Hydro: Head Cover Machining Vertical Pelton Turbine Overhaul Wicket Gate Refurbishment Runner
Machining Shasta Dam Tube Valve Overhaul Pelton Needle Valve Overhaul Facing Plate Replacement
Francis Turbine Wear Ring Replacement Francis Turbine Hydro Electric Turbines & Valve Periodically, all
hydroelectric turbines require a major overhaul. The extent of the work required during an overhaul will
depend a great deal on operating conditions such as water quality and how the unit was loaded. Our
experience can be an asset to your organization for your shutdown. In order for the overhaul to proceed
smoothly and to accomplish all the work required, planning should start well before the overhaul starts.
Based on the inspection of the unit and on the discussions during the scheduling meeting, a list of required
materials, tools, and services should be made. Wilcox can help with this planning and will do so in advance
of your turnaround typically free of charge. We recommend utilizing our experience because we guarantee
that we can save you time and money. The specifications for materials and tools required for the overhaul
should be prepared as well as “Statements of Work”. Wilcox has experience reworking worn or damaged
turbine components as well as designing and manufacturing replacement most components. It is helpful to
obtain reports of previous overhauls since they can prevent the same mistake from being made twice and
may provide tips that can expedite the overhaul procedure. The maintenance files may also provide names
of sources for parts and materials.

Turbine runner: Check each bucket carefully for cavitation damage and cracks. If possible, use die
penetrant or other nonde structive test to check for cracks. Compare seal ring clearance readings with
design clearances. Wilcox has several large vertical mills which can be utilized to inspect runouts,
concentricity, and skim cut runner as needed to repair areas as needed.

Wear Rings: Wilcox manufacturers wear rings up to 18 feet in diameter for replacement on Francis
and Kaplan type runners. Wilcox has access to affordable Ring Rolling mills in the United States and
Mexico with a proven track record for providing high quality rough rings for the both the upper and lower
head cover as well as the runner.

Wicket gates: If sealing surfaces are uneven or damaged, they should be repaired by welding and
machining back to drawing dimensions. The heel and toe sides of the gate should both be measured
when checking the top and bottom clearances. If journals are worn at the bushing areas as they typically
are Wilcox can thermal spray these areas with several coatings to aid resize them. Chroming is also an
option however with current advances in thermal spray coatings the cost can be competitive as well as
quicker thereby reducing the outage window. Wilcox has manufacturer’s representative agreements with
an overseas casting plant used by Alstom power and others to cast new wicket gates. At our Los Angeles
factory we can finish machine these components and prepare them for installation into the reconditioned
turbine.