Expertise for extreme conditions


The chimney in Jyväskylä’s power station needed a material that would resist extremely corrosive conditions inside the chimney.


Austenitic Outokumpu stainless steel Ultra survived all the comprehensive testing, as it proved to be the most corrosion resistant in the present conditions, as well as the most cost-efficient one.


Steel grade: Outokumpu Ultra 254 SMO

In 2010, the city of Jyväskylä, in Central Finland, built a new power station with a 143-meter tall chimney made of coated carbon steel. However, the circumstances were more aggressive than thought, and in few years the chimney was in need of renewal. “We decided to renew the chimney because of its widespread corrosion damage. We needed a material that could withstand the conditions in the flue gas duct and chimney, while also being cost-efficient,” says Aleksi Vuorenmaa, the project manager from Jyväskylä Energy Group.

Jyväskylä Energy Group chose Outokumpu as the material supplier because of its well established reputation as one of the biggest stainless steel providers in the world. “We knew that from Outokumpu we would get the exact material we needed. High corrosion resistance was our most important requirement, and the reason we chose stainless steel,” Vuorenmaa describes.


Comprehensive material testing

In order to find the optimal stainless steel, Outokumpu’s corrosion department in Avesta R&D Center, performed two period field tests, the first one lasting for two years and the second one six months, with a wide range of materials.

The circumstances inside the flue gas duct and chimney are very unpredictable, given the combination of wet and dry conditions with relatively high temperatures. In addition, the presence of deposit forming particles can make the conditions very aggressive to stainless steel. When evaluating the samples, Outokumpu’s experts were mostly paying attention for weight loss and visible corrosion, as signs of too aggressive conditions for the material. Two types of stainless steels performed the best, and Jyväskylä Energy Group chose the more cost-efficient one. Ultra 254 SMO is one of Outokumpu’s most corrosion resistant grades and performed significantly better in comparison to the lower-alloyed alternatives. Ultra 254 SMO is typically used in challenging environments where standard materials will heavily corrode.


Technical support for the material use

Welding of Ultra 254 SMO requires exceptionally good care. Jyväskylä Energy Group felt important to receive support in using the material, as they had no prior experience of that type of stainless steel. Outokumpu is interested in promoting the use of special steels, and this provided a good opportunity to help the customer adopt recommended practices.

”Together with the subcontractor, the manufacturer of the chimney, we received technical support from Outokumpu whenever needed. Especially the consultation for welding the material was very useful in avoiding problems,” Vuorenmaa says. The project was completed in September 2016. “We have high expectations for the material’s sustainability, since according to the test results it proved to be an excellent option for this purpose,” Vuorenmaa states.

Recommended products and insights

Energy and heavy industry

In energy and heavy industry, failure is simply not an option. When one single mishap can explode into a full-blown crisis, only stainless steel can deliver the assurance of control that you depend on.


The Ultra range contains stainless steel products meant for extremely corrosive environments (PRE of more than 27).

Avesta, Sweden

Fueled by a high-octane blend of advanced technology and a long, proud tradition, the Avesta mill showcases precision performance. One of Outokumpu’s fully integrated production sites, Avesta redefines excellence.


Stainless steel is a superb material for sustainable solutions as it is 100% recyclable, efficient and long-lasting. Our vision is to become the customers’ first choice in sustainable stainless steel.

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