Which factor is least likely to cause porosity in a weld?

Which factor is least likely to cause porosity in a weld?

• A. Proper shielding and dryness
• B. Moisture on base metal
• C. Oil on base metal
• D. Dirt on base metal

Answer: (A)

Porosity in a weld happens when gas gets trapped in the molten metal as it solidifies. The most common sources are hydrogen from moisture or hydrocarbons on the surface and issues with the shielding gas. When shielding is properly established and the base metal is dry, the chances of forming those gas pockets drop a lot. That’s why having proper shielding and dryness is the factor least likely to cause porosity. Moisture on the base metal introduces hydrogen as the water vapor decomposes; oil on the base metal releases hydrogen (and other gases) when heated; dirt or grime on the surface can contaminate the weld and trap gas or interfere with proper fusion, increasing porosity risk.

Porosity in a weld happens when gas gets trapped in the molten metal as it solidifies. The most common sources are hydrogen from moisture or hydrocarbons on the surface and issues with the shielding gas. When shielding is properly established and the base metal is dry, the chances of forming those gas pockets drop a lot. That’s why having proper shielding and dryness is the factor least likely to cause porosity.

Moisture on the base metal introduces hydrogen as the water vapor decomposes; oil on the base metal releases hydrogen (and other gases) when heated; dirt or grime on the surface can contaminate the weld and trap gas or interfere with proper fusion, increasing porosity risk.