Certain external types of gases are used or produced during the welding process for the purpose of shielding the weld. The following are the gases that are widely used for this task.

Argon- is colorless, odorless, tasteless and non-toxic.  Used to create an inert gas shield during welding. 

Carbon Dioxide- is a tasteless, colorless, odorless, nonflammable gas.  Commonly utilized with argon as a shielding gas during welding.

Helium- is colorless, odorless, tasteless, nontoxic and chemically inert.  Used to create an inert gas shield and prevent oxidation during welding of metals.

Hydrogen- is colorless, odorless, tasteless and nontoxic.  Used to enhance plasma welding and cutting operations.

Nitrogen- is colorless, odorless, tasteless, and nontoxic.  Small additions to argon based shielding gases can be used for welding stainless steel by the Gas Metal Arc Welding (GMAW or MIG) process.

There are also mixtures of gasses that are used in welding. Common mixes are listed below.

• Argon/carbon dioxide (used for stainless steel)
• Carbon dioxide (used for mild steel)
• Argon/helium/nitrogen (used for aluminum and stainless steel)