Carburizing flame: When more acetylene present than oxygen in the flame then it is said to be carburizing flame or reducing flame. The carburizing or reducing flame is mostly used because of its need for oxygen will reduce oxides, such as iron-
The carburizing flame when burning with an excess of acetylene, which is surrounding the central white cone is a ragged bluish-
Oxidizing flame: If there is an excess amount of oxygen, the flame is said to be oxidizing flame. The secondary cone becomes very short and pointed because insufficient acetylene is passing from the nozzle to form a normal size cone. The excess of oxygen will react with the metal being welded and for this reason an oxidizing flame is employed when welding brasses to reduce the volatilization of zinc. The flame is slightly hotter than the neutral flame.
Neutral flame: When the acetylene and oxygen are in equal proportions in the flame then it is said neutral flame. The inner cone is large and sharply defined and the regulation of the flame is concerned with maintaining these two conditions. If these two conditions are not maintained the flame becomes either oxidizing or carburizing flame. During welding the nozzle tip becomes heated, this alert that the proportion of two gases tending to produce an oxidizing flame. For this reason it is needed to readjustment of flame frequently during welding process.
Pictures of flame
Carburizing flame: Indefinite cone and ragged acetylene feather.
Neutral flame: Clean white cone.
Oxidizing flame: Pale short cone, short hard flame.
The maximum temperature of the oxy-
Types of welding flame for different material