Oxy-acetylene welding is a highly popular fabrication and repair technique in the world of DIY and craftsmanship. Equipped with an intense flame and remarkable precision, this method allows for strong welds on a variety of materials, primarily metal. If you are passionate about manual work and wish to deepen your welding skills, this practical guide will provide you with the key steps and essential advice to master this technique. Whether restoring old objects or creating custom pieces, oxy-acetylene welding is a valuable skill that will broaden your creative horizons.

Understanding the basics of oxy-acetylene welding

Oxy-acetylene welding, also known as autogenous welding, enables the fusion of two metallic elements, notably those made of ferrous steel. It is based on a basic principle: combining a fuel, acetylene, with an oxidizer, oxygen, to generate a flame reaching over 3,000 °C. This highly concentrated flame is applied directly to the metal to perform the weld. A fundamental part of this technique consists of correctly balancing the two gases in order to produce a stable and effective flame.

Safety measures to adopt

Before starting any welding operation, it is crucial to implement rigorous safety measures. First of all, the welder must wear personal protective equipment: goggles or a mask to protect the eyes and face, gloves, safety shoes, and a welder’s apron. Given the high risk of fire linked to the sparks produced, it is essential to ensure that no flammable material is nearby.

Moreover, the workspace must be clear, clean, and well-lit. Gas cylinders must be securely fastened and positioned at a sufficient distance from the welder, connected to the torch by hoses in perfect condition and long enough to allow adequate freedom of movement.

Necessary equipment

The equipment for autogenous welding is quite standard and generally includes:

• A transport cart
• An oxygen cylinder (white shoulder)
• An acetylene cylinder (brown shoulder)
• Pressure regulators (manometers) to adjust gas pressure
• Hoses to carry gases from the gauge to the torch
• Check valves to prevent gas backflow into the cylinders
• A torch tip suited to the task at hand
• A filler metal rod carefully selected according to the diameter needed for the weld bead

Preparation before welding

Before starting the weld, roughly clean the pieces to be welded and place them on a stable workbench, securing them firmly with a vice. Handling moving parts during welding is dangerous.

It is recommended to bend the end of the filler metal rod to avoid any injury in case of accidental contact with the face.

Performing the weld

Start by opening both gas cylinders. Next, open the acetylene valve on the torch and set the cylinder pressure to 0.5 bars. Then close the torch valve. Repeat the operation for the oxygen, this time setting the pressure to 1.5 bars. Slightly open the acetylene and very slightly the oxygen valves on the torch.

Use a lighter to ignite the gas mixture at the tip of the torch. Adjust the oxygen and acetylene valves to obtain a clear and pointed flame, called a jet, which is the hottest part of the flame. This part will be used to heat the joint to be welded and melt the filler metal rod, thus forming the weld bead.

Note: To preserve the membranes of the pressure gauges, remember to reset them to zero once welding is completed.