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

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

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

Chrome Plating Process Continued… Finish Grinding Excellent dimensional control Tolerances as tight as +/- 0.0005” are achievable 2015 FSRUG

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

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

How do proximity probes work? 2015 FSRUG

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

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

2015 FSRUG

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

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

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

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

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

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

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

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

Questions? 2015 FSRUG