UFC 3-570-06
JANUARY 31 2003
Figure 2-4. Concentration Cell Caused by Different Concentrations of Oxygen
Cathodic Area on Pipeline
Reference Electrode
Current Flow in the Earth
Anodic Area on Pipeline
Reference Electrode
Low Oxygen Concentration
2-2.2.3
Moist/Dry Electrolyte. Pipelines or tanks that are exposed to areas of low
and high water content in the electrolyte also exhibit different potentials in these
different areas. Generally, the area with more water content becomes the anode in this
electrochemical corrosion cell. This is most severe when a pipeline passes through a
swampy area adjacent to dry areas or a tank is located in dry soil, but the water table in
the soil saturates the tank bottom.
Figure 2-5. Concentration Cell Caused by Different Concentrations of Water
Cathodic Area on Tank
Dry Soil
Current Flow in the Earth
Anodic Area on Tank
High Liquid Content
2-2.2.4
Non-Homogeneous Soil. Pipelines or tanks that are exposed to an
electrolyte that is not homogeneous exhibit different electrical potentials in the different
2-8
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