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How do you renovate a 400-metric-ton lock gate without making it heavier, while at the same time implementing major technical modifications? That challenge is central to Iemants, a division of Smulders, which—as part of the ZEEKR consortium—is responsible for replacing, renovating, and modifying the lock gates at the Krammer Lock Complex. The enormous gates are not only being fitted with a new coating and updated safety features, but are also having a completely new system installed that significantly speeds up the lock operation process.
Each door is no less than 23 meters wide, 12 meters high, and 4 meters thick. “Despite its size and the many new components, the total weight must not exceed 400 metric tons,” says Martijn Kuzee, project manager at Iemants. “The reason for this is that the door replacement must be able to be carried out at any time using relatively simple materials (i.e., floating gantries). This requires precise calculations and smart adjustments to the internal structure.”
The biggest change is in the way water is moved during lock operations. “Previously, this was done using wall gates in the lock chamber wall; now, six large flow openings are being installed in the doors themselves,” Martijn explains. “Butterfly valves will be installed in these openings to allow the water to flow through the gate in a controlled manner. This reduces the lock-passage time from approximately 45 to 30 minutes.” To make this modification possible, Iemants is redesigning the entire internal structure of the gates. “New technical compartments, six flow pipes with drive shafts, and extensive safety features are part of the modification. At the same time, redundancy is ensured: should a butterfly valve fail, an emergency gate can temporarily close that opening.”
The first door has already undergone extensive work at the Smulders shipyard in Vlissingen. First, the door was thoroughly cleaned, and all components requiring overhaul were disassembled. For gates that have been in use for many years, we account for up to 35 metric tons of fouling and silt. “Because of the new and much larger technical compartments in the gates, the internal air chambers are being rearranged to maintain optimal weight distribution,” Martijn explains. “This ensures that, once completed, equal pressure will be applied to the wheels of the lower roller carriages, on which the doors move within the lock chamber. At ZEEKR’s request, we’ll also test this on the first door with a test lift at our shipyard to verify whether the actual results match the calculations.”
The preservation work is also carried out on-site. “We have several cranes at our shipyard that allow us to lift and tilt the lock gate in one go, so it can be moved into our coating facility,” Martijn explains. “This enables us to sandblast and preserve the gate very efficiently under controlled conditions. The blasting dust is also captured immediately. There’s no risk of it ending up in the environment.” After the new coat of paint is applied, the gate is moved back outside, and various subcontractors reassemble all the components. “Only after all systems have been thoroughly tested at our facility is the door cleared for transport to the airlock. This minimizes the actual disruption during the door replacement.”
