PSI - Issue 59

Kozulin S. et al. / Procedia Structural Integrity 59 (2024) 391–398 S. Kozulin et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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- Choosing welding parameters for each pass to ensure a weld shape factor in the range of 5.4...8.0. - Redistribution of stress field density by symmetrically executing the welding of individual assembly cells. It has been shown that to carry out the MESW CN process for cast carbon steels like 35L, a combination of general-purpose welding wires with increased manganese content (e.g., Sv-08G2, Sv-10G2) and a fused flux based on the SiO 2 -MnO-CaF 2 system (AN-8M, AN-9) is necessary. The material for forming assembly inserts, which accounts for 28-38% of the deposited weld metal, must contain at least 1% manganese with low carbon content. Before conducting an experimental-industrial test of the developed technology on the section of the machine building plant, an experimental weld of a vertically installed band was carried out. The purpose of the weld was to verify the assumption of reducing the angular deformation after welding semi-rings in a vertical position and to practice the welding technique. The experimental weld showed that the residual angular deformation was no more than 0.011 radians, which is 70% less than that of welding semi-rings in a horizontal position. The experimental-industrial test of the developed technology was conducted at the Zdolbuniv Cement Plant, where a crack was discovered in one of the welded bands of rotating kiln No. 5, with a diameter of 4.5×170 m, affecting the entire cross-section of the band. The defective section was positioned in the extreme upper position by rotating the kiln shell. The length of the band's rolling surface (joint thickness) was 900 mm, and the thickness was 355 mm. After cutting out the crack and aligning the edges using gas-oxygen cutting, a rectangular gap with a width of 120 mm was formed. To create holes across the gap, partitions made of metal plates with a thickness of 40 mm were installed (Fig. 4).

Fig. 4. Scheme of MESW CN a through crack in the welded bandage of rotary kiln Ø4.5×170 m: 1 – bandage; 2 – cement kiln body; 3 – entrance pocket; 4 – serial numbers of seams; 5 – melting mouthpiece; 6 – water-cooled pad; 7 – forming insert; 8 – seam; 9 – output bar.

For the input pocket in the kiln shell, a window was cut. The welding of holes was carried out sequentially from the middle of the joint towards its edges using a two-electrode consumable nozzle, which was set perpendicular to the edge preparation plane. Standard copper water-cooled inserts were placed adjacent to the weld areas. After welding all the holes and removing the technological pockets, the band was deemed suitable for operation. Measurements of the geometric parameters of the restored band showed that the deviation did not exceed 2 mm, and the ellipticity was 2.5 mm, meeting the standard requirements. No visual defects were found in the repair zone. The welding time amounted to 14 hours, and the total repair time was 24 hours. The operational performance of the restored band was deemed satisfactory for a period of three years of operation. At the Spassk Cement Plant, the failure of the band of a rotating ki ln with a diameter of 7.0/6.4× 95 m occurred. The band material was steel 35L. The kiln shell was rotated so that the location of the failure was in the extreme upper position. The crack was cut using gas-oxygen and air-arc cutting to fully capture the branching area of the crack. A trapezoidal-shaped cut was formed with dimensions: 140 mm at the bottom and 210 mm at the top. A steel partition of trapezoidal shape with a thickness of 60 mm was installed in the center of the joint. The joint was divided into 9 sections along its length. Holes were created by installing transverse trapezoidal partitions. The volume of the cut amounted to 121. 500 cm³. Entry and exit pockets were manufactured from sheet metal and installed. The joint was preheated to 150°C before welding. A shelter was installed on the kiln shell, under which welding wire spools were placed. The welding equipment installation was lifted to a support platform. MESW CNof