With the gradual popularization and use of natural gas, new requirements have been put forward for gas pipelines in cities. This directly buried thermal insulation and heating steel pipe has the characteristics of thermal insulation and waterproof, corrosion resistance and heat resistance, and strong flame retardancy. Construction is more convenient, not afraid of plant root thorns and other excellent characteristics have become the construction industry transportation petrochemical and other departments of some special materials. Citygas steel pipeThe electrochemical reaction corrosion in soil can be divided into macro-cell corrosion and micro-cell corrosion, which mainly occurs at the junction. When metal pipelines are distributed at the same time, it is easy to produce a large degree of corrosion at the boundary. The repair and replacement technology of trenchless pipelines has just started, the construction method is not mature, and some construction methods are even blank, so the follow-up maintenance of pipelines is difficult.

When two different types of soil contact gas steel pipe, the two interfaces will produce inconsistent potential, resulting in potential difference. Soil is a conductive substance that easily provides an electrical circuit. Thus, the macrocell is caused by a potential difference across the metal. Due to the different soil structure and the specific structure and morphology of various substances in contact with it, the scope is wide and the complexity is high. According to experimental studies, the corrosion of metal objects is very strong, generally 10 times the strength of micro-batteries. And more occurred in the soil structure, mostly local corrosion, easy to cause gas steel pipe perforation. The distribution is more uniform, the area of the cathode and anode is not obvious, and the corrosion to the gas steel pipe is smaller.

Rubber hose is an organic material, not resistant to oil, and stainless steel corrugated hose using stainless steel, the general common corrosive liquid can deal with, and coated PVC protective layer also has a certain flame retardant, corrosion resistance. When the gas steel pipe is located in the soil with different structures, the ventilation conditions are also different due to the difference in density. The potential of the steel pipe in good contact with ventilation is relatively high, and acts as the cathode area in the oxygen concentration pool, causing slow corrosion, while the potential of the steel pipe in poor contact with ventilation is relatively low, and acts as the anode area in the oxygen concentration pool. Therefore, the oxygen concentration battery is an important factor causing the corrosion of the city gas steel pipe.

　　gas steel pipeIt has the characteristics of convenient installation, reliable connection, corrosion resistance, non-gas blocking, good flexibility, long service life, and can be bent at will without deformation, and non-gas blocking. The surface soft protective layer material has the characteristics of safer, easier to clean and beautiful, and the service life of the stainless steel threaded connection metal hose is 8 years. According to the above analysis, it can be seen that the oxygen concentration difference battery poses a serious hidden danger and threat to the safety of the gas steel pipe. After the design realization period is reached, an evaluation shall be carried out, and the continued use, modification or replacement shall be determined according to the evaluation results. Corresponding safety measures shall be formulated for continued use.