Oxy-acetylene welding, also known as oxy fuel welding, gas welding or blowpipe welding, is a time-honored technique that is commonly used to join metals for repair work or creative projects.
In this article, our industrial welding company explains how oxy-acetylene welding works. Keep reading to learn about the main steps in doing oxy-acetylene welding and the benefits and limitations of this trusted method.
How oxy-acetylene welding works
Oxy-acetylene welding is a type of gas welding that involves heating parts with a torch and joining them together with or without a suitable filler metal.
Oxy-acetylene welding creates a strong, durable bond. There are several different oxy-fuel welding methods, each suited to specific applications.
Autogenous welding
Autogenous welding is used to weld two parts made of the same metal, which therefore share the same melting point. Both parts are heated until they melt and bond, without the use of filler metal. To achieve a successful weld, it is essential to reach the melting point quickly without overheating the parts, to preserve their natural properties.
Soft soldering
Soft soldering uses tin wire as a filler metal, which has a melting point below 400°C. This technique is ideal for domestic repairs, electronics, electrical work and more. Soft soldering prevents oxidation and delivers a quality finish. Soft soldering involves heating the parts, applying the tin wire and allowing the assembly to cool. It creates a precise, strong solder joint.
Hard soldering (Silver soldering)
Hard soldering is similar to soft soldering, but uses a filler metal with a higher melting point (reaching up to 700°C) such as copper or silver. This process is used widely in the plumbing and heating industries. Positioning the parts is crucial to achieving a strong, high-quality weld. The process involves continuously applying the torch to the weld line while feeding the filler metal into the weld area.
Brazing
Brazing relies on an even higher soldering temperature, above 900°C. The preferred filler metal is coated brass. This method is ideally suited to larger-scale jobs. The process is similar to that of hard soldering but it results in stronger bonds.
Steps in oxy-acetylene welding
Oxy-acetylene welding must be performed following a well-defined, step-by-step process, to ensure a successful weld. Here are the main steps in ocy-acetylene welding:
1. Prepare the parts
The first step is to prepare the parts that will be joined. This involves carefully cleaning the surfaces of the metals and removing any traces of dirt, oil or paint. Thorough scrubbing with an abrasive will also create microgrooves that help the filler metal stick to the surface.
2. Select a torch and adjust the flame
Choosing the right torch for the welding method and metal type is just as important as the other steps in this process. Depending on the requirements of your welding project, you can choose between a low-pressure or injector type torch, and an equal pressure torch. Before beginning to weld, make sure the flame is properly adjusted so that you can control the temperature and make a proper weld.
3. Lighting the torch
Once you have chosen a torch an opened the gas supply, it’s time to light it. Depending on the type of torch used, there are different ways to do this. For low pressure torches, you will need to open a valve to let the gas flow out. Equal pressure torches require both gases to be ignited using a torch striker and not a match.
4. Heating the parts
This stage involves heating the parts you want to weld to the appropriate melting temperature. Aim the torch at the areas to be welded, and apply heat evenly to avoid distorting or overheating the parts. It is important to maintain the correct distance and angle between the torch and the parts. If you need a professional who can perform high-quality welding, contact us today!
5. Filler metal input
For brazing and soldering methods, the filler metal is added when the parts are hot enough to melt the material being used: tin, copper or silver wire. The filler is placed between the two parts to be welded. Capillary action allows it to penetrate the gaps and form the weld. For autogenous welding, no additional metal is required, as the original metals fuse together directly.
6. Cooling and finishing
Once the weld is complete, move the torch away from the parts and allow them to cool at room temperature. To avoid burns, never handle the parts while they are still hot. After the parts are cool, you can apply finishing touches and achieve a clean, attractive finish using a wire brush or abrasive.
