PSI - Issue 59

Kozulin S. et al. / Procedia Structural Integrity 59 (2024) 391–398

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S. Kozulin et al. / StructuralIntegrityProcedia 00 (2019) 000 – 000

1. Introduction In heavy engineering, cement, mining, metallurgical and other industries a large number of large-sized units are operated, the supporting parts of which work under heavy conditions of dynamic, vibration and other loads. Often such machine parts fail prematurely as a result of the formation of defects in the form of through cracks. Such failures cause long downtime of the equipment and in some cases disruption of the production process, if this equipment is part of the production line. To replace ruined parts, such as rotary kiln support bands, the weight of which reaches 100 tons or more, it is necessary to dismantle them using powerful lifting equipment, which is a fairly time-consuming operation and leads to long downtime of the production line (Fig. 1). The difficulties of performing repair work are often exacerbated by the significant remoteness of the places of operation of the equipment from machine-building enterprises, where specialized equipment and the necessary conditions for the organization of the restoration of destroyed parts are available.

Crack

Fig. 1. Through crack in the support band of the cement kiln.

Restoration work becomes especially important when eliminating accidents in technological lines with a continuous round-the-clock production cycle, as shown in the works of Panteleenko et. al. (2003), Shcherbakov et al. (2018). A significant reserve for saving material, energy and labour resources is the restoration of destroyed large machine parts at the place of operation. Long-term practice has shown that the main reason for long downtime of the mentioned technological lines is the formation of through transverse cracks in the bandages of rotary furnaces (Boganov (1965), Nasedkin (1980)). Analysis of the known methods of repairing through cracks using electric arc welding methods showed their low efficiency, as shown in the works of Kukakin (1968), Taldykin et al. (1977), Dennis et al. (1999), Kozulin et al. (2007). This does not significantly extend the service life of restored parts due to frequent cases of their repeated destruction. The use of electroslag welding (ESW) for these purposes is preferable due to the high productivity of the process and low sensitivity to the quality of preparation of the welded edges as shown in the works of Paton (1980), Sushchuk-Slyusarenko et al. (1969 and 1989), Filchenkov et al. (1980), Yushchenko et al. (1999). However, the specific conditions of repair works practically do not allow using the known ESW methods due to the high tendency of weld metal to formation of hot cracks, difficulty in ensuring guaranteed fusion of welded edges at a large (non standard) gap, complexity of installation and use of multi-electrode equipment, etc. The method and technology of multi-pass ESW with a consumable nozzle (MESW CN), specialized equipment, tooling, scheme of repair of through cracks in large-thickness parts have been developed for on-site repair of such parts as shown in the work of Yushchenko et al. (2014).