Question

Why is oxy hydrogen flame used for cutting and welding metals

Answer 1

A common propane/air flame burns at about 2,250 K (1,980 °C; 3,590 °F), a propane/oxygen flame burns at about 2,526 K (2,253 °C; 4,087 °F),while an oxyhydrogen flame burns at 2,800 °C so it is way better choice than others 

Answer 2

An oxyhydrogen flame is used for cutting and welding of two metallic pieces together due to the heat produced by the flame , i.e , 2800 ° C . At this temperature the metal gets melted easily and hence it can easily be cut apart or welded together.