Which of the following is NOT a common cause of porosity in SMAW welds?

• A. Moisture in electrode coating
• B. Oil or grease on base metal
• C. Rust or contamination
• D. Improper shielding gas

Answer: (D)

Porosity in SMAW welds happens mainly from hydrogen or other gases getting trapped in the molten metal due to contaminants and moisture. Moisture in the electrode coating releases hydrogen when heated, creating gas pockets. Oil or grease on the base metal and rust or other surface contamination also introduce gases that form porosity during welding. In SMAW, shielding is provided by the flux coating on the electrode itself, so there isn’t an external shielding gas to control. Therefore, an improper shielding gas is not a common cause of porosity in SMAW. To prevent this, keep electrodes dry, clean the base metal, and use proper welding technique and cleaning.