TPi October 2011

“Our O-press acts on the 12m-long sheets with a force of up to 60,000 tonnes – comparable with the weight of 1,500 loaded lorries.” The O-press is fitted with six press dies, each comprising an upper and lower section. The press dies for the Nord Stream order have been supplied by Schmolz + Bickenbach Guss Group. Particularly at the start of the process of reshaping from U to slotted pipe, the press dies are subjected to high mechanical loads, as the edges of the sheet formed into a U are relatively sharp. “For us, the challenge is to provide Europipe with dies for this stage of production in a material that combines high-level durability and surface hardness with a huge wear resistance,” commented Götz Axel Weckes, who is the responsible sales manager at Schmolz + Bickenbach Guss Group. Spheroidal cast iron press dies manufactured using the sand casting process have proved successful. The use of this material represents an exception for the Guss Group, which has specialised in special steel casting since the 1980s. As such, only large, demanding parts are still produced in spheroidal cast iron. In the course of over 30 years of cooperation, Europipe and the Guss Group have pushed for a continuous development process – in accordance with the increasing requirements – on the basis of partnership. The form of the press dies has thus constantly been further adapted and its geometry therefore optimised. “We need a partner whom we trust absolutely and who stands reliably at our side even in the case of the most demanding tasks – such as the Nord Stream pipeline,” emphasised Mr Jacobs. On this project particularly, the quality requirements are especially high – the maximum permitted deviation from the precisely round shape is 5mm. These strict requirements

The O-press acts on the 12m-long sheets for Nord Stream with a force of up to 60,000 tonnes

are checked throughout the entire production process by specialists from Europipe and Nord Stream as well as independent experts. This is equally applicable for the Guss Group: as such, the upper and lower sections of up to 13 tonnes and 3m in length undergo an intensive check in the plant after pre-working and annealing. Here, a buyer from Europipe examines the components thoroughly for cracks or other faults. If the specified hardness grade is then also met, the castings are released for final, mechanical processing. The mechanical pre-working and finishing take around nine weeks per pair, which is a good half of the entire production time. The upper and lower sections of the die are finished in assembled condition. The Guss Group has developed its own tool for this processing stage. Using a type of propeller equipped with cutting edges, the machining specialist accurately processes the internal edges and the later working surface of the press die. Despite the huge dimensions, this guarantees a high level of precision – the authorised tolerance is within fifteenths over a length of 3m. In case of greater deviations, there is a risk that the pipe will be formed unevenly. The casting specialist produces press dies for pipes in the broadest range of sizes for Europipe. For the Nord Stream project, the company supplies press dies for the production of 48" pipes. Mr Jacobs summarised: “With Schmolz + Bickenbach Guss, the complete package fits perfectly for us – smooth and personal communication combined with high-level technical competence, with a large capacity and not least with local proximity that is beneficial to us.”

The Nord Stream pipeline comprises two pipelines, each of which is 1,220km long. When completed, it will feed over 55bn m 3 of natural gas into the European gas grid each year

Schmolz + Bickenbach Guss GmbH – Germany www.schmolz-bickenbach.com

Europipe GmbH – Germany europipe@europipe.com www.europipe.com

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Tube Products International October 2011

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