凡是腐蚀都由电流产生。电流从金属流向周围的电解质即产生腐蚀。任何金属放在土壤中,金属与土壤之间就会有电位差存在。这个电位差称为金属的溶液电位。不同金属具有不同的电位。把两种金属用导体联接后埋在地下,就组成一个原电池。发生腐蚀的是电位较高的金属。同一金属对于不同的土壤(如性质不同,温度不同等等)也有不同的电位,因此埋在不同土壤中的同种金属间会有电流产生,发生腐蚀。以下是几种在管线上产生腐蚀的情况:一、由于管子表面不均匀(含有杂质)产生腐蚀(见图 Any corrosion is generated by the current. Current flows from the metal to the surrounding electrolyte causing corrosion. Any metal placed in the soil, metal and soil there will be a potential difference exists. This potential difference is called the metal solution potential. Different metals have different potentials. The two kinds of metal with conductor buried in the ground, to form a primary battery. Corrosion is the higher potential of the metal. The same metal for different soil (such as different nature, temperature, etc.) also have different potentials, so the same kind of metal buried in different soil will have a current, the occurrence of corrosion. The following is the case of several corrosion on the pipeline: First, due to uneven pipe surface (containing impurities) corrosion (see Figure