fwjТрение и и износTitle in english0000-00000000-0000AGU10.32864/0202-4977-2025-46-1-66-75fwj-53Research ArticleСтатьиВлияние графитизации на прочность чугунных труб экономайзеров водогрейных котловEffect of Graphitization on the Strength of Cast-Iron Tubes of Economizers of Hot Water BoilersНедобитковА. И.NedobitkovA. I.

ул. Серикбаева, д. 19, г. Усть-Каменогорск 070004 

D. Serikbayev Str., 19, Ust-Kamenogorsk 070004 

a.nedobitkov@mail.ruАбдеевБ. М.AbdeyevB. M.

ул. Серикбаева, д. 19, г. Усть-Каменогорск 070004 

D. Serikbayev Str., 19, Ust-Kamenogorsk 070004

НАО «Восточно-Казахстанский технический университет им. Д. Серикбаева»КазахстанNJSC “D. Serikbayev East Kazakhstan technical university”Kazakhstan2025280920264616675Copyright © AGU, 20262026AGUAGUhttps://fwj.ejournal.by/jour/about/submissions#copyrightNoticehttps://fwj.ejournal.by/jour/article/view/53

Представлены результаты исследования бывших в эксплуатации с 1986—1991 годов чугунных труб экономайзеров водогрейных котлов, не имеющих внешних визуальных повреждений. Определена закономерность изнашивания в виде графитизации поверхностного слоя внутренних стенок труб экономайзера. Исследования проводились с использованием растрового электронного микроскопа JSM-6390LV с приставкой для энергодисперсионного анализа, а также микротвёрдомера DuraScan 20. Даны снимки участков измерения микротвёрдости на участках, подвергшихся графитовой коррозии. Определены размеры полностью преобразованного в результате графитизации слоя и переходной зоны. Измерена микротвёрдость полностью преобразованного в результате графитизации слоя и переходной зоны. Установлено, что микротвёрдость этих зон существенно меньше микротвёрдости серого чугуна. Приведены результаты энергодисперсионного анализа и характерные диагностические признаки, идентифицирующие процесс графитизации. Предложен метод оценки несущей способности чугунных труб экономайзера в зависимости от величины графитизации. Математическая модель учитывает все основные свойства, особенности и физико-геометрические характеристики реальной конструкции, расчётная схема которой представляет собой жёстко-защемлённую по концам балку, изгибаемую равномерно-распределённой статической нагрузкой от собственной массы трубы и веса, протекающей по ней воды. Полученная расчётным путём остаточная толщина стенки трубы 4,53 мм. после износа её внутренней цилиндрической поверхности, сопоставима с известными опытными количественными данными статистического анализа аварийных ситуаций на экономайзерах. Полученные результаты могут быть использованы как при экспертном исследовании чугунных труб экономайзера, так и для обоснования их выбраковки или продления срока службы.

The article contents the results of examination of cast-iron pipes of water economizers of water-heating boilers, which were in operation in the period of 1986—1991 and which have no external visual defects. We have determined a dependence of wear-out in the form of graphitic corrosion of the surface layer of inner walls of economizer pipes. The researches have been conducted with the use of JSM-6390LV scanning electron microscope equipped with an attachment for conduct of energy-dispersive analysis, and with the use of DuraScan 20 microhardness tester. There are images of areas given, where microhardness testing was performed. The areas were exposed to graphitic corrosion. The dimensions of the layer completely transformed as a result of graphitization and the transition zone were determined. The microhardness of the layer completely transformed as a result of graphitization and the transition zone was measured. It was found that the microhardness of these zones is significantly lower than the microhardness of gray cast iron. We have also presented the results of energy-dispersive analysis and specific diagnostic features identifying the graphitization process. In the article we propose a method of assessment of supporting capacity of cast-iron pipes of water economizers based on the rate of their graphitization. A mathematical model takes into account all main properties, features, physical and geometric characteristic of the real structure, which has an analytical model represented by a beam rigidly restrained on both heads, and which is bending by well-distributed dead weight load arised from the pipe’s own weight and the weight of the water flowing through it. The calculated residual wall thickness of 4.53 mm after wear of its internal cylindric surface is comparable with the known empirical data of statical analysis of emergency situations at economizers. The data given in the article could be used by specialists for expert examination of cast-iron pipes of economizers, as well as for justification of their sorting or life extension.

чугунтрубаэкономайзерграфитизациянапряжениекоэффициент запасарасчетная нагрузкаcast ironpipeeconomizergraphitizationstressassurance coefficientdesign loadReferencesDosa Ion and Tomus Ovidiu-Bogdan. Efficiency of Steam Generator Ecomomizer at Different Loads. — 2018. https://doi.org/: 10.26649/musci.2018.003Dosa Ion and Tomus Ovidiu-Bogdan. Efficiency of Steam Generator Ecomomizer at Different Loads. — 2018. https://doi.org/: 10.26649/musci.2018.003Miswar, Arsyad Hairul, and Arma Lukmanul. Construction Strength Evaluation of Boiler Economizer Tube Materials Based on Hardness Value // AIP Conference Proceedings. — 2023. https://doi.org/: 10.1063/5.0125978Miswar, Arsyad Hairul, and Arma Lukmanul. Construction Strength Evaluation of Boiler Economizer Tube Materials Based on Hardness Value // AIP Conference Proceedings. — 2023. https://doi.org/: 10.1063/5.0125978Лепов В.В., Ачикасова В.С., Махарова С.Н., Захаров В.Е., Павлов Н.В. Анализ разрушения материала трубы поддува котельной, эксплуатируемой в экстремальных условиях Арктики // Природные ресурсы Арктики и Субарктики. — 2020 (25), № 3, 143—151. https://doi.org/10.31242/2618-9712-2020-25-3-14Lepov V.V., Achikasova V.S., Makharova S.N., Zakharov V.E., Pavlov N.V. Failure analysis of the material of water boiler pipe operated in the Arctic zone of the Republic of Sakha (Yakutia) // Arctic and Subarctic Natural Resources. — 2020 (25), no. 3, 143—151. https://doi.org/10.31242/2618- 9712-2020-25-3-14 (in Russian)Olawale J., Odusote J., Rabiu A., and Ochapa E. Evaluation of Corrosion Behaviour of Grey Cast Iron and Low Alloy Steel in Cocoa Liquor and Well Water // Journal of Minerals and Materials Characterization and Engineering. — 2013, no. 1, 44—48. https://doi.org/: 10.4236/jmmce.2013.12009Olawale J., Odusote J., Rabiu A., and Ochapa E. Evaluation of Corrosion Behaviour of Grey Cast Iron and Low Alloy Steel in Cocoa Liquor and Well Water // Journal of Minerals and Materials Characterization and Engineering. — 2013, no. 1, 44—48. https://doi.org/: 10.4236/jmmce.2013.12009John Edward, Boxall Joby, Collins Richard, Bowman Elisabeth, and Susmel Luca. Multiaxial Fatigue of Water Pipe Grey Cast Iron // International Journal of Fatigue. — 2023, no. 178. https://doi.org/: 10.1016/j.ijfatigue.2023.108002John Edward, Boxall Joby, Collins Richard, Bowman Elisabeth, and Susmel Luca. Multiaxial Fatigue of Water Pipe Grey Cast Iron // International Journal of Fatigue. — 2023, no. 178. https://doi.org/: 10.1016/j.ijfatigue.2023.108002Hajali Masood, McNealy Ashan, and Efaz Ikram. Structural Analysis of Large Diameter Cast Iron Pipes under Cyclic Loading and Fatigue Failure. — 2023, 97—106. https://doi.org/:10.1061/97807844Hajali Masood, McNealy Ashan, and Efaz Ikram. Structural Analysis of Large Diameter Cast Iron Pipes under Cyclic Loading and Fatigue Failure. — 2023, 97—106. https://doi.org/:10.1061/97807844Agala A., Khan M., and Starr A. Degradation Mechanisms Associated with Metal Pipes and the Effective Impact of LDMs and LLMs in Water Transport and Distribution // Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. — 2023 (237), no. 8, 1855—1876. https://doi.org/:10.1177/09544062221133948Agala A., Khan M., and Starr A. Degradation Mechanisms Associated with Metal Pipes and the Effective Impact of LDMs and LLMs in Water Transport and Distribution // Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. — 2023 (237), no. 8, 1855—1876. https://doi.org/:10.1177/09544062221133948Tim A. Jur, James I. Middleton Jr., Anthony A. Yurko III, Ronald L. Windham, and James R. Grey Jr. Case Studies in Graphitic Corrosion of Cast Iron Pipe // J. Fail. Anal. and Preven. — 2021 no. 21, 376—386. https://doi.org/10.1007/s11668- 020-01097-0Tim A. Jur, James I. Middleton Jr., Anthony A. Yurko III, Ronald L. Windham, and James R. Grey Jr. Case Studies in Graphitic Corrosion of Cast Iron Pipe // J. Fail. Anal. and Preven. — 2021 no. 21, 376—386. https://doi.org/10.1007/s11668- 020-01097-0Adegbite S., Fahimi A., Evans T.S., Farrow J., Jesson D.A., Mulheron M., and Smith P.A. Trunk Mains Failures: The Effect of Corrosion on Residual Pipe Strength // 4th International Conference on Integrity, Reliability and Failure (2013-06-23 Funchal, Portugal). — 2013Adegbite S., Fahimi A., Evans T.S., Farrow J., Jesson D.A., Mulheron M., and Smith P.A. Trunk Mains Failures: The Effect of Corrosion on Residual Pipe Strength // 4th International Conference on Integrity, Reliability and Failure (2013-06-23 Funchal, Portugal). — 2013Carlos Jara-Arriagada and Ivan Stoianov. Pressure-Induced Fatigue Failures in Cast Iron Water Supply Pipes // Engineering Failure Analysis. — 2024 (155). https://doi.org/10.1016/j.engfailanal.2023.107731Carlos Jara-Arriagada and Ivan Stoianov. Pressure-Induced Fatigue Failures in Cast Iron Water Supply Pipes // Engineering Failure Analysis. — 2024 (155). https://doi.org/10.1016/j.engfailanal.2023.107731Височкин В.А. О правовом обеспечении производства и реализации бывших в употреблении стальных труб // Экологический вестник России. — 2018, № 6, 48—51Visochkin V.A. On legal support for the production and sale of used steel pipes // Ecological Bulletin of Russia. — 2018, no. 6, 48—51 (in Russian)Logan R., Mulheron Mike, Jesson David, Smith P., Evans T., Clay-Michael N., and Whiter J. Graphitic Corrosion of a Cast Iron Trunk Main: Implications for Asset Management // WIT Transactions on the Built Environment. — 2014 (139), 411—422. https://doi.org/10.2495/UW140351Logan R., Mulheron Mike, Jesson David, Smith P., Evans T., Clay-Michael N., and Whiter J. Graphitic Corrosion of a Cast Iron Trunk Main: Implications for Asset Management // WIT Transactions on the Built Environment. — 2014 (139), 411—422. https://doi.org/10.2495/UW140351Yeshanew, Desalegn A., Moera G. Jiru, Hirpa G. Lemu, and Mesay A. Tolcha. Internal Corrosion Damage Mechanisms of the Underground Ferrous Water Pipelines // Advances in Science and Technology Research Journal. — 2022 (16), no. 3, 111— 123. doi:10.12913/22998624/149369Yeshanew, Desalegn A., Moera G. Jiru, Hirpa G. Lemu, and Mesay A. Tolcha. Internal Corrosion Damage Mechanisms of the Underground Ferrous Water Pipelines // Advances in Science and Technology Research Journal. — 2022 (16), no. 3, 111— 123. doi:10.12913/22998624/149369Тимошенко С.П., Гудьер Дж. Теория упругости / пер. с англ. М.И. Рейтмана, под ред. Г.С. Шапиро. — М.: Наука. — 1975 15. Биргер И.А., Мавлютов Р.Р. СопротивленTimoshenko S.P., Goodier J. Theory of elasticity / Trans. from English. M.I. Reitman. G.S. Shapiro (ed.). — Moscow: Naukа. — 1975 (in Russian)Birger I.A., Mavlyutov R.R. Resistance of Materials: A Tutorial. — Moscow: Nauka. — 1986 (in Russian)Birger I.A., Mavlyutov R.R. Resistance of Materials: A Tutorial. — Moscow: Nauka. — 1986 (in Russian)

The authors declare that there are no conflicts of interest present.