Types of flames

Three different types of flames used in gas welding are:

Neutral flame

Carburizing flame

Oxidizing flame

Neutral flame

When oxygen and acetylene are supplied to the torch in nearly equal

volumes, a neutral flame is produced having a temperature of

3200⁰C. 

A neutral flame has two definite zones. A sharp brilliant cone extending a short distance from the tip and an outer cone or envelope, only faintly luminous and bluish in colour.

The neutral lame is used for welding steel, stainless steel, cast iron,

copper, aluminium etc.

Carburizing flame

When there is excess of acetylene than oxygen, a carburizing flame

is produced. This flame has three zones. A sharply defined inner cone, an intermediate cone of whitish colour and a bluish outer cone.

A carburizing flame is advantageous for welding high carbon steel

and hard facing nonferrous alloys like nickel.

Oxidizing flame

When there is excess of oxygen than acetylene, oxidizing flame is

produced. This flame has two zones. A small inner cone which has purplish tinge and a small and narrow outer envelop.

This flame is used for welding zinc, copper, manganese steel, cast iron etc.