ESAB offers a complete line of welding and cutting products and solutions. Explore our equipment offering with ease based on product line and industry.
ESAB is a world leader in welding and cutting equipment and consumables. Explore our complete line of welding & cutting products for virtually every application.
+971 4 8809493
ESAB University Courses are incremental, structured learning modules designed to help you take your skills to the next level. New courses are being added regularly, so please check back often. Click the link to see current courses offered.
Articles cover industry topics more in-depth and are created in partnership with ESAB engineers and master welders. Click the links to see the latest.
Tips from ESAB Experts to help take your welding, cutting and fabrication skills to the next level.
ESAB University videos are curated with tips and best practices from top fabricators around the world. Learn new techniques or improve your current skills with ESAB University videos.
ESAB Welding Handbooks
ESAB Courses are structured learning designed to help welders achieve certain learning milestones and explore topics more in-depth. Check back often for updated resources.
ESAB is a world leader in welding and cutting equipment and consumables. We offer a complete line of fabrication solutions for virtually every application.
ESAB Newsroom - Stay up to date with the latest news from ESAB. View press releases, product announcements, corporate news, and more here.
ESAB EHS (Environment, Health & Safety) initiatives are monitored with the highest degree of importance and commitment to safety is ingrained in our culture.
The history of ESAB is the History of Welding. Go here to view an interactive look at ESAB's history in shaping the future of innovation in welding, cutting, and fabrication.
View available job openings and more on the ESAB Careers page.
ESAB offers a wealth of product support resources, including a range of technical and service publications, from Safety Data Sheets and downloadable product manuals to product certifications.
Visit ESAB's global manual search engine to access the items below and more.
Global User Manuals
Spare Parts List
Product Storage Instructions
View Main Contact Page
View ESAB Location Information
No Playlist Found ! Please Create Your PlayList Here
A cutting torch is an equipment that uses the combined pressure of fuel gas and oxygen for cutting operation. This process is known as “oxy-fuel cutting.” The present article covers the procedures for adjusting the flame for effective oxy-fuel cutting.
Flame Cutting/Oxygen Burning requires some source of intense heat to get the plate hot enough to be cut/burned. This source of heat is referred to as the “preheat flame”. The whole plate does not need to be heated, not even the bottom, just that portion slightly ahead of the cutting reaction. There are some plate materials that must be “preheated” before cutting to keep them from cracking during cutting. Typically, materials with Carbon Levels above 0.25% fall in this category. This is NOT the “preheat” we are discussing. Some materials require “preheating” up to 600 °F. There are also some materials that require “preheating” to achieve a quality cut.
Numerous fuels are used for the fuel/Oxygen mixture called Preheat and each has some feature to make it attractive. Up to about 1970 Acetylene was the primary fuel used but its escalating cost, the growth of plasma, and the aggressive marketing of other fuels have caused it to no longer be a primary choice particularly where plasma is also available. The most common fuels today are natural gas and propane. There are also some mixtures of natural gas or propane with some additive that claims to make them hotter. If in fact, these gases are hotter it is of little value because cutting speeds are limited by preheat capability (temperature) only in thinner materials (1/8 -1/2 inches). In thicker materials, the cutting speed is limited by the capability of the cutting Oxygen stream, not the preheat, so higher flame temperatures are of little or no value.
As previously stated, the purpose of the preheat gases is to raise the temperature of the plate, just ahead of the cut, so a high heat transfer rate from the flame to the plate is required. The factors the operator can control to achieve this transfer of heat are:
The flame temperature is controlled by adjusting the O/F Ratio. The chart below illustrates how the temperature is affected by this ratio. The quantity of preheat can be adjusted by raising or lowering the preheat pressures to the torch. High pressure will result in high flow rates, i.e. a high velocity preheat. Low pressures will result in low flow rates/velocity. The operator can adjust the O/F ratio by looking at the inner cone of the flame. When this inner cone is the shortest length, but still has a very bright appearance this is the hottest flame temperature. This procedure can be used regardless of the total flow of gases.
The quantity of preheat required varies depending on the operation to be conducted. For a pierce start a very high flow rate (at the correct O/F ratio) is required followed by a significantly lower flow rate (again at the right O/F ratio) for the continuing cutting operation. These preheat conditions are often referred to as Hi Preheat and Lo Preheat. A Hi Preheat that is not high enough will result in pierce times of 20-120 seconds. Pierce time being the time the Hi Preheat is on prior to initiation of the Cutting Oxygen. With proper control of the Hi Preheat, the pierce time on ½ to 6-inch material can consistently be 10 seconds or less. If the operation is beveling then the Hi preheat condition is required at all times.
A properly adjusted preheat setting results in a sharp top edge and a slag-free and sharp bottom edge. Sometimes if the mill scale is very heavy a higher preheat will be required to break the mill scale loose while keeping the leading edge of the cut properly heated. Too much preheat will result in a rounded top edge as well as a significant increase in slag. Often this increase in slag will result in a cut that will not drop from the base plate. Sometimes the slag is so tenacious the part must be beaten out of the plate with a sledgehammer.
The actual recommended quantity (CFH) of fuel and Oxygen varies with the tip manufacturer and tip purpose. In general, for practical shape cutting the quantities required are Natural Gas 10-20 CFH and 18-36 CFH Oxygen, and Propane 5-10 CFH and 23-45CFH Oxygen. Flow rates for Propylene are about the same as Propane but with a little less Oxygen. Preheat Quantities vary depending on plate surface conditions, material composition, operator capability, and other factors too numerous to be mentioned. Flame cutting is as much an art as it is a science.