Impregnation process

Boiler pressure processes have been successfully used to impregnate railway sleepers for more than 150 years: A simple Rüping process is used for oak, pine, and larch sleepers. The improved double ruffling process is used for beech sleepers, and the boiler vacuum pressure process is used for pine sleepers.

These processes differ in the process parameters (height and length of the individual vacuum and pressure phases) and types of protective agents (the two Rüping processes use oil preservatives, and the boiler vacuum pressure process uses aqueous wood preservatives).

These large-scale industrial impregnation processes’ common characteristic is that the wood preservative is introduced into the wood using closed systems with negative and positive pressure distributed optimally across the wood.

When properly applied, all processes lead to an optimised, deep, and even distribution of the protective agent into the impregnated zone, which differs depending upon the wood selected.

Boiler pressure processes, when used with suitable and approved wood preservatives, provide correspondingly effective protection, ensuring that wooden sleepers can be used for a long time in the track bed.