What does "fit-up" refer to in welding?

• A. The shielding gas composition.
• B. Correct alignment, gap, and spacing of components before welding to ensure quality welds.
• C. Post-weld heat treatment schedule.
• D. Electrode size selection.

Answer: (B)

Fit-up is the alignment, gap, and spacing of components before welding to ensure quality welds. Getting the fit-up right ensures the joint geometry is correct, root opening is appropriate, and parts sit in the proper relation so the weld can fuse across the joint and achieve the intended strength. Poor fit-up can lead to misalignment, gaps or misfitting edges, distortion, and defects like lack of fusion or porosity, all stemming from not preparing the parts properly before welding. Shielding gas composition, post-weld heat treatment, and electrode size selection relate to other stages of welding, not the pre-weld preparation of the joint.