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Metal Fabrication

Oxy-Fuel Cutting

Oxy-fuel cutting is the most widely applied process for cutting mild steels and low alloyed steels. The process covers the entire thickness range from 1 mm to 2500 mm (0.04 -100 in.); it gives an excellent cut quality and the investment costs are low. Furthermore the process can easily be mechanised. Oxy-fuel cutting is a combustion process. An oxygen jet burns the metal in a narrow section to make a cut and removes the combustion products (slag) from the kerf. The purity of the cutting oxygen is of great importance for the cutting speed that can be achieved. A higher purity level means a higher cutting speed.

Other Applications

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Product NameDescription/BenefitsDownloads
Gases

Assist/Cutting Gases
Oxygen

In the preheat flame, a fuel gas burns in oxygen, generating heat. The flame consists of an outer and an inner combustion zone. The main purpose of the preheat flame in most flame processes is to achieve rapid, local heating. This imposes requirements on the combustion properties of the gas that is used. In cutting, it is not the preheat flame in itself that performs the cutting operation, but rather an oxygen jet. This oxygen jet oxidises the metal, with the evolution of heat, and expels the combustion products (the slag) from the kerf. The purpose of the preheat flame is to heat the metal to the ignition temperature, sustain the cutting process and support the cutting oxygen jet.

In the preheat flame, a fuel gas burns in oxygen, generating heat. The flame consists of an outer and an inner combustion zone. The main purpose of the preheat flame in most flame processes is to achieve rapid, local heating. This imposes requirements on the combustion properties of the gas that is used. In cutting, it is not the preheat flame in itself that performs the cutting operation, but rather an oxygen jet. This oxygen jet oxidises the metal, with the evolution of heat, and expels the combustion products (the slag) from the kerf. The purpose of the preheat flame is to heat the metal to the ignition temperature, sustain the cutting process and support the cutting oxygen jet.

Fuel Gases
Acetylene

Acetylene is the primary fuel for oxy-fuel welding and is the fuel of choice for repair work and general cutting and welding. Acetylene produces the hottest and most concentrated primary flame of all industrial fuel gases. Its calorific value is fairly low, but the portion emitted by the primary flame is very high, about 30%, making acetylene the fuel gas that produces the most heat in the primary flame.

Acetylene is the primary fuel for oxy-fuel welding and is the fuel of choice for repair work and general cutting and welding. Acetylene produces the hottest and most concentrated primary flame of all industrial fuel gases. Its calorific value is fairly low, but the portion emitted by the primary flame is very high, about 30%, making acetylene the fuel gas that produces the most heat in the primary flame.

Ethylene



Fuel Gas Mixtures

There are a number of proprietary fuel gas mixtures where the active constituent consists of methylacetylene and/or propadiene. Both of these gases are very energy-rich, but explosive. For this reason, stabilisers are added, preferably propane, propylene and butane. Mixed gases containing methylacetylene and or/propadiene are the fuel gases that produce the hottest flame, next to acetylene.

There are a number of proprietary fuel gas mixtures where the active constituent consists of methylacetylene and/or propadiene. Both of these gases are very energy-rich, but explosive. For this reason, stabilisers are added, preferably propane, propylene and butane. Mixed gases containing methylacetylene and or/propadiene are the fuel gases that produce the hottest flame, next to acetylene.

Hydrogen

Hydrogen is a highly flammable gas and burns with an invisible flame. In the presence of air and oxygen, it is explosive within a wide mixing range. A mixture of two parts hydrogen and one part oxygen is commonly called oxyhydrogen or explosive air. Hydrogen can also be used as a fuel gas for e.g. gas cutting. Its flame temperature and flame intensity are lower than those of acetylene and many other gases, but higher than those of propane and natural gas.

Hydrogen is a highly flammable gas and burns with an invisible flame. In the presence of air and oxygen, it is explosive within a wide mixing range. A mixture of two parts hydrogen and one part oxygen is commonly called oxyhydrogen or explosive air. Hydrogen can also be used as a fuel gas for e.g. gas cutting. Its flame temperature and flame intensity are lower than those of acetylene and many other gases, but higher than those of propane and natural gas.

Natural gas (Methane)

Natural gas consists primarily of methane. Its composition, and thereby its combustion properties, varies between different natural gas deposits. Natural gas is used mainly for heating purposes, but can also be used for e.g. cutting if it is already installed on the premises. The calorific value of methane is low, and a very small portion of it is produced in the primary flame.

Natural gas consists primarily of methane. Its composition, and thereby its combustion properties, varies between different natural gas deposits. Natural gas is used mainly for heating purposes, but can also be used for e.g. cutting if it is already installed on the premises. The calorific value of methane is low, and a very small portion of it is produced in the primary flame.

Propane

Propane has a higher calorific value per kg of gas than acetylene, but generates a lower portion of this heat in the primary flame. The flame temperature is lower and the oxygen requirement is approximately 4 times higher than for acetylene.

Propane has a higher calorific value per kg of gas than acetylene, but generates a lower portion of this heat in the primary flame. The flame temperature is lower and the oxygen requirement is approximately 4 times higher than for acetylene.

Propylene

The properties of propylene are similar to those of propane. The calorific value is roughly the same for the two gases, but propylene produces a larger portion of its heat in the primary flame, which means that propylene produces a hotter and more efficient flame than propane.

The properties of propylene are similar to those of propane. The calorific value is roughly the same for the two gases, but propylene produces a larger portion of its heat in the primary flame, which means that propylene produces a hotter and more efficient flame than propane.

Audit Services/Leak Detection

Our applications engineers can work with your plant personnel to analyse and understand your entire process. Based on that analysis and your needs, they can recommend process improvement solutions that can help you enhance product quality and consistency, plus optimise gas use. Air Products' services include leak-checking, furnace profiling, analytical calibration, gas analysis process troubleshooting and overall process review.

Our applications engineers can work with your plant personnel to analyse and understand your entire process. Based on that analysis and your needs, they can recommend process improvement solutions that can help you enhance product quality and consistency, plus optimise gas use. Air Products' services include leak-checking, furnace profiling, analytical calibration, gas analysis process troubleshooting and overall process review.

Training

Training can include gas atmosphere safety, properties of gases, metal treating applications, NFPA 86, piping and flow control panel requirements and troubleshooting for atmosphere problems. This information can help keep your furnace operations safe and help prevent accidents.

Training can include gas atmosphere safety, properties of gases, metal treating applications, NFPA 86, piping and flow control panel requirements and troubleshooting for atmosphere problems. This information can help keep your furnace operations safe and help prevent accidents.

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