Oxyfuel Cutting Applications 282

"Oxyfuel Cutting Applications" provides an overview of the oxyfuel cutting process and its safety requirements, equipment components, and operating procedures. Before performing oxyfuel cutting, it is important to correctly setup the oxyfuel outfit and perform essential safety inspections. After lighting an oxyfuel torch, an operator must control the ratio of gas to produce a neutral cutting flame. During the cutting process, an operator must control specific variables, including tip height, gas flow rate, travel speed, and torch angles. Understanding these variables along with the proper cutting procedures help produce a quality oxyfuel cut.

The information in this class helps prepare users to perform oxyfuel cutting, a popular thermal cutting process with a variety of applications. After taking this class, users will be familiar with many of the considerations and variables that go into oxyfuel cutting, which is essential to safely and successfully producing quality cuts.

Class Details

Class Name:
Oxyfuel Cutting Applications 282
Version:
2.0
Difficulty:
Intermediate
Number of Lessons:
25
Related 1.0 Class:
Oxyfuel Welding Applications 207

Class Outline

  • Oxyfuel Cutting: Overview
  • Oxyfuel Cutting Process
  • Oxyfuel Cutting: Advantages and Disadvantages
  • Review: Oxyfuel Cutting
  • Oxyfuel Equipment: Gas Cylinders
  • Regulators and Hoses
  • Torch Components
  • Torch Types
  • Equipment Maintenance
  • Review: Oxyfuel Equipment
  • OFC Setup and Inspection
  • Preparing to Light the Torch
  • Lighting and Adjusting the Torch
  • Types of Flames
  • Flame Identification
  • Review: Oxyfuel Flames
  • Starting a Cut
  • Maintaining the Cut
  • Process Variables
  • Turning Off and Securing Equipment
  • Review: Oxyfuel Process
  • OFC Safety: PPE
  • OFC Torch Hazards
  • Gas Cylinder Safety
  • Review: Oxyfuel Cutting Safety

Objectives

  • Define oxyfuel cutting.
  • Describe the oxyfuel cutting process.
  • Identify the advantages and disadvantages of oxyfuel cutting.
  • Distinguish between oxygen and acetylene cylinders.
  • Describe the functions of regulators and hoses used in oxyfuel cutting.
  • Describe the components of an oxyfuel cutting torch.
  • Distinguish between positive-pressure and injector cutting torches.
  • Describe proper maintenance procedures for oxyfuel cutting equipment.
  • Describe the appropriate equipment setup and inspection for oxyfuel cutting.
  • Describe the steps involved in safely lighting and adjusting an oxyfuel cutting torch.
  • Identify neutral, carburizing, and oxidizing flames.
  • Describe the proper way to preheat and initiate an oxyfuel cut.
  • Distinguish between underhand and overhand grip.
  • Describe the process variables that affect the quality of oxyfuel cuts.
  • Describe the proper steps for turning off and securing oxyfuel equipment.
  • Describe personal protective equipment used in oxyfuel cutting.
  • Distinguish between backfire, sustained backfire, and flashback.
  • Describe safe handling and storage procedures for oxyfuel gases.

Job Roles

Certifications

Glossary

Vocabulary Term Definition
acetone C3H6O. A liquid used in acetylene cylinders to dissolve and store acetylene. Acetone allows for safer storage of acetylene.
acetylene C2H2. A colorless, flammable gas that is the most common fuel gas used in oxyfuel welding. Acetylene should not be used at pressures above 15 psi (103.42 kPa) and becomes highly unstable at higher pressures.
adherent slag The solidified slag that builds up on the back side of material during some oxyfuel cutting operations. Adherent slag is also referred to as dross.
adjusting screw A component in a gas regulator that controls the gas flow from the cylinder into the regulator and prevents any damage to the regulator's components. Adjusting screws must be released prior to opening the cylinder valve.
alloy steel A steel containing intentionally added materials that change the property of the metal. Alloy steels commonly include elements such as chromium, manganese, molybdenum, and nickel.
backfire A torch malfunction in which the flame moves up into the tip of the torch. Backfires are fairly common and are not major safety concerns.
backflow An unwanted movement of gas in the reverse direction. Backflow of oxyfuel gases can be prevented by check valves.
bell-mouthed orifices A hole that has a flared edge and is not a perfect circle. Bell-mouthed orifices will affect the shape and direction of oxyfuel preheat and cutting jet flames.
beveled An edge that is cut at an angle. Beveled edges are an indication of a quality oxyfuel cut.
brass A nonferrous alloy containing copper and zinc. Brass has high tensile strength and corrosion resistance.
brazing A process in which a filler metal is melted at a temperature above 840°F (449°C), but below the melting point of the base metals to form a joint between two base metals. Brazing differs from welding because only the filler metal is melted.
carbon A common nonmetallic element found in all types of steel. Carbon is the main hardening element in steel.
carbon A common, nonmetallic element found in all types of steel. Carbon is the main hardening element in steel.
carburizes Chemically absorbs or adds carbon to a material. Carburizing most frequently occurs with iron or steel.
carburizing flame A type of oxyfuel flame that contains more fuel gas than oxygen. Carburizing flames burn at a lower temperature than the other flame types.
cast iron A metal consisting of iron, over 2.11% carbon, 1 to 3% silicon, and trace amounts of other elements. Cast iron offers heat resistance and compressive strength.
check valves A part of the oxyfuel outfit installed between the hose and the torch. Check valves prevent the unintentional backflow of gases.
chemical reaction A process in which one or more substances are changed into another substance. Chemical reactions alter the physical structure of a substance in some way.
chromium A metallic alloying element that is shiny, hard, and a steel-gray color. Chromium improves the hardenability and corrosion resistance of steel.
concave Inwardly curved in shape. Concave surfaces on an oxyfuel cut typically results from too fast of a travel speed.
copper A reddish-brown metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Copper is often used to make oxyfuel torch cutting and welding tips.
cut face The exposed surface of a cut. Cut faces may exhibit deep drag lines, pressure marks, or a pitted surface if improper cutting variables are used during the oxyfuel cutting process.
cutting jet A concentrated, high-powered stream of pure oxygen. Cutting jets are used to pierce and cut metal during the oxyfuel cutting process.
cutting jet trigger A lever on an oxyfuel cutting torch that controls the release of the high-powered, concentrated stream of oxygen. Cutting jet triggers are used by oxyfuel torch operators during the cutting process but not the preheat process.
cutting tip height The distance between an oxyfuel torch's cutting tip and the workpiece surface. Cutting tip height affects cut quality.
cutting tips A replaceable nozzle for a gas torch that is adapted for oxyfuel cutting instead of welding. Cutting tips are made in a variety of sizes and orifice configurations based upon the fuel gas type used.
cutting torch An oxyfuel cutting tool used to control the fuel and oxygen used to create a flame for preheating and to introduce the oxygen used for cutting. Cutting torches are available in several different types.
cylinder cap A device used to protect the valve mechanisms of a cylinder from physical damage while cylinders are in storage or transport. Cylinder caps must be kept on the gas cylinders when the cylinders are not secured.
cylinder pressure The pressure under which gas is stored within its cylinder. Cylinder pressure is far too great to be suitable for welding or cutting processes and must be reduced to a lower working pressure.
cylinder truck A two-wheeled dolly used to safely secure gas cylinders while in use. Cylinder trucks can be used to safely transport gas cylinders between work locations as well.
cylinder valve A device that opens, closes, or obstructs an opening or passageway to control the flow of gas. Cylinder valves are made of forged brass and designed to withstand high pressures.
cylinder-pressure gauge The device that indicates the pressure of gas present in the gas cylinder. Cylinder-pressure gauges are marked with a graduated scale that is specific to the type of gas in the cylinder.
darkness rating The amount of shading provided by filter plates. Darkness ratings range from 1, which offers the least protection, to 14, which offers the greatest protection.
diameters The distance from one edge of a circular or cylindrical object to the opposite edge through the center. The diameter of an oxyfuel cutting tip's center orifice determines the size of the cutting tip.
double-stage regulator A type of regulator that adjusts the cylinder pressure to the required working pressure in two steps. Double-stage regulators better maintain a constant delivery pressure even though the cylinder pressure may vary.
drag angle A travel angle that points the torch tip opposite the direction of cutting. Drag angles can be used when performing oxyfuel cutting on alloy steels and cast irons.
dross The solidified slag that builds up on the back side of material during some oxyfuel cutting operations. Dross is also referred to as adherent slag.
earmuffs Ear wear that protects hearing as well as the outer ear from flying sparks or debris. Earmuffs consist of two ear coverings connected by a band.
earplugs A protective device that is inserted in the ear to block noise. Earplugs protect against hearing loss.
exothermic A chemical change or process that produces heat. Exothermic processes include the rapid oxidation of iron that is used in oxyfuel cutting processes to create a kerf.
face shield A rigid, transparent plastic sheet that covers a welder's entire face to protect against molten metal, slag, and spatter. Face shields are often worn with goggles to provide additional impact protection.
ferrous Containing iron. Ferrous metals, such as steels and cast irons, can be used with the oxyfuel cutting process.
filter plates The shaded protective lens inside the welding helmet that filter out harmful rays and intense bright light. Filter plates' required amount of shading depends on the welding or cutting process, materials used, and power source.
fire-resistant FR. Designed to resist burning and withstand heat. Fire-resistant materials for PPE are rated and must meet specific safety standards.
fittings A component that can connect, redirect, extend, or terminate the run of a gas hose. Fittings may have either left-hand or right-hand threads depending on the type of oxyfuel gas hose with which the fitting is used.
flame cutting A thermal cutting process that uses a flame produced by oxygen and a fuel gas along with a high-pressure stream of oxygen. Flame cutting, which is sometimes called oxyfuel cutting (OFC) or gas cutting, is a very convenient and cost-effective cutting process.
flame zones The visibly distinct areas of a flame. Flame zones are usually easily distinguished by their slightly different colors and cone shapes.
flashback A torch malfunction in which the flame briefly or continually moves up into the torch and hoses. Flashbacks can cause equipment damage or personal injury if not prevented or controlled.
flashback arrestor A part of the oxyfuel outfit installed between the hose and the torch. Flashback arrestors prevent flashback from reaching into the hoses and causing an explosion.
flashback arrestors A part of the oxyfuel outfit installed between the hose and the torch. Flashback arrestors prevent flashback from reaching into the hoses and causing an explosion.
flow rate A variable that describes how much gas is being moved in a certain amount of time. Flow rate can affect cut quality.
fumes Potentially hazardous gases and particulate matter generated during welding and thermal cutting processes. Fumes produced during welding and cutting include particulates from the electrode, flux, shielding gas, base metal, and any coatings included in the weld or cut area.
fuse plugs A safety device at the bottom of an acetylene cylinder that intentionally fails and melts if the cylinder is exposed to excessive pressures and heat. Fuse plugs help prevent acetylene cylinders from exploding.
gas cutting A thermal cutting process that uses a flame produced by oxygen and a fuel gas along with a high-pressure stream of oxygen. Gas cutting, which is sometimes called oxyfuel cutting (OFC) or flame cutting, is a very convenient and cost-effective cutting process.
gas cylinder Metal containers used to store gases. Gas cylinders are built specifically for each gas and have different properties depending on the gas.
gas hose A type of gas conductor that is flexible and often quite versatile. Gas hoses connect oxyfuel cylinders to the torch in oxyfuel cutting.
gauntlets A type of protective glove that extends past the end of the shirt sleeves to cover the arm. Gauntlets provide an additional level of protection when performing welding or cutting processes.
gouging Removing metal, an old weld, or any imperfections in a workpiece. Gouging can be performed with a variety of methods, including oxyfuel, air-carbon arc, and plasma.
graduated scale A standard of measurement that is often displayed as a series of lines that are divided into stages or quantities. Graduated scales are used in a regulator's pressure gauges to indicate the amount of gas pressure as well as to warn of any unsafe pressures.
hardenable Able to be hardened by normal heat-treatment processes. Hardenable metals are better able to resist penetration or surface scratching.
heat-affected zone HAZ. The area around a cut affected by the heat of the cutting process. The heat-affected zone is not melted, but its mechanical properties are altered by the heat of cutting.
hose connectors The part of an oxyfuel torch where the flashback arrestor is attached to the torch. Hose connectors are made of brass to ensure safety and durability.
ignition temperature The lowest temperature at which a substance or material, when heated, spontaneously catches fire and continues to burn. Ignition temperature is also called kindling temperature.
injector nozzle The part of an injector torch through which high-pressure oxygen must pass prior to reaching the mixing chamber. Injector nozzles have low-pressure acetylene gas flowing around them, which the oxygen pulls along with it into the mixing chamber.
injector torch A type of oxyfuel torch with an internal injector that uses a stream of high-pressure oxygen to pull low-pressure acetylene into a mixing chamber. Injector torches are also called low-pressure torches.
inlet-nipple seat The surface of the small opening on a regulator that connects to a gas cylinder and through which gas is drawn into the regulator. Inlet-nipple seats that are dirty or damaged may result in gas leaks.
inner cone The bright white cone shape easily visible at the center of a neutral oxyfuel flame. The inner cone is located closest to the cutting torch tip and frequently produces the most heat.
intermediate cone The middle, white, cone-shaped area that separates the larger, brilliant, white inner cone and the feathery, bluish outer cone of an oxyfuel carburizing flame. The intermediate cone is unique to carburizing flames and is not present in either neutral or oxidizing flames.
intermediate pressure The midway point between the cylinder pressure and the working pressure. Intermediate pressures are only present when using double-stage regulators.
iron A silver-white, metallic element that is the fourth most abundant element on earth. Iron undergoes a chemical reaction and forms iron oxides when exposed to oxygen.
iron oxide A metallic compound containing iron and oxygen. Iron oxides, such as rust and slag, are formed by a chemical reaction between iron and oxygen.
kerf A cut or opening created in a workpiece during a thermal cutting operation. Kerf sometimes refers to the width of a cut or the width of the material removed by a cutting process.
kilopascals kPa. A unit of pressure derived from the International System of Units (SI). A kilopascal measures the amount of load pressure that is applied over one square meter.
kindling temperature The lowest temperature at which a substance or material, when heated, spontaneously catches fire and continues to burn. Kindling temperature is also called ignition temperature.
kPa Kilopascals. A unit of pressure derived from the International System of Units (SI). Kilopascals measures the amount of load pressure that is applied over one square meter.
left-hand threads A type of thread that is screwed in by rotating it counterclockwise. Left-hand threaded fittings must be used to connect a fuel gas hose to the oxyfuel torch.
low-alloy steels A steel that contains small amounts of intentionally added materials that change the properties of the metal. Low-alloy steels may contain manganese, molybdenum, nickel, or other common alloying elements.
low-carbon steels A steel that contains between 0.05% and 0.30% carbon. Low-carbon steels are generally tough, ductile, and easily welded or cut.
manual A process that requires an operator to entirely perform the process and control the variables. In manual oxyfuel cutting processes, the operator is responsible for performing the cut as well as controlling all other variables, such as the position of the torch and its travel direction and speed.
mechanical cutting A process that uses an electrically powered machine or tool to remove metal from a workpiece. Mechanical cutting methods include machining, shearing, sawing, and grinding.
mechanized A type of process in which the primary operation is performed and controlled by a machine. Mechanized processes often require an operator to input computer code as well as supervise while the mechanized process is carried out.
mixing chamber A part of an oxyfuel torch that is either located either in the torch head or body or as part of the tip. Mixing chambers are where the oxygen and fuel gas combine just prior to being burned by the flame.
needle valve A device that adjusts the flow of a gas along a range between fully on and fully off. The needle valve consists of a sharp conical obstruction that is extended or retracted to block or allow gas flow.
neutral flame A type of oxyfuel flame with a balanced proportion of oxygen and fuel gas. Neutral flames burn at around 5,589°F (3,087°C).
nonpetroleum A material that does not contain any petroleum or petroleum-based products, such as crude oil or gasoline. Nonpetroleum soap is used to check for gas leaks.
OFC Oxyfuel cutting. A thermal cutting process that uses a flame produced by oxygen and fuel gas along with a high-pressure stream of oxygen. OFC, which is sometimes called flame cutting or gas cutting, is a very convenient and cost-effective cutting process.
orifice A hole at the end of a torch tip. Orifice shape and number determines the use of the tip.
outer cone The part of an oxyfuel flame that surrounds the inner cone, and sometimes, an intermediate cone. The outer cone, which is less defined and often produces much less heat than a flame's inner cone, changes shape depending on the fuel gas used and the gas ratio.
overhand grip A method of holding an oxyfuel torch similar to a hammer. Overhand grips offer more stability than underhand grips, but the torch becomes less maneuverable.
oxidizes Chemically combines and reacts with oxygen. In oxyfuel cutting, a stream of pure oxygen oxidizes the iron in preheated ferrous metals.
oxidizing flame A type of oxyfuel flame that contains more oxygen than fuel gas. Oxidizing flames burn at up to 6,300°F (3,482°C).
oxyfuel cutting OFC. A thermal cutting process that uses a flame produced by oxygen and a fuel gas along with a high-pressure stream of oxygen. Oxyfuel cutting, which is sometimes called flame cutting or gas cutting, is a very convenient and cost-effective cutting process.
personal protective equipment PPE. Various safeguarding devices that prevent injury in the workplace. Personal protective equipment includes safety glasses, gloves, masks, and earplugs.
pitted Marked with tiny holes. Pitted workpiece surfaces are often a result of a dirty or damaged oxyfuel cutting tip.
porous Full of holes or having many voids. Porous material inside an acetylene cylinder absorbs acetone, the liquid in which acetylene is dissolved.
positive-pressure torch A type of oxyfuel torch that requires equal pressures of oxygen and acetylene to ensure the gases reach the mixing chamber simultaneously and mix properly. Positive-pressure torches are also called equal-pressure or medium-pressure torches.
pounds per square inch psi. A unit of pressure used in the English system. Pounds per square inch measures the amount of load pressure that is applied over an area of one square inch.
preheat flame A type of flame, ranging from 5,000 – 6,000°F (2,204 - 3,315.56°C), produced by a gas cutting torch. Preheat flames are used prior to cutting a workpiece in order to raise the metal's temperature up to its kindling point.
pressure marks Gouges in the surface of an oxyfuel cut. Pressure marks are caused by too high of an oxygen flow rate.
pressure relief valve A component within a gas regulator that allows pressurized gas to escape if the pressure in the regulator reaches a critical point. Pressure relief valves prevent damage to a regulator.
psi Pounds per square inch. A unit of pressure used in the English system. Pounds per square inch measures the amount of load pressure that is applied over an area of one square inch.
purge To clear an area of impurities or potentially dangerous volatiles. Purging oxyfuel hoses requires leaving a gas cylinder's valve and its corresponding torch valve open for a time period based on hose length and then closing the torch valve.
ratio The relationship between two quantities. Ratios are usually expressed as fractions.
regulator The device used to control the amount of gas that flows from a cylinder. Regulators consist of a valve to control pressure and a gauge to measure the pressure flowing through it.
right-hand threads A type of thread that is screwed in by rotating it clockwise. Right-hand threaded fittings must be used to connect an oxygen hose to the oxyfuel torch.
safety goggles A type of tight-fitting eye protection that completely covers the eyes, the sockets, and the surrounding facial area. Safety goggles offer protection from impact, slag, molten metal, and spatter.
scale A flaky film that forms on the surface of a metal that has been heated to high temperatures. Scale on the surface of an oxyfuel cutting tip can result in a poor-quality cut.
sealing faces The surface of the connections where a cutting tip attaches to the torch body. Sealing faces should be kept clean and free from damage to prevent gas leaks.
setup All the necessary preparation of equipment that occurs before a welding or thermal cutting process can be executed. Setup includes collecting paperwork, tools, or materials and preparing machines.
single-stage regulator A type of regulator that adjusts the cylinder pressure to the required working pressure in a single step. Single-stage regulators are usually less expensive than double-stage regulators.
slag A substance created when metal is melted and separated. Slag is usually composed of metal oxides in thermal cutting processes.
smooth-jawed wrench A type of hand tool that tightens and turns bolts, nuts, and other fittings. Smooth-jawed wrenches are more gentle than wrenches that have toothed-jaws, and they will not mar or damage sensitive brass fittings.
spatter Liquid metal droplets and sparks expelled during a thermal cutting or welding process. Spatter, which can spray up to 35 feet (10.67 m) from the work area, is a safety risk that can cause burns or fire.
stainless steel A type of steel that contains more than 15% chromium. Stainless steel exhibits excellent corrosion resistance.
striker An inexpensive and easy-to-use device that uses friction to safely ignite the fuel gas flowing from an oxyfuel torch. Strikers are also called spark lighters.
sustained backfire A torch malfunction in which the flame continually burns inside the torch, sometimes moving as far into the torch as the handle. Sustained backfires are considered extremely dangerous.
synthetic materials Artificial or human-made. Synthetic materials include plastic and nylon.
thermal cutting A cutting process that uses heat to remove metal from a workpiece. Thermal cutting processes include oxyfuel, air carbon arc, plasma arc, and laser beam.
tip cleaner A device that removes carbon buildup from the orifices of an oxyfuel cutting tip. Cutting tip cleaners come in a variety of sizes to fit different tip orifice diameters.
tolerances An acceptable deviation from a desired dimension that still meets specifications. Tolerances indicate the allowable difference between a physical feature and its intended design.
torch body The main part of an oxyfuel torch that includes the torch valves, cutting jet trigger, and torch handle. Torch bodies have internal hoses that direct the flow of gases to the mixing chamber.
torch handle The part of an oxyfuel torch that the operator holds. Torch handles are connected to the gas hoses with specific fittings.
torch valves The part of the torch used to regulate the amount of oxygen and fuel gas flowing into the torch. Oxyfuel torch valves are a specialized valve type called a needle valve.
travel angle The angle of the torch tip in relation to the workpiece. Travel angles are measured from the side of the cut.
travel speed The rate at which an oxyfuel operator moves the torch along the workpiece to make the cut. Travel speed is measured in inches per minute (in./min or ipm) or millimeters per minute (mm/min).
turbulence An upset in the even flow of gas. Turbulence in an injector torch is caused by high-pressure oxygen exiting the injector nozzle.
underhand grip A method of holding an oxyfuel torch by gripping it between the thumb, index finger, and middle finger, similar to a pen. Underhand grips allow for more careful control of the torch but are not as easy to use as an overhand grip.
valve seat The circular surface upon which a closed gas cylinder valve lies. Valve seats that are dirty or damaged may result in gas leaks.
valve wrench A special tool, usually provided by a gas cylinder manufacturer, which safely opens the valves of specific gas cylinders. Valve wrenches are frequently required to open acetylene cylinder valves.
venturi effect An effect that occurs after a gas or fluid passes through a constriction. A venturi effect in an oxyfuel injector torch creates a vacuum-like suction that allows high-pressure oxygen to draw low-pressure acetylene along into the torch mixing chamber.
visible light Wavelengths of electromagnetic radiation that can be seen with the human eye. Visible light is a form of radiation.
welding helmet A protective eye and face device worn during welding and cutting processes. Welding helmets protect a welder from harmful rays and intense bright light produced during welding processes.
work angle The angle of the torch tip to the surface of the workpiece. Work angles are measured from the end of the cut.
working pressure The pressure of the gas being delivered to the oxyfuel torch. Working pressure is much lower than cylinder pressure and thus suitable for use in welding or cutting operations.
working-pressure gauge The device that indicates the pressure of the gas that is being delivered to the oxyfuel torch. Working-pressure gauges are marked with a graduated scale that is specific to the type of gas in the cylinder.
workpiece A part that is being worked on during manufacturing. Workpieces may be subject to cutting, welding, forming, or other operations.