engineering

Thermal lance

Thermal lance is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Thermal lance rather than just read about it. In short: A thermal lance, thermic lance, oxygen lance, or burning bar is a tool that heats and melts steel in the presence of pressurized oxygen to create very high temperatures for cutting. It consists of a long steel tube packed with alloy steel rods, which serve as fuel; these are sometimes mixed with aluminum rods to increase the heat output.

Key takeaways

Thermal lance belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Thermal lance to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Thermal lance from memory before moving on to harder problems.

Reference excerpt

A thermal lance, thermic lance, oxygen lance, or burning bar is a tool that heats and melts steel in the presence of pressurized oxygen to create very high temperatures for cutting. It consists of a long steel tube packed with alloy steel rods, which serve as fuel; these are sometimes mixed with aluminum 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 torch. An intense stream of burning steel is produced at the working end and can be used to cut rapidly through thick materials, including steel and concrete. 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, in the form of steel wool, 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 Fe2O3; the thermal lance uses steel in the form of rods rather than wool, the rods 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 4,500 °C (8,130 °F), while others calculate it to be 2,730 °C (4,950 °F).

Alternative fuels Thermal lances have been constructed for demonstration using foodstuffs (including bacon, dried spaghetti and Takis) 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.

See also Thermite – Pyrotechnic composition of metal powder and metal oxide

References

External links

U.S. patent 3,921,542 (oxygen-supplied thermic lance, invented by Ernst Brandenberger) U.S. patent 3,460,223 (device for fixing holes by method of smelting, especially into buildings, invented by Berczes et al.)

Illustrations

Worked examples

Example 1 — a first encounter with Thermal lance

Start with the simplest possible case. Write down what Thermal lance claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Thermal lance before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Thermal lance ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Thermal lance

In research: Thermal lance appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Thermal lance in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Thermal lance is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cutting tools, Welding, so understanding it makes those chapters shorter.
In everyday life: Look for Thermal lance outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Thermal lance in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Thermal lance means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Thermal lance out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Thermal lance in simple terms?

Why does Thermal lance matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Thermal lance?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Thermal lance.