The damaged form of SSAW steel pipe surface

SSAW (Spiral Submerged Arc Welding) steel pipes are protected by a very thin, stable layer of fine chromium-rich oxide film. This protective film prevents oxygen atoms from penetrating the steel, thereby providing oxidation resistance and anti-corrosion properties. However, if this film is damaged, air or liquid oxygen can penetrate, causing the iron atoms to oxidize and leading to surface corrosion. There are several common ways this protective film can be damaged:

Deposits of Other Metals:

When particles or fixtures made of different metals are deposited on the surface of SSAW steel pipes in a humid environment, a micro-battery effect can occur between the stainless steel and the foreign metal. This electrochemical reaction damages the protective film, leading to electrochemical corrosion.

Organic Residue:

Organic materials such as vegetable juices, soups, or saliva can adhere to the pipe surface. In the presence of water, these materials form organic acids, which corrode the metal surface over time.

Acids, Alkalis, and Salts:

Adhesion of substances like acids, alkalis, or salts (for example, from wall decoration lye or lime splashes) to the pipe surface can cause localized corrosion.

Polluted Air:

In environments with polluted air containing high levels of sulfides, carbon dioxide, or nitrogen oxides, condensation can lead to the formation of sulfuric, nitric, or acetic acid solutions. These acidic solutions cause chemical corrosion of the steel surface.

These factors highlight the importance of maintaining the integrity of the protective film on SSAW steel pipes to prevent corrosion and extend their lifespan.