Oxyfuel options

May 20, 2023

Choosing a combination torch provides the flexibility to switch between attachments for cutting (shown here), heating or welding/brazing.

Invented more than 100 years ago, oxyfuel remains one of the most popular metalforming processes because of its flexibility, portability, simplicity, and affordability compared to arc welding and plasma cutting systems. There are a myriad of torches and outfits available. They might look similar, but there are important safety, performance, and durability differences. Ask yourself these questions to help select the right outfit for your needs.

Oxyfuel torches come in two basic types. If you only plan to cut or gouge (including deseaming and removing defective welds, scarfing, weld preparation, and washing rivets), then a straight torch offers the most benefits. Because they are simple, they are cost effective and extremely rugged. Straight torches also come in longer reach and high-output models for use in structural steel, steel mill, and scrap applications.

Combination torches offer straight torches used strictly for cutting and combination torches that feature a handle that accepts attachments for cutting, heating, welding, and brazing (note that welding and brazing use the same style of tip. A tip for heating is technically called multi-flame attachments, or MFA).

Torch handles and attachments are sold separately, so you can start with only the ones you need and then buy additional pieces later. Many people start with an "outfit," which includes the torch handle and various combinations of attachments and tips sizes. Outfits also may include the gas hose, oxygen and fuel regulators, tip cleaner, striker, goggles, tip charts, and an operator's manual.

While acetylene remains the most popular fuel for cutting and heating, using an alternative fuel such as propane or natural gas may offer cost, safety, and performance benefits. However, note that "gas welding" requires acetylene for the fuel gas because it gives off CO2 during combustion to shield the molten puddle. Also, note that alternate fuels require fuel-specific equipment regulators, hoses, and cutting and heating tips.

For fuel gas flexibility, select torches with a "spiral" or "equal-pressure" mixer, as they are calibrated to work with both low-pressure fuels (e.g., propane) and high-pressure fuels (e.g., acetylene). These torches keep the gas pressurized and mix them via turbulence between the handle and the torch head.

Oxyfuel equipment manufacturers generally classify torches and regulators as light duty, medium duty, heavy duty, or extra-heavy duty based on the respective gas flow capacities of the torch, tip, and regulator.

People select light-duty oxyfuel equipment for small and thin steel applications because they do not require a high volume of gas flow. Also, a compact torch size makes it easier to manoeuvre in tight spaces and at intricate angles, such as brazing around a pipe circumference or working on complex metal art projects.

A fabrication facility, as well as those in farming and general repair, mechanics, or hobbyists will, at the very least, require the capabilities of medium-duty outfits, while those involved in construction, pipeline, shipbuilding, heavy-equipment repair, scrap, and demolition applications should select a heavy-duty outfit. A good place to start is by reviewing tip selection charts, such as the ones typically found in a manufacturer's catalogue, to match the tip size and flow rates to your application and process, then selecting the corresponding torch or outfit. Cutting and welding tips are classified by orifice size, and heating tips are classified by BTUs per hour.

When it comes to selecting the right tip size, remember that an effective cutting/heating/welding flame requires the burning velocity based on a precise mix of oxygen and fuel. Do not set gas flow rates outside of recommended parameters. Incorrect flow rates can quickly lead to overheating, backfires, ragged cuts, and excess slag. Buying the right-size tip or attachment is relatively inexpensive compared to the cost of fixing a poor cut or a project taking longer than necessary.

This structural steel fabricator uses a heavy-duty straight torch dedicated to cutting for maximum reliability.

The ability of the equipment to withstand environmental conditions (e.g., constant or occasional abuse) and continue to function reliably is another "duty" factor. When it comes to selecting a torch, start with one question: What happens if the torch fails? In this context, descriptions such as medium duty and heavy duty relate to equipment design, materials, and construction.

Professionals such as pipeline welders, a solo heavy-equipment repair operator, or construction contractors, where a malfunction causes a missed deadline or lost income, require premium equipment.

The next question relates to frequency. Professionals who use the torch several times or several hours a day need equipment designed and built for years of trouble-free operation and simple maintenance. Further, these professionals can tell the difference between good and great cutting or heating performance, as well as appreciate a tool's form, fit, and function.

Manufacturers offer medium-duty equipment for fabricators who use oxyfuel equipment just a few times week or for only a few hours a month, and for occasional users who also appreciate good performance.

For torches, look for forged brass heads, brass handles and vales, and rigid stainless steel tubes with heft to stand up to the intended environment and user (torch heads shouldn't be used to knock off slag or thrown on the shop floor, but it happens). On combination torches, a brass coupling nut and a double O-ring should hand-tighten and form a gas-tight seal (no wrench required) between the handle and cutting attachment. Valves and the oxygen-cutting levers should function with firm but smooth and positive motion (e.g., no stickiness or sloppiness).

When it comes to regulators, there is a clear-cut durability and safety difference between next-generation regulators and regulators with a traditional design. Next-generation regulators feature:

That question is rhetorical, as safe operation is the paramount concern. Here, occasional users benefit the most from torches with safety features such as built-in check valves and flashback arrestors, as they are less likely to remember or be required to adhere to best safety practices than daily users.

One common misconception is that check valves are designed to stop a flame; they stop reverse flow of gases, which creates the condition for a possible flashback. Flashback arrestors contain a sintered filter that prevents a flame from passing through the filter element.

Reverse flow occurs because of a gas restriction or an imbalance of pressure. It can be caused by a clogged or blocked tip or allowing one of the cylinders to run out of gas. If a reverse-flow condition exists, a flashback can occur. Flashback is the return of a flame through the torch, into the hose, and even into the regulator.

Backfire is the return of a flame back into the torch, which produces a popping sound. The flame will either extinguish or reignite at the tip. This is normally the result of accidentally bumping a tip against the workpiece, operating the tip too close to the workpiece, or allowing the tip to become overheated (another reason why tip size is important).

Oxyfuel components can be purchased separately or as part of a complete outfit.

The last event is a sustained backfire. This is when a backfire occurs and continues burning in the torch. This condition may be accompanied by a popping sound followed by a continuous whistling or hissing sound. Some of the causes for this are improperly maintained equipment, overheating of the equipment, or improper pressure settings for the equipment being used.

Following selection best practices can ensure your cutting and heating operations function as profitably as possible. Further, a good quality oxyfuel outfit can last a lifetime with proper maintenance. In fact, it's common for a fabricator to use their father's or even their grandfather's torch. Next-generation regulators now come with a lifetime warranty—and that's the lifetime of a regulator, not the owner.

Vinicius Nunes is gas equipment product marketing director, ESAB Welding & Cutting Products, 2800 Airport Rd., Denton, Texas 76207, 940-381-1360, www.esab.com.