Is a size dimension required for square-groove welds?

A size dimension is not required for square-groove welds because the configuration of a square groove inherently defines the contact area where the weld will occur. Square-groove welds have a specific geometry that is established by the edges of the base metals coming together at right angles, allowing for a straightforward visual understanding of the weld's penetration and size without needing to specify additional dimensions.

In contrast, welds such as fillet or bevel-groove welds require size dimensions to clarify the dimensions of the weld throat or the angle of the groove, which are not as easily inferred from the joint configuration alone. This distinction underscores the simplicity of square-groove welds compared to other types that necessitate more detailed specifications to ensure proper welding quality and strength. Therefore, indicating that a size dimension is necessary for square-groove welds would be inaccurate, reinforcing the appropriateness of the answer chosen.