CHALLENGE: The California Department of Water Resources (DWR) faced a daunting repair project on the Oroville Dam, a hydroelectric plant near Sacramento, California, and the tallest dam in the U.S.
During a turbine refurbishment, a subcontractor discovered that an excessive load was being added to the bearings of the turbine runner that turned the generator. The turbine chamber cover plate fasteners needed repairs to keep the plant running smoothly. When considering repair options, DWR discovered the plant’s subcontractors didn’t have the proper precision equipment on hand that was needed for this type of repair, and that using hand tools would take too much time and wouldn’t produce a high-quality repair.
PAYOFF: After discussing the challenge and repair needs, the Operations & Maintenance Department’s lead mechanic worked with CLIMAX experts to determine a top-quality, efficient and cost-effective repair solution. Based on the needs of the project, the decision was made to rent a FF8200 Flange Facer, which has a number of innovative safety features and is capable of precision machining large diameter flanges and holding tight tolerances.
The FF8200 helped the team achieve a tolerance of .002 inches (.0508 mm) across the 121-inch (307 cm) diameter stainless steel turbine runner and completed the job with minimum downtime and disruption to the plant. Once complete, the turbine was reassembled and all three turbines were put back into immediate operation. The department is now considering purchasing one of the machines to keep on hand for other maintenance projects.
Pairing on-site portable machine tools with highly skilled mechanics helped complete this job in an efficient, reliable and cost-effective manner, making the project a huge success.