A general process flow sheet of the corn refining industry is shown to indicate the process steps for which corrosion data were determined. Corrosion data for starch, dextrose and by-product manufacture were taken from field and laboratory corrosion tests. Special techniques for determining the effect of pitting, intergranular corrosion of welds and applied stress were used for some materials tested. Determination of metallic contamination by a corrosion test is explained. The inclusion of economic factors in calculation of a corrosion cost index was employed in evaluating the corrosion data.
Corrosion rates and corrosion cost index values are shown in tables for a number of process steps in the corn refining industry. The materials which indicated satisfactory values are separated from the materials which did not indicate satisfactory service in the environment. The corrosion data are confirmed in some tests by actual experiences with plant equipment. Limiting values for corrosion rates and corrosion cost index are shown.
The corrosion data are summarized to show the materials which may be considered corrosion resistant for certain corn refining processes. The materials are shown in the order of preference. Factors of physical characteristics and availability are shown for some materials.
