The Contractor shall provide scheduled maintenance and on-call repair services that include overhauling various Homa Drainage Pumps and centrifugal pumps, perform motor shaft coupling alignment to the centrifugal pump, repair or replace valves such as check valves and gate valves, and other valves as needed. Repair or replace normal piping and flexible piping, pipe couplings, piping hanger systems, cooling water piping systems associated with pumps, electronic solenoid valves to the pumps, sump pumps, backflow preventers, and insulation. Locations to be serviced on the contract are at the Hampton Roads Bridge Tunnels, Monitor Merrimac Memorial Bridge Tunnels, and T564 Tunnel with the follow: A. TASK I – OVERHAUL HOMA PUMPS SCOPE (SEQUENCE OF REPAIR): The Contractor shall furnish all transportation, labor, supervision, equipment, tools, parts and materials, as necessary to overhaul the Homa Drainage Pumps at the Hampton Roads Bridge Tunnels and the Monitor Merrimac Memorial Bridge Tunnel. All work shall be executed in strict accordance with the procedures noted below. The procedures noted below may not be all inclusive and field adjustments may be necessary to accommodate the work. The Contractor shall: 1. Upon VDOT Contract Administrator or designee’s request, remove the designated pump from the Portal or Mid – Channel Pump Room and transport to the Contractor’s Shop. 2. Install the spare pump provided by VDOT’s Contract Administrator or designee or provide and install blind flanges with gaskets and bolting on the pump suction, discharge piping and vent piping as directed by VDOT’s Contract Administrator or designee. For Homa pumps with water supply to the motor jacket, isolate the water supply connection. 3. Disassemble drainage pump at the Contractor’s shop. 4. Salvage the volute bolting and gasket. 5. Sandblast, inside and outside of the volute. 6. Clean the pump shaft and impeller. 7. Remove and salvage all “O” Rings and gaskets. 8. Clean the threads on the pump shaft for the impeller nut and keyway and check the fit of the impeller to the pump shaft. 9. Check the pump shaft to confirm straightness is within tolerances and all keyways are clean, straight and retain the proper dimensions. 10. Inspect the impeller for excessive wear and/or damage. 11. Check out the motor electrically. Inspect and rewind as necessary after the concurrence of VDOT’s Engineer. 12. Coat the wetted interior of the casing halves and the wetted surfaces of the impeller with a coating of Belzona® No. 1341 Supermetal glide or equal approved by VDOT’s Contract Administrator or designee. 13. Provide and install a new shaftsleeve complete with new “O “Ring on the pump shaft. 14. Press a new wearing ring on the impeller. 15. Press a new wearing ring into the bowl casing section. 16. Assemble the impeller to the pump shaft with a new shaft key and nut and apply LocTite No. 262 to the shaft threads as a thread locking compound. 17. Provide and install a new liquid deflector on the pump shaft. 18. Provide and install new thrust bearing with shims on the pump shaft. 19. Provide and install new radial bearing on the pump shaft. 20. Provide the proposed procedure for balancing to VDOT’s Engineer for approval prior to commencing the balancing operation. 21. Touch Balance the pump impeller and shaft to the following: • .05 inches per second in the vertical direction • .10 inches per second in the horizontal direction • .10 inches per second in the axial direction 22. Reassemble the pump shaft with impeller into the casing back plate. 23. Provide and install new mechanical seal assemblies. 24. Provide and install a new casing gasket. 25. Confirm the proper clearance between the O. D. of the impeller wearing ring to the I. D. of the stationary wearing ring in the bowl casing section (adjust as necessary). 26. Provide and install new bolting for assembly of the casing bowl section to the pump back plate with pump shaft and Impeller. 27. Assemble the back plate and impeller with shaft and mechanical seal assemblies to the bowl casing section and make up all casing bolting. 28. Confirm the proper clearance between the impeller and the back plate (adjust as necessary)
