The fusion of the base metal and filler is achieved by employing a blowtorch as shown in below figure. The torch utilizes a flammable gas (acetylene generally, hydrogen, propane etc.) along with oxygen to produce the required amount of heat.
The flame comprises of following two zones
The flame comprises of following two zones
- Cone : It is at the immediate exit of blow torch. In case of acetylene gas being used, this zone releases hydrogen and carbon monoxide. Temperature at cone tip is about 3000C in case of oxyacetylene flame and the atmosphere is reducing.
- Plume: It is the zone where combustion is completed. This zone can be oxidizing, neutral or reducing based on the oxygen to acetylene ratio with neutral ration lying somewhere in 1 to 1.2.