Wicket Gate alignment Wanapum Dam Turbine Replacement By

Wicket Gate alignment, Wanapum Dam Turbine Replacement By: Travis Wiser Mechanical Engineer Grant County PUD

• • • Introduction Project overview Failure discovery Lessons learned Questions

Wanapum Dam • Owned and operated by Grant County PUD • Mid Columbia Dam • Constructed from July 1959 to Oct 1963

Wanapum Dam Turbines • OEM Dominion Engineering • 10 - Kaplan Turbines • OEM Rated capacity 89 MW/unit • Rated head 78’ • Upgrade began in 2004

• • • Introduction Project review Failure discovery Lessons learned Questions

BEFORE AFTER 120, 000 HP EXISTING PROBLEMS: Cavitation Blade Cracking Blade Sagging Blade Rubbing Vibration Etc. 150, 000 HP El. 470. 0 D=305” El. 458. 23 D=285” El. 461. 54 80 -ft head 85. 7 rpm NEW FEATURES: Complete Runner Shaft/Blade Servo Coupling Bolts Shaft Seal Guide Bearing Outer Headcover Inner Headcover W. Gates + Bush. WG Mechanism Stay Vane Ext’s Bottom Ring Discharge Ring Upper DT Liner Oil Head Mods Gov. Tank Governor Sys Mods Maintenance P-form Draft Tube Mods

Project review • Design Features – Semi to fully spherical – Minimum gap runner • • Runner to bottom ring gap and water passageway. 250” Blade to runner hub gap. 07” to. 137” – Wicket gates, increased from 20 to 32. – Greaseless WG bushings – Removable WG cartridges

Outer head cover Gate ring Wicket gate Bottom ring Embedded distributor Stay vane

Water passageway • • • Original liner removed Bottom ring Stainless steel w/ spherical portion to match runner Replaced outer head cover, carbon steel

Bottom ring installation

Upper Wicket Gate Bushing Upper Wicket Gate Cartridge Intermediate Wicket Gate Bushing Upper cartridge Seal

• • • Introduction Project review Failure discovery Lessons learned Questions

Seal failure • Seal failure on first unit after approx. 7. 5 years of service • Bushing inspection revealed severe wear, cracks, separation from substrate • “fog horning” noise present on units during WG operation Int. Bushing Worn through here Failed seal

Upper Wicket Gate Bushing Upper Wicket Gate Cartridge Intermediate Wicket Gate Bushing Upper cartridge Seal

Upper Gate Cartridge • • New Bushings are greaseless Bushing material is sintered bronze material with PTFE lubricant trapped through sintered layers. Backing material is 300 series Stainless Steel Inside diameter coated with film of PTFE for break-in Upper WG cartridge

Investigation • • • 100% failure of upper seals. determination was material was too soft. RCA of bushing by design Engineer was inconclusive Bushing loading per FEA, 14. 01 MPa Top, 14. 41 MPA mid, 13. 3 MPa Bot Permissible bearing pressure is 150 MPa per bearing manuf. Misalignment from installation should be acceptable per design engineer.

Alignment • • BR and OHC Machined offsite Aligned using plumb wires, . 030” radial miss match on unit W 08 according to 8 locations. Difficulties in aligning – Material coefficient of thermal expansion – Temperature when machined vs installed PUD realignment ( procedure developed by Pat Oldham)

Realignment procedure • • • Use the wicket gate as a plumb wire Center WG stem in upper bushing Center WG stem in intermediate bushing Measure radial and tangential offset Resultant offset measured up to 0. 120” Custom offset machined into each lower canister.

• • • Introduction Project review Failure discovery Lessons learned Questions

Lessons Learned • • • Dissimilar material create alignment complexities Hypothesis is that gate misalignment causing premature wear in bushings (Verified after further operation) Line bore Outer head cover to Bottom ring onsite to eliminate alignment issues.

Questions?