The joints in the welded pipes are easily visible from shore – the pipe segments are just 12 meters long, At the same time, they are heavy in terms of marine pipeline projects – each weighing in at 24 tons. The thickness of pipes is the maximum for this segment, varying from 26.8 mm to 41 mm.
The welding was done directly on board the Castoro Sei, but the pipes were not stored on the ship as is normally the case, but delivered by accessory vessels from which they were unloaded, welded and laid. "The choice of technical welding was a big challenge for our contractor, because were are using unique steel and very thick pipes", project director Artem Kashirov told OGE.
Many other unique technologies are also being employed during this marine project, which is unprecedented in scope. For example, a powerful windlass with a pull of 600 tons and a retractable cable 121 mm in diameter was needed to bring the pipes to shore. "There was a large amount of loose rock on the bed of the Bukhta bay and in order to free it, the largest excavator in the world was used – a Simson ZOL", project engineer Dmitriy Kashirov said. (Read in more detail about the technologies and equipment employed in this stage of the project in the September issue of OGE).
After completing work begun in April to lay the pipeline at the Russian coast, the Castoro Sei will head for Finnish waters where it will lay pipe along the bottom of the sea. About 230 kilometers of pipe was laid in Swedish and Finnish waters before arriving at Portovaya. Pipe along the Russian segment will be laid by the Solitaire vessel.