Reclamation Information Sharing Environment (RISE)

Cavitation resistant coatings have been used in mild cavitation conditions with mixed results and rarely are in service more than a few years before needing repair. Laboratory testing of two commercial polyurethane elastomers (rubber-like properties) provided superior cavitation resistance compared to prior coatings used in cavitating environments. These materials may provide protection in moderate or severe cavitating environments, comparable to stainless steel weld overlays. A field trial was deemed necessary to verify the outcomes of the laboratory findings. These two elastomers were selected for field trials on Nathaniel “Nat” Washington Power Plant Unit G21 turbine runner, a severe cavitation environment. Turbine runners have higher intensity cavitation and the commonly used stainless-steel weld overlays eventually cavitate with significant pitting, requiring repair on a three-year rotation. Initial results showed a small area of damage in the most severe cavitation location near the leading edge on the suction side of the blade.