The construction of the OPAL is one of Germany’s largest pipeline projects. Even before construction work begins there is a great deal to be done along the 470-kilometer-long track. It’s a truly Herculean task – for man and machine.
It’s a sound that probably sends shivers up your spine: the sound of aluminum scraping against steel. Then a worker crawls out the other end of the pipe. He has just pushed the “caliber disc” along the mighty pipeline section on foot. “If the permitted ovality of two percent was exceeded anywhere in the pipe, the disc would get stuck”, bending engineer Alexander Laue explains. The sturdy Thuringian reminds you somewhat of the iron bar benders you used to see deforming metal at annual fairs with apparently very little effort. A hundred years later, Laue doesn’t have to work with his bare hands. A special machine helps him to bend the 15-ton pipes into exactly the right angle.
In a field near Lichtenberg in the Erz Mountains, preparations are underway for the planned OPAL (Ostsee-Pipeline-Anbindungs-Leitung – Baltic Sea Pipeline Link). It will transport the natural gas flowing through the Nord Stream offshore pipeline to the European mainland through Germany to the south from 2011. It will start in Lubmin on the Baltic Sea coast and run to Olbernhau on the German-Czech border. The pipeline will lie one meter underground, and even deeper in some places. But there’s a lot to be done before the pipeline trenches can be excavated and the pipeline laid.
The pre-construction work required clearly illustrates the dimensions of the project. Posts sticking out of the ground at regular intervals mark the pipeline axis. Signposts with coordinates indicate where power cables and other cables not linked to the pipeline are located underground. “This way the digger operators know which areas are taboo,” site manager Marcel Bewernick explains. Stripped top soil lines the working strip. The pipes have been delivered too – some are piled up like pyramids, some are stringed along the track from the stockpile sites.
Each pipe has a number so that the workers know exactly where it belongs. The pipes only look identical when they are delivered. Before they are laid in the ground some of them have to be bent slightly. The section, degree and angle are calculated by the bending engineer using the terrain profile of the pipeline track. The Erz Mountains represent the highest section of the pipeline track and one of the most difficult areas. “We are expecting to have to bend 40 percent of the pipelines here because of the difficult terrain,” Bewernick says.
The OPAL poses a particular challenge for man and machine. While other trunk pipelines in Germany so far had a maximum diameter of 1.2 meters, the OPAL has a diameter of 1.40 meters. The machines and equipment used for the OPAL are the largest ones available in pipeline construction – and an unusually high number are being used.
Specialist firms are contracted to carry out the pre-construction work for the OPAL. At Lichtenberg, for example, two contractors are working together: the Bavarian company Max Streicher, where the bending engineer Alexander Laue is employed, and the Italian company Sicim. The latter not only had to bring specialist staff from Italy but also heavy machinery. And that means: the colossal machines had to cross the Alps, like General Hannibal’s elephants once upon a time.
The work on the track is comparatively uncomplicated. German and Italians work and live here side by side. A functional partnership. Once the working day is over they all meet in a caravan park at the gates of Lichtenberg. They cook, barbecue, and chat together. “Many of our Italian colleagues speak German. If that doesn’t work we try in English. Or with our hands and feet,” says Alexander Laue. A few Italian men nod their heads. “Si. Ja”, they say collectively. Just at that moment the tracked vehicle starts squeaking along with the next pipe hanging from the crane. Laue climbs up to the operator’s cabin of the bending machine.
With hand signals he gives instructions to the crane driver and two workers until the pipe is hanging right in front of the opening of the bending machine. Laue pulls a lever. The mandrel, a hydraulic clamping device, enters the pipe and adapts to the inside diameter by expanding. Another pull of the lever and the pressure of the machine begins bending the two-cm-thick steel sheet. The maximum bending angle is 14 degrees, and 28 bending steps are necessary for this. That shows you how gently the force is applied to the material.
Delicacy is also one of the key objectives of the project when it comes to nature and landscape. “Nature conservation has been an important factor in the planning for the OPAL from the very beginning,” project manager Hans-Georg Egelkamp underlines. “A pipeline doesn’t always take the shortest route from start to finish. Instead, the route is decided in an intensive dialog with the competent authorities, land owners, municipalities and environmental associations.” That is probably why the pipeline has largely met with approval in the states it will cross through – Mecklenburg-Western Pomerania, Brandenburg, and Saxony. In Saxony, for example, in a recent survey by Emnid, 72 percent of those asked were in favor of the pipeline being built.
Four site managers supervise the work in Saxony, and an expert from BASF looks after the welding side. There is also an appraiser from the Hessen TÜV (Germany’s Technical Inspection Agency) constantly on site. Engineering offices provide expert advice in matters of archaeology, ecology and geology.
Once the pipeline has been laid, the trenches are refilled with the soil and then the original top soil is returned to the surface. A few months later there will be little left to see of the pipeline. But there’s still a lot to do before then. Site manager Bewernick gets in his jeep. After a few kilometers on dirt tracks the vehicle leaves the track and fights its way up a steep slope using its 4-wheel drive. The tires stumble over the uneven surface, while the shock absorbers groan.
When the heavy construction machines appear in the distance, Bewernick knows he has reached his goal. “This is where the beveling takes place,” he explains and points to a formation of steel and tubes hanging on a crane. It is the beveling machine. It is applied to one end of the pipe by a worker. The machine starts running. “It works like a lathe – only the other way round,” the site manager says. “Here the tool turns round the piece it is working on.” Already the first spiral-shaped steel shavings fall onto the plastic sheets. They have turned a blueish color with the heat of the turning process. When the machine is removed again, the pipe has a tulip-shaped profile, a “beveled end”. It is necessary for the welding process machines used here: a straight pipe edge could not be welded by an automatic welding machine.
On the way to the next section of the track Bewernick explains why a pipeline is a “linear construction”: the individual stages have to be completed in a certain sequence and there is a convoy named after each stage. The first larger convoy is the topsoil convoy followed by the pipe delivery convoy and the bending convoy. After the “trench opening” convoy, the lowering convoy and the filling convoy, comes the recultivation convoy. It’s like a race track, Bewernick says. “If one team is working too slowly, the one behind will catch up.”
In order to avoid rear-end collisions like this, the convoys have to keep a certain distance from each other. The jeep requires a good 15 minutes to get from the beveling convoy to the welding convoy, for example. Both the beveling and the welding are carried out on the pipeline track. The truck stops beside a pipe string, above which five tents, i.e., the welding cabins, have been built. Beneath them the ends of the pipes lie opposite each other ready to be welded together. They have been pre-warmed by induction coils. Once more the welder aims the infrared thermometer at the pipe to check the temperature. 132 degrees Celsius. The man pulls his mask over his face and shuts the cabin door behind him. A few minutes later all you can see from the outside is a flickering blue light. “Without the cabin the wind would blow away the inert gas. The gas stabilizes the arc during the welding and protects against ambient influences,” welding inspector Werner Bigott explains. This is how the workers guarantee that no mistakes are made during welding. The welding continues until the pipe leg is 2000 meters long. When transport paths are crossed the sections are shorter. Later the entire pipeline is lowered into the trench using crawlers with special cranes called sidebooms.
Evening has come. The workers make their way to the camp. Marcel Bewernick drives to the construction office in Lichtenberg. “It’s not quite quitting time for me yet,” he says. Before sitting down at his desk he goes to the wall where there is an endless chain of DIN-A0 sheets of paper. He writes something on them with a pencil. “That is the progress plan. And that here,” he says pointing at the plan, “that’s what we achieved today.”
Text: Gabriele Sümer
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