Concor recently showcased its engineering and construction expertise at Eskom’s Kusile power station in Mpumalanga by taking on a critical project to restore the power station’s boilers. This was in response to the unexpected failure of the original flue gas duct, known as the West Chimney for Kusile Unit 1, which had severely impacted South Africa’s electricity supply. The project involved constructing three steel flue gas stacks, each using 605 tons of steel, to urgently bring the boilers back online.

Juan Passmore, Project Director, Kusile Chimney West – Repair & Related Works Project at Concor, explains that the temporary nature of the structures and the tight deadlines required the team to execute the project rapidly while ensuring that materials and subcontractors were available to meet the demands. The design, intended for eventual dismantling once the West Chimney was repaired, added complexity to the project.

“In collaboration with ICC Commonwealth, Concor selected steel as the optimal material due to its availability and suitability for the accelerated schedule. Early acquisition of the necessary steel plates allowed the design process to begin promptly, focusing on the specific requirements of the project,” he says.

The final design featured freestanding structures; each 116 metres tall with a 7 metre internal diameter. These stacks were strategically located near the power station’s turbine units, and measures were taken to ensure their stability, including the addition of helical strakes to counteract wind effects.

The steel stacks were fabricated in controlled conditions at a facility in Vanderbijlpark, minimising the need for on-site work. Concor’s subcontractor worked around the clock to meet the stringent deadlines, fabricating the stacks in segments that were then transported to the site for assembly.

Given the temporary nature of the project, the stacks were coated with a single layer of primer, and foundations were laid using 16 piled foundations for each stack.

Passmore says that site installation was meticulously planned, with preassembly occurring away from the power station’s operating areas to minimise disruption. “High-capacity cranes were used to assemble the stacks on-site, with operations carefully timed to avoid wind and lightning risks,” he says. In total, 4,776 bolts were used to secure each stack, ensuring a stable and secure structure.

“Concor’s successful completion of this fast-track project underscores our capability to manage complex, time-sensitive projects in challenging environments, solidifying our leadership in the South African construction industry,” Passmore concludes.