Floodgates to fight rising sea levels

Courtney Tenz


The city of Gothenburg in Sweden was looking to replace old wooden sluice gates at the Gårda Dämme with an aesthetically-appealing yet strong and durable material.


The high strength and ability to resist saltwater corrosion made Outokumpu Forta duplex stainless steel the ideal material to create the replacement sluice gates to last for next 120 years and more.


Steel grade: Outokumpu Forta LDX 2404

A port city on Sweden’s west coast, Gothenburg is comprised of a number of small islands that are intersected by beautifully laid-out canals. Bridges are scattered across the archipelago to make it easy to cross from one neighborhood to another. With so many waterways in the city and rising sea levels due to climate change, the risk of flooding forms an increasing concern.

When the old wooden sluice gates at the Gårda Dämme were beginning to rot, they needed to be replaced. The authorities looked into the ideal material for a permanent, modern solution, but still a one that would not lose the original aesthetics.


Designed to last a lifetime – and then some

Outokumpu’s Forta duplex stainless steel has crucial advantages that led to its selection for the project.

For floodgates in a high risk area, finding a high strength material is obviously a priority in order to hold back the floodwaters. At the same time, a long lifespan with low maintenance are important criteria in the selection. With Forta LDX 2404, the new sluice gates have a design life of 120 years, with the possibility of extending their life for centuries if rubber sealing is duly checked.

Though the canals in Gothenburg normally hold fresh water, inflows of salty sea water are not uncommon. Chloride resistance was thus one additional criterion for consideration in selecting the material. Stainless steel duplex has ten times the corrosion resistance of carbon steel, making it the longer-lasting alternative to replace previously used wood.

The new sluice gates at the Gårda Dämme have been in place since 2013. The five gates measure 3.1 × 2.2 meters and weigh in at about 7 tonnes. They were made from 400 tailor-made components to meet the original attractive look.

The end result is an attractive solution built to last, and residents of Gothenburg are quite pleased with the results.


Preparing for the upcoming

As sea levels are anticipated to rise throughout the world and threaten cities across Scandinavia and other coastal areas, solutions for upgrading floodgates and updating sea defenses are going to grow in importance. Thanks to its exceptional corrosion resistance and chloride resistance, duplex stainless steel will likely play an important role in these flood protection measures. Cost efficiency over the life cycle and low maintenance prove it an ideal material for the purpose.

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