What is a benefit of a double-welded joint?

A double-welded joint provides the significant benefit of reducing residual stress within the welded structure. When welding materials, high temperatures are generated, leading to thermal expansion, which can cause stress as the materials cool and contract. A double-welded joint typically involves two passes of welding material, which can lead to a more uniform heat distribution and less localized heating, ultimately resulting in a more balanced thermal contraction. This reduction in residual stress increases the overall integrity and durability of the joint, making it less prone to defects such as cracking or warping.

In contrast, the other options do not align with the inherent advantages of a double-welded joint. While some might argue that a double weld could be quicker to set up, it generally takes more time compared to a single weld due to the additional work involved. Moreover, double-welded joints typically require more precise techniques and thorough preparation, which could imply a higher skill level rather than less. Lastly, while tack welds may not be necessary in some cases, the requirement for tack welds often depends on the specific project and isn't a guaranteed advantage of double-welded joints.