What is interpass cleaning and why is it important in multi-pass GMAW?

• A. Interpass cleaning involves removal of oxidation, spatter, and contaminants from the previous pass
• B. Interpass cleaning means turning off the machine between passes
• C. Interpass cleaning involves cooling the weld with water between passes
• D. Interpass cleaning is optional

Answer: (A)

Interpass cleaning is cleaning the weld surface between passes to remove oxidation, spatter, and other contaminants from the bead just laid. This matters because the next pass must fuse to the previous weld, and any oxide film or residue can prevent proper wetting, trap gas, or introduce inclusions. Those issues can lead to porosity, lack of fusion, and weaker overall welds in a multi-pass GMAW process. In practice, you clean the surface with a wire brush, grinder, or similar tool and ensure the surface is clean and ready before starting the next pass. The other options describe actions that aren’t cleaning (like turning off the machine or cooling with water) or claim it’s optional, which would not support consistent weld quality.