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Products and solutions, 2011-02-15, 02:26 PM

New refrigeration equipment for Königssee bobsleigh and luge track

It was an unusual job. A roughly 40-strong team from ThyssenKrupp Xervon has supplied the legendary Königssee bobsleigh and luge track with new refrigeration equipment. During the last seven months, a total of 32 kilometers of pipes and 560 fittings have been installed in the partially rebuilt and partially modified track. There was deadline pressure throughout because the upgraded track had to be ready in time for the competitions now getting underway.

Familiar to winter sports fans, Königssee artificial ice track in the Berchtesgadener Land in Bavaria has been the venue for many luge, bobsleigh and skeleton competitions since 1960. It is the world's oldest artificially refrigerated track and, with its 18 bends, is still considered by experts to be one of the technically most demanding bobsleigh and luge tracks on the World Cup circuit. So that its status will remain unchanged, the 1640 meter track is being comprehensively modernized, rebuilt and brought into line with the current rules of bobsleigh and luge competition at a total cost of €22 million. In the first part of the project, which was completed on time for the approaching winter season, the finish house and the entire lower section of the track beyond the finishing bend through to the run-out were completely rebuilt. Other parts were modified.

The ThyssenKrupp team comprising project manager, site manager, designer, 17 fitters, 12 welders, 2 senior fitters and 2 machine operators can look on months of hard work. From the end of April until the beginning of December, they gave up their usual workplaces in industrial installations and refineries in favor of the unique scenery of the Watzmann mountain and Königssee lake. However, the tight schedule left little time for marveling at the view. Accompanied by 5 personnel containers, 2 containers for tools and 2 for materials, 15 welding machines and lifting gear, the experienced specialists had come to install the refrigeration equipment in the sections of track under construction and modernize the long-distance pipework from bends 6 to 18.

The refrigerant that chills the artificial ice track is integrated in the on average 15-30 cm thick concrete channel. It runs in separate refrigeration sections known as collectors. Each collector consists of individually shaped pipes. The liquid refrigerant flows through them and, via further piping, is fed outward into various collectors before returning to the refrigerant circuit.

Made to measure

The custom-building of the various refrigeration units and their integration in the refrigeration circuit was ThyssenKrupp Xervon's main task. This comprised all of the pipework including cutting-to-size, laying and welding.
The job also included the supply and installation of weld-in fittings, the integration of new control elements (temperature measurement points, solenoid valves) in the existing automation system as well as various coating and insulation tasks plus the entire project management for all this work inclusive of documentation and materials management. A total of 32,000 meters of stainless steel pipes with diameters of DN 20 to DN 300 were installed. Inclusive of fittings, this amounts to about 140 metric tons of materials that, assembled into ready-to-install units, had to be transported to the track, lifted into the formwork and fitted. This was accompanied by the installation of about 560 fittings, 12 tons of pipe fasteners and about 120 individual items of electrical, control and instrumentation equipment.

A challenging task for Xervon project manager Robert Liepold, site manager Mario Lemke and the team on site. It was not only a question of monitoring and organizing their own craftsmen, but also of constantly coordinating them with the track engineering and concreting specialists. As soon as the design of a track section had been finalized, the Xervon designers got down to producing their working plans (isometric drawings) for the piping and ordering the required materials and ready-to-install fittings. Before laying could get underway, the foundations of the track section in question had to be laid, the external formwork for the concrete channel erected and the reinforcing steel mesh fitted, to which the piping was attached with special fasteners and then welded together. To then give the concrete track its final shape, the concreters applied shotcrete and smoothed it by hand.

A task that called for plenty of spatial imagination and craftsmanship. Just consider a single track bend: Its three-dimensional shape – curvature, gradient and height – are determined solely by the spatial extension of the concrete channel. And the piping laid within the channel has to follow precisely this shape, i.e. it has to be laid and welded in arcs of different radiuses and lengths. The execution tolerances here are extremely narrow and are in the millimeter range.

Absolute precision and totally leakproof – this is the standard of quality demanded of the pipe-laying work. As a check, ThyssenKrupp Xervon had the individual sections examined for cracks by dye penetration inspection. About 10 percent of the welds were also X-ray tested. After installation and welding of the sections to create complete collectors, the latter were also filled with nitrogen. The latter was left at reduced pressure in the piping until the completion of work to make any damage immediately visible to the downstream trades.

Disruptions

However, the real challenge of this sophisticated installation work lay not in its correct and expert execution, but in its dependence on external factors. The best example was the unusually inclement weather conditions. Frequent rain and extremely early snowfalls had a profound impact on work procedures. The same can be said of the extremely elaborate and time-consuming design of the complex track geometry. Rebuilding and modernization were divided up into several subsections of between 7.5 and 72 meters. “But even within these subsections, we were rarely able to work continuously” explains Mario Lemke, highlighting the special difficulties. Rapid adjustment of the execution plans, immediate manpower supplementation and procurements of materials at short notice were therefore part of the daily routine for the Xervon team.

"The flexibility and willingness of all our employees to leap into action wherever needed and to enthusiastically finish any extra work that arose at short notice enabled us to complete the work on schedule," says Robert Liepold in praise of his men. Their many years of experience of assignments in industry where any deadline overshoot can be very costly came in very handy on the site in Bavaria. “We always set ourselves the goal of keeping well within the demanded deadline. This creates leeway and also helps the other trades involved,” says Liepold. At the end of the day, you can only win this kind of game, like in sport, as a team. This year, they return to the starting blocks. And then, in a second project phase, they will be modifying the two entry areas for the skeleton and bobsleigh participants, among other things.

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