Enersense International Plc | Press Release | March 12, 2026 at 09:00:00 EET

Enersense installed three kilometres of cooling pipelines in a subsea cable manufacturing tower in Karlskrona, Sweden. At 200 metres, the tower is the second tallest building in the Nordic countries and the tallest industrial building in the region. The challenging project was completed according to plan.

The tower is used to manufacture high-voltage subsea cables used, for example, to connect offshore wind power to the grid in Sweden. Enersense installed the tower’s cooling pipelines, which are a key part of the subsea cable manufacturing process.

Installing the pipelines in such a tall tower was a demanding project and was carried out in sections. The pipelines were assembled at ground level in pieces, like large Lego blocks. The sections were then lifted inside the tower to heights of up to 160 metres.

The project’s pressure test reached nearly 200 metres

“Assembling pipelines at this height was an exceptional project. When working inside the tower, it is impossible to see the whole structure at once, so the work progresses piece by piece. In the final stage, the pipeline joints were X-rayed to ensure the welds met the required quality standards. Despite the challenging nature of the project, we received very positive feedback on the quality of our work,” says Ville Poutiainen, Project Executions Director.

Enersense also carried out a pressure test on the pipeline system. In this project, testing was particularly important because of the significant pressure difference between the top of the tower and ground level. The hydrostatic pressure test was conducted in accordance with the EU Pressure Equipment Directive at a height of nearly 200 metres and, according to the inspectors’ assessment, ranks among the highest pressure tests ever carried out in Northern Europe. The pressure test was completed successfully.

“The height is roughly equivalent to almost two towers of the Helsinki Olympic Stadium. The views over Karlskrona were spectacular. From the tower, you could watch ships in the harbour and the surrounding historic town as the work progressed. The atmosphere on site was also extremely positive, and cooperation with all partners went very smoothly,” says Supervisor Keijo Suihko.

Project customer for Enersense is Maillefer. The subsea cable manufacturing tower is scheduled to begin operations later this year.

About us
Enersense delivers the essentials of tomorrow’s society. It acts as a lifecycle partner to customers in energy transmission and generation, the industrial energy transition, telecommunications and data centres. The company designs, builds, maintains and modernises critical infrastructure across the Nordics and the Baltics. Around 1,700 Enersense experts work for a more sustainable future, for example, with power lines and telecommunications networks, at substations and power plants. Enersense had a revenue of EUR 307 million in 2025, and it’s listed on Nasdaq Helsinki (ESENSE). www.enersense.com.

Image Attachments
Located on the Baltic coast, the subsea cable manufacturing tower in Karlskrona stands next to the city’s maritime centre, which is a UNESCO World Heritage Site.

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