Industrial gases include SO2, CO2,NO2, CI2,H2S and NH3 etc. Although the content of these components is very small, but the corrosion of steel is not negligible, among which SO2 has the greatest impact, which can make the passivation film on the metal surface damaged. These gases are acidic when dissolved in water, forming acid rain that corrodes metal installations. The steel structure in atmospheric environment is affected by sunshine, wind, sand, rain, snow, frost and dew, temperature, humidity throughout the year. Among them, oxygen and moisture in the atmosphere are the important factors causing outdoor steel corrosion.

The marine atmosphere is characterized by a large amount of salt, mainly NaCI, which settles on the metal surface. Due to its moisture absorption and conductive effect of increasing the liquid film on the surface, CI ions themselves also have a strong erosive effect, thus aggravating the corrosion of the metal surface. Closer to shore, the steel corrodes influence more, many times faster than inland atmosphere.