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Welding
Unlike brazing, silver soldering and soft
soldering where the to components are 'stuck' together using an alloy, welding requires
the job itself to be melted and fused together. During this fusing process small
indentations occur at the joint and these are filled using a rod made from the same
metal as the original job, producing a single piece of metal whose joint is as strong as
the original pieces. In schools the main type of welding is oxy - acetylene . Acetylene
gas is burned in oxygen to produce a very hot flame capable of melting steel with
ease. Another type of welding is electric arc welding which relies on a stream of
sparks to melt metal.
Unlike soldering joint preparation does not rely on cleanliness, although paint and rust
should be removed before starting. With thin materials (up to say 4 mm) joint
preparation only requires a small gap which can be filled with the melted rod. Thicker
materials require slants to be filed on edges so that deeper penetration of melting can be
achieved.
The welding gasses need to be at the correct pressure and valves are provided for this
purpose. The welding cylinders are coloured black (oxygen) and maroon (acetylene).
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