What is the minimum rail length for successful thermite welding operation in straight tracks?

The minimum rail length for successful thermite welding operation in straight tracks is 15 feet because this length ensures that there is enough material to establish a solid and effective weld. A shorter length may not provide adequate surface area or structural integrity required for the weld, potentially leading to weaknesses or failures in the joint. Additionally, a length of 15 feet allows for sufficient alignment and manipulation during the welding process, ensuring that the thermite reaction can take place smoothly and uniformly across the rail joint. This consideration is essential to maintain the integrity and safety of the rail infrastructure.