Practical. Powerful. Portable.
In recent years there’s been much discussion about the value of plasma-arc and laser processes for cutting and welding, but oxy-fuel is still the most commonly used method worldwide.
The equipment is robust, easy to use and the cost of entry is relatively modest. You can purchase high-end oxy-fuel equipment for $250 – $350. The gas cylinders can be rented, are portable and, because electricity is not required, you can cut and weld almost anywhere.
There are several thousand types of regular and specialty cutting tips and welding nozzles available. Some are designed to cut off the base of an I-beam or remove the head of a rivet. Other tips extend up to 24” from the torch. There are tips made to fit into awkward places or cut at odd angles, and long lasting tips with special alloy wear rings.
4-Step Method of Selecting the Right Cutting Tips
Choosing the correct cutting tip for the job is critical to performance and safety. It’s easy when you use the 4-Step Method, but you need to understand these four things about your project and equipment:
1. Seat Type
This is determined by brand. You must know the manufacturer or model of your torch and/or the part number of the cutting tips you want to replace as this determines the seat type.
If this important step is skipped, damage to the equipment or dangerous flammable gas leakage can result. Tip seats vary greatly with torch model (shown here in yellow).
2. Metal Thickness
The thickness of the metal being cut is very important because the center hole of the cutting and gouging tip is sized to deliver the proper amount of oxygen at the proper pressure for a specific thickness. The pre-heat orifice is also sized to handle the proper amounts of mixed gas to heat a given thickness of metal adequately. Oxy-fuel equipment is capable of cutting mild steel from 3 mm (1/8”) to 300 mm (12”).
Tips are designed specifically for the applications in which they are to be used. There are different tips used for cutting, gouging, and heating. They may be one piece of solid copper, or a two-piece hybrid with a brass inner piece and a copper outer piece. Some cutting tips are specially designed to use with automated cutting machinery for high-pressure cutting that permits quicker, cleaner, more accurate cuts.
4. Fuel Gas
There are many types of gases used in oxy-fuel cutting operations. Cutting tips, designed differently for each fuel gas, optimize how the oxygen and gas are delivered.
The hottest most-versatile gas, acetylene, is very easy to use for all purposes. Pre-heat time for cutting and gouging is relatively short because the flame temperature is between 5,600 and 5,800 F. However, this gas is the most expensive gas available and is not the most efficient for heating large areas.
Commonly used as a generic name for many types of gases. These range from specific gases, with their own chemical formulae, to gases that are primarily propane mixed with ethylene or other chemicals that generally burn hotter than propane. Cutting, gouging, and heating can all be done with reasonable efficiency. Pre-heat times can be longer, but using the proper tip design can eliminate this issue. Propylene yields flame temperature between 4,800 and 5,300F. This gas is not generally used for welding.
Propane and Natural Gas:
Have flame temperatures between 4,500 and 4,600F and are the least expensive gases available. Propane is the most efficient for heating because of its high BTU output and the large heavy heating tips that are available. These gases are not used for welding.
Resources, References & Guides
Use our online catalog to search for cutting, welding, heating and specialty tips.
Tips can be searched by brand and tip part#; and each listing includes information about fuel gas, application, features and length.
Hundreds of tips for more than 20 brands are listed in this catalog; including Harris®, Esab®, Smith® and Victor®.
Tip orifice shown above at actual size.
Recommended Best Practices:
For more information about cutting process, procedures and safety practices the American Welding Society (AWS) publishes Recommended Practices For Safe Oxy-fuel Gas Cutting Torch Operation.
Revised and expanded, this book describes the oxyfuel gas cutting process and presents the latest procedures and safety requirements, using terminology and practices compatible with International Organization for Standardization (ISO) documents. Illustrations show torch and nozzle configurations, and examples of production-cut surfaces. ANSI Approved. approx. 53 pages.
Follow this link to buy it from the AWS Online Store.
Overview of The Cutting Process
Your oxy-fuel equipment manual will explain how to adjust the torch and regulators to achieve the optimal flame for pre-heating and cutting. If you don’t have a manual you can download the ATTC equipment manual here.
When metal is removed, as in the cutting and gouging processes, it is first necessary to pre-heat the steel to its’ kindling temperature. When the steel becomes “cherry red”, the added oxygen causes an exothermic reaction that removes the metal. The oxygen must be 99.9 percent pure to produce a quality cut.
Depending on the brand and model of your torch, the pre-heat gases are mixed in different ways. Some torches are tube-mix while others mix the gases in the head or in the tip itself.