The document discusses gas welding, specifically oxy-acetylene welding. It describes how oxy-acetylene welding uses oxygen and acetylene gases to generate a flame hot enough to melt and fuse metals. It also discusses the different types of flames (neutral, reducing, oxidizing) used in oxy-acetylene welding and their purposes. Finally, it provides an overview of the equipment used, including oxygen and acetylene cylinders, regulators, hoses, torches, and more.

1. SUBMITTED TO SUBMITTED BY
MR. ADITYA MISHRA ADITYA SINGH JADON
ASSISTANT PROFESSOR UID –K11075
MECHANICAL DEPATT. BRANCH –CIVIL (6TH SEM)

2. Gas Welding
 Gas welding is a welding process that melts and joins
metals by heating them with a flame caused by a
reaction of fuel gas and oxygen.
 The most commonly used method is Oxyacetylene
welding, due to its high flame temperature.
 The flux may be used to deoxidize and cleanse the
weld metal.
 The flux melts, solidifies and forms a slag skin on the
resultant weld metal.

3. Oxyacetylene WeldingUtilizes oxygen and a fuel gas to heat
metal until it is in a molten state and
fuse multiple pieces of metal together.
Can be used with or without a filler rod.
Great for brazing dissimilar metals
together.
Older technology that can be replaced
by GTAW

4. Oxyacetylene Welding
•Also known as “oxyacetylene welding”
•Uses an oxyfuel gas flame
•Can be applied with or without pressure
•Can be applied with or without the use of
filler materials

5. Gas Welding Oxy-acetylene Welding:
CaC2 + 2H2O = Ca (OH) 2 + C2H2
C2H2+2.5O2= 2CO2+H2O(vapour)+ 306.800 cal /mol

6. temperature
distribution in a neutral
oxyacetylene
The secondary combustion is also called the protection
envelope since CO and H2 here consume the O2 entering
from surrounding air, thereby protecting the weld from
oxidation.

7. Oxyacetylene Welding
• Flame formed by burning a mix of acetylene
(C2H2) and oxygen
• Fusion of metal is achieved by passing the inner
cone of the flame over the metal
• Oxyacetylene can also be used for cutting
metals

8. Oxyacetylene WeldingUses a high-temperature flame from the
combustion of acetylene and oxygen

9. Gas Welding
Oxyacetylene welding (a) overall
process, (b) welding area.

10. GAS WELDING
 Sound weld is obtained by selecting proper size of flame, filler material
and method of moving torch
 The temperature generated during the process is 33000c
 When the metal is fused, oxygen from the atmosphere and the torch
combines with molten metal and forms oxides, results defective weld
 Fluxes are added to the welded metal to remove oxides
 Common fluxes used are made of sodium, potassium. Lithium and
borax.
 Flux can be applied as paste, powder,liquid.solid coating or gas.

11. TYPES OF FLAMES

12. Types of Flame
 There are three types of flames in oxyacetylene welding:
• Neutral flame - Acetylene (C2H2) and O2 are mixed in equal amounts and
burn at the tip of the welding torch. The inner cone gives 2/3 of heat whereas
the outer envelope provides 1/3 of the energy.
• Reducing flame - The excess amount of acetylene is used, giving a reducing
flame. The combustion of acetylene is incomplete (greenish) between the
inner cone and the outer envelope. Good for welding aluminium alloys, high
carbon steels.
• Oxidizing flame - The excess amount of O2 is used, giving an oxidizing flame.
Good for welding brass.

13. Three types of flame in
oxyacetylene welding

16. TYPES OF FLAMES
 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)
 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) (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

17. Three basic types of oxyacetylene flames used in oxyfuel-gas welding and cutting
operations: (a) neutral flame; (b) oxidizing flame; (c) carburizing, or reducing flame.

18. Three basic types of oxyacetylene flames used in oxyfuel-gas welding and
cutting operations:
(a) neutral flame; (b) oxidizing flame; (c) carburizing, or reducing flame.

19. Types of Gas Welding
 1. Leftward Welding
 2. Rightward Welding

20. Gas welding two types

21. GAS WELDING EQUIPMENTS

22. GAS WELDING EQUIPMENTS
1. Gas Cylinders
Pressure
Oxygen – 125 kg/cm2
Acetylene – 16 kg/cm2
2. Regulators
Working pressure of oxygen 1 kg/cm2
Working pressure of acetylene 0.15 kg/cm2
Working pressure varies depending upon the thickness of the
work pieces welded.
3. Pressure Gauges
4. Hoses
5. Welding torch
6. Check valve
7. Non return valve

24. Oxy-Acetylene welding

25. Gas welding Apparatus
1. Oxygen cylinder
2. Acetylene cylinder
3. Pressure gauges
4. Valves
5. Hose pipes
6. Torch
7. Welding tip
8. Pressure regulators
9. Lighter
10. Goggles

26. Gas welding torch

28. Gas Welding - Advantages
• Simple equipment
• Portable
• Inexpensive
• Easy for maintenance and repair

29. Gas Welding - Disadvantages
 Limited power density
• Very low welding speed
• High total heat input per unit length
• Large heat affected zone
• Severe distortion
• Not recommended for welding reactive metals such as
titanium and zirconium.