Mobile electron beam welding provides the solution for fabricating large structures

In conjunction with the ManOS (Cost-Effective Manufacture of Offshore Wind Turbine Foundations) project, and specifically to showcase its reduced pressure EB gun and the capabilities of mobile local vacuum sliding seal technology, TWI hosted a recent seminar and technical demonstration at its Low Carbon Energy Manufacturing Technology Centre in Middlesbrough, UK. The event on 19 April 2012 was attended by partners of the ManOS project (see below) and delegates from UK industry and academia with interests in large-scale steel fabrication and offshore wind power engineering.

Chris Punshon, Consultant, Electron Beam Processes at TWI began by presenting the progress made by the ManOS project, which aims to enable faster, efficient and cheaper production of offshore marine foundations. The project, funded by the UK TSB, has successfully developed and demonstrated EB wedding in thick section steels with offshore application relevance and validated the resulting metallurgical and mechanical properties. The ManOS partnership comprises TWI, Nippon Steel Corporation and Aquasium Technology Ltd, with KBR acting in a consultative role.

Chris introduced the focus of the event – the demonstration of a full penetration, 60mm wall thickness, 1300mm longitudinal seam weld in a 2350mm diameter S355 steel tubular (representative of an offshore wind turbine tower foundation structure), which took less than 6 minutes to complete.

Prof. T Ishikawa, Nippon Steel Corporation, Japan, concluded by presenting delegates with details of a proprietary grade of S355 steel, which has recently been granted Germanischer Lloyd’s approval for EB welding due to its excellent as-welded and post-weld heat treated properties, including exemplary sub-zero impact toughness.

All attendees noted that they were impressed by the demonstration, the technology supporting the EB welding capability, and the opportunities that this mobile variant brings for application of EB welding to large structures where conventional EB has been prohibited due to the need to operate within a vacuum chamber.