Sleepers, the silent cornerstone under this steel dragon, bear the heavy pressure of 10000 tons of trains and also experience the erosion of wind, rain, insects and ants. Untreated ordinary wood will decay and deform in the open and humid environment for several years, endangering driving safety. How to give the sleeper a long life? The answer of railway engineers lies in an ancient and exquisite craft - oil immersion corrosion prevention. The key to this is the unique and efficient "high-temperature cooking", and the protagonist is not water, but oil.
Walking into the sleeper factory, the air is filled with rich pine fragrance. Yes, pine is a great choice for making oil soaked sleepers. It has straight texture, loose and porous wood fiber structure, like a natural capillary network, providing an excellent channel for the further penetration of anti-corrosion oil. Batches of logs arrive from the forest area, and huge trunks are stacked like mountains, which is the starting point of sleeper life.
These pine logs will not be processed immediately. They are neatly and orderly stacked on the wide open-air storage yard to start a crucial "rest" - natural drying. The wind blows and the sun shines. The pine tree breathes quietly in the alternation of day and night, releasing internal water slowly and evenly. This process usually takes months or more. Of course, there is another way - Manual drying. Manual drying can greatly reduce the drying time, but the cost will also rise.
When the internal moisture content of pine trees meets the requirements, they enter the processing workshop. The roaring machine peels off the rough bark and exposes the bright yellow wood core. The huge sawing machine accurately cuts logs into regular sleeper prototypes according to the standard size. Then, a seemingly simple but extremely critical process came on stage - notch processing. The high-speed rotating scoring cutter wheel quickly cuts across the sleeper surface, leaving dense grooves of different depths. These dents are like countless small "canals" opened on the wood surface, increasing the surface area of the wood in contact with the preservative oil, and opening up a "channel" for the preservative oil to penetrate into the wood. Without them, the oil can only adhere to the surface, and it is difficult to go deep into the core of the wood, so the anti-corrosion effect will be greatly reduced.
The prepared pine sleepers are neatly packed into a special large cylindrical steel tank - anti-corrosion tank. The tank door closes slowly, and the world is isolated. The real magic starts under the high temperature and pressure in the tank.
The high-temperature liquid anti-corrosion oil is continuously pressed into the tank by the high-pressure pump, quickly filling the whole space and immersing all sleepers. The strong pressure makes the scalding oil like an impenetrable spirit. It penetrates, diffuses and fills the deepest part of the wood along the crisscross nicks on the wood surface and through the capillary pipes inside the wood that expand due to high temperature.
High temperature cooking, using oil instead of water, is the soul of the oil impregnated sleeper technology. Water boils and vaporizes at high temperature, which makes it difficult to form a continuous high-pressure infiltration environment inside the wood, and the water itself has no preservative effect on the wood. The special anti-corrosion oil has a boiling point much higher than that of water. It can maintain a stable liquid state at high temperature. Its viscosity is reduced at high temperature, but its fluidity is enhanced, which is more conducive to in-depth penetration. Eventually, the oil will remain permanently in the wood, forming a strong protective barrier.
It is this seemingly contradictory but actually exquisite combination of "high-temperature cooking" and "oil immersion" that enables ordinary pine sleepers to have extraordinary ability to resist decay, moths and harsh environment. They are laid on the road, silently bearing the wheels of the times, and are reborn in the baptism of oil and fire. They have become the truly immortal cornerstone to protect the safety and smoothness of the ten thousand mile railway line.
