One of the main reasons for oil-field pipeline failure is groove corrosion. The residual life of such pipelines is estimated based on defectoscopy corrosion rate—a ratio of the formed «groove» depth to the pipeline operation start time. In this case, it is supposed that, in the future, the «groove» will deepen at the same rate for the remaining period of the pipe’s operation. However, sometimes, oil-field pipeline operation experience shows that the remaining time of safe operation is much less than the calculated one. In this article, such a discrepancy is explained via the acceleration of the groove corrosion rate in the process of «groove» deepening due to the increasing level of mechanical stresses in the surrounding metal, which intensifies the corrosion process as a result of the mechanochemical effect. Based on a literature analysis and calculated data, the kinetic equation of the groove corrosion rate for an oil-field pipeline is proposed, which accounts for the acceleration of the process rate as the pipeline is operated and allows the more accurate estimation of its remaining service life.

In order to reduce emissions of carbon dioxide into the atmosphere, which is formed as a result of production petroleum products use, it is proposed to use hydrogen as an environmentally friendly energy resource. At the same time, hydrogen has a high permeability through materials, which leads to its inevitable diffusion losses through the pipeline wall during hydrogen transportation and storage. Based on the literature data and mathematical transformations, a computational model was proposed to estimate hydrogen leakage during transportation by a pipeline at a pressure up to 1.2 MPa and at a temperature from 300 to 600 K. Using tabular literature data on permeability coefficients based on the calculation model, possible losses of hydrogen during its transportation through a pipeline made of different grades of austenitic corrosion-resistant steels (304, 304L, 310, 316, 316L, 316LN, 321, 21-6-9, 21-9-9) at temperatures from 300 to 600 K were determined. Based on the results of calculations, it was concluded that 304L steel is the most effective material for reducing hydrogen permeability (maximum losses ~69 l/year at a temperature of 600 K). At the same time, the largest losses of hydrogen are observed in a pipeline made of steel 310 (903 l/year at a temperature of 600 K). In other steels, the volume of losses varies in the range of ~200-300 l/year. The analysis of the steel compositions showed that a decrease in the concentration of carbon, nitrogen, sulfur and phosphorus leads to an increase in its resistance to hydrogen penetration.

The paper considers the possibility of using composite polymer-metal coatings to reduce water permeability. Coatings including modified fluoroplastic enamel (MFPE) and aluminum have been prepared and tested. The aluminum coating was applied by cold gas-dynamic spraying. MFPE was modified to increase the adhesion and crosslinking density of the coating using carbon nanotubes, SiC, h-BN nanoparticles, and a photoinitiator 819 for UV curing. The Devanathan-Stachurski method was used as a method for estimating hydrogen diffusion through a coated metal. Graphite coating was used for testing polymer coatings, which was also separately tested for hydrogen permeability. The diffusion coefficients and the diffusion flow of hydrogen through steel with and without coatings have been experimentally determined. The reduction coefficients and efficiency of reducing the diffusion and diffusion flow of hydrogen are determined for the coatings. It was found that MFPE /Al coatings can ensure the effectiveness of reducing diffusion by 87.7 % and diffusion flow by 77.1 %. For MFPE, these values were 68.8 % and 67 %, respectively, and for graphite – 52.1 % and 57.4 %, respectively. The determining influence on the protective properties of a fluoroplastic coating is exerted by the type of nano-additives (SiC or h-BN) and their ability to distribute evenly, where the best combination is CNT with SiC with the maximum ratio of diffusion reduction coefficients 89.5 % and permeability 86.8 %. The patterns identified for fluoroplastic compounds are fully preserved on coatings with an adhesive layer of Al+AlOOH, which increases the coating thickness and increases the effectiveness of diffusion reduction for all formulations, including CNTs with SiC up to 97 % and diffusion flux up to 89.3 %. The possibility of using a composite coating for in-tube coatings during additional testing is proposed.