Comparative analysis of the use of epoxy and fluoroplastic polymer compositions as internal smooth coatings of the inner cavity of steel main gas pipelines

Development of the oil and gas complex is inextricably linked with the improvement of transportation methods for extracted hydrocarbons. Use of internal internal smooth coatings is one of the ways to increase the efficiency of systems transporting natural gas. These coatings allow to reduce the cost of gas transportation and to protect additionally the inner pipe cavity from corrosion damage. Due to the trend of moving natural gas production to areas of the Far North with very low negative temperatures and an increased proportion of heavier hydrocarbon components in the transported gas, it is necessary to propose new technical solutions to ensure the efficient operation of main gas pipelines in new conditions. The authors propose to study the possibility of using a fluoroplastic coating that has not been previously used for gas pipelines and is considered as a promising one. This article presents a comparative analysis of the used epoxy coatings and promising fluoroplastic coatings applied to the surface of steel plates. The epoxy coating was applied to the surface of the plate which was cleaned by sandblasting, and before applying a fluoroplastic coating with low adhesive properties, the plate surface was prepared to ensure a strong adhesive bond by preliminary laser treatment and subsequent cold phosphatizing. In the course of the work, a complex of studies of the physical and mechanical characteristics of coatings was carried out, including determination of the impact strength of coatings at normal and negative temperatures, and determination of elasticity by the Erickson method, as well as determination of bending strength, and determination of equivalent roughness. According to the results of the research, it was revealed that the fluoroplastic coating has greater elasticity, bending strength and impact strength at low temperatures compared to the epoxy coating. In addition, it was found that fluoroplastic coatings are not inferior to epoxy coatings in terms of equivalent roughness, which affects the amount of hydraulic resistance. Thus, this work gives an idea of the relevance of using fluoroplastic coatings as internal smooth coatings to ensure more efficient operation of the gas pipelines in conditions of negative temperatures, with simultaneous increase of the proportion of heavier hydrocarbon components in the transported gas.