1. Hard Chrome Plating in Feedwater Pumps
Presented By: Kurt J. Weis
Rotating Equipment Repair, Inc.
2015 FSRUG

2. The Hard Chrome Plating Process
Prep Machining (typically 0.004”-0.005” per side)
Surface cleaning/polishing
“Stop-off” of surfaces that are not to be plated.
Lacquers, foils, tapes & waxes
2015 FSRUG

3. Chrome Plating Process Continued…
Immersion into chrome plating tank
Chromic Acid
Insoluble lead alloy anode
Part acts as the cathode
Plating rate of 0.001” per hour
2015 FSRUG

4. Chrome Plating Process Continued…
Finish Grinding
Excellent dimensional control
Tolerances as tight as +/ ” are achievable
2015 FSRUG

5. Hard Chrome Properties
Ultra Hard (65-70 HRC)
High galling resistance
Excellent adhesion (>10,000 PSI)
Adheres to a wide range of materials
Steel, Stainless Steel, Aluminum, Copper, Bronze etc.
High abrasion resistance
Corrosion resistant
2015 FSRUG

6. Applications in Feedwater Pumps
Dimensional restoration
Bearing journals, shaft fits, impeller bores, etc.
Bearing journal damage on a high speed feedpump shaft
Damage was repaired via hard chrome plating and grinding
2015 FSRUG

7. How do proximity probes work?
2015 FSRUG

8. Proximity Probes Continued…
Eddy Current Transducer
Modulations in DC voltage directly proportional to air gap distance between probe tip and shaft surface
Modulations in AC voltage directly proportional to vibration
2015 FSRUG

9. Material Effects on Proximity Probes
Slope of linear relationship between air gap and DC voltage is strongly material dependent
This relationship can be dramatically changed with the addition of a chromium layer
2015 FSRUG

10. 2015 FSRUG

11. Case Study
In April 2011, a newly rebuilt Flowserve CHTA BFP trips upon initial startup due to high vibration readings
2015 FSRUG

12. Case Study Continued..
Pump ran for approximately 4-8 seconds before IB proximity probe registered vibrations of 4.69 mils resulting in a trip
2015 FSRUG

13. Hand held vibration equipment
Case Study Continued..
After discussions between RER and plant engineering, proximity probe logic adjusted to subtract 2 mils to allow further readings to be taken
Hand held vibration equipment
2015 FSRUG

14. Actual vibration registered by handheld: 0.07-0.08 in/s
Case Study Continued..
Actual vibration registered by handheld: in/s
2015 FSRUG

15. GE-Bently Nevada (vibration probe manufacturer) contacted
Case Study Continued..
Plant records were consulted, chrome repair during previous repair was discovered
GE-Bently Nevada (vibration probe manufacturer) contacted
Custom logic provided for 410SS w/ 0.020” chrome layer
2015 FSRUG

16. Know the exact axial location of each proximity probe
How do we deal with this?
Know the exact axial location of each proximity probe
Combat this phenomenon by allowing for a relief in the shaft where chrome is not applied
2015 FSRUG

17. Delaval Tilt Pad Journal Bearings
Bearing design/vibration probe location makes a relief from chrome impractical
2015 FSRUG

18. Custom Logic
If incorporation of a shaft relief is not possible, contact your proximity probe supplier, as custom logic programing is available that will account for the chrome layer
2015 FSRUG

19. Questions?
2015 FSRUG