Gas welding includes some of the oldest methods of welding which are still in use today. Its survival is down largely to the fact that it doesn’t require an energy source, like most other processes, meaning that it is much more portable. It is less used in heavy industry as electrical methods allow for more control and efficiency in large scale projects, however given its proficiency to weld both metals and plastics in a wide range of environments as well as the attribute of portability it boasts, Gas Welding is still favored by many welders and smaller welding companies.
As the name suggests, gas is used in this weld, predominantly oxygen. Uses gases in the weld, especially oxygen to weld using pure oxygen create a hot enough flame to weld and to cut. Temperatures delivered by the most popular gases range from around 2000°c (3600°F), created from propane and air flame to 3100°c (5600°F) from an acetylene and oxygen flame, although Hydrogen and Oxygen combine can produce a flame in excess of 3500°c (6300°F).
There are however two main methods in Gas Welding which remain popular today and although there are a number of others, there limited use and inferior weld mean only two dominate. They are Oxyacetylene Welding (OAW) also known as Oxy-Fuel Welding and Oxyhydrogen Welding (OHW).
Oxyacetylene Welding (AKA Oxy-Fuel Welding)
Distinctions: Inexpensive equipment, versatile for range of materials
Applications: General repair
Oxyacetylene Welding is perhaps the most common Gas Welding method, often referred to as Oxy-Fuel Welding. As with most other Gas Welding methods, it is used less in heavy industry today and its application centers more around general repair.
The equipment required is fairly inexpensive. Here, a flame is what creates the heat required to fuse two or more work pieces together and is generated from acetylene in oxygen. Temperatures of this flame can reach 3100°c (5,600°F) and whilst they are cooler than a number of methods which use electricity to generate heat, a proficient weld is created. The heat is applied through an Oxyacetylene welding torch which allows for a relatively small area to be welded at a time, which also helps to concentrate the heat transfer. To prevent burning, the torch must be continuously moved around the area designated for welding.
Filler is sometimes require in this process but it is not essential. It is dependent on the type of material being welded. In the welding process itself, one drawback is however the fact that the gas arc cools slower to that of an electric arc, meaning the weld can be more prone to stresses. Nonetheless, Oxyacetylene Welding is a very popular method employed by many, thanks to its versatility and the relatively inexpensive equipment required.
Distinctions: Hydrogen and oxygen produces flame
Gas Welding methods do not vary as much as seen in other processes. As such, Oxyhydrogen Welding is performed much in the same way as Oxyacetylene Welding in that a flame produces the heat required to fuse two or more materials together. The temperature of this flame, fuelled by both pure oxygen and hydrogen can reach upwards of 3500°c (6,300°F).
This combination of gases was one of the first mixes in welding and has certainly stood the test of time.
Whilst its applications are more limited than other gas welds, it does still benefit from its portable energy source. However, the gas mix is perhaps more expensive than other more popular fuels on the market, which also limits its widespread use today.