule #1 – Make Conservative Decisions

6. FSRUG Two Rules: Rule #1 – Make Conservative Decisions Rule #2 – Maintain Design Control

7. FSRUG Two Rules: Rule #1 – Make Conservative Decisions Rule #2 – Maintain Design Control Plant Priorities:

8. FSRUG Two Rules: Rule #1 – Make Conservative Decisions Rule #2 – Maintain Design Control Plant Priorities: 1.Nuclear Safety

9. FSRUG Two Rules: Rule #1 – Make Conservative Decisions Rule #2 – Maintain Design Control Plant Priorities: 1.Nuclear Safety 2.Legal Requirements

10. FSRUG Two Rules: Rule #1 – Make Conservative Decisions Rule #2 – Maintain Design Control Plant Priorities: 1.Nuclear Safety 2.Legal Requirements 3.Efficiency

11. Lubrication System – Static Sump FSRUG

12. Lubrication System – Static Sump FSRUG -Bearing Housing contains oil as a static sump -API-610: Oil Rings (and flingers) used to deliver oil (GPM) to the bearings shall have an operating submergence of 0.12" or 0.25" above the lower edge of the bore of an oil ring. -Flingers are positively attached secured to the shaft. -Oil is lifted by oil ring to shaft and flows to bearing -Oil can be lifted by oil ring and flows to an internal cast trough in bearing housing and flows to bearing -Heat Sink: Oil Cooler located in bottom of sump in the oil or cast in the Bearing Housing. Pumpage or separate closed cooling water system.

13. Oil Ring Submergence FSRUG Particulate in Oil? -Stability issues identified in the 1990s. Testing identified oil rings can go unstable and bounce around. Mechanical contact inside the bearing housing would nick off pieces of oil ring (non-ferrous, silicon bronze). Particulate in oil (non-ferrous). -Increased submergence improved stability of oil rings and oil delivery (GPM). -The multitude of pumps in the Field operate satisfactory. -Look for particulate (oil ring material) from oil sampling.

14. Oil Ring Submergence FSRUG Particulate in Oil? Drive End or Thrust End -Design for Between Bearing Pump: -Oil Rings – Same size (minimizes risk on installing in wrong location) -Oil Submergence in both bearing housings (same oil level) -Oil Ring Submergence – different on each end -Reason: Journal surface for oil ring can be different – -Drive End shaft diameter can be larger to transmit torque -Submergence may be more shallow on drive end -Look for oil ring particulate on drive end. -Solution: If particulate present, then Increase submergence

15. Oil Ring Journal Surface Peripheral Velocity Limit FSRUG Oil Ring Rides on a Journal Surface -Journal Surface Peripheral Velocity Limit, 45 to 59 fps -Peripheral Velocity = [ π x D/12] x RPM/60, in fps (FT/Sec) -At 45 fps, Slip commences between the oil ring and journal surface and degrades delivery of oil (GPM) -At 59 fps slip continues to degrade delivery of oil (GPM), until a Force Feed Lubrication System would be required.

16. Oil Ring - Maintenance FSRUG Consider Oil Ring as a consumable item -Replace Oil Ring when bearing housing is disassembled -Oil Ring can wear over time and affect performance (delivery of oil)

17. Oil Ring – Example of Damage FSRUG

18. Oil Ring – Example of Damage FSRUG

19. Oil Ring – Example of Damage FSRUG

20. Forced Feed Lubrication System FSRUG Typical Schematic

21. Forced Feed Lubrication System FSRUG Pressure Setting Logic:

22. Forced Feed Lubrication System FSRUG Bearing Housing Assemblies w/Oil Pump

23. Forced Feed Lubrication System FSRUG Reservoir Layout

24. Forced Feed Lubrication System FSRUG -Separate Ancilliary System to Main Pump includes: -Reservoir (suction source) -Oil Pumps: -Shaft Driven off main pump Thrust Bearing Housing (and coupled) -Auxiliary pump (electric AC, optional DC) mounted vertically on top of Reservoir -Pressure regulator (relief valve) for both oil pumps in Reservoir -Lube oil supply piping with oil cooler, filter (duplex)

25. Forced Feed Lubrication System FSRUG Continued: -Supply Tubing Feeds Bearings (e.g., Drive End Bearing, Non-Drive Thrust End Bearing) -Supply Oil flow to each bearing (GPM) is metered by an orifice to each bearing (Typical Example): -Journal Bearing (Orifice 0.093" Dia, Pressure 12 PSIG, Flow 0.6 GPM x 2 bearings) -Tilt Pad Trust Bearing (Orifice x" Dia, Pressure 12 PSIG, Flow 1.12 GPM per Side – Active and Inactive) -Leakoff through relief valve -Total Capacity: 3.44 GPM Plus leakoff -Option to Feed Driver (Motor) Bearings

26. Forced Feed Lubrication System FSRUG Standard Rule for Supplying Forced Feed Lube System: -Electric Driver (motor) – Pump Supplier provides Lube System -Turbine Driver – Turbine Supplier provides Lube System -Ball Radial / Ball Thrust Bearing Arrangement can be Lubricated by Static Sump or Pressure Lube -Sleeve Radial / Ball Thrust Bearing Arrangement can be Lubricated by Static Sump or Pressure Lube -Tilt Pad Type Thrust Bearing Arrangement requires Pressure Lube

27. Forced Feed – Drain Piping FSRUG -Gravity Drains from bearing housing(s) to reservoir -Bearing Housings must be well vented -Drain line designed to be half full to assure vented from bearing housing back to reservoir -Hard Pipe (not flex hose) -Drain line sloped: Example, 2" Schedule 80 Pipe -0.25"/FT Slope (4.28 GPM) -0.50"/FT Slope (8.56 GPM)

28. Forced Feed – Drain Piping FSRUG

29. Forced Feed – Bearing Housings to be Well Vented FSRUG

30. Forced Feed – Bearing Housings to be Well Vented FSRUG

31. Forced Feed – Drain Piping for Motor Driven Assy FSRUG

32. Forced Feed – Drain Piping for Turbine Driven Assy FSRUG

33. -Replacement Relief Valve -(Obsolesence) – Minor Mounting Changes -Results in re-plumbing reservoir internals FSRUG Forced Feed System – Challenges

34. Changes in Supply Oil Pressure -to improve heat sink with increased flow -potential impact to pressure switch setpoints -potentially impacts maximum capacity of pump to supply oil to bearings and relief valve. -Supply Orifice is integral to bearing housing -One plant added orifice outside of bearing housing. Now have 2 orifices in series. Now required to run lube oil supply pressure at 24 psig to deliver the required oil. FSRUG Forced Feed System – Challenges

35. -Original lube oil pumps were designed for Clock-Wise (CW) Rotation. Pumps are gear type positive displacement. The thrust plate is installed on the pump to handle thrust from "CW" rotation. -Original pumps were allowed to operate Counter-Clock-Wise (CCW) rotation; however, thrust plate was never installed on the opposite end of the pump for thrust. The CCW pump thrust condition was accepted as long as pump differential pressure was limited to 24 psig (max). FSRUG Forced Feed System – Challenges

36. Industry Events: 1989 - Plant Turbine Trip with Loss of Lubrication Oil for Turbine, Generator and Excitor Bearings. –Causes: –Backup AC and DC Oil Pumps were not periodically tested to assure function –DC Backup Oil Pump tripped from protective relay (not sized properly) Reliability Issues for System –Cause: Excessive moisture in oil. –Water in Oil – 3 Types: Free Water, Emulsified, Relative Humidity –Most common Water Separation System: Bowser (WWII Technology) – branch side stream oil and enter a sudden enlargement; slows velocity down and allows free water and some emulsified water to separate. –Bowser Type System replaced with Coalescing Filters: Removes the 3 types of water present in the system. Improves system reliability and shortens outages for startup. FSRUG

37. Industry Events: 2011 - Plant Turbine Trip with Loss of Offsite Power Results in Loss of Oil to Main Feedwater Pump / Turbine and Bearing Damage –Cause: DC Backup Oil Pump Failed to Provide Oil to Main Feedwater Pump and Turbine Drive Bearings. 2011 – Main FW Pump Loss of Main Oil Pump Results in Pump Shut Down and Reduced Plant Power Output –Cause: Shaft Driven Oil Pump coupling disengages from Main Feedwater Pump 2012 – Plant Main Transformer Fire, Subsequent Turbine Trip and Turbine / Generator Bearing Damage –Cause: DC Backup Oil Pump tripped from protective relay FSRUG

38. Water Intrusion – Traditional Oil Deflector vs. INPRO Deflector See EPRI NMAC Lube Notes, November 2004, Bearing Operation with an Oil-Water Mixture FSRUG

39. SOURCE REFERENCES: Centrifugal Pumps: Design & Application, Lobanoff and Ross (practical application) Centrifugal and Axial Flow Pumps, Stepanoff (theory) Centrifugal Pumps, Gülich Vertical Turbine, Mixed Flow & Propeller Pumps, Dicmus Centrifugal Pump Handbook, Sulzer Pump Handbook, Karassik Centrifugal Pump Clinic, Karassik Centrifugal Pumps Selection & Operation, Karassik Centrifugal Pumps, Karassik FSRUG

40. WHO IS THIS SYSTEM ENGINEER?

41. FSRUG TAYLOR SMITH – Comanche Peak

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43. THE (HAPPY) END QUESTIONS ? FSRUG