Welding - Types of Compressed Gases
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What types of compressed gases are used in welding, and what are their hazards?
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The table below lists common welding gases along with general information on how and where they are used.
| Common compressed gases used in welding | Purpose | Example of welding or application | WHMIS Classification by CNESST* | Hazards |
| Oxygen gas | Heating gas | Oxy-cutting and oxy-welding | Oxidizing gases - Category 1 Gases under pressure - Compressed gas | May cause fire Gas under pressure May explode if heated |
| Propane | Heating gas | Oxy-cutting and oxy-welding | Flammable gas – Category 1 Gases under pressure – Liquefied gas | Extremely flammable gas Gas under pressure May explode if heated
|
| Propylene | Heating gas | Oxy-cutting and oxy-welding | Flammable gas – Category 1 Gases under pressure – Liquefied gas Simple asphyxiants - Category 1
| Extremely flammable gas Gas under pressure May explode if heated May displace oxygen and cause rapid suffocation
|
| Hydrogen | Heating gas and shielding gas when combined with argon and carbon dioxide | Specialized welding processes that require high temperatures such as 3371°C to 3982°D (6100°F to 7200°F) for materials like tungsten | Flammable gas – Category 1 Gases under pressure – Compressed gas Simple asphyxiants - Category 1
| Extremely flammable gas Gas under pressure May explode if heated May displace oxygen and cause rapid suffocation
|
| Acetylene | Heating gas | Oxy-cutting and oxy-welding | Flammable gas – Category 1 Gases under pressure – Dissolved gas Simple asphyxiants - Category 1
| Extremely flammable gas Gas under pressure May explode if heated. May displace oxygen and cause rapid suffocation. May react explosively even in the absence of air at elevated temperature or gauge pressure above 15 pounds per square inch gauge (psig) (103 Kilopascal (kPa)) or absolute pressure above 30 pounds per square inch absolute (psia) (206 kPa).
|
| Argon | shielding gas | Flux-cored arc welding (FCAW) | Gases under pressure - Compressed gas Simple asphyxiants - Category 1
| Gas under pressure May explode if heated May displace oxygen and cause rapid suffocation |
| Helium | shielding gas | Gas metal arc welding (GMAW) | Gases under pressure - Compressed gas Simple asphyxiants - Category 1
| Gas under pressure May explode if heated May displace oxygen and cause rapid suffocation
|
| Nitrogen | shielding gas, heat treatments | Laser welding, plasma cutting, and some heat treatments | Gases under pressure - Compressed gas Simple asphyxiants - Category 1
| Gas under pressure May explode if heated May displace oxygen and cause rapid suffocation
|
| Carbon dioxide | shielding gas | Flux-cored arc welding (FCAW) | Gases under pressure - Liquefied gas 1
| Gas under pressure May explode if heated May displace oxygen and cause rapid suffocation May increase respiration and heart rate.
|
*Please note that these classifications were retrieved from the Commission des normes, de l'équité, de la santé et de la sécurité du travail (CNESST) site on December 5, 2023 and was established by CNESST personnel to the best of their knowledge based on data obtained from scientific literature and it incorporates the criteria contained in the Hazardous Products Regulations (SOR/2015-17). It does not replace the supplier’s classification which can be found on its Safety Data Sheet.
- Fact sheet first published: 2024-02-26
- Fact sheet last revised: 2024-02-26
