Manufacturing of Large Steel Components for Nord Stream Project

Nord Stream is the gas supply route from Russia through the Baltic Sea to Europe and represents one of the new pipeline projects for guaranteeing Western European gas supply in the future. The project is the longest 48" offshore pipeline to date. The combination of large diameter and high design pressure meant that the materials for all components had to be carefully defined and specified. A considerable effort was made in the project to pre-qualify suppliers and to supervise the manufacturing phase to ensure that the high quality requirements were achieved. This paper describes some technical considerations made when selecting the suppliers of line pipe, valves and bends, and provides further details of bend manufacturing. The Nord Stream Project requires several induction bends in the material grade L 485 and L 450 with high material strength, good ductility at low temperatures and with a high wall thickness due to the high design pressure. All bends are specified as fully quenched and tempered with tight geometric tolerances. Only a few companies were pre-qualified to supply large diameter bends according to the Nord Stream specification. Salzgitter Mannesmann Grobblech in Mülheim won the contract and supplied 38 bends with diameters from 28" to 48" to the Nord Stream Project. The production results showed that all requirements with regard to the mechanical properties and the dimensional tolerances were successfully met.