Oxy-Fuel Cutting — What It Is and Why It Matters
Oxy-fuel cutting (also called oxy-acetylene cutting or torch cutting) is a thermal cutting process that uses a fuel gas flame to preheat steel to its kindling temperature, then introduces a stream of pure oxygen that rapidly oxidizes and blows away the metal. The exothermic reaction between iron and oxygen does the actual cutting — the flame just starts the process.
The most common fuel gas is acetylene, though propane, propylene, and natural gas are also used depending on the application. An oxy-fuel rig consists of two cylinders (oxygen and fuel), regulators, hoses, and a cutting torch with interchangeable tips.
Oxy-fuel excels at cutting thick carbon steel — it handles plate several inches thick where plasma cutters cannot reach. The equipment is inexpensive, completely portable with no electricity required, and the same rig can also be used for heating, brazing, and welding. The drawbacks are slower cutting speed compared to plasma, a wider heat-affected zone, and the limitation that it only cuts ferrous metals (it cannot cut stainless, aluminum, or copper).
Frequently Asked Questions
Why can oxy-fuel only cut steel?
Oxy-fuel cutting relies on an exothermic oxidation reaction — iron burns in pure oxygen. Metals like aluminum and stainless steel form oxide layers with melting points higher than the base metal, preventing the sustained oxidation chain reaction needed for the cut.
Is oxy-fuel cutting still relevant with plasma available?
Absolutely. Oxy-fuel remains essential for cutting thick plate steel (1"+), field work without electrical power, preheating joints before welding, and heating stuck bolts or bent components for straightening. Many shops run both plasma and oxy-fuel for different tasks.