What is the minimum temperature for the rail head and base before welding in cooler conditions?

The minimum temperature for the rail head and base before welding in cooler conditions is established to ensure optimal conditions for the thermite welding process. At temperatures below the specified minimum, the materials may not reach the appropriate level of ductility and toughness required for a successful weld.

Choosing 110°F signifies that it is sufficiently above the critical threshold where the rail materials, usually made from steel, can adequately absorb and dissipate heat during the welding process. This temperature helps prevent issues like cracking or insufficient fusion, which can compromise the integrity of the weld. Maintaining this temperature allows for better heat conductivity and improves the overall quality of the weld.

For context, temperatures such as 95°F, 105°F, and 115°F are either too low to effectively prepare the materials or too high, increasing unnecessary risks or complications in the welding process. Thus, 110°F strikes the right balance for successful thermite welding under cooler conditions.