Rail stressing

Environmental cold can lead to the contraction of the fixed railway track causing brittleness and cracks.

Before it is installed, the rail is altered by stretching with hydraulic tensors or heated to its stress-free temperature to make these dangerous problems less likely.

This type of stress can cause sun kink where a length of a railway buckles laterally (sideways).

[6] Before laying new track, repairing track, or changing the sleepers, the rail is mechanically or thermally altered (stressed) so that its length equals the same at a chosen stress-free temperature; the rail can then be fixed in place with no thermal forces in effect.

For example, the CRT may be reached due to a removal of a rail section or an Insulated Block Joint (IBJ).

A "stressing kit" (hydraulic rail tensor), such as the Permaquip HSM70 Stressor, or other method is used to adjust the other end and make the join ready for welding.