Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers


Alkaline Environment

Last updated: December 31, 2018

What Does Alkaline Environment Mean?

An alkaline environment is a setting that is strongly basic or contains alkali components. This usually refers to an environment with a pH value higher than 7.0, since a pH below 7.0 is considered acidic.

Alkaline environments are less prone to cause corrosion than acidic environments, but it is possible for alkalinity to cause corrosion as well.


Corrosionpedia Explains Alkaline Environment

In alkaline environments, the number of hydrogen atoms are able to counterbalance acids. Therefore, when a solution is said to be alkaline, it is known as basic and has the formula to counter the effects of acids, which are a major contributory factor in corrosion.

Although alkaline environments are less dangerous, metal corrosion can still take place in alkaline environments, especially when there is existing dissolved oxygen. Water solutions can dissolve the oxygen present in the air quickly, which produces the oxygen necessary for the process of corrosion. One typical example is iron rusting when it is exposed to a damp atmosphere.

One typical example of metal that corrodes in an alkaline environment is zinc. This material is not usually used in either alkaline or acid solutions because it undergoes corrosion in both types of environments. Acids in minute amounts can hasten the corrosion rate far beyond the approved limits. On the other hand, although alkaline solutions are less corrosive to zinc in this case, the alkaline environment is still corrosive enough to damage any structure made from zinc.

The corrosion caused by imbalance in pH is normally resolved by adding the proper amount of alkali as well as using inhibitors like sodium chromate, borates, silicates and others that inhibit corrosion of metals in alkali environments.

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