Steel pipe installation ND 600 with GRUNDORAM Gigant for power supply

02.11.20 - Good news in Summer 2019: The steel and technology group ThyssenKrupp is investing around 80 million Euros in the construction of a new forging centre at its ThyssenKrupp Gerlach plant in Homburg/Saar (Germany) to produce front axles for commercial vehicles in the future. Long-term supply contracts with various truck manufacturers have already been finalised. Serial deliveries of the axles is to start at the beginning of 2021.
The front axle production is a new business field for the Saarland-based group, who up to know have only forged crankshafts. Alexander Becker, head of the forging technology field, was all the more satisfied in July 2019: "Our customers have made a conscious decision in favour of the Homburg location. They have placed their orders there, in order to secure a safer supply of these special components within Europe in these times of international customs risks and ever-growing logistical costs.” The heart of the new forging centre will be a new forging press, 10 m in height and weighing 1.700 t, with an immense press capacity of 16.000 t.

Power for the forging centre

The news from Winter/Spring 2020 sounds even better: The forging press is already in production in the city of Erfurt, the preparations and planning for the construction of the forging centre are in full swing. An expanded power supply on the ThyssenKrupp Gerlach site is a pre-condition, in order for the forging centre to be able to operate at all, amongst other things for the new induction oven PL 20 for melting steel. The responsible municipal utilities Homburg, have compiled and presented their plans for the following necessary measures:
  • The extension of the transformer station in Beeden, by one switch section
  • The construction of a new cable path between the transformer station Beeden and the outlet station 1 at ThyssenKrupp Gerlach
  • The technical connection to the new outlet station 1
  • As well as operation start-up
The extension of the transformer station in Beeden by one switch section was already completed in March; the elements for the switch section are delivered with a heavy goods vehicle and installed. Next on the agenda is the construction of the 750 m length cable path between the transformer station Beeden and Station 1 of ThyssenKrupp Gerlach.

Sporting Requirements

In the first construction section of this path over a 350 m length, the product pipes for control cables, light conductor cables and medium voltage cables were to be installed at a depth of 1,20 m. Then it starts to get exciting: The cable route must cross a railway line in operation as well as being sandwiched between footpaths and road sections, in front and behind it, at a traffic crossing, before heading straight on to the outlet station 1 on the factory premises.
The external frame conditions for this crossing are sportsmanlike: The total bore path (road/footpaths – railway line – footpaths/road) covers 12 m, the existing supply and disposal pipes cross respectively, restricting the working area and the western roadside borders on a steep embankment. Last not least, both the railway line and the road junction here in Homburg’s industrial area are highly frequented.

Tight conditions, clear decisions

The managers responsible at the municipal utilities decided, with these frame conditions in mind as well as the time aspect and economic advantages, to apply the underground, dynamic installation method for this crossing, the steel pipe ramming method to be precise. From an economic point of view alone, a crossing with the open trench method would be highly inefficient and in any case: The Deutsche Bahn did not allow the open trench method.
The company Diesler Tief- und Strassenbau GmbH, Homburg were commissioned for the steel pipe installation, who received advice and support from TRACTO-TECHNIK’s Michael Gastreich for this task. He planned to apply a GRUNDORAM Type Gigant for this pipe ramming task, as high dimensional precision and target accuracy, as well as total reliability were required. This pipe rammer, which develops an impact energy of up to 2.860 Nm, can ram in steel pipes as protection and/or medium pipes of 200 mm up to 2.000 mm diameter in soil classifications 1 to 5, without the need of time-consuming abutments underneath roads, railway tracks, buildings etc.

Pits, Pipes, Cutting Shoes

With the agile excavators and a bit of shovelling, the team had quickly excavated the starting and target pits with depths of 2,30 m in the loose, but self-supporting mottled sandstone layers. There was definitely no possibility to install an abutment for press driving, as the starting pit was in a tight space between an existing sewage pipe and the specified distance to the railway tracks.
Both steel pipes, each with a length of 6 m, ND 600 diameter and wall thickness of 12,5 mm, were ready and waiting on the day of the undercrossing, directly next to the starting pit; they were later to be used as protection pipes to retain three 20-kV-lines. In order to reduce mantle friction during the pushing process, a cutting shoe was welded on site to the inside and outside: the inner shoe directly at the front of the pipe and the outer shoe approx. 1,5 m further back, in order to additionally allow a decent guidance for the pipe in the soil.

On your mark, get set, ram

Suspended from the crane, the first 6 m steel pipe was then lowered into the starting pit, brought into position and the cotter segments were inserted in only a few simple steps. Michael Gastreich, who carried out the preparation work with great composure and routine explained, “They prevent the pipes from flaring and benefit an optimal induction of the impact energy.” Then he went one step further and added a soil removal adapter, which allows soil to partially exit from the pipe during the ramming process.
Now everything was in place, the heavy-duty, but only 2 m length pipe rammer was lowered into the starting pit to be assembled. After the frictional connection to the steel pipe and connection to the air compressor, precisely 20 cm space remained to the aforementioned sewer pipe. Now that is precision work! Pipe pushing could now begin: ‘Switch on’ compressed air, no additional steering necessary and off we go. In the loose sandy soil the GRUNDORAM Gigant rammed the 6 m length steel pipe ND 600 at a depth of 2,30 m precisely beneath the first half of the total bore path in merely 18 minutes. As the structure of the surrounding soil was not destroyed during the ramming process, this also guaranteed that the pipe was embedded solidly in the ground.
The rammer, together with the cotter segments and soil removal adapter were disconnected quickly and uncomplicated, the second steel pipe then lowered into the starting pit and welded to the first pipe. Then the rammer was assembled and started once again. After 45 minutes the pipe, now with a total length of 12 m, reached the target pit, beyond the road and railway tracks – the underground installation was successfully completed without any problems or obstacles. To complete the task, the soil, which had entered the pipe during the pipe ramming process and had not completely escaped, was finally removed with a suction excavator.

80 Million well invested

So far, everything had gone to plan for the public utility company, municipal utilities Homburg. This should also be the case for the remaining construction section with a total cable path of 750 m up to ThyssenKrupp Gerlach’s new outlet station 1, including the technical connection and implementation. The completion of the forging line and start of serial deliveries are on the agenda for early 2021. Even for ThyssenKrupp Gerlach everything will seemingly go to plan. “The main press for the forging line is the first eccentric press, worldwide, of this size, power and implementation speed to be activated”, according to Dr. Franz Eckl, Managing Director of the forging company in Homburg. “With this power unit we will be able to produce around 360.000 forging components annually.”
The crossing of the cable path of the railway line and road with the dynamic pipe ramming method has contributed to the planned success of this ambitious project, in terms of high cost and time savings. Now that is good news!



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