It is common knowledge that steel expands at high temperatures and shrinks at low temperatures. The result during temperature changes is that rails either expand or shrink. Rails are not the only objects susceptible to ‘expansion’; (steel) bridges, for example, can extend or reduce in size as well. The forces ensuing from this process also have quite an impact on the rails. Usually, sleepers in combination with ballast are able to absorb these forces. However, in some cases, they are so strong that the rails are pushed outwards, causing so-called rail buckling (particularly in the rail curves). It is therefore crucial that there is sufficient room for the rails to dilate. In other words: to be able to move to some extent in a horizontal direction. This requirement is made possible by the ‘expansion weld’.
The expansion weld consists of two adapted rails positioned in such a manner, that they are able to expand or shrink independently without obstruction. As a result, neither of the two is burdened. Apart from their application on bridge structures, expansion joints are also regularly used at other locations within the railway system where large forces have an effect on the rail structure.
In collaboration with our railway partners, we developed the idea to execute the flash butt welding procedure for connecting long rails at our RSC. The ready-made rails can then be delivered at the construction side in the desired length of up to a maximum of 360 meters. The expansion joints with a maximum length of 36 meters can be transported on a truck. Longer lengths are also possible, however, these will be delivered on our Robel train.
