Authors: N.V. Ababkov, M.V. Pimonov, E.E. Levashova, A.V. Shchepetkov, A.S. Sivushkin, P.A. Syrkin

Title of the article: Reseach of mechanical properties and microstructure of straight-seam and seamless pipes of heat networks

Year: 2025, Issue: 6, Pages: 19-28

Branch of knowledge: 2.5.8. Welding, related processes and technologies

Index UDK: 621.785.616

DOI: 10.26730/1999-4125-2025-6-19-28

Abstract: The reliability and durability of heating networks largely depend on the quality of the pipes they are constructed from. Premature failure of heating network pipes causes accidents and is undesirable for utilities. This article examines the mechanical properties, microstructure, and radiographic inspection results of metal specimens obtained from longitudinally welded and seamless pipes. Most of the specimens presented in the study were made of grade 20 steel, with one specimen made of grade 09G2S steel. A comparison of mechanical properties revealed that all pipes meet the requirements of regulatory and technical documentation. Radiographic inspection revealed weld defects only in specimen No. 7. Metallographic examination of the specimens revealed welding defects in all longitudinally welded pipe specimens, including weld reinforcement overhangs. Gas pockets, pores, and microcracks were also detected in the weld reinforcement. The presence of such defects can lead to an increased rate of corrosion in the metal. Corrosion resistance studies showed that the grade 09G2S steel specimen is the most resistant, which is explained by the presence of alloying elements. For pipes made of grade 20 steel, corrosion resistance indicators are quite similar. An analysis of the obtained results allows us to recommend seamless pipes for use in heating networks, as they are free of defects that are typical of straight-seam welded pipes, which are stress concentrators and can lead to more rapid failure.

Key words: microstructure mechanical properties non-destructive testing straight-seam welded pipes seamless pipes defect

Receiving date: 29.09.2025

Approval date: 15.11.2025

Publication date: 22.12.2025

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