Concrete Weight Coating in Kotka

Wasco Coatings Europe is tasked with concrete weight coating and storing about 200,000 pipes for the Nord Stream 2 Pipeline. Over 108,000 of them will be coated at its logistics hub in the port of HaminaKotka, Finland. Visit the picture gallery for a detailed look at the entire production chain, from delivery to storage. In the video, you'll also get an insight into the economic benefits of the project for Kotka and the surrounding region.

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When pipes from the Russian pipe mills are delivered to Kotka by rail, Wasco employees unload the trains and bring the incoming pipes to the inspection area. Once the quality team ascertains that the pipes have arrived in good condition and meet the requirements, the logistics team can transport them to the storage area.

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Shane Prudhomme, VP Global Pipe Coating at Wasco, is the Operations Manager and top Wasco representative for the Nord Stream 2 project. “It’s the biggest thing going on in the world of pipelines right now – it’s a very large project,” he says. “There are technical execution challenges, schedule pressure, and of course it’s high-visibility.”

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Pipes are brought to the inbound station at the coating plant aboard MAFI trailers that Wasco uses for onsite transport. The coating plant was built during the first Nord Stream project, and Wasco has made up-graded it to meet the Nord Stream 2 requirements. “One of the things we did is replace the lighting from incandescent to LED, because it’s brighter and allows us to see better. This leads to an overall improvement of our quality,” says Shane Prudhomme.

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A worker operates an overhead crane to unload the pipes and feed them into the production line one by one.

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The pipes are very dusty when they arrive, so the first step is to prewash them inside and out with water. In winter, this unit also removes any snow from their surface.

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After this initial rinse, the employee who operates the washing station moves the pipes on to the main washing unit, which is a closed installation, to be high-pressure washed and then blow-dried.

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Each pipe is then weighed and measured precisely using laser technology. This data is recorded in the plant’s pipe tracking system (PTS) along with the pipe’s unique identification number. The PTS transmits that information to the next stations, where the workers need it to configure the different machines involved in the production process.

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Two welding machines produce cages for the pipes from steel wire sourced in Spain. These cages reinforce the concrete coating and ensure that it adheres properly to the pipe.

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Each wire cage is made to measure for a specific pipe based on the data transmitted by the PTS. The plant in Kotka coats pipes of two different wall thicknesses – 30.9 and 34.6 millimetres. The wall thickness of a Nord Stream 2 pipe varies according to which part of the pipeline it will be used for: The deeper underwater it will rest, the thicker its walls are to withstand the pressure associated with that.

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The workers at this station must wear facial shields for protection from things like sparks flying and loose wire ends. Wasco always puts its employees’ safety first: “Every morning, all the workers are brought together for a safety discussion – every single day, before each shift,” says Shane Prudhomme. “If it’s not safe we will shut down to make adjustments, and do whatever we need to do, because that’s our number one priority.”

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The Nord Stream 2 pipes are treated as unique entities, so the cages are customised accordingly: They get their own barcode and identification number to match the pipe they are made for.

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Workers cut the wire by hand to separate off a finished cage: They have to be very careful, because there is tension in the wire and it could whip back at them. “We rely heavily on behavioural-based safety, because it’s the most effective,” says Shane Prudhomme. “It’s about people understanding the risk of a certain activity.”

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Before a pipe is inserted into its cage, the cage is fitted with so-called “D-pegs”. These ensure that it will be maintained at a constant distance from the pipe, and that the pipe will fit snugly inside it.

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A pipe is inserted into its custom-made cage. Before each insertion, the workers check that the identification numbers of cage and pipe match up.

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To ensure that the pipe is well-aligned and that the wire cage is properly tensioned around it, it is also fitted with additional “A-pegs”. The workers have to install all of the pegs by hand.

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Inspectors check that the cages are correctly positioned around the pipes before they are moved to the coating station with an overhead crane. “It’s standard in the industry for pipes to roll when they come off of something, but at our facilities they’re moved on a conveyor or with a crane – at no point is there free movement,” says Shane Prudhomme. “This is one of the major things we do to improve safety.”

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A stockpile of pipes that are ready to be coated is kept near the concrete coating unit at all times to serve as a buffer in the production line. End caps keep the dust out while the pipes are stored here. If pipe deliveries to the plant run low or if a production problem occurs upstream, this stockpile is used to keep the coating process going and maintain the plant’s output rate.

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The concrete weight coating is applied at a speed of approximately 190 kilometres per hour inside a closed installation. The raw materials for it – cement, magnetite, agglomerate, sand, iron ore and water – are delivered separately and mixed directly at the plant’s coating unit.

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The function of the concrete weight coating, as its name suggests, is to weigh the pipes down so that the pipeline will be stable on the seabed. The pipes spend approximately three minutes inside this unit: Once coated, each pipe’s weight is doubled to 24 tonnes on average. Wasco’s goal is to reach an output of 250 pipes per day at the plant in Kotka.

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The ends of the coated pipes need to be cleaned to remove any concrete residue. They also undergo another inspection at this stage: “A specific amount of concrete has to go on the pipes, and the coating has to be uniform and smooth,” Shane Prudhomme explains.

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The Nord Stream 2 pipes have different wall thicknesses, so the thickness of their concrete coating also varies – between 60 and 110 millimetres. The coated pipes then enter the so-called “curing chamber”, where they will be steam cured for 14 hours. This process helps the coating to dry and harden properly, so that the pipes can later be handled without damaging it.

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When they leave the steam cure, the pipes are inspected once more to ensure that their concrete coating meets Nord Stream 2’s quality specifications with regard to hardness, density and outside diameter. They are then fitted with protective end caps, which will stay on throughout their time in storage. Just like the wire cages for the coating, each end cap has a unique identification number to match its pipe.

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Before they can exit the plant, the pipes have to pass through two final stations: the brushing unit (left), which removes any loose particles from their surface, and the paint unit (right), which applies paint stripes in a colour code that provides a visual indication of the pipe’s specific characteristics.

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A coated pipe is lifted onto a MAFI trailer with an overhead crane to be transported to the storage area.

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Coated pipes are transported out of the plant and driven to the storage area in pairs. Each joint has a designated storage place: Signalmen tell the drivers exactly where the pipes need to go based on the information provided to them by the pipe tracking team.

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Anita Aranyász is one of 18 Wasco employees on the pipe tracking team in Kotka. “Tracking is one of the most important tasks, because if there’s a problem with a pipe then we need to know immediately where it is. Each pipe is treated as an individual: It has a designated place where it should go,” she explains. “We need not just to keep an overview of the situation, but also to be able to provide others with relevant information on specific pipes.”

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Wasco’s logistics team uses reach stackers to handle pipes on the storage yard and place them in their specific storage spot. These machines can carry two bare pipes at once when they are delivered to Kotka – but after the pipes have been concrete weight coated and their weight has doubled, they must be handled one by one.

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Alexander Suarez, who already participated in the first Nord Stream project, now works on Wasco’s logistics team in Kotka: “We always have to be careful when working with the pipes, to avoid damaging them,” he says. “Sometimes we work in the dark, or in the snow: We just have to follow the precise instructions on how to stack them on the storage yard.”

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“There are very specific measurements to be respected,” says Alexander Suarez, who has been training to operate the reach stackers. “When you start a new stack, you have to make sure it’s perfectly straight, because the first pipes are going to support the entire pile and define its orientation. New stacks are always measured according to the previous ones next to them.”

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About 51,000 concrete coated pipes will remain here in Kotka to feed the pipe-lay vessels once construction starts on the northernmost section of the Nord Stream 2 Pipeline. The rest will be transhipped to the port of Koverhar in Hanko, Finland to be stored there.

Concrete