Concor’s Rapid Engineering Fix at Kusile Power Station

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.

Concor played a key role in stabilising South Africa’s electricity supply by constructing three temporary steel flue gas stacks at Kusile Power Station.

Site installation demanded meticulous planning and execution with the construction taking place in a brownfields environment.

Each stack is supported by piled foundations consisting of 16 piles of 900mm diameter, varying in depth from 8m to 20m.

Each stack required 4,776 galvanized pre-tensioned bolts ensuring rapid and accurate pre-tensioning.

Given the temporary nature of the stacks, a single coat of red oxide primer was applied to a blasted SA2.5 surface, as the design life was limited to just three years.

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FAQs and Answers

1. What was Concor’s role at Kusile Power Station?
   Concor was contracted to construct three temporary steel flue gas stacks to restore functionality at Kusile Unit 1.
2. Why were steel stacks used instead of rebuilding the chimney?
   Steel stacks were chosen for their quick availability, ease of fabrication, and suitability for a fast-track temporary solution.
3. How tall were the temporary steel stacks?
   Each flue gas stack was 116 metres tall with a 7-metre internal diameter.
4. What challenges did the Concor team face?
   The team faced tight deadlines, wind safety considerations, and the need to fabricate and install stacks in a brownfields environment.
5. Where were the steel stacks fabricated?
   The stacks were fabricated in Vanderbijlpark under controlled conditions to minimise on-site work.
6. How were the stacks secured?
   Each stack used 4,776 galvanised pre-tensioned bolts and 16 piled foundations for structural stability.
7. Was the project temporary or permanent?
   The installation was designed as a temporary fix, with a projected design life of only three years.
8. How did this project impact South Africa’s power supply?
   The rapid intervention helped stabilise power generation at Kusile, positively impacting national electricity availability.