Progress in the renovation of the sea lock in Wilhelmshaven: one of the largest lock gates in the world has been completely coated with corrosion protection.
With a length of 60 m, a height of 20 m, a depth of 10 m and a weight of 1,700 t, the gate of the Great Sea Lock is one of the largest of its kind in the world. The completion of the main coating work marks significant progress in the project, which began in 2018. 26,000m2 of steel has been coated with corrosion protection.
The choice fell on the Stelpant coating system from Steelpaint. A two-component epoxy system from another supplier had proved unsuitable for use in autumn and winter, as the cold would have rendered the coating unusable.
Muehlhan Germany, which worked together with Hermann Maschinenbau in a working group for the port authorities WNA Hannover and WSA Weser-Jade-Nordsee, opted for the one-component polyurethane system Stelpant, which cures at temperatures down to -5 °C and a relative humidity of up to 98%. Thanks to this system, the coating work could continue throughout the winter so that the door could be floated back in and reinstalled for interim use.
The coating package consisted of a 75 µm thick zinc primer Stelpant-PU-Zinc, followed by two 225 µm thick layers of Stelpant-PU-Combination 300. “Together, the layers provide excellent corrosion protection against salt water, abrasion and mechanical stress in one of the harshest marine environments in Europe,” Steelpaint said. The zinc primer provides cathodic protection and excellent adhesion, while the polyurethane intermediate and top coat ensures abrasion resistance, flexibility and durability even in aggressive marine conditions. The system is certified by the Federal Institute for Hydraulic Engineering in Karlsruhe for use in hydraulic steel structures and for environments from Im1 to Im3 in accordance with DIN EN ISO 12944-5.
“Has shown what our technology can do”
“This was one of the largest and most challenging projects we have been involved in in recent years. But it has shown what our technology can do,” says Fynn Baumfalk, Key Account Manager at Steelpaint. “The schedule was repeatedly postponed, and even now some areas are still unfinished. However, our coatings were applied on time and exactly where they were needed and delivered the expected performance.”
According to Steelpaint, the main corrosion protection of the refurbished gate has been completed, but some minor finishing work is still required. Some hot work also needs to be repeated before recoating. Baumfalk confirmed that the Stelpant coating system will also be used in these areas. The gate is scheduled to be fully commissioned in 2026. Due to its location, the sea lock is exposed to severe salt corrosion, tidal erosion and abrasive silt and therefore requires the highest level of protection.
The lock regulates the water level in Wilhelmshaven’s inner harbor, strengthens flood protection and provides safe access for naval and merchant fleets. The port handles a large proportion of Germany’s crude oil, coal and LNG imports. The JadeWeserPort is the only deep-water container terminal in Germany and the most important North Sea base of the German Navy. It has a natural depth of around 18 m and can accommodate ships up to 430 m long and with a draught of 16.5 m.
The success of the Stelpant coating could lead to Steelpaint being selected for further phases of the extensive refurbishment of the JadeWeserPort dock. Three completely new dock gates will be put into operation towards the end of the decade. A feasibility study updated in 2019 confirmed the economic viability of a second container terminal 2 km north of the existing one.
