What are common causes of porosity in welds and how can it be prevented?

• A. Hydrogen or moisture in consumables; oil/grease; dirty metal; prevent by drying electrode, cleaning metal, proper shielding, correct amperage and travel speed
• B. Porosity is caused by moisture in the air
• C. Porosity is only due to operator error
• D. Porosity cannot be prevented

Answer: (A)

Porosity happens when gas gets trapped in the molten weld and remains as voids as it solidifies. The main culprits are hydrogen-related contamination: moisture or humidity in consumables (like damp electrodes or fluxes), oil or grease on the metal, and dirt or oxidation on the metal surface. If the shielding from the weld arc isn’t kept intact—due to improper gas coverage, drafts, or a dirty nozzle—the protective atmosphere can break down and allow gas to be drawn into the weld pool, forming porosity. Prevention focuses on cleanliness and proper shielding: dry and store consumables before use, clean the metal surface to remove oil, grease, rust, and other contaminants, ensure the shielding gas is clean and flowing correctly with minimal drafts, and use the right amperage and travel speed to maintain a stable arc and an appropriate weld pool size. These steps help keep hydrogen out of the weld and maintain good shielding, reducing porosity.