Town Gas Steel Pipe By The Rail Transport Of Electromagnetic Interference Test And Evaluation Methods,

As the flourishing development of the subway traffic and the common usage of urban gas, the electromagnetic interference and corrosion to buried gas pipe-lines attract more and more attention now. Investigation shows that, more than 90% urban buried gas pipe-lines'defects and leakage are caused by rail traffic disturbing current, which results great loss to national economy and damages the pipe-lines'safe operation seriously.In our country, the gas pipe-lines are developed in the 1950s, and the establishment of subway traffic has its only 40 years'history, so thorough research on dynamic current interference and corrosion has not been performed until now. Due to the complexity and variability of the field environment, current detection techniques and instruments can not be applied in the detection of the dynamic disturbing current on buried gas pipe-lines and the evaluation of the severity of the interference. So to find a dependable detection and evaluation method is the guarantee of the safety operation of buried gas pipe-lines. This subject carries out the theoretical and experimental research centering on this task and completes the main work as following.By the contrast with current detection techniques and according to the dynamic characteristics of subway electromagnetic interference, the pipe-to-soil potential sequential dynamical monitoring technology is put forward. On the base of lab experimental research and according to the fluctuation conditions of the pipe-to-soil potential, the severity of the electromagnetic interference is estimated initially.Subway electromagnetic interference and corrosion experimental model is built based on the principle of subway electromagnetic interference. The experimental platforms of DC and AC electromagnetic interference to pipes are established in the lab, and the inference rules of different soils and disturbing currents are researched, and the relationship between pipe-to-soil potential and disturbing current is explored here.Images of surface corrosion morphologys are acquired, and then corrosion characteristics through the technology of digital image processing are obtained. Based on the fractal theory, surface corrosion morphologys have characteristics with fractal and the fractal dimension can be considered as a parameter for describing complexity quantitatively.The software is developed for pipe-to-soil potential dynamic monitoring and corrosion evaluation using LabVIEW, Microsoft SQL database and C++. It can realize the real-time monitoring for pipe-to-soil potential. Meanwhile, it can realize format documents saving and calling back, database saving and conditional inquiry, then the severity of interference is judged and the remaining life of the pipe is predicted at last. The residual service life of the pipe and the magnitude of the disturbing current density can be estimated by extracting the corrosion morphologys and calculating the fractal dimension.