EXOTHERMIC: The Process
"A reaction involving the release of heat into its surroundings."
Exothermic Cutting or "Oxygen Lancing" allows trained operators to melt (cut), pierce, or gouge any metal (ferrous/non-ferrous) and some types of masonry by flowing pure oxygen through a steel pipe, tube, or rod. Exothermic cutting is used in Demolition, Hydraulic Pin Removal, Rescue/Entry, and Breaching operations around the world.
Pure Oxygen is an oxidizer or "accelerant:" it reduces the temperature required for objects to ignite, while simultaneously increasing the burn rate. Contrary to belief, oxygen (O2) is non-flammable; it does not burn. However, any object surrounded or saturated by pure oxygen is considered a "fuel." And once provided an ignition source (i.e. open flame or spark), the result is exothermic in that the object will violently burn to produce high temperatures and heat. Steel is no different than any other object; It is considered a fuel. Once brought to burning temperature by an electric arc or sufficient heat source, pure oxygen can be added to produce an exothermic reaction capable of reaching temperatures up to 7,200-7,400°F. High temperatures produced by burning steel provides the means to burn/cut just about any metal. However, in relation to exothermic cutting, specific ratios of pure oxygen and steel must exist to achieve effective burns. This is why utilizing specific rod designs, oxygen volumes, and techniques can enable operators to achieve faster, safer, more efficient cuts. A common misconception is that exothermic cutting rods ignite due to magnesium. This is false. Once an operator terminates the flow of oxygen, the exothermic reaction stops. In contrast, Magnesium, once ignited, can burn in normal atmospheric conditions without the aid of pure oxygen.
Another type of cutting is called Oxy-Arc. What makes Oxy-arc cutting unique is the addition of continuous DC current (300-350Amps) through the rod during the exothermic process. The slang term for Oxy-Arc is called "burning hot," as temperatures can reach upwards of 10,000°F due to the presence of an electric arc. "Burning hot" is common practice for underwater cutting because of its increased efficiency to cut thicker and/or highly oxidized (corroded) material. Manufactures make consumables specifically designed for the Oxy-arc cutting process. Typical features of these rods include an improved insulation layer to protect operators from shock and an increased volume of steel (thicker walled tube) to deliver more heat while stabilizing rod consumption during the burn. Its not uncommon for operators to use normal exothermic cutting rod for Oxy-arc cutting. The downside of using normal exothermic rods for Oxy-arc cutting is decreased consumable time, torch damage from electrolysis (underwater), and increased risk of shock. Rods like the Aqua-Lance™ are specifically designed for Oxy-arc cutting and perform very well on materials greater than 3/4" in thickness.
Methods like Oxy/fuel can have increased costs/risks due to fuel gases, less portability, inability to cut non-ferrous metals, and lower cutting temperatures. In contrast, exothermic cutting is faster, highly portable (only requires oxygen), hotter, and can cut both ferrous and non-ferrous product. Some would even argue that its easier to train exothermic operators, thus can greatly improve job/mission success rates. The ability for exothermic cutting to reach extremely high temperatures, provide tremendous amounts of heat (rod dependent), and ability to pierce through incredibly thick material has guaranteed its acceptance in the heavy industry for demolition of scrap metal, removal of frozen hydraulic pins, slag removal, and underwater demolition. Exothermic cutting also finds use in Military/Government forced entry and Fire-Rescue Recovery operations where conventional means are ineffective.