Here you can find out all about a special structure we supplied for Stein Harbour (Limburg), which is home to companies including DSM. In addition to 250 metres of slackening structures, we also manufactured a lifting structure comprising a main girder and two 40-tonne columns. An impressive feat! After all, with a main girder weighing 125 tonnes and measuring 66 metres in length, this was an imposing structure even for us.
How does it work?
Slackening structures are designed to protect quays from damage caused by shipping traffic. The Chemelot site in Stein has a harbour where large quantities of hazardous substances are handled. It is obviously important that these activities are carried out safely. OCI Nitrogen, for example, uses a pipeline to deliver ammonia to the harbour. While this is being transferred onto inland vessels, regulations require the harbour to be closed off completely to other shipping. This is possible thanks to the lifting towers, between which is the main girder. The girder works like a lift bridge, closing off the harbour to other vessels when products are being loaded or unloaded. Once this work has finished, the lift bridge is opened with the help of a vertical lifting structure, powered by two large electric motors, allowing the vessel to leave the harbour safely. The entire structure was manufactured in Heeg, before being transported over water to Limburg, where the slackening structures were assembled.
A mega girder!
The lifting towers and part of the slackening structures had been installed in Stein at an earlier stage. It was then just a question of waiting for the huge main girder. This was manufactured in Heeg in three sections, before being assembled on our own quay – a 66-metre-long girder! We then had to equip this lifting structure with an operating mechanism, such as motors, winches, pulley housing, electrics, etc., and all this had to be loaded onto a submersible pontoon. Submersible? Yes, for assembly it was important to be able to sink the pontoon so the enormous lifting structure could be hung at the correct height. Fortunately, we had called in professionals from Schot, Mammoet and Lekstroom to help us with this task.
Nauta involved at an early stage in the design
The barrier structure itself was developed in close collaboration with Van den Biggelaar civil and hydraulic engineering and Sitech, which provides support with site and manufacturing services in the process industry. Working together at an early stage in the project ensured that Nauta was able to tailor the design precisely to the wishes of the parties concerned. This resulted in an optimum solution, while minimising the costs involved. The collaboration between all the parties was excellent once again and it is almost a shame that the project is over! Time, then, to look ahead to the next challenge.