Gas cutting is a method of melting through materials — typically metals — using a combination of gases and oxygen. Comparing gas-cutting gases and techniques can help you find the solutions you need for maximum quality and productivity.

Gases Used for Gas Cutting

Gas cutting is a key process for producing essential items in many fields, including shipbuilding, construction and medicine. It has a number of applications, from using gas cutting on welding deformations to metal fabrication. There are three main elements to consider when distinguishing between the different types of gas cutting — the highest flame temperature, the volume of gas required for combustion, and the level of heat the combustion produces.

Thanks to their various advantages, five types of gas are commonly used for cutting:

Propane: Propane has a low peak heat level but a higher area of effect since the heat surrounding the nozzle extends greatly. This makes the cutting flame more spread out, but propane’s cutting speed is impressive. However, the low heat level makes the piercing speed significantly slower.
Acetylene: Acetylene has the highest flame temperature, reaching around 3600 degrees Celsius, which also means it’s the fastest gas-cutting type. Unlike propane, acetylene is focused on the inner core. It lowers the distortion percentage and reduces the area of the metal affected.
Natural gas: Natural gas has heat distribution levels of around 1,490 kilojoules per cubic meter (kj/m³) and a peak flame temperature of 2770 degrees Celsius. The low heat distribution levels, low peak flame temperature and slow piercing speed make natural gas a low-performance option.
Methylacetylene-propadiene (MAPP): If you need a gas with high pressure levels, such as for underwater cutting, MAPP is an excellent option, which is a mixture of methylacetylene, propadiene and other hydrocarbons. That said, the cutting speed is relatively average. The peak flame temperature is around 2900 degrees Celsius, but it has high release levels of around 15,445 kj/m³ for primary flames.
Propylene: Propylene is a liquid petroleum gas that has a high level of heat release of around 72,000 kj/m³ in the outer cone. Its flame temperature is just under 2900 degrees Celsius, similar to that of MAPP. The peak flame is average and it also has a high fuel gas volume requirement, which could be an expensive cut.

4 Kinds of Gas Cutting Techniques

Just as there are multiple kinds of gases used in gas cutting, there is more than one type of gas cutting technique. Here are four of the most common gas cutting systems:

Oxy-Fuel Cutting

Oxy-fuel is a thermal cutting method that uses fuels like gasoline met with oxygen to make cuts into metal items. The welder preheats the metal below its melting temperature using the fuel and oxygen mixture. They then use a pure oxygen jet to create an oxide of the metal in the preheated area. The exothermic reaction causes a slag, and the oxygen injected into the area blows the slag out of the kerf.

Oxy-fuel systems weigh around 35 pounds and don’t need electricity, so they’re portable and convenient. One of the greatest features of oxy-fuel systems is their versatility. They can be used to solder, cut, weld and gouge. Keep in mind that oxy-fuel systems are only used for applications containing iron or ferrous metals, such as steel.

The type of fuel gas you select determines the cut quality and preheating times. Typically, cutters use at least four basic fuel gases — propylene, natural gas, acetylene and propane. Paired with oxygen, these gases create the metal oxide chemical reaction. 

Oxy-fuel is generally better for thicker metals. It can easily cut through steel that’s around 6-12 inches in width. Torchers have greater cutting speeds than the typical hand-held plasma cutting systems, so keep that in mind when working with steels of more than 1 inch in width.

Some systems can cut through more than 20 inches of steel width. They also offer added safety, as some systems come in extended lengths to keep the operator a safer distance from the intense heat and slag. The longer hoses also allow for greater portability.

Plasma Cutting

Plasma is a type of ionized gas that relies on electricity for cutting power. It requires energy and electrically neutral gas to conduct electricity.

Gas and electricity combine in the chamber between the nozzle and electrode, causing the gas to become imbalanced. This process creates plasma gas, and the air pressure buildup forces it through the nozzle. The more energy you add to the cutter, the hotter the arc becomes, which gives you excellent cutting capacity.

Plasma cutters are best for cutting and gouging. They require electrical power, but they can still be considered portable since most job sites have electrical sources readily available. In terms of simplicity, plasma systems are much easier to use than other gas cutting systems and require minimal cleanup.

The average hand-held plasma system can cut through a maximum width of 1 inch. It works on nonferrous metals like cast iron and aluminum. One notable benefit is that it creates minimal slag, which allows for smooth and aesthetically pleasing cuts. This cutting method also saves time and money because, unlike with oxy-fuel, you don’t have to preheat the metal before cutting. It’s also faster with thinner metals and doesn’t create distortion, even when working with stacked metals.

If you’re working with shaped metals, plasma is advisable, as it’s quicker and more precise. Plasma also offers additional safety since it doesn’t expose you to an open flame or require handling explosive gases. However, safety isn’t a major concern if you invest in a cobot for your operation, as it can help prevent injuries and engage safety modes. Contact a Meritus Gas team expert for more information on our cobot equipment.

Laser Cutting

Laser cutting uses intense energy from a beam of light to rapidly heat and melt through a metal surface. There are two types of laser beams — pulsed and continuous. 

Pulsed laser beams use high-energy laser beams in short bursts. The compressed pulses allow the laser to shoot high-energy beams. Continuous laser beams create a stream of light beams without taking intermittent breaks, cutting for a longer period at a time. 

Once the laser beams melt through a particular section of a metal surface, a high-pressure gas like oxygen is used to blow away excess molten material. This process gives you a smooth, clean final cut.

Laser cutting offers many benefits compared to traditional cutting techniques. Its no-contact nature reduces maintenance costs. You can also create intricate designs with high-quality edges, no slag and a neat finish. The narrow kerf width allows for low wastage and maximum cost-effectiveness. Laser cutting is quick and precise, making it popular in various industries, including aerospace and automotive. 

One aspect to consider is that most laser-cutting machines’ cut depth is typically limited to under an inch in metal thickness. An expert tip for attaining low surface roughness, small kerf width and angle and minuscule heat-affected zone is to opt for a low laser power with a high cutting speed and finish it off with medium gas pressure using nitrogen as an assist gas.

CNC Machine Cutting

Computer numerical control (CNC) technology uses specialized software to improve precision and speed. It automates the fabrication process and improves worker safety. This software streamlines prototyping and creates precise measurements. It saves time and effort by integrating computer-aided design, allowing fabricators to identify potential errors prior to production. 

It can be integrated with oxy-fuel, plasma and laser cutting techniques for minimal waste, safety and efficiency. Computer-aided manufacturing makes the cutting process easier for operators and creates perfect finishes. It also helps fulfill regulatory requirements for safe operation.

Contact Meritus Gas Partners for Your Gas Cutting Needs

Innovative cutting technologies allow you to create quality finishes with speed and power. At Meritus Gas Partners, we partner with the best in the business to bring you reliable welding and cutting equipment. We’re passionate about helping businesses save money on hard goods, gases and consumables.

Visit any of our locations near you or contact us today and let us help you compare gas-cutting techniques to find the right combination of products to increase your process’s efficiency and quality. 

An oxy-fuel cutting torch is one of the most useful, but dangerous tools. It provides welders with a convenient and clean way to efficiently cut metal. However, when using a cutting torch, you are literally playing with fire, which means safety is extremely important.

When used correctly, an oxy-fuel torch is safe and offers unmatched efficiency. Read on for the basics of using an oxy-fuel torch, installing and shutting down processes and a checklist for safer usage.

Why an Oxy-Fuel Cutting Torch Can Be Dangerous

It’s important to understand the triangle of combustion to comprehend the danger of oxy-fuel cutting. Combustion requires fuel, oxygen and a source of ignition, which are all elements that need to be controlled. Oxy-fuel processes produce sparks and flames, so having a clean, well-ventilated workspace is essential to safe operation. This process also produces small amounts of infrared rays, so be sure to wear the appropriate personal protective equipment as outlined in ANSI Z87.1.

The primary fuel choice for oxy-fuel gas-cutting processes is acetylene. This gas has an exceptionally high flame temperature, reaching highs of 3600 degrees Celsius, which makes it the fastest gas-cutting option. While the intense heat helps it cut through metal quickly and effectively, it also makes it one of the riskiest welding equipment options, when used improperly.

Contact a Meritus Gas team expert for the latest and safest oxy-fuel cutting torch equipment!

How to Safely Handle an Oxy-Fuel Cutting Torch

Safe handling ultimately comes down to how you handle fuel cylinders, the pressure coming out of the cylinders and the regulators. Here are some safety guidelines and video demonstrations from Harris Products Group on the handling and storage of gas cylinders:

Transport cylinders with caps installed.
Securely chain cylinders to a cart or structure.
Remove the cylinder caps and store in a safe place.
Debris is the enemy of a regulator, so make sure the valves are free of debris. Aim the oxygen cylinder valve outlet away from you, people and flammable surfaces and open the oxygen cylinder valve momentarily to blow out any trapped debris. DO NOT crack the fuel gas valve. Instead, clean it out with a wet cloth.
Visually inspect the oxygen and fuel gas regulator for damaged surfaces. Do not use the regulator if there are any damaged components.
Inspect the inlet and outlet ports to ensure they are clean and free of oil or debris
Assemble regulators onto the cylinder valves and tighten with a wrench.
Turn the regulator adjusting knob or screw counter-clockwise until it moves freely with no tension.
S-L-O-W-L-Y open the oxygen cylinder valve first and then the fuel gas cylinder valve.
Check both the oxygen and fuel gas regulators for leaks with a solution of warm soapy water or a pressure test. If using warm soapy water, apply the solution to the inlet connection and observe for leaks indicated by the formation of bubbles. If bubbles form, re-tighten the cylinder connection with a wrench and repeat the test. If bubbles continue to form, DO NOT USE and contact your gas supplier. For the pressure test, turn off the cylinder valve and wait 2-3 minutes. If the pressure on the gauge drops, then there is a leak. Re-tighten the connection and repeat the pressure test. If the pressure continues to drop, DO NOT USE and contact your gas supplier.

Now, you’re ready to install the hoses and cutting torch.

How to Install a Cutting Torch

Following the proper setup procedures ensures the torch is functioning properly and maximizes safety. Here’s how to properly install a cutting torch:

Inspect both hoses for cracks.
Attach the hoses and tighten the connections with a wrench.
Inspect the torch for damage and close the valves. Do not use the torch if there are damaged components.
Ensure hoses are straight and not kinked.
Check the entire system for leaks: Turn the oxygen regulator adjusting screw clockwise to get 10 psi on the gauge. Once we have 10 psi, perform a pressure test by closing the oxygen cylinder valve and observing both gauges for 2-3 minutes to ensure the pressure does not drop. Release the excess pressure by opening the oxygen torch valve.
Conduct the same pressure test with the fuel gas.
Open the oxygen and fuel gas cylinder valves again. Set the proper pressures based on manufacturer’s recommendations. Pressures should be set to “at flow.”
Always purge the system before lighting any torch! Always use torches that have check valves. Flashback arrestors can be used where appropriate. Contact the gas equipment manufacturer for guidelines on when and how to use flashback arrestors.

Now, let’s look at how to light the torch and adjust the flame.

How to Light, Adjust and Shut Down an Oxy-Fuel Torch

Knowing how to properly adjust and shut down an oxy-fuel torch is essential to prevent leaks, fires and burns. It also helps prevent over-pressurizing and wasting fuel. Here are the top tips to properly light, adjust and shut down an oxy-fuel torch:

Light only the fuel gas. You should never light both gases at the same time!
Determine if you have too much fuel gas, too little fuel gas or the right amount. You are looking for a properly adjusted or “neutral flame,” which is a sharply defined inner cone with no outer feather
If you have too little fuel gas, you will have a smoky flame. Clear the smoke by opening up the fuel valve more and introduce the oxygen to adjust to a “neutral flame.”
If you have too much fuel gas, close the fuel gas needle valve, clear the smoke and introduce the oxygen.
Always shut off the oxygen first and then the fuel gas to extinguish the oxy-fuel torch.

For more detailed safety information, please refer to Harris Products Oxy-Fuel Safety Guidelines. This blog is intended to offer useful reminders and guidelines — not to serve as a substitute for full hands-on operator safety training.

Checklist for Handling an Oxy-Fuel Torch

Even workers who are trained and have years of experience can sometimes forget essential safety steps when things get busy. Here’s a checklist to follow to work with an oxy-fuel torch more safely:

Check that cylinders are free from oils and grease, which raise the risk of combustion. 
Ensure the cylinders are secured to a cylinder rack or stationary support to prevent them from tipping over. 
Look for damage to O-rings, which can affect the fit and cause leaks.
Check the regulator or torch handle for an adequately installed reverse flow check valve to prevent backflow into the regulator, torch or hose.
Ensure the area has sufficient ventilation and wear the required PPE to prevent respiratory problems.
Remove debris from the valve with nitrogen or an oil-free rag.
Tighten the regulators and check that the connection is clean.
Leak test all the connections with an approved leak test solution and tighten the connection or take the equipment in for repairs if it persists.

Contact a Meritus Gas team expert for the best equipment to make the oxy-fuel-cutting process more efficient and safe.

Why Training Is Important for an Oxy-Fuel Torch

Training is crucial for understanding best practices and safety measures in welding and cutting. Workers who are already trained should keep up with the latest safety resources to stay updated on regulations.

Specifically, safety training can help prevent flashbacks that occur when an explosion goes through the hoses, cylinders, hoses and torch. Professional education can explain how flashbacks occur, what to look for to prevent them and how to spot them. It teaches operators to properly install flashback arrestors and follow protocol to adequately and safely cool the cylinders down.

Operator safety training also underlines how to work with acetylene to cut, weld, gouge or braze more efficiently and safely.

Contact Meritus Gas Partners for Gases and Welding Equipment

At Meritus Gas Partners, we’re determined to help businesses find the right equipment and tools for welding to scale their operations. We can help you upgrade your equipment and set up automation solutions to boost safety and efficiency. Find a partner near you for the best welding and gas solutions. Our professional team will help your business get the best prices and products to improve productivity and safety.

With decades in the industry and the best partners in the business, we can offer you everything from troubleshooting equipment to customized gas and automation solutions that guarantee your maximum efficiency. Contact us to request a solution!

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