When it comes to your oxy-fuel torch setup, performance and safety are key. Arguably one of the most important components that will affect both of these is your cutting tip choice. Choosing the right tip for your application will not only provide smoother cuts but will also help protect you and your torch and eliminate any downtime from tip or torch damage. When reaching for a cutting tip for your torch, make sure to account for these four factors.
1. Seat type
Gas equipment manufacturers design tip seats specifically and uniquely for the torches they sell — tips are not interchangeable, making it essential to double-check that the tip you’re using is compatible with the torch. Many manufacturers use metal-to-metal or hard seat tip designs. Hard seat tips rely on tip nut torque and precisely machined surfaces to seat properly. The soft seat tip design by Miller is more pliable and will conform to imperfect surfaces, allowing it to seal and still work properly. The tips can be hand-tightened (no tools necessary), which makes for quick and easy tip changes.
2. Application
Tips are also designed to match specific applications. Processes such as cutting, heating, gouging or brazing all require different tips to ensure the application’s process doesn’t exceed the capabilities of the tip or negatively impact the work being done.
3. Metal thickness
The best operating experience (and work outcome) comes from the right cutting tip size. The thickness of the workpiece metal will determine the size of the tip, with thicker metals typically requiring bigger tips. You always need to size the tip to the work and then adjust the fuel and oxygen pressures accordingly.
For example, if you’re using a cutting tip that’s meant for 2-inch metal on a 1/4-inch-thick workpiece, an improper tip can waste gas and generate unnecessary amounts of heat and sparks. Additionally, the heat-affected area will show signs of dross on the edges of the cut, requiring grinding to clean up the area.
Note that your torch has a maximum cutting thickness based on how it’s designed and its flow capabilities. You should never use a tip designed to cut a higher thickness of metal than your torch is designed to cut.
To make this easier, tip charts exist to help choose the right size option for whatever task you’re tackling.
4. Fuel gas
Different fuel gases have different characteristics that affect their function, so you’ll want to choose a cutting tip designed for the fuel gas you are using.
Using the wrong cutting tip for the fuel gas can burn tips up quickly and may result in a backfire. With fast-burning fuel, like acetylene, the flame is present and stable immediately, and no tip recess is necessary. Slower-burning fuels, like propane or natural gas, require a tip that’s designed with a recess at the end of the tip to give the flame time to start and stabilize before exiting the tip.
Another application in action: heating
For heating applications, the process in choosing a torch tip is very similar. You still need to assess the seat, metal thickness and fuel type; however, there are other items to consider for heating applications.
For example, a heating tip is going to focus heavily on the heat energy produced by the tip, which is measured in British thermal units (Btu). The heat, or Btu output, of the tip needed will depend on the metal thickness. A good rule of thumb is that you’ll want a higher Btu tip as the metal thickness increases. Using a lower Btu tip on a thicker piece of metal will take longer to heat the area than using an appropriately sized, higher Btu tip.
When factoring in the fuel gas being used for heating, you still choose a tip to match the fuel, but it’s equally important to use the proper cylinder size. The right cylinder size ensures that there is sufficient gas flow for the specific heating tip. The flow requirements for a given heating tip size are determined by the fuel consumption (which is measured in standard cubic feet per hour) and oxygen consumption (which determines the minimum cylinder size to use).
If you are using a heavy-duty heating tip that produces a higher Btu, there are additional steps needed for optimum safety and output. More heat produced means you will consume more fuel, requiring larger fuel and oxygen cylinders depending on the fuel gas being used. With acetylene fuel gas, you may need to manifold cylinders together for a safe operation. For propane applications, which consume a lot of oxygen, you will want a larger oxygen cylinder to meet the correct fuel-oxygen ratio. Refer to your tip manufacturer’s owner’s manual for the recommended number of cylinders to be used. Using a larger heating tip will also require heavy-duty regulators, which will provide the high gas flow to meet tip consumption requirements. Lastly, you'll likely need hoses with a larger diameter to supply the proper gas volume.