Technical Diagnostics and Non-Destructive Testing, 2024, №04



2024 №04 (07)

DOI of Article 10.37434/tdnk2024.04.01

2024 №04 (02)

---

Technical Diagnostics and Non-Destructive Testing #4, 2024, pp. 3-12

Corrosion-mechanical state of the heat pipeline after long-term operation

P.S. Yukhymets¹, L.I. Nyrkova¹, R.I. Dmytriienko¹, H. Kaminski², C. Zaruba², P. Linhardt², G. Ball², V.M. Yehorenko³

¹E.O. Paton Electric Welding Institute of the NAS of Ukraine 11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine. E-mail: yupeter@ukr.net
²TU Wien. 1040, Vienna, Karlsplatz, 13, Austria. E-mail: heinz.kaminski@tuwien.ac.at
³CE «Kyivteploenergo». 5 Ivan Franko Sq., 01001, Kyiv, Ukraine. E-mail: yehorenko.vm@kte.kmda.gov.ua

Metal properties of heat pipeline areas thinned under operating conditions are a necessary component for determining its real state, and therefore their research is an actual task. The work investigates the corrosion-mechanical state of a heat pipeline made of VSt3sp steel after more than 40 years of operation. Based on the conducted research, it was established that corrosion of the feeding pipeline is more severe than that of the return pipeline, while the external corrosion of the pipelines is more intense than the internal one. Cracking of the oxide layer accelerates with increasing stresses in the range of the design pressure and leads to activation of the corrosion processes and formation of through defects that prevents destruction by the mechanism of low-cycle fatigue. It is shown that tensile and yield strengths of the steel correspond to the minimum normalized values. The reduction in plasticity of the feeding pipeline metal does not exceed 10 %, while that for return pipeline is below the minimum normalized value which is probably due to strain aging. The least damaged layer adjacent to the inner surface of pipes has increased strength and plasticity characteristics due to the pipe manufacturing technology. While hydraulic test may not lead to the expected destruction at the location of through defects, its probability rises with increase of the test pressure. 14 Ref., 5 Tabl., 15 Fig.
Keywords: heat pipelines, corrosion, mechanical properties, hardness, through defects

Received: 26.11.2024
Received in revised form:02.12.2024
Accepted: 20.12.2024

References

1. Torop, V.M. (2022) Performance of hydraulic testing of piping of heat networks to achieve the specified reliability of their operation. Tekh. Diahnost. ta Neruiniv. Kontrol, 3, 35–41 [in Ukrainian]. DOI: https://doi.org/10.37434/tdnk2022.03.06
2. Pleshivtsev, V.G., Pak, Yu.A, Filippov, G.A. (2008) Factors that reduce the structural strength of pipe metal and the prospects for creating new pipe steels for heating networks. In: Proc. of 3rd Sci.-Pract. Conf. on Heat Networks. Modern Practical Solutions [in Russian]. www.rosteplo.ru/Tech_stat/stat_shablon.php?id=2076pov
3. Penkin, A.G., Terentyev, V.F., Maslov, L.G. (2004) Assessment of the degree of degradation of mechanical properties and residual service life of pipe steels using acoustic emission and kinetic hardness methods [in Russian]. www.sds.ru/articles/degradation/index.html
4. Yukhymets, P.S., Dmytrienko, R.I., Palienko, O.L., Yehorenko, V.M. (2022) Mechanical properties of metal of critically thinned sections of the heat pipelines and features of their destruction. Tekh. Diahnost. ta Neruiniv. Kontrol, 4, 2022, 34–46 [in Ukrainian]. DOI: https://doi.org/10.37434/tdnk2022.04.06
5. Yukhymets, P.S., Nyrkova, L.І., Gopkalo, О.P. (2022) Specific features of corrosion heating network pipelines made of 17G1S steel. Materials Sci., 58(1), 35–40. DOI: https://doi.org/10.1007/s11003-022-00627-5
6. (2005) GOST 380 Carbon steel of ordinary quality. Brands [in Russian].
7. (1980) GOST 10705 Electric-welded steel pipes. Technical conditions [in Russian].
8. (2005) DSTU EN 13018 Non-destructive testing. Visual control. General requirements [in Ukrainian].
9. (1985) GOST 9.908 Unified system of protection against corrosion and aging. Metals and alloys. Methods of determining corrosion indicators and corrosion resistance [in Russian].
10. (2009) DIN EN ISO 6892-1 Metallic materials. Tensile testing, Pt 1: Method of test at room temperature.
11. (2018) ISO 6507-1 Metallic material. Vickers hardness test. Pt 1: Test method.
12. (2024) ASTM E112 Standard test methods for determining average grain size.
13. (1999) EN ISO 2566-1 Conversion of elongation values. Pt 1: Carbon and low alloy steels.
14. (1986) PNAE G-7-002 Standards for calculation of strength of equipment and pipelines of nuclear power installations [in Russian].

---

Advertising in this issue:

---