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environment, static and dynamic stresses, temperature, etc.) and, as a result, their destruction. The corrosion condition of pipelines is determined by the degree of corrosive influence of the environment on them and the level of protection against this influence.
These growth rates are due to the occurrence of several types of corrosion processes that differ in their mechanism of occurrence: chemical corrosion, electrochemical corrosion and stress corrosion cracking. Chemical corrosion
Chemical corrosion of metals is a heterogeneous interaction of metal with a corrosive environment in which metal oxidation and oxidant reduction occur simultaneously. The driving force of the chemical corrosion process is a decrease in the total free energy of the oxidizer-reducing agent system due to the chemical reaction. The most common type of chemical corrosion is corrosion of metals in gases, especially at elevated temperatures.
Electrochemical corrosion is most common at the facilities of the oil and gas complex. The reason for this process is the appearance of a large number of corrosive galvanic cells on the surface of the metal in contact with the electrolyte. The occurrence of such corrosive elements is caused by different values of the intrinsic potentials of individual sections of the metal surface.
This difference in potentials on the metal surface is due to both internal and external factors. Internal factors include: the nature of the metal, its crystalline structure, the presence of internal stresses, temperature, the different nature of metal surface treatment, the presence of impurities in the metal (segregation, slag, etc.). References:
1. Makhmotov E.S., Alekseev S.G., Aldyarov T.K., Didukh A.G., Nefedov A.N., Kudaibergenov S.E., Abdullin H.A. The possibility of assessing the development of corrosion processes on the inner surface of an oil pipeline // Oil and gas. 2013. No. 1. pp. 45-50.
2. Markin A.N., Nizamov R.E., Sukhoverov S.V. Production Chemistry: guidance manual. Vladivostok: Dal'nauka, 2011. 288 p.
© Аманова A., EegeHeeB M., EawMMOBa LU., fl36epg,bieB C., 2024
УДК 62
Гараев Г., преподаватель, Международный университет нефти и газа имени Ягшигельды Какаева;
Агаджанов А., студент
Международный университет нефти и газа имени Ягшигельды Какаева;
Ахмадулин А. - Г., студент Международный университет нефти и газа имени Ягшигельды Какаева;
Аккаева А., студентка
Международный университет нефти и газа имени Ягшигельды Какаева CORROSION UNDER THE ACTION OF NAPHTHENIC ACIDS
The increasing pressure in the refining industry to increase profits is especially noticeable in companies with a high degree of vertical diversification, which seek to offset the huge costs of production. Volatile oil prices lead to unstable profit levels for refineries, which makes it difficult to choose the type of oil and optimize the range of petroleum products. The timing of oil purchases is measured in weeks, and previously made decisions on the choice of grade may no longer be the most profitable. And the transition from one type of oil to another with a significant difference in quality can be performed "on the go".
In this brochure, we take a closer look at the corrosion caused by naphthenic acids. Oil with a high total acid number causes corrosion under the action of naphthenic acids - a particularly aggressive and often localized corrosion mechanism characterized by the "orange peel" effect. The problem is mainly typical for primary oil refining and vacuum distillation plants, for gas oil and refined products supplied to subsequent conversion and hydro - treating plants may also exhibit a high total acid number, which poses a danger to carbon steel equipment.
In the oil refining industry, two main strategies are used to mitigate the effects of corrosion — replacing sensitive areas of metal structures with more corrosion-resistant ones and/or installing new inhibitor dosing points where corrosion problems have not been previously observed. Both strategies should be combined with continuous monitoring of corrosion in critical locations to verify the distribution of inhibitors and/or corrosion resistance of the metal in reinforced areas. Temperature
Naphthenic acids act most aggressively on atmospheric and vacuum distillation plants at temperatures above 200-220 ° C, starting from the hot part of the heating line, on the coils of the furnace, the lower part of the column, the discharge of fractions of light and heavy gas oils, the selection of processed products, until they cool below this critical temperature threshold.
Metal composition
The effects of naphthenic acids are most dangerous for carbon steel, the corrosion rate can range from 40 to 50 mm per year when using raw materials with a total acid number of 3 mgCON/g or more at temperatures above 300 °C. Stainless steel shows much greater resistance, although different grades provide different levels of corrosion resistance in certain temperature ranges, as shown below.
Flow rate
Naphthenic acid molecules themselves are relatively inert until they are "activated" by a high flow rate during the narrowing and expansion of the pipeline, the presence of bends, elbows and tees, or other changes in the flow profile, for example, at the pump outlet, injection nozzles or mortise probes. This makes such areas the most susceptible to corrosion.
Sulfur content in crude oil
In some cases, an increased sulfur content in crude oil with a high total acid number can reduce its aggressiveness. With a high sulfur content in oil, a passivating layer of iron sulfide is formed on the metal surface, which protects the surface from an aggressive environment. Some inhibitors work on the same principle of passivation. But the iron sulfide layer itself constantly corrodes the metal. This phenomenon is unstable, which disappears, for example, when the installation is stopped or the flow rate changes. Separation of naphthenic acids by boiling point
Different types of oil with the same total acid number may contain different forms of naphthenic acid molecules, which separate at different boiling points. Figure 10 shows that the most aggressive effect of naphthenic acids of Gryphon, Captain and Cerro Negro oil brands will be on the primary distillation column, while the effect of naphthenic acids of Doba oil on the vacuum unit. Knowing the temperature distribution of naphthenic acids is crucial in determining the monitoring strategy. Corrosion monitoring probes
Submersible corrosion probes have been used since the 1960s and represent a well-established technology. This technology is based on the use of an element with a consumable tip, which is located in the working environment and is usually made of the same brand of material as the surrounding elements in contact with the medium. References:
1. Baranov A.N., Guseva E.A., Krasnoperov A.N., Pobedash A.S., Yudin A.N. The study of corrosion processes in aluminum production and the development of new methods of metal protection // Izvestiya higher educational. Non-ferrous metallurgy. 2008. No. 4. p. 10.
2. Yanushkin A.S., Baranov A.N., Losev A.B., Yakimov S.A. Investigation of the possibility of replacing electrolytes during electro-diamond treatment with conventional lubricating cooling media // Herald. Irkutsk. 2007. Vol. 30. No. 2. pp. 25-30.
© rapaeB r., AragwaHOB A., AxMagy^MH A. - r., AKKaeBa A., 2024
УДК 62
Керимбердиева М., студент, Международный университет нефти и газа имени Ягшыгелди Какаева,
Ашхабад, Туркменистан Джанабаева Т., студент, Международный университет нефти и газа имени Ягшыгелди Какаева,
Ашхабад, Туркменистан Момилов М., студент,
Международный университет нефти и газа имени Ягшыгелди Какаева,
Ашхабад, Туркменистан Нуров Н., студент,
Международный университет нефти и газа имени Ягшыгелди Какаева,
Ашхабад, Туркменистан Научный руководитель: Оразгельдыев Д., преподаватель, Международный университет нефти и газа имени Ягшыгелди Какаева,
Ашхабад, Туркменистан
ДЕФЕКТЫ ПРИ СТРОИТЕЛЬСТВЕ И РЕМОНТЕ МАГИСТРАЛЬНЫХ ТРУБОПРОВОДОВ
Аннотация
Рассмотрены основные виды дефектов, возникающих при строительстве и ремонте магистральных трубопроводов, их причины и методы устранения.
Ключевые слова:
магистральные трубопроводы, дефекты, коррозия, диагностика, ремонт.
Магистральные трубопроводы играют ключевую роль в транспортировке различных жидкостей и газов на большие расстояния. Надежность их эксплуатации напрямую зависит от качества строительства и последующего обслуживания.
Внутренние дефекты можно классифицировать следующим образом. Во-первых, коррозия и эрозия. Эти дефекты часто связаны с химическим составом транспортируемой среды. Внутренняя коррозия приводит к уменьшению толщины стенок труб, что снижает их прочность и увеличивает риск разрыва. Эрозия, вызванная воздействием высокоскоростного потока жидкости или газа, может привести к локальным утонениям и разрывам. Во-вторых, отложения и наслоения. На внутренних стенках труб могут накапливаться различные осадки, такие как минеральные соли или парафины, что снижает пропускную способность трубопровода и приводит к повышению давления и скоростям потока.
Внешние дефекты также имеют свою специфику. Во-первых, это механические повреждения, которые могут возникать в результате воздействия внешних сил, таких как ударные нагрузки или давление грунта. Например, при строительстве могут возникнуть повреждения вследствие некорректного
