Casting of liquid steel
New construction of a continuous casting plant for Stahlwerk Bous GmbH
Already back in 1889, seamless tubes were rolled in Bous using Mannesmann’s pilger rolling process. The Bous factory – the former Mannesmannröhren-Walzwerk AG – can claim that it was the first place where seamless steel tubes were serially produced. In order to be able to improve the supply of high-quality base material for the manufacture of tubes, an electrically operated steel mill was started up in 1961. This factory became an independent subsidiary and was acquired by Georgsmarienhütte Holding GmbH in 1998.
The logo of Georgsmarienhütte GmbH on the new continuous casting plant at Bous in the Saarland remained visible from afar. The project comprised buildings for the continuous casting plant, the associated waterworks, the technical and energy services and the segment and dolomite workshop. With the help of the extension to the production facility it was possible to enhance and supplement the existing structure of the works.
The site layout plan of the buildings for the facility was developed by GMH Engineering GmbH, Georgsmarienhütte, and successfully implemented in cooperation with pbr as designers and engineers for Stahlwerke Bous GmbH.
From the design to the construction
Commissioned as overall designers and engineers, pbr AG provided services in all service phases in architecture, structural design, services installations as well as engineering and traffic structures. The project involved the movement of about 30,000 m³ of soil and needed 23,000 m³ of concrete with 1,500 tonnes of reinforcement steel cast into the formwork for the highly sensitive foundations with extreme and dynamic load exposure. A total of 2,500 tonnes of profile steel was used for the loadbearing structure. In some cases foundation elements reached to a depth of 9 m. Owing to the proximity of the River Saar, these had to be secured against buoyancy using ground anchors. Some of the buildings are over 40 m high from ground level to the eaves. In spite of these challenges, the project was completed on time for the commissioning of the production plant.
The speed with which the design and implementation of industrial buildings is achieved is an important factor for success. This is because industrial construction projects need to be completed in short periods of time. Any delays in the construction progress cause expenses for the client, which means that reliable completion deadlines are of paramount importance. The design of buildings for industry and commerce presents a significant challenge to architects and engineers. Coordination of the contractors involved has to be strategically thought through, and interfaces have to be optimised. In addition, industrial buildings are subject to extreme loads – e.g. due to heavy production plant, high temperatures or chemical influences. Often it is necessary to consult specialists in order to be able to find solutions for specific situations.
The period of time available for the construction of the extension of the Bous steel mill was also extremely short – from December 2007 to May 2009. The raw material for the continuous casting plant has to be conveyed from the existing steel production process using ladle transport, including newly procured special transport vehicles. For the purpose of the extension of the existing production plant it was necessary to analyse the existing factory structure and plan an efficient solution for the new building in order to ensure a smooth production process and hence minimise operating costs. Within the building, the ladles carrying the liquid steel are moved using an overhead crane with a capacity of 110 tonnes and the ladle turret. Then the material is processed in the newly set-up continuous casting plant using lines 1 or 2.
While still liquid, the steel runs through the manufacturing process, through roller segments, and is shaped and then tempered to processing temperature in a cooling chamber. It is then conducted to the horizontal via a bend and cut to the specified lengths at the flame cutting machine. At the end of the system the material is handed over either for further processing in a downstream, connected walking beam furnace and a downstream rolling line, or for dispatch and sale.
In view of the fact that the various different kinds of construction activities necessary for the operation of the plant had to be carried out at the same time, about 400 construction workers, mechanical engineers, electricians and services installers for media such as gas, water and power, worked on the site.
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