Surface treatment of steel pipes 50 metres below Esplanadi

In summer 2018, the energy company Helen will start using two massive heat pumps 50 meters below Esplanadi in the Centre of Helsinki. During the construction project FSP was responsible for the surface treatment of the heat pump pipeline.

Eero Kaartokallio says FSP was able to start the surface treatment project with a very short response time and complete it in the agreed schedule.

This is a significant investment in renewable energy in which Helen is building its second large, industrial-scale heat pump facility in Helsinki. The pumps will provide both district cooling and district heating for residential and commercial buildings in the Helsinki region.

The two huge new heat pumps will increase Helsinki’s district cooling capacity by recycling heat that would otherwise be wasted and transferring it to the district heating network. When heat can be produced through recycling, less of it need be generated from fossil fuels.

Eero Kaartokallio, project manager at Helen, is happy with the partnership with FSP during the construc- tion project. This extensive Helen construction project began with planning and equipment procurement in 2016, after which the project proceeded to the busy construction stage in autumn 2017. FSP joined the project as a surface treatment provider at the start of 2018.

Each heat pump entity is 11 metres long, about 6 metres wide and about 5 metres high.

“The main function of surface treatment is to protect the heat pump’s steel pipes from corrosion, or, in other words, to prevent rust. In underground steel pipes there is a large temperature difference between the inner and outer surfaces, which means there is a risk of conden- sation on the surface of the pipes. In addition to surface treatment, tight insulation is also used to prevent condensation on the pipes,” Kaartokallio says.

Kaartokallio most appreciates the professional attitude and quality displayed in the FSP partnership. FSP has met his company’s expectations in this demanding surface treatment project.

“Cooperation with FSP has been a positive experi- ence for us. We have received what we ordered. Our previous good experiences of FSP spurred on this cooperation.”


Kaartokallio also highlights flexibility, which has been important in this construction project with numerous phases.

“FSP was able to start the surface treatment project with a very short response time and complete it in the agreed schedule. The surface treatment had a tight schedule because we had to move quickly to the next work phase of the project.

“The fact that the pipes were brought to the building site with the primer coating on already speeded up the project. FSP was responsible for primer coating the welding seams and for applying the finishing coat to all the pipes.

“FSP also gave us valuable advice on paint selection. The paints had to have certain properties because of the extreme conditions involved.”

“Because surface treatment underground in a tunnel in a tight schedule was involved, this was really a place for us to shine. The challenging nature of this project made our success even sweeter. We used innovative working methods and lifting technology, all in line with safety regulations. We already had strong experience in underground surface treatment,” says FSP supervisor Kari Holm.

The surface treatment equipment was brought from ground level in a van along a narrow, approximately 500 metres tunnel to the building site of the pump facility under construction, which is about 50 metres below Esplanadi.


In practice, the Helen heat pump system works by re- cycling and storing heat, which would normally go to waste, from buildings. The system pumps cold water into buildings and stores lost heat in water. The water returns to the heat pump facility, where it can be re- cooled.

For this purpose, a cooling water reservoir of about 26,000 cubic metres has been built under Esplanadi. The bottom of this underground reservoir or “battery store” is about 100 metres from ground level. A battery is used to cool water, after which it can flow to cooling equipment in buildings.

The joint renewable heating capacity of both heath pumps will be 22 megawatts. This joint renewable heating capacity is enough to heat 10,000 apartments.

The investment will reduce Helen’s carbon dioxide emissions by about 20,000 tonnes a year, as the heat pumps can replace fossil fuels in district heat genera- tion. The investment is worth over 10 million euros.

Helen Oy

  • One of Finland’s largest energy companies
  • Three power stations in Helsinki, more than ten heat facilities, two underground cooling centres, and the world’s largest heat pump facility
  • Sells electricity all over Finland and district heat and cooling in Helsinki
  • Its energy generation has been awarded as the world’s most efficient
  • Aims to achieve 100 per cent climate neutrality
  • 400,000 customers all over Finland