The problem of combating internal corrosion is relevant at gas facilities in the conditions of production and transportation of hydrocarbons with the presence of aggressive CO₂.The article discusses the main conditions for the occurrence of carbon dioxide corrosion in a gas pipeline, the operating conditions of which will differ from oil fields (the degree of filling of the pipe space with the liquid phase and the aggregate state of the main produced fluids - oil and gas/gas condensate).This will influence corrosion manifestations, which requires special consideration and approach to modeling corrosion tests for gas pipeline conditions.

The study of corrosion processes that occur during transportation of gas with the presence of a liquid phase through a gas pipeline served as the basis for the development of two corrosion stands that allow for simulation tests under carbon dioxide corrosion conditions characteristic of the main gas fields of the Russian Federation. With their help, the most intense corrosion effects are reproduced, corresponding to the parameters and modes of movement of gas-liquid media: liquid circulation and variable wetting of the gas pipeline wall, which lead to the prevention of the formation or destruction of films of corrosion products, which causes the formation of general and local corrosion damage on steel.

The ability to reproduce on both corrosion stands the nature of the movement of the liquid phase, thermobaric conditions and the chemical composition of water corresponding to real environments makes it possible to simulate in the laboratory dynamic corrosion conditions inside the gas pipeline of the production and transportation facilities of untreated gas of PJSC Gazprom. In test stands, the main parameters that influence internal carbon dioxide corrosion are set and regulated: temperature, partial pressure of carbon dioxide, mineral composition of the aqueous phase or dynamic conditions for the transfer of liquid phase flow through a pipeline.

An analysis of the corrosion products obtained after testing using electron scanning microscopy and X-ray diffraction methods made it possible to establish the influence of corrosion conditions on the morphology of their formation.

Corrosion monitoring of oilfield equipment condition is a necessary requirement for ensuring the reliability of technological processes of oil production and transportation. The «electrical resistance» (ER) method is one of the corrosion monitoring methods used in the oil and gas industry. The disadvantage of the ER method is that the devices currently used do not allow to assess the local corrosion losses on the surface of the material, that is, they cannot identify the process of local corrosion development, while it is local corrosion that leads to failures of oilfield equipment. In the article, based on the consideration and interpretation of experimental data (laboratory and field), it is shown that the analysis of the dependencies «electrical resistance of the sensor sensitive element – time» makes it possible to detect the manifestation of local corrosion.

Laboratory experiments were carried out in an oxygen-free model of the aqueous phase of production from producing wells in Western Siberia and in a medium providing intense local corrosion of carbon steel at a partial pressure of carbon dioxide of 1 atm.

The experimental curves were approximated using the least squares method using the MS Excel «Solver» application.

Further development of the proposed approach will make it possible to improve corrosion meters implementing the ER method to register local corrosion.

The corrosion rates of carbon and stainless steels in tropical seawater determined using methods of linear polarization resistance, zero resistance amperometry, potentiometry and gravimetry. Research was carried out with steels used in shipbuilding, both carbon and stainless. The experimental methods, equipment and stands used in the process of the work are described.

Measures are proposed to ensure the tropical resistance of electrochemical equipment in the splash zone at a marine stand. The concept of “tropical resistance” includes a number of indicators such as the resistance of steels to the marine atmosphere; resistance to biofouling; resistance to general and local corrosion in seawater.

The test results showed that measuring the corrosion rate of steels 30KhGSA, 08kp, St3, 08KhZ, 12KhN10T and NS-5T in tropical seawater by electrochemical methods gives more adequate results compared to the gravimetric method.

The corrosion-electrochemical behavior of the lithium-doped aluminum conductor alloy AlV0.1 in a NaCl solution was studied using the potentiostatic method at a potential sweep rate of 2 mV/s. The dependence of the change in the free corrosion potential on time for the original AlV0.1 alloy and alloys with lithium show a shift of the potential towards positive values. It is noted that an increase in lithium concentration leads to a shift in the potentials of free corrosion, repassivation and pitting to the region of positive values.

With an increase in the concentration of chloride ion in the NaCl solution, a shift to the negative region is observed in the values of the electrochemical potentials of the aluminum conductor alloy AlV0.1 with lithium additives. An increase in the concentration of chloride ion contributes to an increase in the corrosion rate of alloys, regardless of their composition. It has been shown that the addition of lithium reduces the corrosion rate of the aluminum conductor alloy AlV0.1 by 8…13% in a NaCl solution.

Currently, there are various electrolytes for the electrochemical deposition of copper coatings. The most used of them in industry for direct coating of steel are cyanide electrolytes. Obviously, the use of cyanide electrolytes is undesirable due to their high toxicity. In a number of countries, including the Russian Federation, standards have been established that prohibit or strictly regulate the use of cyanides in various technological processes. This study’s outcomes are connected with the development of an alternative alkaline copper plating electrolyte based on hydroxyethylidene diphosphonic acid to replace toxic cyanide solutions.

The study has shown that the proposed electrolyte based on hydroxyethylidene diphosphonic acid is capable of ensuring to obtain copper coatings that are not only of high quality but also demonstrate adhesion strength to the steel base.

These results open up new vistas for the development of safe and effective alternatives to cyanide electrolytes in electrodeposition processes of copper coatings, helping to reduce the environmental load and improve the safety of technological processes in industry.