In producing of flame to welding generally oxy-acetylene is the most convenient. In there acetylene is used as a fuel gas, which is combusted with oxygen to produce a flame. There are various type of fuel gas is used for flame, like butane, propane, hydrogen, natural gas etc. That is depend on type of material, how temperature is required for welding etc.
The chemical composition of oxy-hydrogen welding flame is
2H2 + O2 → 2H2O
It is indicate that the produced flame is strongly oxidizing flame. Where low melting temperature is required for welding there can be oxy-hydrogen flame is used. The metal like lead, aluminium etc. low melting temperature materials can be welded.
In oxy-hydrogen gas welding equipments are more or less same as oxy-acetylene, only differ in pressure control valve regulator. In this welding a special type of regulator is used. In this type of flame no carbon is existed. Steel welding can not
possible with oxy-hydrogen flame. Because it needs higher temperature. Higher temperature can be obtained by increasing of oxygen, but flame can not be obtained perfectly. In oxy-hydrogen flame there are no facilities to combustion the both gases as oxy-acetylene. So, it not possible to obtained neutral flame.