− Before the older chimney could be dismantled, inspection work and internal reinforcement needed to be carried out so it simply would be safe to lift down, says Boris Antonsson, Supervisor at Jernbro in Gothenburg.
The chimney is located on the mountain by the Lundby tunnel and therefore Lundbyleden was closed one night when it was time for dismantling with the help of a crane. Due to the somewhat inaccessible location, it was a bit tricky to slide heavy machinery onto the forest path leading up to the chimney.
− The length and weight of the chimney also contributed to it being considered a somewhat risky job. The size also meant that we needed to take the weather into account, because if it’s too windy, this type of work can’t be done. However, the lift-off went surprisingly well. Prior to the disassembly, we had manufactured a temporary chimney which we assembled directly after the old one was taken down, says Boris.
This was followed by construction and building of the new final chimney. As the original chimney was connected to a 10 m long pipe that runs through the mountain to a mountain room, the new chimney needed to fit that pipe and existing foundation bolts. Reinforcing and building new suspensions for the mountain pipe were also needed. In the new production, Jernbro’s subsidiary GMK was involved, as they have high competence in welding and forging.
− In connection with an odor investigation, a dispersion calculation showed that any odor disturbance would at most affect 35 people for a maximum of 88 h/year. A sustainability analysis also showed that technical, work environment-related and financial benefits outweighed increased odor risk. Therefore, the decision was made to mount a chimney only 5 m high instead of 25 m, explains Andreas Tromstedt, Project Manager at Gryaab.
− The new chimney consisted of five parts, which were lifted up one at a time with rings, before finally being fixed. The work was somewhat complicated, but fun as it was like putting together a lego set, says Boris.
− Our collaboration worked very well and I think that all parties learned a lot during the journey, says Andreas.
− From the beginning of 2023, a new framework agreement between us and Gryaab applies, which concerns the manufacture and assembly of load-bearing steel structures and is valid for 4 years. Due to the agreement, I look forward to new projects with Gryaab that contribute to a cleaner environment, Boris concludes.
Image: Lift of the old chimney. Reinforcements of the old chimney. The temporary chimney. Jernbro’s workshop. The new chimney.
