For statically loaded structures, under what condition shall undercut not exceed 1/16" in any length of weld?

The stipulation that undercut should not exceed 1/16" in any length of weld for statically loaded structures is particularly relevant for materials greater than 1 inch in thickness. This is because thicker materials are often subjected to higher stress and load conditions, which can be exacerbated by any imperfections such as undercut. Undercut refers to the groove that forms at the weld toe, which can create a stress riser and potentially lead to premature failure of the joint under load.

For thicker materials, the structural integrity is critical, and minimizing undercut helps to ensure that the weld penetrates adequately and bonds well, providing a reliable connection capable of supporting the loads. As the thickness increases, the allowable undercut is limited more strictly to maintain the strength of the weld and the overall structure. Hence, this condition is tailored to ensure safety and performance in welded joints where the stakes are higher due to increased material thickness.