Corrosion Mechanism of Steel Plate Coiled Pipes

Release date:

2021-01-11

Author:

Source:

Category:

Steel Pipe Knowledge

Corrosion that occurs on the surface of steel pipe coils exposed to the atmosphere is referred to as atmospheric corrosion. This phenomenon arises because the atmosphere contains water vapor, which condenses on the pipe surface to form a thin water film. The water film dissolves oxygen and other impurities from the air, leading to electrochemical corrosion. Since the water film is extremely thin and offers low resistance, and oxygen from the air is continuously supplied, the cathodic process is primarily driven by the depolarization of oxygen. The corrosion of steel pipelines in the atmosphere is influenced by factors such as atmospheric conditions, metal composition, surface morphology, orientation, droplet runoff, and operating conditions.

　　1. Principles of atmospheric corrosion.

　　Exposed to the atmosphere Steel plate rolled pipe On the surface, corrosion caused by the action of water and oxygen is referred to as atmospheric corrosion. This occurs because the atmosphere contains water vapor, which condenses on the pipe surface to form a thin water film. The water film dissolves oxygen and other impurities from the air, leading to electrochemical corrosion. Since the water film is extremely thin and offers low resistance, and oxygen from the air is continuously supplied, the cathodic process is primarily driven by the depolarization of oxygen. The corrosion of steel pipelines in the atmosphere is influenced by factors such as atmospheric conditions, metal composition, surface morphology, orientation, droplet flow, and operating conditions.

　　2. Principles of soil corrosion.

　　Soil corrosion refers to the corrosion of buried steel plate‑wrapped pipes caused by the soil environment; it is a form of electrochemical corrosion. Soil is a complex multiphase mixture, with pores between particles filled with air, water, and various salts, giving it electrolytic characteristics.

　　a. Microcorrosion cells are corrosion cells that form due to the surface condition of buried steel pipelines. Because of defects in the pipeline, it may contain heterogeneous materials; when such non‑uniform steel contacts the soil, differences in electrode potential at these localized areas give rise to microcorrosion cells.

　　b. A macrocorrosion cell is a corrosion cell arising from differences in soil properties. When a buried steel plate coil passes through soils with widely varying physicochemical characteristics, a significant potential difference can develop, and the distance between the two electrodes of the resulting corrosion cell is relatively large; hence, it is referred to as a macrocorrosion cell.

What is the significance of pickling large-diameter steel pipes?

Production process of welded steel pipes

More News

■

What are the product categories offered by spiral pipe manufacturers?

—

2023-05-11