Study into the Use of Alternative Technologies in the Manufacture of Rolled and Welded Tube-to-Tube Sheet Joints
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STUDY INTO THE USE OF ALTERNATIVE TECHNOLOGIES IN THE MANUFACTURE OF ROLLED AND WELDED TUBE-TO-TUBE SHEET JOINTS A. V. Yakhin, D. V. Karetnikov, R. G. Rizvanov, and A. S. Tokarev
UDС 621.791.14
An alternative technology for the manufacture of rolled and welded tube-to-tube sheet joints using friction welding without heat treatment is proposed. The aim of the study was to evaluate the operational characteristics of samples simulating rolled and welded tube-to-tube sheet joints using alternative technology, as well as their comparison with samples made using the basic technology involving heat treatment. The test results confirmed the conformity of samples made using the alternative technology in terms of density and strength, as well as in the predicted reliable operation resource for samples made according to the basic technology. Keywords: shell-and-tube heat exchanger, rolled and welded joint, reliable operation resource, energy saving.
50% of the equipment used by petrochemical and oil refining companies consists of heat exchangers, primarily including shell-and-tube heat exchangers [1]. A tube bundle comprising heat-exchange tubes, tube sheets, and baffles constitutes a vital component of the shell-and-tube heat exchanger. The service life and reliability of this type of heat exchanger are largely determined by consistency of tube-to-tube sheet-joint parameters [2]. Rolled and welded tube-to-tube sheet joints obtained by welding tubes to the tube sheet, followed by roller expansion, are typically used in heat exchangers operated at pressures above 14 MPa and temperatures above 450°C, as well as at lower pressure and temperature values, while meeting special requirements for the tightness of joints associated with fire or explosion hazard and the toxicity or radioactivity of the working medium [3]. In the petrochemical industry, versions M10 and B2 (according to GOST R 55601-2013 Heat exchanger apparatus and air cooling apparatus. Tube expanding in tube-sheets) are the most common in terms of the material used in heat exchangers involving the use of 12H18N10T steel in the manufacture of tube bundles. High-alloy corrosion-resistant steel 12H18N10T is used for the manufacture of equipment in the oil refining and petrochemical industries due to its high corrosion resistance in high-temperature media of the main oil refining processes and operability under pressure at temperatures coming up to 600°C. A distinctive feature of producing permanent joints from high-alloy corrosion-resistant steel 12H18N10T consists in the susceptibility of joints to intergranular corrosion. Given that the temperature of metal in the heat-affected zone ranges from 500 to 800°C, chromium carbide precipitates along the grain boundaries of austenite. This can lead to brittle structural fracture during operation [4]. Heat treatment (stabilizing annealing) of 12H18N10T steels is carried out to prevent the intergranular corrosion of steels at operating temperatures of more than 450°C, as well as to relieve residual stresses [4]. Costs incurre
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