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All Sersa Technik AG welding masters in Switzerland are SoW-5 L75 and SkV-Elite L25 certified.

The specialist training course followed the approval of aluminothermic welding with a wide welding gap (goldschmidt elektro-thermit SoW-5 L75) for the entire network of the Swiss Federal Railways (SBB) by the federal office of transport (BAV).


The method is reliable, robust and ideally suited for joining vignole rails in all types of operating tracks, at all speeds, with heavy-load traffic and, due to the short execution time, with high traffic density. The use of wide-gap aluminothermic welding not only optimises the construction process in the long term, but also offers customers other significant advantages:


  • Replacement of defective aluminothermic welds with standard gap and flash-butt welds (without UT defects).
  • Use when changing switch components (no need to weld over an existing weld or change the connecting rail).
  • Use for untight welds.
  • Using the new weld with a wide welding gap means that the following criteria must be met:
    Rail profile EN 46E1, 54E2 and 60E1/E2 (no welds with profile change).
  • Rail steel grade R260, R350HT and R350LHT (R370CrHT only for Sow-5 L75).
  • Distance to nearest AT welding 4 metres.
  • Distance to nearest EA welding 1.5 metres.
  • Distance to insulation joint at least 4 metres.
  • When replacing welds, it must be possible to completely remove the old weld bead for the welding gap.
  • Distance of rail feet (inside-inside) in switches at least 120 mm.


The new aluminothermic welding process with wide welding gap (SoW-5 L75) impresses customers and specialists alike.


The Swiss market (Rhomberg Bahntechnik) succes-
sfully used the SkV-Elite L25 welding process in the Hardhof project of the Zurich City Transport Authority to the satisfaction of all parties involved.


As part of the SoW-5 re-examinations, further employees of the welding division of Goldschmidt Elek-
tro-Thermit are trained in both welding procedures (SoW-5 L75 and SkV-Elite L25).

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