Acid plants corrosion rate factors

As with other factors, no direct statements can be made relating the reaction of a soil to its corrosive properties. Extremely acid soils (pH 4 0 and lower) can cause rapid corrosion of bare metals of most types. This degree of acidity is not common, being limited to certain-bog soils and soils made acid by large accumulations of acidic plant materials such as needles in a coniferous forest. Most soils range from pH5 0 to pH8 0, and corrosion rates are apt to depend on many other environmental factors rather than soil reaction per se. The 45-year study of underground corrosion conducted by the United States Bureau of Standards included study of the effect of soils of varying pH on different metals, and extensive data were reported. 

The nomograph of Figure 3-3 can be used to provide an estimate of the corrosion rate in the regenerator overhead and the contactor bottoms of amine plants when CO2 is the only acid gas present. De Waard and Lotz (1993) also discuss the use of correction factors to account for the effects of corrosion product films, pH, system pressure, system geometry, glycol or methanol, crude oil, inhibitors, and flow velocities on corrosion rates. 

Temperature, acid concentration, and acid velocity are three main factors that influence the corrosion rate of acid plant equipment. 

---