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Signs of Construction: Welding

A lot goes on after rail has been delivered to the Aurora Line/I-225 Rail project and it is stored in stacks. First up is welding. Workers must weld each 80-foot stick or piece of rail into 800-foot strings, which they then stockpile. With special track equipment, workers drag the strings into their approximate location and place them atop concrete ties.

The project will implement two types of welding: flash-butt, a machine-driven method, and thermite, which depends on a welding kit. Subcontractor Chemetron Railway Products Inc. performs flash-butt welding on our project, an approach that fuses rail through electricity to melt the ends and hydraulically push them together to create a weld.

Meanwhile, thermite welding relies on a welding kit that, once ignited, melts steel inside a crucible that flows into a mold to bind rails. Rail temperatures are extremely hot during both methods and melt steel, reaching temperatures up to 1,600 degrees Fahrenheit during flash-butt welding and 6,000 degrees Fahrenheit during thermite welding. Trained personnel are equipped with welding gloves and face shields to protect them from these high temperatures.

The photos below give a step-by-step overview of the welding process:

Step 1: The excavator picks each stick up from the stockpile and places it on the guideway.



Step 2: Crews grind the weld faces and align the two rails to the proper tolerances before welding begins.



Step 3: Flash-butt welding fuses the two rails together.



Step 4: The new weld is ground flush with the rest of the rail.



Step 5: The rail is pulled to the area where it will be stored until it is time to place on the concrete ties.






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