What is the maximum temperature that the rail base must cool to before placing pads adjacent to thermite welds?

The maximum temperature that the rail base must cool to before placing pads adjacent to thermite welds is 250 degrees. This is an important requirement in thermite welding because it ensures that the weld joint is sufficiently cooled to prevent thermal damage to the pads or any materials applied next to the weld. Placing pads while the weld is still too hot could compromise the integrity of both the weld and the pads, leading to potential failures or defects in the overall structure.

The cooling threshold of 250 degrees allows for the weld to achieve a stable condition that minimizes the risk of thermal stress and distortion. At this temperature, the weld has cooled enough to prevent any further adverse reactions with the pads, ensuring a solid and durable bond where the pads will be applied. Therefore, following this guideline helps to maintain the structural integrity and safety of the railway system.