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Company History

Reidar Frölich Braathen founded Oslo Sveisebedrift (Oslo Welding company) close to the Aker River in 1932. Starting with a blank sheet of paper & with a minimum of resources the founder developed and manufactured the first fully welded water heater in Norway. Reidar’s active work through 50 years established the platform for OSO’s future and the foundation of a true Norwegian industrial adventure.

After the 7 first years of hard and focused work, the company had more than 100 employees.


During the following years the company experienced great success, benefitting from almost complete market dominance in Oslo municipality.

As war broke out, the family moved the enterprise to Eggedal where Braathen’s father in law, Halvor Sondreson Hadeland, owned a farm. The inventiveness carried on and Braathen constructed and sold steel potato pickers to the district in addition to extensive foresting.


In 1945 the OSO factory by the Aker River was abandoned. After relocating the factory in Oslo over the next 10 years, the company needed more space and moved to a shut down cement factory in 1955. After another 9 years of expansion all production was relocated to the current OSO factory by the Drammen River. The highly automated serial production company is now Europe’s leading manufacturer of stainless steel water heaters.

En Norskeid Familibedrift