One of the primary causes of porosity in GTAW is which of the following?

• A. Hydrogen pick-up
• B. Moisture in shielding gas
• C. Contamination by oil
• D. Improper current level

Answer: (A)

Hydrogen pickup from sources in the welding environment is what causes porosity in GTAW. When hydrogen finds its way into the molten weld pool, it dissolves there and, as the metal solidifies, the hydrogen gas forms bubbles that become tiny pores in the weld. The shielding gas’s job is to keep air out, but if that shielding gas is moist or contaminated, hydrogen enters the weld and creates porosity. That direct link—hydrogen entering the weld from a source like moisture in shielding gas or contaminants—is why hydrogen pickup is the primary cause. Moisture in the shielding gas is a common way hydrogen gets in, while oil contamination can also release hydrogen-containing hydrocarbons under heat, contributing to porosity, and improper current level tends to affect heat input and fusion more than directly causing gas porosity.