The Balticconnector offshore pipeline is laid on the seabed of Baltic Sea phase by phase – the pipelaying process on the vessel

The pipelay vessel Lorelay, owned by the Allseas, commenced the installation and pipelaying of the offshore pipeline on 20th of May 2019 in Inkoo. The preparation and planning started months ahead and now the vessel advances 2–3 kilometres per day towards Paldiski in Estonia.

The initial vessel mobilization took place in Rotterdam. The mobilization consisted loading out of temporary installation aids i.e. pull-in and laydown heads, above water tie-in lifting clamps, welding and field joint coating consumables. During the mobilization the production line on the vessel (so called “firing line”) has been prepared for the pipeline installation by means of changing the tensioner pads to suit the Balticconnector pipeline diameter and adjusting the vertical position of the roller boxes on the vessel and the stinger. The position of the roller boxes is driven by the pipeline installation analysis carried out months ahead of the vessel mobilization, as part of the preparatory works. The pipeline installation analysis provides the stinger radius, expected installation tension and it confirms that the pipeline can be safely installed without overstress and within allowable fatigue limits. A combination of the geometry of the pipe ramp (the stinger), the axial tension and the stinger radius ensures that the pipeline integrity in the overbend is guaranteed.

Once, the mobilization was completed, the vessel commenced its voyage to Paldiski, Estonia for the intermediate mobilization.

The mobilization in Paldiski consisted mobilization of the personnel, loading out of first 500 pipe joints, carried out tensioners and A&R winch calibration. After the successful testing of the pipeline installation equipment, the vessel sailed to start-up location near by Inkoo, Finland.

After successful dynamic position (DP) trials, the vessel positioned itself for the recovery of the pull-in wire. The pull-in wire has been pre-installed prior the vessel’s arrival. One end of the pull-in wire was connected to the pull-in winch located 1400 m away at the Inkoo landfall and second end was connected to the pull-in head.

Once the connection between pull-in heads was completed, the pipeline production commenced. On the vessel for the Balticconnector project, there are 8 working station. Each station has its own designated task – it is a good old school of Henry Ford concept. First four stations are used for welding (each station fills in specific part of the weld). Next station is utilized to confirm that the weld meets acceptance criteria. The other three stations are used for installed anticorrosion and infill coating in the weld location. Each pipe joint has an average length of 12.2 m, hence the distance between each station is the same.

Eight stations on pipelaying vessel Lorelay are ran 24/7

During the shore pull, the single pipe joint is transferred from cargo holds to the firing line by means of conveyers. Once the pipe is in the bead stall area called “ready rack” the pipe joint is checked by qualified quality inspector who confirms the sequence and number of the pipe. Then the pipe moves to the bevel area, where the bevel machine is used to prepare the ends of pipe joint for welding. Once, the beveling operation is completed, the pipe joint moves to the next location where the induction coil is used to pre-heat the pipe joint ends to approximately 100-degree Celsius prior welding.

After, the pre-heating operation the pipe joint is brought to the 1st welding station called “beadstall”. The pipe joint is welded to the pipe string, only root and hot pass are done. Once, all station has completed its task, the vessel acknowledges the pull-in operator that is ready for pull. The shore pull-in winch operator commence spooling in the pull-in wire, while tension operator on the vessel pays out on the tension machine, thus causing the pipe string to move towards shore, the length of the move corresponds to the joint length of 12.2 m. once, the joint arrives to the next station, the pull-in operation is stopped. In the station no. 2 the first filling of the weld takes place. It shall be noted that in the same time each of other 7 stations perform its task simultaneously includes heat shrink sleeve and in-fill PU installation. This operation is repeated until the pull-head reach its target box onshore, meaning that 1400 m of the pipeline has been installed. The pipeline installation process is 24 hours 7 days a week work. Thus, 221 people onboard work in 12 hours shifts every day.

Once the pull-in operation has been completed, the normal pipelay is initiated. The vessel is installing pipe joint one after the other in the same manner as during shore pull, with the difference that instead of utilizing the pull-in winch, the vessel itself moves 12.2 m ahead every time the firing line is ready for pull.

Assuring the installation of the pipeline to the designated location with ROV

During the normal lay operation, the location where the pipeline has its first contact with the seabed (the closest to the vessel) is being monitored by ROV (remotely operated vehicle) this operation is called “Touch down point monitoring”. The ROV monitoring helps to confirm the lay parameters, assures the pipeline is installed at the design location at the seabed and confirms the integrity of the pipeline. Due to the distance between the TDP and the pipelay installation vessel, the support vessel is used for deployment of the ROV.

As the production of the pipeline (pipeline installation) continues process and the pipelay vessel cargo haul is not capable of storing all pipe joints, it requires constant pipe joint supply. This is achieved by means of pipe supply vessel (PSV). On the Balticconnector project two PSVs are utilized. Each of them travels on the daily basis between the pipeline installation vessel and the storage location in Paldiski. Pipe joints are loaded on board pipelay vessel from the PSV coming alongside, using the pipe transfer crane. On board Lorelay the joints are transferred from the landing area, either directly into the firing line via the conveyor system, or to the cargo hold area for storage via an envelope hatch. After transportation to the hold, the joints are stacked.

Working as a team

Life onboard, especially on the pipeline installation vessel, might seem boring but it is the opposite. There are 220 individuals from 17 different countries, so it is very multicultural environment.  There is always a playful competition between two shifts, who can weld more pipes within 12 hours but keeping at the same time high quality and zero repair rate.

Outside of the work, there is a very comfortable recreation room with nice couches and big TV screens, where you can go and relax after 12 hours shift. The food is just outstanding, but there is a one problem with it – it is all you can eat and that includes awesome deserts… luckily there is a well-equipped GYM, so it is possible to burn some extra calories.

This all creates very nice and positive atmosphere. Of course, there are better and worst days but overall everyone finds a common understanding and works together as a team. That is the essential part of this work; everyone has a designated task and is very important link in the pipeline installation chain. Everyone is looking after each other’s back, so that at the end of the project we all come back home safe to our families.

Michal Latacz

Michal Latacz
Senior Project Engineer at the Balticconnector Offshore Pipeline Project