Experimental and numerical investigation of flow- accelerated corrosion in 90° elbow

Abstract

A comprehensive study of flow-accelerated corrosion in 90 °C elbow has been investigated by array electrode technique and computational fluid dynamics (CFD) simulation. The corrosion current densities at the outward bend are found to be higher than those of the inward bend, which are opposite to the distribution of fluid velocity and shear stress obtained from CFD. The presence of differential flow galvanic corrosion apart from the oxygen-absorbed corrosion controlled by mass transfer process is confirmed by the corrosion current densities and mass transfer coefficients. Moreover, a simplified one-dimensional galvanic corrosion model is used to evaluate the corrosion rate by differential flow galvanic corrosion system, and the validity of this model has been also proved. In addition, the galvanic corrosion current densities calculated from the simplified one-dimensional galvanic corrosion model are consistent with the exponential results and the actual failure tendency of the elbows in Taiwan PWR nuclear power plant.