What is the fuel gas used in the process of gas welding?

In gas welding, the fuel gas is typically mixed with oxygen to produce a high-temperature flame necessary for melting metals. This mixture allows for precise control over the heat output, making it suitable for welding various materials. The flame's characteristics, including temperature and chemical composition, can be adjusted depending on the specific welding requirements.

While natural gas, propane, and methane can be used in other welding and cutting processes, they are not the primary means of creating the sustained, high-temperature flame needed for gas welding without the addition of oxygen. Gas welding specifically relies on the combination of a fuel gas with oxygen, which enhances the combustion process, resulting in a hotter and more efficient flame for welding purposes. This understanding of the need for an oxygen-fuel gas mixture is key in differentiating it from other options which may not meet the specific heat requirements for gas welding.