Which statement best describes porosity causes and prevention?

Which statement best describes porosity causes and prevention?

• A. Porosity is never preventable
• B. Porosity is caused by proper shielding gas selection
• C. Porosity is caused by welding speed alone
• D. Contaminants and moisture can cause porosity; proper cleaning and drying reduce porosity

Answer: (D)

Porosity in welds comes from gas pockets that form when the molten metal traps gas as it solidifies. The most common culprits are surface contaminants and moisture—oil, grease, dirt, rust, paint, or moisture on the workpiece or in the filler material and even in the surrounding environment. If you clean the weld area thoroughly and dry all components before welding, you remove these gas sources and reduce the hydrogen that can cause porosity. Shielding gas and welding parameters matter, but cleaning and drying address the primary causes, making porosity less likely. The other statements either misstate the cause or oversimplify the issue, such as implying porosity is unpreventable or caused by proper shielding gas selection or by welding speed alone.

Porosity in welds comes from gas pockets that form when the molten metal traps gas as it solidifies. The most common culprits are surface contaminants and moisture—oil, grease, dirt, rust, paint, or moisture on the workpiece or in the filler material and even in the surrounding environment. If you clean the weld area thoroughly and dry all components before welding, you remove these gas sources and reduce the hydrogen that can cause porosity. Shielding gas and welding parameters matter, but cleaning and drying address the primary causes, making porosity less likely. The other statements either misstate the cause or oversimplify the issue, such as implying porosity is unpreventable or caused by proper shielding gas selection or by welding speed alone.