1. SGFP Lube Oil Systems & Maintenance – Part 2
FSRUG
Feedwater Systems Reliability Users Group (Jan 2014)
San Antonio, TX
SGFP Lube Oil Systems & Maintenance –
Part 2
Presenter:
Art Washburn, P.E.

2. FSRUG

3. DISCUSSION POINTS FSRUG 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
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. Rule #1 – Make Conservative Decisions
FSRUG
Two Rules:
Rule #1 – Make Conservative Decisions

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

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

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

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

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

11. Lubrication System – Static Sump
FSRUG
Lubrication System – Static Sump

12. Lubrication System – Static Sump
FSRUG
Lubrication System – Static Sump
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 Journal Surface Peripheral Velocity Limit
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
Oil Ring – Example of Damage

18. Oil Ring – Example of Damage
FSRUG
Oil Ring – Example of Damage

19. Oil Ring – Example of Damage
FSRUG
Oil Ring – Example of Damage

20. Forced Feed Lubrication System
FSRUG
Forced Feed Lubrication System
Typical Schematic

21. Forced Feed Lubrication System
FSRUG
Forced Feed Lubrication System
Pressure Setting Logic:

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

23. Forced Feed Lubrication System
FSRUG
Forced Feed Lubrication System
Reservoir Layout

24. Forced Feed Lubrication System
FSRUG
Forced Feed Lubrication System
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)
Reverse Rotation Protection for the Shaft Driven Oil Pump

25. Forced Feed Lubrication System
FSRUG
Forced Feed Lubrication System
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: GPM Plus leakoff
Option to Feed Driver (Motor) Bearings

26. Forced Feed Lubrication System
FSRUG
Forced Feed Lubrication System
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
Forced Feed – Drain Piping
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)
Reservoir Level (Normal Operation) – below drain line [Maintain design required level with a range]

28. Forced Feed – Drain Piping
FSRUG
Forced Feed – Drain Piping

29. Forced Feed – Reservoir Level Above Drain Piping
FSRUG
Forced Feed – Reservoir Level Above Drain Piping

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

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

32. FSRUG
Forced Feed – Drain Header Vertical Piping Replaced with Metallic Flex Hoses/Fittings (likely Choking the drainage)

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

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

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

36. Forced Feed System – Challenges
FSRUG
Forced Feed System – Challenges
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.

37. Forced Feed System – Challenges
FSRUG
Forced Feed System – Challenges
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).

38. Industry Events: FSRUG
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.

39. Industry Events: FSRUG
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

40. Industry Events: FSRUG
2014 – Freezing Weather, Heater Drain Pump Packingless Stuffing Box dP Sensing Lines Freeze, Loss of Stuffing Box dP, Reduced Plant Power, Secured Heater Drain Pump, Pump Discharge Check Valve Leaked By, Pump Rotated Backwards. Forced Feed Lube System – No Aux Backup Oil Pump (Thrust Bearing Failed and Melted Drive Coupling), Main Lube Oil Shaft Driven Pump – No Reverse Rotation Protection (Lube Oil Pump Failed). Lost Generation Until Parts Replaced.
Cause: Vintage Forced Feed Lube Oil System Lacking Features to Adequately Protect the Main Pump and Equipment.
2014 – Safety Related Horizontal Raw Water Pump. Forced Feed Lube Oil System Drain Header Backing Up and Leaking Oil from Drive End Bearing Housing.
Cause: Brg Hsg Not Well Vented (clogged), Header Slope (not per spec), Flex Hose Fittings choking capacity to drain

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

42. SOURCE REFERENCES: FSRUG
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
API-614: Lubrication, Shaft Sealing and Oil-Control Systems & Auxiliaries

43. FSRUG

44. FSRUG
THE (HAPPY) END
QUESTIONS ?