| Buried metal pipeline are widely used in the delivery of large amount of concentration liquid, it is an important help for human life and production.At present, insulation and cathodic protection are implemented to the majority of buried metal pipeline. Significant corrosion, leakage haven't occurred after the double implementation of cathodic protection and insulation of buried metal pipeline in the beginning years of operation.But a wide range of localized corrosion and leakage of large-scale phenomena has continued to happen for buried metal pipeline in next few years, ten years of operation. It has brought enormous economic losses and the spirit of trauma to human life and production.In this paper, large deep research and discussion are conducted according to the phenomenon of a large amount of localized corrosion and leakage after the implementation of the double protection of buried metal pipe. The phenomenon of a large amount of localized corrosion are given the definition of cathodic protection "dead zone" corrosion and cathodic protection shielding corrosion.According to the large-scale dual protection of the yellow jacket pipe and asphalt tube commonly used in pipeline transportation of oil fields, three widespread and serious harm phenomena of the yellow jacket pipe fluid-filled corrosion, the yellow jacket pipe insulation shielding corrosion and asphalt tube immersion corrosion are put forward.The reason for a large amount of localized corrosion is identified by principle analysis, factor analysis, research on atmospheric corrosion, soil erosion studies, field investigation, field testing, laboratory simulation test, the main influencing factors and serious consequences caused by the main factors are analyzed in detail. Taking all these studies, the economic and conducted easily system protecting against the corrosion is set up. Through the online tracking and monitoring, the rationality of the system protecting against the corrosion is verified respectively.
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