Study of abnormal distributions of corrosion defects along the length of the main gas pipeline

When assessing the operation of interfield gas pipelines on frozen ground, the efficiency of their electrochemical protection (ECP) is analyzed, among other things. The paper presents the results of the study of anomalies in the ECP of underground pipelines operated in frozen ground conditions. Computer mathematical modeling methods were applied, laboratory experiments were conducted using a test rig. Using computer modeling, the key factors contributing to the acceleration of corrosion processes were identified: the formation of a water layer around the pipeline during ground freezing and shielding of the protective potential of ECP, which leads to a local increase in the corrosion rate. It has been experimentally confirmed that at the temperature of transported gas above 0°C and in the presence of frozen ground ECP loses its efficiency due to potential distribution disturbance. It is shown that the use of an auxiliary anode increases the homogeneity of the protective potential and eliminates the shielding effect of frozen ground. The obtained results can be used for optimization of ECP systems in cryolithozone to reduce the risk of accidents in pipeline transport.