Why Does Steel PIPE Rust？

Reasons for Steel Pipe Rusting

Steel pipe rusting is a complex chemical process, which is mainly caused by the following factors:

1. Oxidation reaction

The main component of steel is iron (Fe), and oxidation reaction occurs when iron comes into contact with oxygen (O₂) in the air.

2. The role of moisture

Water is not only a catalyst for oxidation reaction, but also dissolves carbon dioxide in the air to form a weak acid solution, which further accelerates the corrosion of the metal surface.

3. Electrochemical corrosion

In the presence of moisture, micro-battery structures will form on the surface of steel.

4. Environmental factors

Humidity: In a high humidity environment, the moisture content in the air is higher, which increases the possibility of oxidation reaction.

Temperature: Increased temperature usually accelerates the rate of chemical reactions, including oxidation and corrosion processes.

Pollutants: Pollutants in the atmosphere such as sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) can combine with water to form acid rain, exacerbating the corrosion of steel.

Soil conditions: Buried steel pipes are easily affected by factors such as soil type, pH value, and water content. Some types of soil are highly corrosive.

5. Mechanical damage

If the surface of the steel pipe is scratched, hit or otherwise physically damaged, destroying the original protective layer (such as coating or galvanizing), the exposed metal part is more susceptible to corrosion.

6. Influence of internal medium

For steel pipes that transport fluids, the nature of the internal medium will also affect its corrosion. For example, transporting acid and alkali solutions, seawater or liquids containing dissolved oxygen will accelerate the corrosion of the inner wall of the pipe.