# WHAT IS THE OXYFUEL PROCESS?

Oxyfuel.

It is a chemical combustion process in which 2 gases are mixed generating a flame that can reach 3200 degrees Celsius.

A preheat flame is formed by mixing oxygen with a fuel gas; this flame heats a point on the metal until it reaches ignition temperature, then oxygen is injected which rapidly oxidizes most of the metal in a narrow zone to make a cut. The slag is displaced by the oxygen jet, moving the torch across the workpiece at an appropriate speed to produce a continuous cut.

What are the conditions for oxyfuel cutting?

• The ignition temperature of the metal must be lower than its melting point.
• The combustion products (slag and oxides) must have a lower melting point than the metal.
• The combustion products must not be gaseous in any appreciable proportion.
• The combustion of the metal must generate sufficient heat.
• Sustain combustion.
• The material must have a relatively low thermal conductivity.

What metals can be cut with oxyfuel cutting?

Apparently only a few metals meet the conditions mentioned above, such as: carbon steels and low-alloy steels. However, it is possible to cut other metals using “special” procedures. Stainless steel, high-carbon steel, aluminum, and copper cannot be cut.

What gases should be used in the oxyfuel cutting process?

To carry out the oxyfuel cutting process successfully, the oxygen must be at least 99.5% pure.

The most common fuel gases are acetylene and propane. Acetylene produces the hottest and most concentrated flame, at approximately 3200°Celsius.

The components of the oxyfuel cutting equipment are:

• Pressure regulators: Reduce cylinder pressures to appropriate working pressures.
• Flashback arrestors: Prevent flashback.
• Check valves: Designed to keep the gases in their hoses, preventing backflow.
• Torch: The component where the gases are mixed.
• Cutting tip.

Characteristics of oxyfuel cutting flames

• Main function: to preheat the steel to ignition temperature.
• Supply the necessary heat during cutting.
• Protect the oxygen jet from airborne impurities.
• Remove oxide from the plate surface.

Flame types

Carburizing flame

Neutral flame.

Color: white

Inner cone: well defined

Uses:

Cutting of carbon steels and low-alloy steels.

Oxidizing flame.

Color: bluish

Inner cone: well defined with feather

Uses:

Straightening

Fast cuts of low quality.

Quality piercing and beveling.

How to select the flame?

1. A. Preheat flame with excess fuel gas.
2. B. Neutral preheat flame without cutting oxygen.
3. C. Neutral preheat flame in the presence of the cutting oxygen jet.