Study On Evaluation Method Of Internal Corrosion Of Low Pressure Gas Pipeline

Energy is one of the basic conditions for human survival and social development.As an important part of energy,natural gas will be more and more used in production and life.As an effective carrier of natural gas transmission,gas transmission pipeline is bound to usher in rapid development.At the same time,the safety operation of natural gas pipeline is concerned.As one of the main factors affecting the safety of natural gas pipeline,internal corrosion will not only limit the safety and effective life of the gas transmission system,but also lead to pipeline leakage and safety accidents.The main method of internal corrosion detection is magnetic flux leakage detection,which is widely used in long-distance gas transmission pipelines.However,for some low-pressure natural gas pipelines,the internal detector used in internal detection is easy to get stuck and can not move forward.Even some natural gas gathering and transmission pipelines are not equipped with receiving and transmitting devices,so it is impossible to use magnetic flux leakage detection to collect internal detection data.Therefore,it is urgent to establish a set of internal corrosion evaluation method for low pressure and low gas transmission pipeline,which can predict the location of corrosion and evaluate quantitatively before the internal corrosion.In this paper,firstly,through the analysis of the influencing factors of internal corrosion,the main influencing factors of corrosion of Liao He gas supply pipeline,i.e.the relationship between material,transmission medium,fluid erosion and corrosion rate,are explored by the method of experiment and numerical simulation.The occurrence mechanism of internal corrosion is clarified,which provides the theoretical and data basis for the prediction of internal corrosion.The research results are shown in the table The exposed medium plays a decisive role in the corrosion of pipelines.Then,according to the analysis of corrosion mechanism,the high-risk locations of corrosion are predicted,13 locations are predicted,and the risk ranking of these locations is carried out.The results show that the location with mileage of 4620 m has the highest risk of corrosion,and the locations with mileage of 3960 m and 5700 m have the lowest risk of corrosion.Through the establishment of corrosion rate prediction model,the remaining life of the pipeline is predicted.Norsok model and De warrd model in OLGA simulation software are used to calculate and analyze the corrosion situation of the gas supply pipeline.The research results show that the accuracy of the internal corrosion results predicted by De warrd model is higher.De warrd model is selected as the internal corrosion prediction model of the gas supply pipeline,and the predicted remaining life of the pipeline is 33.1 years.Finally,the reliability of the evaluation method is analyzed by comparing the field excavation data with the corrosion experiment data and the model prediction data.The analysis results show that the evaluation method is scientific and accurate.