Cast Iron Water Pump Repair
Case History #009 REV.04-97
Nuclear power plant, northern New England
Cast iron main condenser circulating water pump in salt water service was suffering the normal effects of corrosion and wall-thinning. In places, graphitization had built up to an inch in thickness and pitting was as deep as 1/2-inch. This pump was scheduled for a major overhaul. The owner included a complete coating application as part of this procedure.
All wet pieces of this pump were coated to include the drive motor mounting plate, deflector plate, upper elbow, top drop pipe, lower drop pipe, diffuser, volute and bell mouth.
After high-pressure washing to remove marine growth, the components were allowed to dry. Each piece was abrasive-blasted to gray / white metal with a minimum 3-mil profile prior to coating. Two coats of Arcor™ S-16 were applied by hand with Arcor™ TS-RB installed as an intermediate rebuilding layer in areas of pitting and erosion. Particular attention was given to the volute where cavitation caused by the pump impeller had removed as much as 1 inch of the base metal. This area was primed, filled with ARCOR™TS-RB and sanded smooth before top-coating.
Because of the close tolerances between the volute and the pump impeller, coating on this component was applied with a squeegee to keep it very smooth and extra thin.
This pump was coated in August 1993. To date, this pump is still in service. Two volute casings were repaired with Arcor™ epoxies prior to this project.
Sanding interior surfaces prior to top-coating.
Application of ARCOR S-30 Blue to pump impeller.
Application of S-30 Blue Completed.