- Oxy-acetylene welding is a process that uses the combustion of acetylene and oxygen to produce a high-temperature flame (around 3,500 °C or 6,330 °F) that melts and joins metals. - Acetylene (C₂H₂) acts as the fuel gas. - Oxygen (O₂) is used as the oxidizer, supporting the combustion and increasing the flame temperature. - Other fuel gases can be used with oxygen (like propane, natural gas), but acetylene is the most common for welding due to its high flame temperature.