What do you understand by gas welding ? Write down various type of gas.

Gas welding-

Gas welding is a technique of fusion welding in which heat for welding is obtained by the combustion of a fuel gas.  The edges or surfaces to be joined are melted by the heat of a gas flame at very high temperatures.  The molten metal is allowed to flow together and a solid continuous joint is obtained when the molten metal solidifies.  The gas welding is particularly suitable for joining metal sheets and plates of thickness from 2 mm to 50 mm.  For welding sheets of thickness more than 15 mm additional metal (known as filler metal) in the form of welding rod is melted into the gap between the two parts to be joined.

Gas welding

   A flux is also used during welding to remove impurities and oxides present on the surface of metal to be joined so as 5o obtain a good weld quality. The principle of gas welding is show in fig.

what-is-welding-give-its-applications.
what-is-drilling-machine-and-write...

    Various combinations of gases used for gas welding are as follows-

        (a) Oxy-acetylene (3200-3300℃)

        (b) Oxygen-methyl acetate procedure (2600-2900℃)

        (c) Oxy-propylene (2500-2850℃)

        (d) Oxy-propane (2450-2775℃)

        (e) Oxy-methane (2350-2750℃)

        (f) Oxy-hydrogen (2400℃)

        (g) Air-propane (1750℃)

    Out of these most widely used gas combination for producing a hot flame for welding metals is oxygen and acetylene (C2H2) because it gives the highest flame temperature.