During the months of July and August 2020, the technical expertise of the WA Integra service team at Welding Alloys Russia was required for a challenging repair job. The requirement was to repair a kiln tyre for the Heidelberg Cement plant near Tula, South of Moscow.
The kiln tyre has an external diameter of 6.1m, width of 7.2m and had a thickness of over 4.3m. FLSmidth began by conducting ultrasonic testing on the kiln tyre, during which a crack was detected. There was no cracking visible on the surface and the detected crack was anticipated to require around 45kg of welding consumable (electrodes and wire) to repair. A month later, further visual inspections of the kiln tyre were conducted and it was revealed that the crack had propagated to the surface. By the next day, the crack had increased by 40mm and in total, the surface crack now measured 140mm.
The WA Russia team had previous experience of repairing a kiln tyre, which had been carried out in December 2017; this kiln tyre is still operational today without problem. Site preparation for this type of job involves a scaffold platform to be assembled above the kiln ring for the team to work from with a tented area to protect them from the elements, the ancillary equipment that is required to carry out the work also has to be lifted into position close to the work area.
To ensure the work was carried out to a high standard, a team of independent external advisors were engaged by Heidelberg to monitor the work performed by the team. The work was also captured by Heidelberg through use of a webcam and 24/7 streaming of the video back to their technical specialists in Leimen, Germany along with photos capturing every stage of the repair.
WA Russia first created a detailed outline around the cracked area before removing the damaged area. Based on the initial report, they planned to drill the crack ends to stop the cracks spreading any further, and had prepared retaining plates and brackets to be welded in place to stop any movement of the tyre. During the inspection process, it became apparent that the crack was considerably larger than the previous inspections had indicated. In the space of a fortnight, the crack had increased and was assessed to require up to 600kg of welding consumable, meaning additional technicians and materials were required to repair the kiln tyre.
The team carried out further NDT checks throughout the process to ensure they fully identified the extent of the cracked area and crack propagation. Once they had a clear idea of the degree of the problem, they could proceed with the repair. They began by pre-heating the tyre in preparation to air-arc gouge to remove the cracked area, the gouged area was then ground to bottom out all of the cracks and subsequently thoroughly cleaned the area in preparation for welding. Because the area to weld was quite complicated, a calculation of the total area to be welded was carried out using 3D software, giving the team an accurate overview of the quantity of consumables needed to complete the repair.
Preparation continued by preheating the area, this preheat temperature had to be maintained throughout the duration of the job. The WA Russia team initially started the repair using WA GAMMA 182-E electrodes, as this gave better access to the base of the crack, which was difficult to weld using an automated process.
Once the base of the crack had been sufficiently welded with the GAMMA 182-E electrodes, the team could continue with an automated process to rebuild, using both automatic and semi-automatic processes. This was welded using Welding Alloys’ GAMMA 182 welding wire with shielding gas, which is resistant to hot cracking, has improved ductility and is resistant to corrosion.
The repair was brought back to its original profile, the tyre was then post-weld heat treated. The team finished by dressing the repaired surface, leaving sufficient material to accommodate for shrinkage.
In total, it took 19 days to complete this complex repair using 588kg of welding consumables. Working efficiently and to schedule ensured the project was a success and the plant could continue production again.
The WA Integra service team at Welding Alloys Russia demonstrated exceptional technical skill, expertise and flexibility in their ability to complete the repair under challenging conditions, ensuring they provided the customer with a high-quality solution.
“It is only now that I managed to find the time to express my thanks for support in the repair of kiln tyre crack in Tula. Everything went in a perfect way, rapidly, with good quality and without any incidents”. Thomas Kolbe, Technical Director Russia - HeidelbergCement Rus LLC