Whenever most people think of welding, it is probably gas welding that first comes to mind. However, it is not only one of the most iconic forms of welding in the public eye, but also happens to be one of the most popular among many industries around the world.
And for very good reason (well, reasons), as you are about to find out.
Here we'll explore exactly what gas welding is, and discover why it still remains one of the most important forms of welding around the world.
What is gas welding?
Put simply, gas welding is the process of using heat generated from burning a fuel gas (like acetylene) to cut and/or join metals together. Gas welding is one of the most important types of welding because of its scope of application.
It is one of the oldest forms of heat-based welding and remains the go-to option for many industries.
The reason why this welding technique is still very popular is because of its ease of use and low-cost nature. Carrying out a welding process with gas welding is relatively easy and does not necessarily require expert welders.
When a fuel such as acetylene is used, the flame can reach temperatures of just over 5,700°F (3200°C). This temperature is lower than what we get from an arc welding machine, but the advantages previously mentioned outweigh this drawback for various types of repair and construction work.
How is gas welding done?
When metals are welded using gas welding equipment, fuel gases are mixed with oxygen to produce a concentrated flame at a high temperature. This flame directly strikes a weld area and melts the materials in question (often, but not always, with the addition of filler material).
The melted section of each piece of metal forms something called a melt or weld pool where the liquid metals diffuse into one another and, once cooled, form a strong joint. This form of welding can be used for many common types of metals.
Completion of weld requires the welder to slowly remove the flame from the joint, giving it time to harden without oxidation.
Most commonly, oxygen is mixed with gases like acetylene, hydrogen, propylene, butane, and others. The choice of gas used for welding depends on the type of project, cost, and flame control.
The most commonly used gas welding fuel gas is acetylene. This is so popular, in fact, that it is not uncommon to replace the term gas welding with either oxy-acetylene welding, depending on the fuel that is used.
What are the main parts of a gas welding system?
You can probably already guess some of the main components of a gas welding system, but what other parts are needed?
Let's take a look.
- A fuel cylinder: One of the most important parts of a gas welding system is, obviously, the fuel gas. This is usually stored in a cylinder of some kind. The cylinder is sealed and is made from heavy-gauge steel to prevent the compressed fuel from weakening the cylinder. These cylinders are usually painted a Maroon color.
- An oxygen cylinder: Another critical component of a gas welding system is a constant supply of pure oxygen. The oxygen cylinder holds the compressed oxygen required for the weld. Both the oxygen and fuel cylinders are made to withstand the pressure from the respective gases. These are usually, but not always, painted black.
- Pressure regulator: As both the fuel and oxygen gases are stored at high pressure, some method is required to reduce the pressure for safe use during the welding process. This is where a pressure regulator comes in very handy. Typically this device helps supply oxygen at a steady pressure of between 70 and 130 KN/M2, and the gas supply at between 7 and 103 KN/M2.
- Control valves: Both gases have their separate control valves. A control valve is used to control the amount of gas being released from the cylinder. Control valves are also crucial for controlling the fuel to oxygen ratio.
- Mixer chamber: This device is used, as the name suggests, to safely mix the fuel and oxidant. The control valves are used to regulate the flow of gases from the cylinder to the mixer chamber.
- Welding torch: This is the "business end" of the gas welding gear. This usually contains the mixer chamber and the control values too. At the other end of the torch is a nozzle where the fuel-oxygen mixture is burnt together for ease of application by the welder.
What are the advantages of gas welding?
As previously mentioned, gas welding is a very popular form of welding. But why?
This is because it has some very distinct advantages over its competitors. These include, but are not limited to:
- It can be used to join many different types of metal: - Gas welding can be used to weld ferrous and non-ferrous metals together. This is one of its greatest strengths compared to other welding processes.
- It does not require the use of electricity: - When we compare gas welding to the other popular weld methods like arc welding, gas welding, gas welding does not require any electricity to operate. Hence, you can use gas welding in places that do not have access to electricity.
- Cheap Equipment costs:- The initial required capital for gas welding is very low when compared to other forms of welding. For some applications, this is very beneficial.
- Doesn’t require specialized labor: Gas welding doesn’t require highly specialized labor. This makes it easier to find gas welders, as well as keeps the labor charge low.
- Gas welding gear is very portable: The whole setup for gas welding is relatively easy to pick up and move around, unlike some other forms of welding.
What are some of the disadvantages of gas welding?
While gas welding does have some tangible, and important, benefits over other forms of welding, it is not perfect. Some of its drawbacks include, but are not limited to:
- Not suitable for thick sections.
- Gas welding tends to provide a low surface finish. This means its welds usually need post-weld finishing if aesthetics are important.
- Cannot be used for high-strength steel. This is because, but in its very nature, the heated zone can affect the mechanical properties of the parent metals.
- The slow rate of heating and metal joining compared to other forms of welding.
- Cannot reach the temperatures of arc welding
- Doesn’t have a dedicated flux shielding system. This can result in some very serious weld defects.
What are the most common applications of gas welding?
Gas welding is used in a variety of industries. Here are some of the most common ones.
- Repair works: One of the most common applications of gas welding is for repair works.
- Fabrication of sheet metal: Thin to medium sheet metals are easily weld using gas welding.
- Aircraft industry: Oxy-Acetylene welding is commonly used in joining various aircraft parts.
- Automotive industry: Used to weld parts of the frame and the chassis.
- Joining High carbon Steel: Gas welding is very effective in melting high carbon steel.
As we have seen, gas welding is one of the most important, and widely used, weld methods around. A combination of its relatively low cost, ease of use, and portability make gas welding one of the most popular weld methods that we use today.
Commonly, novice welders "cut their teeth" by mastering gas welding before moving on to more advanced, and technically challenging forms like ARC or MIG welding. If you are looking to establish a career in welding, gas welding is an ideal jumping-off point.