Which contaminants are removed during surface preparation to reduce porosity and lack of fusion?

Which contaminants are removed during surface preparation to reduce porosity and lack of fusion?

• A. Oil, grease, rust, and moisture
• B. Paint and rust only
• C. Only moisture
• D. Only oil

Answer: (A)

Contaminants on the metal surface disrupt weld quality by trapping gas and preventing proper wetting and fusion. Oil and grease on the surface vaporize and release gases that can become porosity in the weld. Moisture contributes hydrogen, which can form hydrogen-induced porosity as the weld solidifies. Rust and rust scale create nonmetallic inclusions and roughness, hindering proper fusion and leading to lack of fusion in the weld. Cleaning away these substances—oil, grease, rust, and moisture—directly tackles the main sources of porosity and incomplete fusion, making this the best choice. Paint can also be a contaminant, but the listed combination addresses the primary factors most associated with porosity and lack of fusion.

Contaminants on the metal surface disrupt weld quality by trapping gas and preventing proper wetting and fusion. Oil and grease on the surface vaporize and release gases that can become porosity in the weld. Moisture contributes hydrogen, which can form hydrogen-induced porosity as the weld solidifies. Rust and rust scale create nonmetallic inclusions and roughness, hindering proper fusion and leading to lack of fusion in the weld. Cleaning away these substances—oil, grease, rust, and moisture—directly tackles the main sources of porosity and incomplete fusion, making this the best choice. Paint can also be a contaminant, but the listed combination addresses the primary factors most associated with porosity and lack of fusion.