What method is typically not acceptable for tack welding on reinforcing bars without authorization?

Utilizing unfused connections is typically not acceptable for tack welding on reinforcing bars without authorization because it compromises the integrity and strength of the weld. High-quality welding requires proper fusion between the base metals to ensure structural stability and performance. Unfused connections indicate that the metal pieces are not appropriately bonded, which can lead to weak points in the structure.

In the context of welding practices, proper technique and training are critical to achieving solid bonds that meet safety standards. Tack welds should be strong enough to hold components in place until the final, complete weld is applied. If the connections are not fused, they do not provide the necessary support and could fail under load, which is particularly critical in applications involving reinforcing bars. Therefore, any method that does not guarantee proper fusion would require specific authorization before being used in a structural context.