Natural Potential Analysis Of 3PE Anti-corrosion Layer Pipeline

According to the measurement and research of the natural potential of the pipeline with 3PE coating for the oil company in one region, the author summarizes the regularity of distribution of the natural potential and analyzes the environmental influence factors in the abnormal natural potential pipelines. The author analyzes comprehensively all the factors which have the impact on the pipeline natural potential in the laboratory and site, including pipeline material, anticorrosive coating, sacrificial anode, decoupler, soil resistivity, depolarization time, regional cathodic protection, polarized product of pipeline cathodic protection, soil potential gradient and RF stray current interference. Meanwhile, the author also proposes the application conditions and the measurement procedure for the measurement of pipeline natural potential through the experiment result. The conclusion is get that the stray current interference is the key reason to cause the abnormal natural potential of pipeline with 3PE coating.In abnormal section of the pipeline natural potential, the cathodic protection effect has been evaluated by the coupon weight-loss, synchronous interruption and the test block power interruption method. The result shows that the coupon weight-loss and the test block power interruption method can evaluate the cathodic protection effect in abnormal section of the pipeline natural potential effectively. And there is a certain deviation in evaluating the cathodic protection effect with the synchronous interruption method.In accordance with the result of this thesis, the author analyzes comprehensively the effect all the factors to the natural potential of pipeline with 3PE coating and establishes the measuring procedure of the natural potential of pipeline with 3PE coating. The author also proposes the advice and the solution to the measurement and the evaluation methods in the abnormal section of the pipeline natural potential with 3PE coating.