Controlling the gases arising from the use of oxygen and acetylene, consisting mainly of carbon dioxide with the addition of oxides of nitrogen where an oxidising flame is used, and carbon monoxide.

The combustion of any fuel, eg, acetylene, propane or methane, with oxygen from a cylinder rather than air at normal or increased pressure, gives a hotter flame that is often easier to control.

The creation of a joint using a filler (welding rod) of similar composition to the metal being joined, using electricity to generate an arc.

The cutting of metals by means of a plasma arc that produces a high-temperature stream of ionised gas capable of cutting metal. Hand-held torches usually use compressed air as the gas but mixtures of argon and either hydrogen or nitrogen may occasionally be used.