Which is necessary before performing a thermite weld on ties?

Performing a thermite weld on ties requires ensuring that the area of the weld is free from defects, which is why grinding defects is necessary. This step is crucial because any irregularities or imperfections, such as stress fractures, rust, or surface contaminants, can negatively affect the integrity and strength of the weld. By smoothing out the surface and eliminating these defects, the weld can achieve proper fusion and bonding, resulting in a strong and durable joint.

Prior to welding, addressing any defects helps ensure proper heat distribution during the thermite reaction and minimizes the risk of failure. Without this preparation, the weld may not meet the necessary specifications and could lead to structural issues later on. Therefore, grinding defects directly contributes to the quality and safety of the thermite weld.