Abstract
A corrosion test for carbon steel tube with obstruction that had narrow inner diameter was conducted. Water treatment conditions of thermal power plants were applied for the test to evaluate wall thinning rates. The wall thinning rate under an AVT (All Volatile Treatment) condition was larger than that under an OT (Oxygenated Treatment) condition. Wall thinning occurred at the front of narrow obstruction and the neighborhood of the front.
Corrosion test results and hydrodynamic analyses using a turbulent flow model indicated that the values of turbulent energy and mass transfer coefficient at wall surface were associated with wall thinning rate and wall shear stress was not the dominant factor of wall thinning rate. The wall thinning rate derived from mass transfer coefficient was almost the same as that from the corrosion test. Therefore the dominant factor of the wall thinning rate was considered to be mass transfer rate of Fe ions dissolved from magnetite layer on the component surface.
