What happens to the weld size when it is not specifically indicated on a welding symbol?

When a weld size is not explicitly specified on a welding symbol, it typically defaults to a standard size as determined by industry standards and practices. The correct answer indicates that the default size is set to 1/2". This convention stems from the need for a consistent approach in welding specifications, as a default weld size helps maintain structural integrity and quality across different applications. Using a 1/2" default size ensures that the weld will provide adequate strength for many general applications, especially in structural welding.

As for the other options, marking the size as 1/4" or 1" does not align with standard practices for default sizes in welding applications. Moreover, considering the weld size as negligible would not provide any assurance of weld quality or strength, which is essential in ensuring the safety and reliability of welded structures.