There is a direct relationship between flow velocity and flame propagation rate. The higher the flame propagation rate, the higher the flow velocity can be set. The higher the flow velocity, the higher the gas volume combusted per unit of time. The more gas is combused, the higher the concentration of heat released.
Flame heating means local heating preparatory to hot forming, e.g. bending of pipes, necking of distributors, dishing of vessel bottoms, or for preheating and reheating in welding and flame cutting. Both normal welding torches and specially developed high-output oxy-acetylene torches are used for these heating procedures. The use of high-output heating torches is recommended in particular when large quantities of heat are to be applied to the work piece with the highest speed and concentration possible.
