gas welding overview

Gas Welding: Definition, Equipment, Flames, Working, Types, Advantages, Disadvantages, Applications [With PDF]

Amrit Kumar Manufacturing Technology 6 Comments

Before going to Gas welding let me discuss what is welding?

So, welding is defined as 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.

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

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

Definition of Gas Welding:

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.

Equipment of Gas Welding:

These are the equipment which needed to perform gas welding:

  • Cylinders
  • Oxygen cylinders
  • Acetylene cylinders
  • Pressure regulator
  • Torches
  • Goggles
  • Gloves
gas welding equipment

Let me discuss each one of that equipment in detail.

Cylinders:

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.

cylinders for gas welding

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 of about 70 – 130 Kn/m2 and gas at 7 – 103 Kn/m2 to the welding torch.

Torches:

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.

welding torch

Goggles and Gloves:

These two Goggles and Gloves are used for safety purposes. 

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

Types of Flames Used in Gas Welding:

Generally, there are three types of flames used in Gas Welding, and those are:

  • Neutral Flame
  • Oxidizing Flame
  • 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 with oxygen flow. 

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

However, other gases such as propane hydrogen and coal gas can be used for joining lower melting points of metals and for brazing and silver soldering.

Working Principle of Gas Welding with Diagram:

gas welding

The above figure shows all the equipment is set carefully and 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.

working gas welding

Types of Techniques Used in Gas welding:

There are three types of techniques used in gas welding:

  1. Leftward Technique
  2. Rightward Technique
  3. All positional rightward Technique

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

Types of Gas Welding:

These are the types of gas weldings:

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

Advantages of Gas Welding:

Gas Welding has the following advantages:

  • Less is versatile
  • Adapted too many different jobs
  • Equipment is relative to low cost
  • Portable
  • Self-sufficient
  • Independent from the availability of external energy sources

Disadvantages of Gas Welding:

Here are some disadvantages of Gas Welding:

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

Applications of Gas Welding:

Gas welding used for:

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

So this is all about Gas Welding, I hope you like my article. I also wrote articles on some other welding processes do check out those too.

And moreover do not forget to share the article on your favorite social platform.

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FAQ:

What is Welding?

The welding process is a material joining process that 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.

What are the types of Gas Welding?

These are the types of gas weldings:
1. Oxyfuel Gas
2. Oxy-acetylene
3. Oxy-hydrogen
4. Pressure gas welding
5. OAW
6. OHW
7. PGW

What are the types of Flame?

Generally, there are three types of flames used in Gas Welding, and those are:
1. Neutral Flame
2. Oxidizing Flame
3. Carburizing or Reducing flame


Reference:

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About the Author

Amrit Kumar

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Amrit is a Co-founder of Learn Mechanical Portal (Previously owned "Engramritkumar.com"). 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.

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Comments 6

  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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