To speak simple, Gas welding is a process of joining two metals with the application of heat from the flames so that they will melt and join together. In the last session, we had discussed Electric Arc Welding process along with Arc Recovery Time and Arc Characteristics whereas, in today's session, we can discuss Gas Welding Process with its Definition, Equipment, Working Principle, Types of Flames, Advantages, Disadvantages & Applications in a detailed way.
Gas Welding is a welding process that melts and joins the metals by heating them with a flame caused by a reaction of fuel gas and oxygen. The flux may be used to deoxidize and cleanse the weld metal. The flux melts, solidify and forms a slag on the resultant weld bead.
There are 3 types of Gas welding process which are presented below.
From the above types, Oxy-Acetylene Gas Welding was presented below in a detailed way.
The most commonly used Gas Welding is Oxyacetylene gas welding because of its high flame temperature.
The Gas Welding Equipment consists of the following parts which are mentioned below.
The working principle of the Gas Welding process is as follows.
Oxygen and acetylene gases will be drawn from their respective cylinders mixed in the torch body so that the mixture is processing certain high pressure.
When these high-pressure mixture is passing through the convergent nozzle, the pressure energy is converted into velocity energy and coming out from the nozzle at high velocity.
When the initiation for the burning of this mixture is given, the continuous flame is produced and the heat available in the flame will be used for melting and joining of the plates.
C2H2 + O2 → 2CO + H2 + heat
2CO + O2→ 2CO2 + heat
H2 + 1/2 O2 → H2O + heat
For complete combustion of one unit Volume of acetylene, 2.5 units of volumes of oxygen are required.
Note:Out of 2.5 units,1 unit volume of oxygen is obtained from the Oxygen cylinder and 1.5 units of volume of oxygen are obtained from the atmosphere.
Based on the amount of oxygen taken from the oxygen cylinder, the flame produced in oxyacetylene gas welding is divided into three types.
The types of Flames in Oxy-Acetylene Gas Welding are as follows.
The detailed explanation of three types of flames is as follows.
O2/C2H2 = 1
The inner and Outer cone will be distinguished based on the color I.e. the inner cone is red or yellowish whereas the outer cone is a light blue color.
Red Colour Flame → Incomplete Combustion.
Light Blue Colour Flame → Complete Combustion.
Where N = 10 to 15 mm.
T max = 3260°C
This flame is used for joining and cutting of all Ferrous and Non Ferrous metals except brass.
During the joining of brass workpieces, the zinc present in the weld bead will be getting evaporating and only copper is leftover in weld bead which is not giving required Mechanical properties of the weld bead.
O2/C2H2 = 1.15 to 1.5
Inner Cone is in between N/3 to N/2.
T max = 3380°C
Because of an excess amount of oxygen supplied from the oxygen cylinder, the amount of oxygen to be taken from the atmosphere is reducing. Therefore, the mixture is burning within a short duration from the tip of the nozzle.
Due to the high average temperature of the flame, high melting point metals can be welded easily.
O2/C2H2 = 0.85 to 0.95
Inner Cone is in between 2N to 3N.
Tmax = 3040°C
The oxygen to acetylene ratio is 0.85 to 0.95 and the inner cone is in the range of 2N to 3N and the maximum temperature is 3040-degree centigrade.
because of the short supply of oxygen, the flame has to travel for larger distances to completely burn.
Hence, the heat lost by convection and radiation will become considerable.
Due to this, the maximum temperature is only about 3040-degree centigrade.
The Advantages of the Gas Welding Process are as follows.
The disadvantages of the Gas Welding process are as follows.
This is the complete Explanation of Oxy-Acetylene gas welding process which was explained in a detailed manner.