Cutting steel is a very crucial process that can be hazardous if not handled properly. An oxy-acetylene cutting torch can cut different steel as long as the composition falls within 3% carbon. However, handling the process with precision is needed for proper execution.
Hence why many people often ask questions like how does the oxy-acetylene cutting torch work?
If you’re new to this process and would like to understand it better, then you must keep reading. This article would help you understand how to set up your oxy-acetylene cutting torch when to use it and several tips that would come in handy.
How Does The Oxy-Acetylene Cutting Torch Work?
You’ve already established that an oxy-acetylene cutting torch is mainly used for cutting metal. All you need to do is set it up and you can get to work with it immediately.
However, it’s also crucial for you to understand how the cutting torch works before you decide to handle it. This will help you get a good quality cut every time you handle it and prevent any accidents that may occur.
The oxy-acetylene cutting torch primarily works via a combustion process that is caused by the mixture of acetylene and oxygen.
This combination process produces aflame with heat exceeding 3000°C, which is enough to cut through mild steel. Mild steel is any steel that has a carbon component that is a maximum of 0.3%.
How is this possible? Well, mild steel has an ignition temperature (700°C- 900°C) that gets rid of any component that protects it from oxygen.
So what happens is that the oxy-acetylene cutting torch preheats any mild steel to get it to that temperature. During this process, the steel that is being acted on will give off a cherry red color, indicating that it has been adequately preheated.
Once the steel is preheated, it loses the components that protect it against oxygen. Hence, oxygen acts on it.
Oxygen Will Give Off An Exothermic Reaction
When oxygen acts on the steel, it causes a reaction (exothermic), transforming the mild steel into oxidized liquid steel. This oxidized liquid steel is then removed and the solid steel within it is revealed. You might be wondering how you can tell when the solid steel is exposed. This is how;
While the oxy-acetylene flame is turned on, the exothermic reaction will keep causing a crust to form on the steel. This only occurs when the protective component against oxygen is still present in the steel. However, once you notice that there’s no crust forming, that means the solid steel has been revealed. Hence, you can cut through the solid steel.
The oxy-acetylene cutting torch cut is easily the fastest, most precise, and premium quality cuts you can achieve on steel.
Here’s out to set up an oxy-acetylene cutting torch;
- Connect the cutting attachment to the welding torch handle. Ensure only to fasten the coupling nut with your hands to prevent any damage to the O rings.
- Choose the required type and size of the tip. Make sure there are no damages to the tip, as this could lead to fires and explosions. Take your time to check the preheat and oxygen holes if they are clogged or not.
- Set the tip on the cutting extension head and tighten with a wrench of pressure between 15-20 pounds
- Open the oxygen valve present on the welding torch
- Loosen the preheat oxygen control valve present on the cutting attachment. Modify the oxygen regulator and choose the pressure required.
- Tightly close the present oxygen control valve
- Open the fuel valve located on the welding torch handle and choose the delivery range required
- Close the fuel control valve
- Depress the cutting oxygen level and get rid of the high-pressure cutting oxygen passage
- Open the fuel valve located on the torch handle. Use the one-half turn and light it up with a spark lighter.
- Keep increasing the fuel supply until the flame clears about ⅛” at the tip. After this lessen the supply a little until the flame is at the tip.
- Open the preheat oxygen control valve slowly until the preheat flame has a sharp inner cone shape.
Once this is done, lower the oxygen level until the flames become neutral. If you desire a carburizing flame, then refer back to the different types of flames we discussed before.
This should let you know when you have achieved that. Be sure always to have protective goggles and bodywear when you are working with a cutting torch.
How Does An Acetylene Torch Work Underwater?
The previous section has answered the question, “how does the oxy acetylene cutting torch work?” But did you know that it can also be used underwater?
With the need for different technological projects, it’s inevitable for underwater constructions to take place. And during this process, you do need to cut steel as well, but you might be wondering how you can light a flame underwater. This is where you need an underwater torch kit.
An underwater kit is very similar to the usual oxy-acetylene cutting torch kit but works differently. Just like the regular kit, it comprises the basic parts;
- A torch tip
- Two separate tanks
- A mixing chamber
- Hoses for the acetylene and oxygen
- A handle
However, the process of igniting a flame that can cut through the steel is different. The underwater cutting torch flame exits through the torch tip after the oxygen is mixed with acetylene. But you need a stable gas to maintain a steady flame all through the working process. Otherwise, the cutting process will be interrupted.
So what you need is a gas yielded at a high pressure which will balance/counter the strong water pressure. Also, you will need different jets that are filled with compressed air, which will create a bubble to enclose and protect the flame from water.
This bubble protecting the flame will then extend to the adjacent region directed on your work location. Hence, allowing you to use the cutting torch underwater easily.
Many underwater welders use this technique for multiple construction processes successfully. Although it sounds pretty easy and simple, you need to be very experienced before completing this process successfully.
Most underwater welders are expert swimmers and divers and have been trained to handle the underwater cutting torch expertly.
When To Use Oxy Acetylene For Cutting
Aside from learning the answer to the question “how does the oxy acetylene cutting torch work?” as well as how it functions underwater, you also need to understand that there are specific situations when you can use it. The only way for you to understand when to use the oxy-acetylene cutting torch is to learn the different types of flames it produces;
- Neutral Oxy-Acetylene Flame
The neutral flame is the most common and exists only when equal amounts of acetylene and oxygen interact with each other. This flame usually has no chemical effect on molten metal and it gives off a gentle hiss when emitted. This specific flame is mainly used for brazing, welding, and silver soldering different types of metal.
- Oxidizing Oxy-Acetylene Flame
The oxidizing flame is produced when there is more oxygen in the mixture with acetylene. In contrast to the neutral flame, this flame gives off a distinct roar when it is emitted. This type of flame is majorly used for welding metals made of zinc and copper and manganese steel. Also, it produces base metal oxide which helps protect the base metal.
- Carburising Oxy-Acetylene Flame
The carburizing flame is a more specialized flame created when there is more acetylene in the mixture of oxygen and acetylene. Although it produces a gentle hiss like the neutral flame, it is used for more technical processes. The carburizing flame is mainly used for welding high carbon steels and lead and several surface hardening processes.
Generally, the oxy-acetylene cutting torch is used for welding, soldering, and surface hardening. However, the type of flame you produce can determine what type of steel you can work on.
Different Types Of Cutting Torch Tips
The different parts of your oxy-acetylene cutting torch are important for getting the best quality cut of metal.
Hence, you need to be aware of the different types of tips available. The tips on cutting torches are usually crafted for different types of fuels.
This makes it important for reaching the appropriate temperature and achieving the best cut.
A perfect example is that the most common acetylene torch tip cannot be used with propane because it doesn’t have the right number of holes needed for it to get to its optimal temperature. Hence, an acetylene tip will make using propane for cutting ineffective.
Here are the two types of tips you can find for cutting torches;
- One-Piece Tips
This first category is usually manufactured with 4-6 preheated holes and as such can tolerate light, medium, and heavy preheating processes.
Mostly made from copper alloy, one-piece tips are used with acetylene, propylene, and methyl acetylene propadiene (MAPP). You would typically find this cutting torch tip effective for cutting sheets, gouging out metal, and several other functions.
- Two-Piece Tips
Two-piece tips are used for slower-burning fuels such as propane and require the perfect type of torch to be effective. For instance, many expert welders have explained that injector torches with propane offer cleaner cuts that are made quicker than acetylene.
It’s often best to consider the fuel you intend to use your cutting torch tip before making a final decision. This will help you make an informed choice that is beneficial for your project.
Oxy-Acetylene Cutting Torch Tips Size Charts
Another vital part of learning about how does the oxy-acetylene cutting torch work is to be aware of the different cutting tip sizes. The Oxyacetylene cutting torch tips size chart above shows the different sizes you need for various uses. This chart contains the following crucial factors that are considered for every size such as;
- Metal Thickness
- Acetylene Pressure
- Cutting and Preheating oxygen
There are also some instructions to help you make the best decision. Generally, getting the best cutting tips can be challenging because manufacturers can assign numbers to their tips that do not correlate with the chart.
Hence, it’s mostly advisable always to check the oxygen bore size to ensure they are compliant. Also, be sure to consider the amount of the intended fuel gas required to run the tip.
This will ensure there are minimal overheating and problems with the quality of your cut.
Oxy-Acetylene Cutting Torch Gas Pressure Settings Chart
The pressure settings for using the oxy-acetylene cutting torch are also an essential part of getting quality cuts. It’s often the best idea to follow the recommendations of the manufacturer you decide to patronize from.
The photo above depicts a typical chart to show the gas pressure settings when working with oxygen and acetylene. You can see the different gas pressure settings required for welding and cutting based on several parameters such as;
- Metal thickness
- Rod diameter
Although this isn’t the standard for all manufacturers, you can see that all the elements need to be adhered to before you can get the best cut. Ultimately, you need to check every factor before proceeding with handling an oxy-acetylene cutting torch accurately.
Difference Between Oxygen And Acetylene Cylinders
The major difference between the oxygen and acetylene cylinders lies in how they differ as gases.
Acetylene is never used in a pure state because it is a very volatile gas.
It is usually stored in a maroon cylinder with a solvent such as acetone which helps to reduce the process of dangerous reactions such as decomposition and explosion.
On the other hand, pure oxygen is kept in black cylinders and available in different purities such as food grade, industrial grade, ultra-high purity, etc.
Oxygen is non-flammable but might intensify fire and might explode if heated.
Frequently Asked Questions
Q. How Thick Can You Weld With Oxy Acetylene?
You can weld metal sheets that have a thickness that ranges from 2mm-50mm.
However, for any still that has a thickness that is equivalent or more than 15mm, a filler metal is included which acts as a welding rod.
Welding with oxy-acetylene is faster and gives you the ability to regulate the flame temperature. With total control, you can access the quality of your work easily.
Q. Can You Use Propane For Cutting Torch?
Propane can be used for cutting a torch to cut steel. However, cutting steel with propane takes a longer time to accomplish compared to oxy-acetylene when you use the same technique.
While oxy acetylene releases as much as 40% of its heat in the inner flame, propane gives off only 10% of its heat.
Hence, propane gives off most of its heat from the outer flame cone.
The fact is oxy acetylene preheats faster than propane, but the major issue is that most people use the same technique.
If you can adopt a different cutting technique with propane, then it will probably be just as effective.
Nevertheless, propane is mostly used for cutting in scrapyards and ship demolition because precise and quality cuts are not criteria.
Q. How Thick Of Steel Can You Cut With Oxy Acetylene?
You can cut any steel as thick as 13mm (0.5″) with oxy-acetylene. Usually, as a rule of thumb, you need to follow the manufacturer’s setting information when it comes to cutting tips.
This includes the following criteria like the thickness and gas pressures needed for a quality cut.
Alternatively, if you do not have an instruction to work with and need to cut steel less than an inch and a half thick, you can set the oxygen regulator for the 40 PSIG and the acetylene regulator for 10 psig. Otherwise, it’s always advisable to follow the instructions.
Q. Can An Oxy Acetylene Cutting Torch Be Used For Preheating?
An oxy-acetylene cutting torch can be used for preheating base materials. However, there are concerns about this process, as some people believe that the high temperature from acetylene is challenging to apply uniformly.
Also, there is a concern about the process leading to carburization. But everything lies in the adjustments.
You should make sure you’re using a properly adjusted flame, a well-sized tip, and tempil sticks to keep track of the heat.
The temperatures should be kept at 225°F for heavy members and specific situations. It can range from 400°F- 600°F. As long as the flame is adjusted and kept moving, it will preheat fairly.
Q. Why Is Stainless Steel Not Cut By Oxy Acetylene Cutting?
Stainless steel cannot be cut by Oxy acetylene because it does not oxidize (response to a reaction with oxygen).
The process of cutting metals such as steel with oxy-acetylene exposes it to oxygen which cracks it open and reveals solid steel that is eventually cut. This is only possible because steel can be oxidized.
On the other hand, stainless steel cannot be cut by Oxy acetylene because of the creation of an oxide that inhibits oxidation from happening.
Q. Which Is Better To Torch With? Acetylene Or Propane?
Acetylene and propane are both effective for cutting metal, however, acetylene is the better option to torch with. Acetylene and propane both give off heat, but up to 40% of the heat emitted by acetylene is located in the inner core of its flame. Whereas propane only gives off 10% of its heat in the same areas.
Hence, oxy-acetylene cuts through metal faster and more precisely compared to propane.
Q. Why Won’t A Cutting Torch Cut Through Rusty Metal?
A cutting torch won’t cut through rusty metal because it has already been oxidized. Usually, a clean sheet of metal passes through oxidation, which creates cracks (rust) before the solid metal is exposed. A rusted metal, however, cannot undergo this process. Nevertheless, you can still cut the metal.
The flame heats the rusted areas until it is hot enough to pop the surface off. This will expose the solid metal and the cutting process will continue appropriately.
Q. Can We Use Propane Instead Of Acetylene For Oxy-Acetylene Welding?
Propane cannot be used in place of acetylene for Oxy acetylene welding because it does not have a reducing zone like acetylene.
Propane is a slower burning gas compared to acetylene and as such would pass through the cutting torch as a vapor instead of a gas. Hence, it won’t burn as acetylene would.
Q. Do You Need A Welding Mask For Oxy-Acetylene Welding?
You don’t need a welding mask for oxy acetylene welding because, unlike electrical welding, gas welding does not produce UV. Instead, welding goggles are advisable to protect your eyes from intense visible light.
Q. What Pressure Should Oxygen And Acetylene Be Set At?
The gas pressures for oxygen should be set at 20-30psi and 3-5psi for acetylene for cutting steel with a thickness of between ³/¹6″-¼”.
However, it’s always a great idea to follow the manufacturer’s instructions by using different sizes of tips. Consider multiple parameters such as the thickness of the metal, the type of tip, etc.
Q. What Do You Turn On First, Oxygen Or Acetylene?
You open the oxygen valve first to release pressure until the pressure gauge isn’t moving before proceeding to open the valve completely. After this, you can open the acetylene valve but not more than 1½ turns.
Figuring out the answer to the question how does the oxy-acetylene cutting torch work? It is essential for producing top-notch cuts in metal.
We hope with this guide, you can understand the different processes required for operating a cutting torch.
Also, be sure to follow the necessary criteria required when using a specific tip for either welding or cutting.