Knowledge of Environmental Adaptability Selection of Rails and Accessories
How to select rail and elastic bar materials for alpine regions?
Railways in alpine regions need to use rails with low-temperature toughness, whose material must meet the requirement of impact energy ≥27J at -40℃ to avoid low-temperature brittle fracture. Elastic bars should be made of low-temperature resistant alloy steel and undergo special heat treatment to maintain good elasticity even in extreme low temperatures. Ordinary carbon steel is prone to hardening and cracking in alpine environments and cannot withstand repeated impacts of train dynamic loads. Meanwhile, the connection parts of accessories need enhanced sealing to prevent ice and snow from seeping in and causing frost heave damage. When selecting, priority should be given to products that have passed low-temperature impact tests to ensure compliance with track usage standards in alpine regions.
What anti-corrosion measures are required for bolts and railroad spikes in coastal salt spray environments?
Coastal salt spray environments are highly corrosive, so bolts and railroad spikes need to adopt hot-dip galvanizing process with a coating thickness of not less than 80μm, passing a salt spray test of more than 1000 hours. An additional epoxy coating can be used for double protection to isolate salt from contact with the metal surface and slow down corrosion. Avoid using ordinary carbon steel materials; instead, choose alloy steel with stronger corrosion resistance as the base material. Anti-corrosion washers should be matched during installation to prevent electrochemical corrosion at gaps. Regularly inspect the state of the anti-corrosion layer and touch up in time if damage is found to ensure the continuous effectiveness of the anti-corrosion effect.
What characteristics should be focused on when selecting under-rail base plates for desert areas?
Desert areas have strong winds, large sandstorms and significant temperature differences, so under-rail base plates need to have good wear resistance and UV aging resistance. Prioritize polyurethane or composite rubber base plates, whose surfaces should be sand-proof treated to prevent sand particles from embedding and affecting elasticity. The base plates must have a wide temperature adaptation range, maintaining stable performance at -30℃ to 60℃ without hardening or softening. At the same time, they should have sufficient compressive strength to prevent local overload damage caused by sand accumulation. During installation, clear sand around the track to avoid sand particles being trapped between the base plate and sleeper, resulting in uneven force.
What load requirements must fishplates and pressing plates of heavy-haul railways meet?
Heavy-haul railways usually have an axle load exceeding 30 tons, so fishplates need to select heavy-duty models with a material tensile strength of ≥800MPa, which can withstand frequent heavy-load impacts. Pressing plates must have a lateral load capacity of ≥120KN to ensure no rail displacement. The bolt hole design of fishplates needs to be optimized to disperse stress concentration and avoid bolt fracture. The contact surface between the pressing plate and the rail should be precision-machined with a contact area of ≥95% to ensure uniform force. All components must pass 2 million cycles of fatigue testing to ensure no failure risk under long-term heavy loads.
Why is insulation performance emphasized for fastening systems in urban rail transit?
Most urban rail transit adopts third-rail power supply, so the fastening system needs to have good insulation performance to prevent stray current from corroding metal components. Poor insulation performance will lead to current leakage, which not only wastes energy but also accelerates the electrochemical corrosion of rails, bolts and other components. Insulating base plates and sleeves in the fastening system should be made of high-quality insulating materials with a breakdown voltage of ≥3KV to ensure effective electrical isolation. Meanwhile, insulating components need to be aging-resistant and wear-resistant to adapt to long-term use in high-humidity underground environments. Regularly test insulation performance to avoid potential safety hazards or equipment failures caused by insulation failure.