Which option describes a correct order of passes for a full-penetration groove weld from root to cap?

• A. Prepare joint and bevel, clean, tack parts to maintain alignment; deposit a root pass; add fill passes; finish with a cap pass.
• B. Finish with a cap pass, then root pass, then fill passes.
• C. Only use a single deep pass.
• D. Preheat and then cap pass only.

Answer: (A)

In a full-penetration groove weld, you build the weld from the root to the cap. Start with careful joint preparation: bevel the groove so the root can fuse properly, clean the parts to remove contaminants, and tack them to maintain alignment. Then deposit a root pass to establish fusion at the root and start the penetration through the joint. After the root is solid, add fill passes to build up the weld thickness along the weld contour while controlling heat input and distortion. Finish with a cap pass to produce the final surface finish and ensure the top layer is fused and shaped correctly. This sequence ensures complete penetration, good fusion along the root, proper weld contour, and a sound cap.

The other options don’t fit because they disrupt the required order or omit essential steps. Finishing with a cap before the root and fills prevents proper penetration and fusion. Relying on a single deep pass cannot reliably achieve full penetration and control. Preheating and capping only neglect the necessary root and fill passes needed for a true full-penetration weld.