What is the consequence of neglecting interpass cleaning in multi-pass welding?

• A. Interpass cleaning has no effect on weld quality
• B. Neglecting interpass cleaning can lead to defects and poor bonding on subsequent passes
• C. It reduces the need for shielding gas
• D. It increases weld speed

Answer: (B)

Interpass cleanliness is essential because each new weld pass must fuse with the material below it. If you skip cleaning between passes, oxides, scale, slag, or other contaminants from the previous pass stay on the surface and can be trapped under the next bead. This prevents proper fusion at the interface, leading to defects such as lack of fusion, porosity, and slag inclusions, which weaken the weld and create irregular bonding. Cleaning between passes ensures a solid metallurgical bond, consistent bead quality, and fewer defects. Cleaning also helps minimize moisture-related hydrogen issues that could cause crack-prone areas. So neglecting interpass cleaning doesn’t improve anything; it directly increases the risk of defects and poor bonding on subsequent passes.