The corrosion forms of seamless steel pipes in buried pipelines are divided into local corrosion and uniform corrosion. Local corrosion is the main one and the risk is the greatest. Pipeline is mainly electrochemical dissolution in soil erosion process. The formation of corrosive cells leads to pipeline perforation and corrosion. According to the distance between anode and cathode of corroded batteries, corroded steel tubes of corroded batteries can be divided into micro and macro battery corrosion. The so-called corrosion of micro-batteries refers to the corrosion between the anode and cathode of pipeline micro-batteries with the action of several millimeters or even only a few microns. Its shape characteristics are very uniform, so it is also called uniform corrosion. Because the micro-anode is very close to the cathode, the corrosion rate of the micro-battery does not depend on the resistivity of the soil, but only slightly on the micro-process of the anode and cathode electrodes. Micro-electrolysis corrosion of buried steel pipes is less harmful.


The so-called macrocell corrosion, current, action macro refers to the corrosion of the pipeline composed of several centimeters or even several meters of anode and cathode areas. Macro unit corrosion, also known as local corrosion. Because the dielectric resistance far from the soil in the anode and cathode areas accounts for a considerable proportion of the total resistance of the corroded battery circuit, the corrosion rate of the macrocell is related not only to the anode and cathode electrode technology, but also to the soil. Resistivity correlation. Macroscopic corrosion rate of batteries can reduce soil resistivity. This is due to macro-cell corrosion in buried pipes or pitting on patchy corrosion surfaces, which is quite dangerous.