Background to the corrosion test in the North Sea
There is a fast-growing need for a new generation of marine and offshore structures to support applications such as offshore wind and marine-related infrastructure, including coastal protection.
Across these applications, reliability, long service life and low maintenance are key requirements - often for design lives of 35 years or more. However, the conventional approach of using carbon steel with protective coatings and corrosion allowances has important limitations. Coatings require maintenance, while corrosion allowances can increase material use and structural weight. In demanding offshore and marine environments, maintenance operations are complex, costly and often operationally disruptive.
Stainless steel, specifically high-strength duplex grades, offers a competitive alternative to coated carbon steel since its corrosion resistance and strength helps create lightweight, durable structures that require little to no maintenance.
Outokumpu’s North Sea field exposure programme demonstrates the performance of different duplex stainless steel grades across relevant marine corrosion zones, including atmospheric, splash, tidal and submerged exposure. The data support informed material selection by helping to match the appropriate stainless steel grade to the actual exposure conditions and service requirements. This is key to achieving the intended benefits of duplex stainless steels: long service life, low maintenance and reliable performance in demanding marine environments.
Overall, our findings show that duplex stainless steels provide a robust alternative to carbon steel solutions in offshore applications.