Reliable establishment of the technical condition of metal structures, including gas pipelines is based on three fundamentals: definition of the level of defectiveness, establishment of the stress-strain state, and the degree of degradation of steels mechanical characteristics. If the first two fundamentals shoot the moon in recent years, this cannot be said about the degree (magnitude) of degradation of the mechanical characteristics. To date, the main phenomena were established, which cause damage and crack formation in steel trunk pipelines under the influence of operational factors. Most of these phenomena are associated with hydrogenation factors, the role of which depends on the source of hydrogen entering the metal, and the level of actual stresses.
The main hydrogenation factors are considered: stress corrosion cracking, hydrogen corrosion, delamination, hydrogen brittleness causing damage growth in steel and cracking in the structures, and in some cases their destruction. On the example of low-alloy steel grade 17GS, it is shown that the development of stress corrosion cracking leads to a change in the mechanism of crack propagation: a significant increase in the share of intergranular failure in the fracture, primarily in the rolling plane. As a result, the anisotropy coefficient of metal impact strength increases and depends not only on the carbon (perlite) and sulfur (sulfide) contents in steel, but also on the degree of weakening of the ferrite grain boundaries.
Using the example of an oil pipe with a diameter of 530 mm, the effect of hydrogen corrosion on the fracture mode of impact specimens is studied. It is established that the presence of hydrogen in the metal leads to the appearance of KCV — B bond, where B is the fraction of the viscous component in the fracture of two linear sections. Section I is characterized by low-energy fracture (4.4–15 J/cm2), where a shear fracture mechanism is acting along the rolling planes. In section II, a ductile cleavage mechanism is acting with high work (32–246 J/cm2) of crack propagation. It is shown that determining the degree of intergranular embrittlement of steel makes it possible to more reliably establish the technical condition of the structure and its residual life.
- Varlamov D.P. Stress corrosion cracking and destruction processes in the pipes of gas trunk line during aging. Deformatsiya i razrushenie materialov = Deformation & Fracture of Materials. 2011. № 9. pp. 45–48. (In Russ.).
- Ioffe A.V., Tetyueva T.V., Revyakin V.A., Borisenkova E.A., Knyazkin S.A., Denisova T.V. Corrosion-mechanical destruction of pipe steels in the process of operation. Metallovedenie i termicheskaya obrabotka metallov = Metallurgy and heat treatment of metals. 2012. № 10. pp. 22–28. (In Russ.).
- Goritskiy V.M. Diagnostics of metals. Moscow: Metallurgizdat, 2007. 384 p. (In Russ.).
- Goritskiy V.M., Shneyderov G.R., Goritskiy O.V. Effect of hydrogen corrosion on the resistance to brittle fracture of the oil pipe with a diameter of 530 mm from 12GSB ferritic-pearlitic steel. Deformatsiya i razrushenie materialov = Deformation & Fracture of Materials. 2019. № 8. pp. 40–48. (In Russ.).
- Rybakov A.A., Goncharenko L.V., Filipchuk T.N., Lokhman I.V., Burak I.Z. Causes of stress-corrosion destruction of the mounting ring connection of the gas trunk line. Avtomaticheskaya svarka = Automatic welding. 2014. № 3. pp. 54–57. (In Russ.).
- Tabachnikova T.N., Tereshchenko N.A., Yakovleva I.L., Chirkov Yu.A., Kushnarenko V.M. Influence of non-metallic inclusions on the formation of cracks and the structure of pipe steel during long-term operation. Deformatsiya i razrushenie materialov = Deformation & Fracture of Materials. 2011. № 8. pp. 35–40. (In Russ.).
- Sosnovskiy L.A., Makhutov N.A., Bordovskiy A.M., Vorobev V.V. Statistical assessment of the pipeline material properties degradation. Zavodskaya laboratoriya. Diagnostika materialov = Industrial laboratory. Diagnostics of materials. 2003. Vol. 69. № 11. pp. 40–49. (In Russ.).
- 8 Gafarov N.A., Mitrofanov A.V., Burmistrov A.G., Kichenko B.V. Detection and weakening of corrosion in the pipelines and equipment contacting with acid gases. Zashchita ot korrozii i okhrana okruzhayushchey sredy = Corrosion protection and environmental safety. 1997. № 6. pp. 5–9. (In Russ.).
- Makhutov N.A., Permyakov V.N., Kravtsova Yu.A., Botvina L.R. Assessment of the condition of the product pipeline material after its long-term operation. Zavodskaya laboratoriya. Diagnostika materialov = Industrial laboratory. Diagnostics of materials. 2007. Vol. 73. № 2. pp. 54–59. (In Russ.).
- Goritskiy V.M., Shneyderov G.R., Durneva A.A. Study of the causes and mechanisms of destruction of the section of the trunk pipeline of steel 17G1S. Deformatsiya i razrushenie materialov = Deformation & Fracture of Materials. 2019. № 4. pp. 32–39. (In Russ.).
- Pleshivtsev V.G., Pak Yu.A., Filippov G.A., Chevskaya O.N., Livanova O.V. Factors affecting pipelines operational reliability. Deformatsiya i razrushenie materialov = Deformation & Fracture of Materials. 2007. № 1. pp. 6–11. (In Russ.).
- Goritskiy V.M. Application of impact strength characteristics in the engineering practice. Moscow: Metallurgizdat, 2016. 304 p. (In Russ.).
- Goritskiy V.M., Shneyderov G.R., Nechiporenko P.R., Gorchakov O.V. Diagnostics of the Degree and Velocity of Metal Damage of the Plated Vessels Working under Excessive Pressure, Operated in Hydrogen and Hydrosulphuric Environments. Bezopasnost Truda v Promyshlennosti = Occupational Safety in Industry. 2017. № 9. pp. 58–64. (In Russ.). DOI: 10.24000/0409-2961-2017-9-58-64
- RD 03-421—01. Methodical guidelines for diagnosing technical condition and determining the residual life of vessels and apparatuses. Ser. 03. Iss. 17. Moscow: ZAO NTTs PB, 2019, 134. (In Russ.).
- Goritskiy V.M. Thermal brittleness of steels. Moscow: Metallurgizdat, 2007. 384 p. (In Russ.).
- Bandyopadhyay N., Kameda I., McMahon C.J. Hydrogen-induced cracking in 4340-type steel: effects of composition, yield strength and H2 pressure. Metallurgical and Materials Transactions A. 1983. Vol. 14. Iss. 4. pp. 881–888.
