Anticorrosive coating rule table, the rule of law cathode. But once the anti-corrosion coating is damaged, exposed iron part will accelerate localized corrosion. Therefore, anti-corrosion coating and cathodic protection is relative to the joint statement of the way to rid the economy and effective. Antiseptic way spiral steel pipe buried pipelines for three electrochemical process corrupts, as in pipe wall plus anti-corrosion coating, loop resistance can be increased, reducing the corrosion current; external DC power supply, so that the soil pipe to cause a negative potential to form cathode cover, may discourage potential difference between the anode and cathode, anode and cathode processes carried out basically from the end.
In the sacrificial anode protection laws in general, the use of magnesium alloy as a sacrificial anode to protect the pipeline. Due to damage suffered in the course of the output current, magnesium alloy sacrificial anode design application life the best match of the useful life of the pipeline, neither happened squandered too soon to add protection costs. It should be noted that, when the soil resistivity and high waters are protected through the pipeline, the sacrificial anode protection should not be used. Different methods have different antiseptic antiseptic quality and costs, should be protected in accordance with different pressure steel pipe, which is different from its use in different environments and different gas transportation, comprehensive account of the cost of corrosion and corrosion protection methods. For the city gas system, due to the underground pipe network intensive, cathodic protection applied power to other pipelines interference, can cause its own benefit victims of the situation in his home. The use of negative potential than the metal pipe and pipe the data protection laws of the sacrificial anode is connected to does not render such cases, therefore, city gas mains gas corrosion method should be used with martyrdom anodic corrosion coatings combine.
However, in considering the economic aspects of justice should note two points: ? a preservative investment in gas pipeline construction time, maintenance costs ② gas pipeline network to run after. Because of city gas pipeline network in the urban areas, put into operation after maintenance inspection hard and high costs, it should be appropriate to increase the time to invest to reduce routine maintenance work after commissioning the pipeline now commonly buried gas pipeline external corrosion coating There are three layers PE composite structure, epoxy powder (FBE), coal tar enamel, coal tar epoxy and PE tape and other five. In our country, from the useful life, fully consider economic factors, such as maintenance costs, three PE composite structure generally preferred anti-corrosion coating. The buried pipeline in the U.S. and Europe are three main anti-corrosion coating PE composite structure, epoxy powder corrosion.
