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What Is Oxy-Acetylene Welding? All You Need to Know

Feb 10, 2021 ·

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There are a variety of welding processes for fusing together metal. From flux-cored welding, to GMAW/MIG welding, to GTAW/TIG welding, to SMAW welding, each welding process serves a specific purpose depending on the environment and types of materials being welded.

Another type of welding is oxy-acetylene welding. Also known as oxy-fuel welding, oxy-acetylene welding is a process that relies on the combustion of oxygen and a fuel gas, typically acetylene. You might hear this type of welding referred to as “gas welding.”

Gas welding is used almost exclusively for welding thin metal sections. You can also use oxy-fuel welding for heating tasks, like releasing frozen bolts and nuts, heating heavy stock for bending and soft soldering tasks.

Oxy-acetylene welding is a flexible and forgivable welding process, making it a great choice for amateur and part-time welders. Oxy-acetylene welding equipment is also portable and easy to use.

Juan Baltazar, program manager for education and development at Universal Technical Institute (UTI), provides insight into the oxy-acetylene welding process and the equipment used to get the job done.

How Does Oxy Acetylene Welding Work?

Oxy acetylene welding uses a high-heat, high-temperature flame that is produced by burning a fuel gas (most commonly acetylene) mixed with pure oxygen. The base material is melted with the filler rod using a flame from the combination of oxy fuel gas through the tip of the welding torch (commonly called oxy acetylene torch welding).

The fuel gas and oxygen gas are stored in pressurized steel cylinders. Regulators in the cylinder reduce gas pressure.

Gas flows through flexible hoses, with the welder controlling the flow via the torch. The filler rod is then melted with the base material. However, melting two pieces of metals is also possible without the need of the filler rod.

What Are the Main Differences Between Oxy-Acetylene Welding and Other Welding Types?

The main difference between oxy-fuel welding and arc welding types like SMAW, FCAW, GMAW and GTAW is the heat source. Oxy-fuel welding uses a flame as the heat source, reaching temperatures up to 6,000 degrees Fahrenheit.

Arc welding uses electricity as a heat source, reaching temperatures of roughly 10,000 F. Either way, you’ll want to be careful and safe when welding around any type of scorching temperatures.

In the early days of welding, oxy-fuel welding was used to weld thick plates. Today it’s almost exclusively used on thin metal. Some arc welding processes, such as GTAW, are replacing the oxy-fuel welding process on thin metals.

What Is Typical Oxy-Acetylene Welding Equipment?

Oxy-fuel welding basic equipment includes the following:

  • Cylinders: Steel pressurized cylinders contain oxygen and the fuel gas.
  • Regulators: The flow of gas needs to be controlled. Regulators take high pressure and reduce it to a lower working pressure.
  • Hoses: A nonporous hose is used to move the oxygen and fuel gas to the torch. To prevent the wrong hose from being installed or set up incorrectly, the oxygen hose is usually green and the fuel gas hose is usually red.
  • Hose fittings: Siamese hoses are one piece with hoses that have been molded together. Hoses can also be taped together. Oxygen hoses have right-hand threaded fittings. Fuel-gas hoses have left-hand threaded fittings. Hose connections shouldn’t leak after they’re tightened. Regulator-mounted and torch-mounted flash arrestors should be used on oxygen hoses and fuel hoses. Regulator-mounted flash arrestors stop flashbacks and backfires from entering the hoses and, potentially, the cylinders.
  • Safety valves: Safety valves keep the flow of gas going in one direction, preventing gas from flowing back into the wrong line or cylinder. They also reduce the possibility of a flashback.
  • Torches: Torches may vary in design, but all are made to provide complete control of the flame.
  • Tips: Because there’s not an industrial standard system for identifying tip sizes, welders need to master various tip sizes. Tip sizes are comparable to numbered drill sizes. There are some torch sets where each tip has its own mixing chamber.

With Any Type of Welding: Safety First

Like all types of welding, safety is very important with oxy-acetylene welding. Juan says aspiring welders should learn about safe oxy-fuel setup and system testing procedures before welding.

It’s important to refer to the manufacturer’s operating instructions and safety recommendations for how to handle gas cylinders, how to mix the gases and proper use of oxy-fuel torches and tip sizes. Juan says it’s also important to understand the proper use of the following welding gases:

  • Acetylene
  • Methylacetylene-propadiene stabilized gas (MAPP™)
  • Propylene
  • Natural gas
  • Propane

To ensure safety, Juan says welders should be familiar with the welding safety standards outlined by the American Welding Society, ANSI Z49.1:

  • Protect the eyes, ears, head, hands, torso and feet from burns.
  • Check the area for combustible materials.
  • Make sure everyone around has proper personal protective equipment (PPE).
  • Always know what direction the torch/flame is pointed.
  • Follow the proper setup and tear-down procedures.

“Welders are exposed to hot metal, bright lights and noxious fumes every day,” Juan says. “Many jobs involve working around heavy equipment that can cause serious injury if the proper safety precautions aren’t followed.”

Become a Welder: UTI’s Welding Training School

If you’re interested in learning about welding, UTI’s 36-week Welding Technology program can teach you the skills you need to succeed.1 Juan says the following skills are used in welding:

  • The ability to understand technical plans, drawings and blueprints
  • Manufacturing capabilities
  • Attention to detail and ability to spot flaws and defects
  • Basic math skills with the ability to calculate dimensions and take accurate measurements

The UTI Welding program covers both oxy-acetylene welding and arc welding techniques. Students graduate prepared for entry-level welding careers in construction, structural, pipe and fabrication industries.2

“Aspiring welders should consider both the demands and the opportunities welding presents,” Juan says. “Welders need to be prepared to work in tight spaces, at elevated heights and outside in all seasons. They need to endure many hours standing or crouching and be willing to wear goggles and other safety gear.

“Welders must be physically and mentally fit, with excellent hand-eye coordination and the ability to remain focused on a repetitive task for long periods of time,” Juan continues. “There’s currently high demand for skilled labor in the U.S.”6

To learn more about UTI’s Welding program, contact UTI online or call 1-800-834-7308.

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1) UTI is an educational institution and cannot guarantee employment or salary.

2) For program outcome information and other disclosures, visit

6) UTI graduates’ achievements may vary. Individual circumstances and wages depend on personal credentials and economic factors. Work experience, industry certifications, the location of the employer and their compensation programs affect wages. UTI is an educational institution and cannot guarantee employment or salary.

Universal Technical Institute of Illinois, Inc. is approved by the Division of Private Business and Vocational Schools of the Illinois Board of Higher Education.


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