A thermal lance, thermic lance, oxygen lance, or burning bar is a

tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates b ...

that heats and melts

steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...

in the presence of pressurized

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

to create very high temperatures for cutting. It consists of a long steel tube packed with

alloy steel Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. The differe ...

rods, which serve as fuel; these are sometimes mixed with

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

rods to increase the heat output.

Operation

One end of the tube is placed in a holder and oxygen is fed through the tube. The far end of the tube is pre-heated and lit by an

oxyacetylene Principle of burn cutting Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the United States) and oxy-fuel cutting are processes that use fuel gases (or liquid fuels such as gasoline or petrol, diesel, ...

torch. An intense stream of burning steel is produced at the working end and can be used to cut rapidly through thick materials, including

and

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

. The tube is consumed by the process within a few minutes.

Applications

Often used as a heavy duty demolition tool, the thermic lance is also used to remove seized axles of heavy machinery without damaging the bearings or axle housing. This technique is often used on the pins and axles of large equipment such as cranes, ships, bridges, and sluice-gates. In addition, thermal lancing is used to clean the bottom of steel furnace pots, which accumulate a skull layer of slag and iron during operation.

Principle of operation

Steel wool Steel wool, also known as iron wool, wire wool or wire sponge, is a bundle of very fine and flexible sharp-edged steel filaments. It was described as a new product in 1896.''Iron Age'', Vol. LVII, p.871, cited by ''Journal of the Iron and Steel ...

can burn at atmospheric (20%) concentrations of oxygen because it has a high surface area-to-mass ratio and relatively low mass, which prevents the heat from being dissipated in the bulk of the material. When the oxygen concentration is increased, steel wool will burn faster. Burning steel wool is simply the rapid oxidation of iron into ; the thermal lance uses steel rods which will burn with a sufficiently high supply of concentrated oxygen. The temperature at which a thermal lance operates varies depending on the environment. Some estimates put the maximum temperature at , while others calculate it to be .

Alternative fuels

Thermal lances have been constructed for demonstration using foodstuffs (including bacon and dried spaghetti) as the fuel instead of steel rods; a supply of pure oxygen is more important to drive rapid oxidation than the fuel being burned.

History

Leo Malcher filed for a patent in 1922 entitled "Process of attacking compact mineral material, noncombustible in oxygen". The patent uses "a suitable disintegrating flux to act upon the material at the point where it is desired to attack it ... the fuel employed in the example to be described is metallic iron, and is arranged in the form of two concentric pipes". The annulus between the two pipes was filled with a flux (sodium carbonate borax and sodium chloride in equal proportions) and oxygen was supplied through the inner tube.

References

External links

* (oxygen-supplied thermic lance, invented by Ernst Brandenberger) * (device for fixing holes by method of smelting, especially into buildings, invented by Berczes et al.) {{DEFAULTSORT:Thermal Lance Cutting tools Welding