GAS WELDING
Oxy-Acetylene welding
The flame is produced at the tip of welding torch.
Oxygen and Acetylene are the gases used to produce the welding flame.
The flame will only melt the metal.
A flux is used during welting to prevent oxidations and to remove impurities.
Metals 2mm to 50mm thick are welded by gas welding.
The temperature of oxyacetylene flame is about 3200°c. Fig 3 shows Gas welding equipments.
Advantages
Gas Welding Equipment
Gas Cylinders
- Pressure
- Oxygen – 125 kg/cm2
- Acetylene – 16 kg/cm2
Regulators
- Working pressure of oxygen 1 kg/cm2
- Working pressure of acetylene 0.15 kg/cm2
- Working pressure varies depends upon the thickness of the work pieces welded.
Pressure Gauges
Hoses
Welding torch
Check valve
Non return valve
Gas Welding Equipment
Types of Flames
- When acetylene is burned in air, it produces a yellow sooty flame, which is not enough for welding applications
- Oxygen is turned on, flame immediately changes into a long white inner area (Feather) surrounded by a transparent blue envelope is called Carburizing flame (30000c)
- This flames are used for hardening the surfaces
- Addition of little more oxygen give a bright whitish cone surrounded by the transparent blue envelope is called Neutral flame (It has a balance of fuel gas and oxygen)
- Most commonly used flame because it has temperature about 32000c
- Used for welding steels, aluminium, copper and cast iron
- If more oxygen is added, the cone becomes darker and more pointed, while the envelope becomes shorter and more fierce is called Oxidizing flame
- Has the highest temperature about 34000c
- Used for welding brass and brazing operation
Advantages
- Equipment has versatile
- Same equipment can be used for oxy acetylene cutting and brazing by varying the torch size
- Heat can controlled easily
- Slower process
- Risk is involved in handling gas cylinders
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Regards,
Gas welding equipment