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Gas welding process : Definition, Working and Applications

I hope you are very much aware with the term i.e. Welding. We have seen the overview of a welding process and also we have discussed the Arc welding process with the help of our previous posts.

Let us get more in depth and understand now Gas welding with the help of this post. So, let's start with the Gas welding process here with the help of this post.

Gas welding process

Gas welding process is basically a fusion welding process. It joints metals using the heat of combustion of an oxygen/air and fuel/gas (acetylene, hydrogen, butane) mixture. The flame thus melts and fuses together the edges of the parts to be welded, with the addition of a filler metal.

The oxyacetylene gas welding is commonly used in practice. The set-up for oxy-acetylene welding is displayed here in the following figure.

Oxy-acetylene is used to weld almost all metals and alloys. Acetylene is mixed with oxygen in correct proportions in the welding torch and ignition. The flame resulting at the tip of the torch is sufficiently hot to melt and join the parent metal.

The flame reaches a temperature of about 3000 degree Celsius. A filler rod is generally added to the molten metal pool to build up the seam slightly for greater strength.

Oxygen cylinder

Oxygen is filled in the cylinder at a pressure of 150 kg/cm2. This cylinder is made up of steel and it is black in color.

Acetylene cylinder

Acetylene is dissolved in acetone in a cylinder containing porous calcium silicate filler. These cylinders are usually filled to pressure of 16 kg/cm2.

Welding torch 

The welding torch, as displayed in the following figure, is used to mix the gasses in the right proportions to control the volume of gasses at the welding tip and to direct the flow. It has a handle to carry it and two inlet connections for gasses at one end.

Each inlet has a valve to control the volume of oxygen or other gasses. The two gasses mix up in a mixer and flame is produced by ignition.

Pressure regulator

It is located on the top of the gas cylinder. Its function is to reduce the pressure from the cylinder and to maintain it at constant value.

Hose and hose fittings

The hose is a rubber tube which permits the flow of the gas. There are two hoses required to carry oxygen and acetylene separately. They connect the regulator mounted on cylinders to the torch. Generally, a green color hose is adopted for oxygen and a red color hose for acetylene.


Goggles fitted with colored lenses should be provided to protect the eyes from harmful heat and ultraviolet and infrared rays.


These are used to protect hands from heat and the metal splashes during welding.

Wire brush

Its function is to clean the surfaces of joints before and after welding. 

Now we will see the types of flames in gas welding process in engineering practices with the help of our next post.  

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