The onshore part of the pipeline (in Greece and Albania) will have a diameter of 48 inches (1.2 metres), while the diameter of the offshore segment and Italy onshore will be 36 inches (0.91 metres). The thickness of the steel pipe wall will be 17.5 to 31 mm (there are four different classes of pipe).
Onshore pipe-laying work is undertaken in ‘spreads’ at several locations across the entire pipeline route, rather than starting at one end and working towards the other. The width of the construction corridor depends on the terrain.
The actual construction activity at each construction ‘spread’ is estimated to last approximately three months. Additional time will be needed for reinstatement.
Techniques such as horizontal directional drilling are used for crossing roads and rivers, and special care is taken to minimise any adverse effect on the environment during construction.
After construction, the pipeline will be buried at least one metre under the ground and will therefore be invisible.
Onshore pipeline dimensions in Greece and Albania
At its highest point, in Potom in the Albanian mountains, the pipeline will reach approximately 2,100 metres above sea level. It will cross nine mountain peaks more than 500 metres high, while its steepest slope will be on a gradient of 40 degrees.
The overall construction phase is expected to be completed in 2019. The final phase - before the pipeline is operational - is the project commissioning phase, due to take place in the second half of 2019.
Compressor stations and other above-the-ground facilities
The above-ground facilities will include two compressor stations, block valve stations and the pipeline receiving terminal in Italy.
Two compressor stations, one near Kipoi, in Greece, and the other on the Albanian coast near Fier, will be used to ensure gas transportation through the pipeline. For upgrading to 20 bcm in the future, it would be necessary to construct two new compressor stations at Bilisht, Albania and Serres, Greece.
Block valve stations will be placed 30 km apart on the pipeline for blocking gas flow during routine maintenance or in an emergency.
Offshore pipeline and landfall construction
TAP will traverse the bottom of the Adriatic Sea at the shortest crossing - between Fier in Albania and Italy’s southern Puglia region, a distance of just 105 km. This choice of route also took into consideration strict environmental protection requirements and the specific nature of the Adriatic seabed.
Laying the pipes at depths of more than 800 metres will allow the use of specialist S-type lay barges, a state-of-the-art technology employed widely in pipeline construction. The barge will move forward as the pipe string is laid to its rear in the water, following a distinctive S-shaped curvature to the seabed.
Pipes 12 metres long will be welded to the pipeline string on the deck of the barge. The steel outer pipe will have a diameter of 36 inches and a thickness of 20 to 34 mm, depending on the depth of water. At depths of less than 300 metres, the pipe will be coated with concrete for protection from potential damage.
The deepest point of the pipeline below sea level will be 820 metres in the strait of Ontranto in the Adriatic Sea.
Special equipment will be used at the landfalls in Italy and Albania to ensure that the pipe is brought ashore with the minimum adverse effect possible to the local environment and showing respect for the coastal area. For example, in Italy the landfall will be constructed using micro-tunnelling technology to allow the pipeline to enter onshore under the ground, so as not to affect the beach area.
The offshore pipeline installation is due to take place in 2019.
For more details on construction of country specific pipeline sections and infrastructure, please visit our country sub-pages.