gas welding

Gas Welding-Definition, Equipment, Types of Flame, Working Diagram, Types, Temperature, PDF

Amrit Kumar Manufacturing Technology 5 Comments

Are you looking for Gas Welding? So today we will study the Definition, Working Diagram, Types, Temperature, Advantages, Disadvantages, Application, PDF. Here you will get the articles of Mechanical Engineering in brief with some key points and you will get to know an enormous amount of knowledge from It. So If you find this articles helpful, please let us know in the comment box, either if any correction required too, also let us know in the comment box.

Gas Welding:

Before going to Gas welding we first discuss welding.

So, Welding is defined as 

It is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence.

This is often done by melting the workpiece and adding a filler material from a pool of molten material that cools to become a strong joint,

but sometimes the pressure is used in conjunction with heat, or by itself, to produce the weld.

This is in contrast with soldering and brazing which involves,

Melting a lower-melting-point material between the workpiece to form a bond between them, without melting the workpiece.


“The welding process is a material joining process which produces coalescence of Material by heating them

to suitable temperature with or without application of pressure or

by the application of pressure alone and with or without the use of filler materials”.

Gas welding is a type of liquid state welding process, in which fuel gases burns to generate heat.

Gas Welding Definition:

This heat is used to melt interface surfaces of welding plates which are held together to form a joint.

In this welding process, mostly oxy-acetylene gas is used as working fuel gas.

This process can be done with or without the help of filler material.

Gas Welding Main Parts or Component or Equipment:

  1. Cylinders:
  2. Oxygen cylinders:
  3. Acetylene cylinders:
  4. Pressure regulator:
  5. Torches:
  6. Goggles and
  7. Gloves:


Oxygen and acetylene are stored under pressure in a steel cylinder.

They are seized by the amount of oxygen or acetylene that they hold.

Cylinders should always be secured and used in the upright position.

When a cylinder is not being used the valve cap should always be in place.

Oxygen cylinders:

These cylinders are made of steel and are usually painted green.

They contain compressed oxygen at presses that can be as high as 2200 PSI.

All cylinders have valves and are fitted with a screw-on steel cap

that protects the cylinder valve when the cylinder is not in use.

Acetylene cylinders:

These cylinders contain acetylene under pressure are painted black made of steel and have cylinder valves.

The cylinders contain porous filler material,

which is fitted with acetone that allows the acetylene to be safely be contained in the cylinder at 250 PSI.

Acetylene should never be used at a pressure that exceeds 15 PSI

as it becomes highly unstable which depending upon the condition could cause it to decompose and explode.

Pressure regulator:

Both oxygen and fuel gases are filled in the cylinder at high pressure.

These gases cannot use at this high pressure for welding works,

So a pressure regulator is used between the flow.

It supplies oxygen at a pressure about 70 – 130 Kn/m2 and gas at 7 – 103 Kn/m2  to the welding torch.


The torch assembly consists of the handle Oxygen and fuel gas valves and the mixing chamber.

Welding tips or cutting attachment with the handles can be used, for welding, heating and cutting operations.

Oxygen and fuel gas flow through tubes inside the handle which blend in the mixing chamber or tip.

It is at the tip that the mixed gas is ignited.

Goggles and Gloves:

These two Goggles and Gloves are used for safety purpose.

Goggles protect eyes and Gloves protects the hand from radiation and flame of fire.

Gas Welding Types of Flames:

  1. Neutral Flame
  2. Oxidizing Flame
  3. Carburizing or Reducing flame

 Neutral Flame:

Welding is generally carried out using the neutral flame sitting which has equal quantities of oxygen and acetylene.

Oxidizing Flame:

The oxidizing flame is obtained by just increasing the oxygen flow rate.

Carburizing or Reducing Flame:

The carburizing or reducing flame is achieved by increasing acetylene flow in relation to oxygen flow.

Because steel melts at a temperature of 1500 degree centigrade the mixture of Oxygen and acetylene is used as it is the only gas combination with enough heat to weld Steel.


Other gases such as propane hydrogen and coal gas can be used for joining lower melting point of metals and for brazing and silver soldering.

Gas Welding Working Diagram:

Gas Welding

The above figure shows all the equipment are set carefully and Now

The gas cylinder and oxygen cylinder connected to the welding torch through pressure regulators.

A regulate pressure of gas and oxygen supplied to the torch where they properly mixed.

The flame is ignited by a striker.

Take care the tip of a torch is pointing downward.

Now the flame is controlled through valves situated in the welding torch.

The flame is set at the natural flame or carburizing flame or oxidizing flame according to the welding condition. Now,

The welding torch moved along the line where joint to be created.

This will melt the interface part and join them permanently.

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3 Types of technique in Gas welding:

Leftward technique:

The leftward technique is used almost exclusively and is ideally suited for welding butt, fillet, and

lap joints in sheet thickness up to approximately 5 mm.

Rightward technique:

The rightward technique finds an application on plate thickness above 5 mm for welding in the flat and horizontal-vertical position.

All positional rightward technique:

This is a modification of the rightward technique and

It is ideally suited for welding steel plate and

in particular, pipework where positional welding (vertical and overhead) has to be carried out.

Types of Gas Welding:

Oxyfuel Gas
  • Oxy-acetylene
  • Oxy-hydrogen
  • Pressure gas welding
  • OAW
  • OHW
  • PGW

Gas Welding Advantages, Disadvantages, and Application:


  1. Process is versatile
  2. Adapted too many different jobs
  3. Equipment is relative to low cost
  4. Portable
  5. Self-sufficient
  6. Independent from the availability of external energy sources.


  1. Welders skill required in manipulating the torch, the flame, and the filler rod.
  2. The flux required for most materials compared to low carbon steel.
  3. Reactive or refractory metals are unsuited to gas welding.
  4. Slow metal joining rate.


  1. For joining thin materials.
  2. Joining most ferrous and nonferrous materials.
  3. Used in automatic and aircraft industries and sheet metal fabrication.

Preparing for Competitive Exam? If Yes, then must go for this book:

The most valuable and trusted Mechanical Objective book by R S Khurmi 5000+ Objective.

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About the Author

Amrit Kumar


Amrit is a Co-founder of Learn Mechanical Portal (Previously owned ""). He completed his diploma in Mechanical Engineering from Acharya Polytechnic Bangalore and also completed his B-Tech from Delhi. Amrit is now preparing for Govt. exams. If you need help, you can ask him regarding any suggestions in the mechanical engineering field. He loves to meet new people.

Comments 5

  1. Very interesting. I will be glad if i get textbooks on all types of welding.
    I am doing advanced joining and advanced measurement.
    Thanks alot

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