A pre-fabricated conical section being installed in the Mondi boiler.
A flue gas stack is being prefabricated at the construction site. lifted into and out of the boiler one bottle at a time, so for 24 welders, there will have to be 24 separate lifts to get them all safely supplied at height. And when the cylinders are empty, a separate lift must be arranged to remove and replace each one. So it was important for us to incorporate Afrox’s Multi-User Pressure Panel (MUPP) into this project,” Schwim explains.
Mitigating against challenging conditions
Richards Bay’s high humidity poses sig- nificant corrosion challenges. To mitigate this, Steinmüller Africa has deployed laser cleaning technology to remove surface contaminants without compromising weld integrity. “Laser cleaning is ideal, because these components are already prepped, and while it does come with a protective weld primer applied, some components had already started rusting on arrival. Laser cleaning quickly removes this rust without changing the tube length or the prep accuracy. After laser cleaning, a weld pre-primer is applied: “I’m quite surprised at how good modern weld pre-primers are. It’s the first time I have worked with them, and once the joint is laser cleaned and the primer is sprayed on, it’s still not rusted two weeks later. So the prep can be lightly brushed and it’s ready to weld.” The primer has been extensively tested and proven successful in maintaining weld integrity in high-moisture conditions with- out affecting the welding performance or the properties of the finished weld. Other Steinmuller Innovations Beyond the Mondi boiler project, Stein- müller Africa is pioneering new lifecycle extension technologies for Eskom’s high- pressure heaters, which preheat water before it enters boilers. These heaters often develop tube leaks that were previously re- paired by manual plugging, with limitations on the size of the plug that can be inserted. Now, through a two-year research and development (R&D) process, Steinmül- ler Africa has developed and qualified a non-standard explosive plugging process for sealing larger tube diameters, which
Although still working on the ground, SteinMüller is already utilising this solu- tion. “It is just easier to have one single manifold pack of gas stored somewhere permanently, so that a welder never has to fetch and carry full and empty gas cylinders around the site,” he notes. The idea underpinning the MUPP solu- tion is to leave gas cylinders on the ground in a safe, secure and convenient fenced-off area. A single braided steel hose connects the gas to a pressure-regulated MUPP with eight connection points, allowing eight welders to be serviced simultaneously. Initially developed for at-height welding on boilers, the solution enables an MUPP to be installed where welders work, eliminating the need to lift gas cylinders into the boiler. “We think it works well. We plug it in, check for leaks and then we can supply eight welders at the same time,” says Friedrich Schwim. “We plan to have three teams of welders working at three different levels, so we have invested in three of these multi-user panels for the Vuselela Project,” he adds. This is not the first time Steinmüller has adopted this solution, having used it on the Camden Power Station site. “We also find it useful in our workshops. In the Pretoria workshop, for example, we used a MUPP when we built the Eskom HP heaters, because it results in less gas having to be moved to the point of welding,” he adds.
A boiler membrane wall panel. For long structural welds, Steinmüller uses a qualified metal-cored wire procedure. Laser cleaning is used before welding, and a weld prep primer is added after. was previously unfeasible. “We have been doing explosive weld plugging for the past 12 years, but we could only repair 17 to 18.5 mm OD tube holes. We’ve now devel- oped an approved procedure for bigger plugs, based on Eskom’s current needs,” Schwim explains. “When an HP Heater tube started to leak, these were repaired by cutting off the tube, pressing in a cap and welding a seal around the outside edge. Weld fusion was limited to the surface area around the cap and this could corrode through relatively quickly. The fusion zone of the explosive plug is longer, across the full thickness of the heater shell, so there is much more material to resist corrosion. In addition, we can use a plug with a little nickel in it to resist corrosion,” he explains. “Our ability to reengineer technology, adapt to environmental realities and de- liver under pressure defines who we are,” says Schwim. “We are building more than infrastructure, we are laying foundations for Africa’s industrial resilience,” he con- cludes. https://steinmullerafrica.com
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November-December 2025
AFRICAN FUSION
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