When welding joints with varying thickness, what is the typical sequence of passes?

• A. Cap, root, then finish with an extra pass.
• B. Only one pass.
• C. Root pass, then fill passes, ending with cap.
• D. Cap, root, then fill.

Answer: (C)

Starting with the root pass is essential because it establishes fusion right at the joint’s root, ensuring penetration through the groove even when the metal thickness varies. After the root is solid, fill passes build up the weld to approach the final thickness, distributing heat and material through the joint. The last cap pass sits on top to shape the surface, seal the weld, and provide final strength. This sequence prevents issues that would occur if you tried to cap first or single-pass welds: a cap-first approach wouldn’t establish proper root fusion, and a single pass can’t fill a groove with varying thickness.