At the later stage of pipeline operation, corrosion aging seriously increases cathodic protection materials

Another special feature of long distance pipeline is the degradation of allowable performance during operation. First of all, when the pipeline has serious defects, depressurization operation is an important means of pipeline risk control. In the late period of operation, the pipelines are corrosion-aged seriously. When the maintenance is not economical, the maximum operating pressure of the pipelines should be determined again through integrity evaluation, which is also the general practice of integrity management in foreign countries. The process of redetermining the maximum operating pressure of the new pipeline requires a large number of pipeline design and manufacturing documents, as well as testing and testing data at various stages, and sampling analysis on the operating pipeline when necessary. Therefore, the quality certification documents and testing data of all phases of the pipeline are also very important. 1.2 Particularity of Risk Control during Pipeline Construction The Special Equipment Safety Law divides the risk control of special equipment into four stages: design, manufacture, installation and operation. From the design point of view, other special equipment is mainly designed for the structure of the special equipment itself and ancillary facilities, and the long distance pipeline is mainly designed for the environment of the pipeline. From the point of view of risk control, other special equipment v, the necessary condition of the integrity of the management.