Reclamation Information Sharing Environment (RISE)

Cavitation resistant coatings have been used in mild cavitation conditions with mixed results, and rarely lasted more than a few years before needing repair. Laboratory testing identified two commercial polyurethane elastomers with better cavitation resistance than prior coatings used in draft tubes for cavitation resistance. These two elastomers, PE1 and PE2, were selected for field trials on Nathaniel “Nat” Washington Power Plant Unit G21 turbine runner, a severe cavitation environment in which stainless steel weld overlays require repairs of pitting damage on a three-year rotation. The goal of the field trial is to determine if the elastomers can reduce stainless steel cavitation in a severe cavitation environment to lengthen the repair cycle and reduce cost. This interim report documents the surface preparation and coating of Blades 7 and 13 with PE2 and PE1, respectively.