Cost-Efficient Mass Production of Offshore-Wind-Jackets Accomplished by New IndustrialSolutions

Stephan Brauser, Georg Michels
Salzgitter Mannesmann Renewables, Duisburg, Germany


Salzgitter Mannesmann Renewables and St3 Offshore have together created a strategy to address a step change in foundation cost reduction through the use of a sustainable industrial supply chain for Jacket foundation manufacturing. This cost reduction has been achieve through the development of an innovative, production focused, standardized Jacket design that combines the utilization of Salzgitterīs unique standard tube portfolio and the implementation of automatically welded, prefabricated components, during serial production at the cutting edge manufacturing plant of Bilfinger Mars Offshore. This manufacturing strategy is forecast to deliver a cost reduction in the Jacket structure of more than 30%.


AG and Bilfinger Mars Offshore (BMO) have jointly leveraged their strengths and created an approach to reduce production cost for Jackets that includes the utilization of standardized tubes and the serial production of Jackets based upon automated prefabrication of components. Standardized tubes made in a serial production line offers cost benefits or around 30% compared to current tailor-made pipes made by a JCO procedure. In addition, higher dimensional accuracy leads to reductions in fitting and welding costs as well as reduced failure rates during production. Additional benefits of using pre-fabricated of components, in particular X- and K-nodes, produced by robotized welding technology and serial assembly leads to a significant reduction in overall Jacket production time and cost. 


Various full-scale automatic welding trials of K- and X-nodes has proven these cost reductions are possible. In order to investigate the cost competitiveness of the overall approach, an extensive study has been carried out against point to point fabricated Jackets. The outcome of this study shows a significant cost reduction of more than 30% in the main jacket structure. However, to fully realize the major cost savings of a serial produced jacket foundation, the Jacket design needs to fit within the limits of automatic manufacturing and utilize standardized tubes to guarantee the lowest cost solution.


 Salzgitter and St3 have proven that by utilizing new production technologies manufacturing cost can be reduced by 30%. Main driver for cost decline are: utilizing of automatic welding strategies, such as robotized welding of nodes and orbital welding. In addition a consequent focusing on the implementation of mass produced tubes has significantly contributed to the overall cost reduction.


Significant cost reduction of Jackets is achievable by automation of manufacturing technologies and utilization of mass produced tubes.