Natural gas transmission
The most important components of the gas transmission network are the transmission pipelines, including valve stations, the compressor stations and the pressure reduce and metering stations located at the gas delivery points. Gasum is the Finnish transmission system operator (TSO) under the Natural Gas Market Act. Gasum owns the steel pipelines and equipment required for gas transmission.
Gas is transmitted to sites close to where gas is used along underground transmission pipelines. The pipelines are laid at a depth of 1–2 m, and their location is marked with signposts. The gas pressure in current transmission pipelines is 30–54 bar, but new pipelines are constructed to withstand 80 bar as well. The pipelines are steel pipelines coated with polyethylene plastic. The protection against corrosion provided by the coating is supplemented by a cathodic protection system. The high-pressure transmission pipeline network is 1,300 km long.
Valvesincrease the safety of the network. Valve stations are installed at intervals of 8–32 km along the transmission pipeline network. Their safety cut-off devices can be used to cut off gas transmission and distribution and release gas from a pipeline section using a measure called blowdown. There are a total of 166 valve stations in the transmission network.
Monitoringand alert data from along the network is submitted to the Kouvola central control room via link stations belonging to the gas network's data transmission system. The link stations are usually located in conjunction with valve stations. The data transmission system consists of 15 link stations.
Compressor stationsare used to raise gas pressure and that way increase the natural gas transmission network capacity. Finland's compressor stations are located in Imatra, Kouvola and Mäntsälä. There are a total of nine gas turbine operated turbo compressors at the compressor stations. Four of these are in Imatra, three in Kouvola and two in Mäntsälä. The total shaft power output available is 64 MW.
Pressure reduce and metering stations
From the transmission pipelines natural gas is led into pressure reduce and metering stations where the transmission pipeline pressure is reduced to a level suitable for customers. There are 135 pressure reduce and metering stations in the transmission network, and the amount of gas delivered to consumers is measured at these stations. Stations are fenced off and equipped with gas leak alarms, automated safety equipment and remote control systems as well as an individual means of isolation outside the station.
Gas is odourised before delivery to customers. In special cases gas can also be delivered unodourised, but this requires a permit from the authorities.
Transmission pipeline diameter
The diameter of the transmission pipeline ranges between DN1000 and DN100. The average calculated diameter is DN500.
Information system used: Network database PIMS Control system SCADA
Other: 80% of the pipelines can be inspected internally
Interconnection points to other transmission networks
physical interconnection point Imatra / Gazprom (RU)
Interconnections to distribution networks
Balance settlement zones
The transmission network owned by Gasum Oy is fully covered by one balance settlement zone.
Injection of biogas into the network
Mäkikylä biogas facility /Kouvola
Suomenoja biogas facility / Espoo
Kujala biogas facility / Lahti
Riihimäki biogas facility / Riihimäki
Network pressure requirements
Operating pressure: Max. 54 bar, with 80 bar operating capacity in some sections of the network
Pressure requirements for the different network sections:
Porvoo 31.5 bar
Tampere (Naistenlahti) 30.0 bar
Kirkniemi 30.0 bar
Inkeroinen 30.5 bar
Values in use in Finland
Gas day: 0:00 am–0:00 am UTC +2
Heating (calorific) value applied:
Net calorific value (NCV)
Reference conditions for volume: 0 °C, 1.01325 bar
Combustion reference temperature (NCV, GCV, Energy, Wobbe)