What basic steps should be taken to prepare base metal surfaces before GMAW?

• A. Remove oil/grease, paint, rust, and dirt; degrease if needed; dry surfaces; clean with a wire brush or grinder; inspect for contamination and ensure a clean, dry surface.
• B. Bake the metal before welding to remove moisture.
• C. Apply oil to prevent oxidation.
• D. Wash with soap and water only.

Answer: (D)

Preparing the metal for GMAW starts with a clean, dry surface free of contaminants that can cause porosity, poor fusion, or hydrogen-related cracking. The basic steps are to remove oil and grease, paint, rust, and dirt from the area to be welded. If oils or greases are present, use an appropriate degreasing method so they’re fully removed. Then dry the surface thoroughly to prevent moisture from being trapped in the weld zone, which can release hydrogen under heat. After degreasing and drying, clean the surface mechanically with a wire brush or grinder to remove oxides, scale, and any loose debris. Finally, inspect the area to confirm it’s clean and dry before welding.

Washing with soap and water alone often isn’t enough because it may not remove oils, solvents, or heavy paints completely and can leave moisture behind. Chemical degreasers plus proper drying ensure the surface is truly ready for a quality weld.