Environmental Engineering Reference
In-Depth Information
Figure 4.14
Anodic protection of a steel storage tank containing sulfuric acid.
to maintain passivity corresponds nearly to
i
passivity
, which again indicates the rate
of corrosion under protection.
Anodic protection has been very successfully employed for the protection of
carbon and stainless steel storage and transportation vessels for sulfuric acid as
well as for the stainless steel heat exchangers in sulfuric acid plants. The corrosion
rate of the unprotected structures in these media is very high, and it would be
highly uneconomical to provide cathodic protection because the current require-
ment will also be enormously high, as represented by
i
app(c)
in Fig. 4.15. On the
other hand, the current requirement for maintenance of anodic protection is usu-
Figure 4.15
Polarization diagram illustrating current requirement in anodic protection.
