falling through cracks in the floor.
•On old-style acetylene cylinders with a removable valve wrench, always leave the wrench in place when using the equipment, so it can be shut off quickly in an emergency.
•When transporting compressed gas cylinders by vehicle have the cylinder caps in place and secure the cylinders so they will not move around as the vehicle starts and stops. Never transport cylinders with the regulators in place.
•Never carry compressed gas cylinders inside a car or car trunk.
What is the best way to weld on a sealed cylinder, tank, vessel or container?
Never weld on a sealed container regardless of its size. Even if the vessel is clean and empty, penetration of the shell could release hot gases from the interior. They could also drive the torch flame back towards the welder. If the cylinder is empty and contains no residual vapors, vent it to atmosphere by opening a valve, hatch, bung, or by drilling a hole. An even more dangerous situation results when the cylinder contains residual flammable vapors whether it is vented to atmosphere or not. This will almost certainly result in an explosion. Clean or purge the cylinder with an inert gas, then have it checked for lack of explosive vapors by a qualified person. Vent it to the atmosphere and begin welding. In some cases filling the vessel with water, or other liquid and welding below the liquid is acceptable, but this is an area for experienced, knowledgeable welders.
Why use a striker to light an oxyfuel torch and not a match?
The striker keeps your fingers away from the flame that can ignite into a large flame. The use of a butane cigarette lighter for torch ignition can cause a large fire or explosion with the potential power of a half-stick of dynamite.
Why should the welding area be well ventilated to draw the weld fumes away from the welder?
Many fumes from the welding process are poisonous and must be avoided. Welding fumes from cadmium plating, galvanized sheet metal, lead, brass (which contains zinc), and many fluxes (especially those containing fluorine) are poisonous. They can have both immediate and long-term adverse health effects. Welding supply companies, welding equipment manufacturers, and materials suppliers will provide MSDSs (Material Safety Data Sheets) on request. Often they are available for downloading via the Internet from the manufacturer. They detail the hazards of materials and equipment and show how to deal with them safely. They are particularly helpful in understanding the fume hazards of fluxes, solders, and brazing materials.
Practice is the best of all instruction.
Aristotle
Introduction
Oxygen-fuel cutting is an important industrial process. Much more acetylene is used for cutting metals than for welding them. For many cutting applications, there is no more effective and efficient process. Used in construction, manufacturing, and repair operations, cutting equipment is inexpensive, portable, and easy to use. In some applications, propane or natural gas may be more cost-effective and replaces acetylene as the fuel gas. We will explain how the oxygen-fuel cutting process works, its capabilities and limitations. We will also cover cutting torches, troubleshooting, operating tips, safety, and then present some helpful accessories. Finally we will discuss other thermal cutting processes important in today’s industry.
Process Name
What term does the AWS use for any cutting process using oxygen and any fuel gas?
Oxy-fuel cutting.
What is the AWS abbreviation for oxy-fuel cutting?
The abbreviation for all oxy-fuel cutting is OFC.
What is the AWS abbreviation for the oxyacetylene cutting process?
The abbreviation for oxygen-acetylene cutting is OAC. OAC is just one member of the OFC family.
Equipment
How do you convert oxyacetylene welding equipment into an oxygen-acetylene cutting equipment?
Conventional OAW equipment (outfit) is readily converted to perform light to heavy OAC by exchanging the welding nozzle on the torch handle to a cutting accessory head fitting into the handle, Figure 2–1.
Figure 2–1Oxygen-acetylene cutting equipment
How does an OAC cutting torch or accessory cutting assembly differ from an OAW torch?
The OAC cutting head still contains a means of mixing oxygen and acetylene to produce an approximate temperature of 6300°F (3100°C). But it has added means to deliver a stream of pure oxygen to the cutting point. An oxygen lever opens this pure oxygen stream when the welder, fitter or cutting-operator depresses it. See Figure 2–2.
Figure 2–2Oxy-fuel cutting torches. An injector cutting torch (left) and a mixing chamber positive pressure cutting torch (right)
What are the advantages of a cutting accessory head over a regular cutting torch?
A cutting accessory head is less expensive than a one-piece cutting torch; it is quicker and easier to change back and forth between the cutting and welding functions than between a welding torch and cutting torch. With its greater length, a one-piece cutting head puts more distance between the cutting action and the welder and usually can handle greater oxygen flows for large jobs. Some cutting torches have cutting heads at a particular angle for a given task to relieve operator fatigue. The position of the cutting handle is a matter of preference and varies by manufacturer.
The two cutting torches in Figure 2–2 have different designs. How do they differ and what are their advantages?
The torch on the left side of Figure 2–2 uses an injection chamber or venturi to draw the fuel gas into the oxygen stream and operates with fuel pressures 6 oz/in2, such as those supplied by an acetylene generator or a regulated natural gas system delivering in water column inches or about
