What Is Gas Welding?- Parts, Process and Uses

What is Gas Welding?

Gas welding is a liquid-state welding process in which fuel gas is burned to produce heat. The heat produced from the burning fuel gas is also used to melt the interface of the welded plates, which are kept together to form the joint. Oxyacetylene gas is the fuel gas that is primarily used in this process.

The gas welding process can be performed with or without the aid of fillers. When filler metal is used, it is inserted manually into the weld area directly.

In brief, gas welding is the process of cutting and/or joining metals with the heat generated from burning a fuel gas (e.g., acetylene). Gas welding is one of the most common types of welding because it has such wide application.

Gas welding is one of the oldest heat-based welding operations and is still an option for many industries.

Gas welding has been popular because it is easy to work with and economical. The gas welding operation is relatively simple and does not necessarily require a skilled welder.

With fuels like acetylene, the flame temperature can be slightly above 5700°F (3200°C). Although this temperature is lower than the temperature developed by an arc welding machine, the advantages of gas welding in many types of repairs and construction work certainly out-weigh this disadvantage.

How Does Gas Welding Work?

Gas welding is one of the most historically important forms of heat based welding and is used in many industries. The edges of the base material are heated to a point where they will melt and fuse to the metal creates the weld. Many gases burn at very high temperatures and this is possible.

The gas welding process is much simpler than arc welding. All the equipment is connected carefully in this process. The gas and oxygen cylinders are attached to the welding torch through pressure regulators. The pressure is then adjusted to the burner where the gas and oxygen are properly mixed.

The flame is initiated using a striker. It is important to note that the tip of the torch is pointed down as the flame is created. The flame is now controlled using a valve on the welding torch that is use to control the inner portion of the flame.

The flame is then adjusted to a neutral flame, carburizing flame, or oxidizing flame dependent upon the welding circumstances. Now the welding torch travels along the line to perform the joint. The energy from the flame causes the interface parts to join together in a permanent manner.

Gas welding type

There are many different gas welding methods; yet, the most common methods are known as oxyacetylene welding or oxy-gasoline welding processes. The gas welding process can melt both ferrous (containing iron) and non-ferrous metals; it does not use electricity as a source to produce a weld. 

During the process of oxy-acetylene welding, oxygen and a fuel gas is used (usually acetylene) is a mixed gas. Oxy-acetylene welding is primarily utilized in the welding of thin metal sections.

During oxy-gasoline welding, oxygen and gasoline are combined to make a mixed gas. Compared to acetylene, this method is better suited for torch-cutting steel.

Main Parts of Gas Welding

You can guess some of the main components of a gas welding system, but what other parts do you need?

Let’s see:

• Fuel cylinder: Fuel gas, one of the major components of the gas welding system, is typically held in a cylinder. Cylinders are sealed and constructed of heavy gauge steel so that it will hold its compressed form. Most of these cylinders are the color of a dark brown or yellowish brown.
• Oxygen cylinder: Essential supply of pure oxygen is another major component of the gas welding system. Oxygen cylinders contain the compressed oxygen to used in welding. These compressed gases must be built to withstand the high pressures in which they are stored, which is similar for both the oxygen and fuel cylinders. Taking note of the color, they are usually, but not always, a black color.
• Pressure regulator: Because they are stored at high pressure, using both fuel and oxygen gases in a welding process requires a strategy for reducing pressure – this is where a pressure regulator is useful. The industry supplies oxygen to the welding process, using the equipment usually at a constant pressure of 70 – 130 KN/M2. The gases still using pressure can be reduced ranging from 7 to 103 KN/M2 . 
• Control valves: Each gas has control valves. Control valves are intended to allow for a variety of flow from the cylinder. Control valves are also important for controlling the ratio of the fuel and oxygen.
• Mixing chamber: As the name suggests, the mixing chamber is used for safe mixing of fuel and oxidant. It is a mechanical device, having a control valve that regulates the flow of gas from cylinders and directs it to the mixer chamber.
• Welding Torch: This is the “end of the job” for gas welders. In most cases, this does not eliminate the mixing chamber and control values. At the other end of the welding torch, a nozzle that burns a mixture of fuel and oxygen, allowing the welder to do their job.

Applications of gas welding

Some important applications are:

• For joining most ferrous and non-ferrous metals, carbon steel, alloy steel, cast iron, aluminum and its alloys, nickel, magnesium, copper and its alloys.
• For joining thin metals.
• For joining metals in automotive and aerospace industries.
• For joining metals in sheet metal processing plants.
• Connecting materials that require relatively slow heating and cooling.

Advantages of Gas Welding

The following are the advantages of gas welding:

• Gas welding can be used to weld different metals: Ferrous and non-ferrous metals can be welded using gas welding. This is one of the most significant advantages over other forms of welding.
• No electricity needed: Unlike common welding processes such as arc welding, gas welding requires no electricity to operate. For this reason, gas welding can sometimes be the welding method of choice in regions where electric power is not available.
• Better temperature control: Gas welding allows for better control of the metal temperature in the weld. Because the welder can manipulate the gas flame, there is more ability to control the temperature of the metal.
• More control over filler metal deposition: In arc welding, the heat source and filler material are all the same “unit”. With gas welding, the heat source and filler metal are independent of each other, allowing for a little bit more control over the deposition rate of the filler material.
• Low-cost equipment: Gas welding has the least initial capital required compared to other forms of welding. Because there is limited initial capital, it is beneficial to have it available for various applications.
• No specialized or professional labour needed: Gas welding does not require the same level of expertise as other forms of welding. This makes it easier to find and use a gas welder, which ultimately drives down labour costs.
• Gas welding equipment is portable: Portable welding is a rare phenomenon, given that most welding methods are more difficult to transport and manage.

Disadvantages of Gas Welding

Disadvantages include, but are not limited to:

• Not suitable for thicker sections
• Gas welding produces a poor surface finish. This means that where aesthetics count, welds will likely have a post-weld finish.
• “Not for high-strength steel. This is because by the process itself the heated zone can affect the mechanical properties of the base material.
• Lower heat and speed for metal joining than other welding processes.
• Inability to get to the boiling temperature of the arc welding
• No continuation flux protection system. This could lead to very serious welding defects.”

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