An OxyFuel cutting and welding rig is the most versatile tool you will have in your metal working arsenal. The same basic setup can do the following.

Cut carbon and low alloy steels.
Weld Carbon and Low alloy steels up to 1/4" thick
Braze and Solder both steels and numerous other metals.
Heat and Bend numerous metals.


This guide will cover the follow about the OxyFuel rig and it's uses and various issues you may encounter.

Equipment
Fuel Gases
Safety

Welding
Cutting
Brazing & Soldering.



Equipment:
fuel tank - Holds your fuel gas, contains a shutoff valve Never! open more than 1 turn, in gas of an accident this allows you to quickly shut the gas to the tank.

Oxygen tank - Holds your Oxygen, Contains a shutoff valve, always open this all of the way otherwise air can potentially leak out of the valve assembly.

fuel regulator: A regulator designed to precisely control the pressure of the fuel coming from the tanks to the torch. it is IMPORTANT! that the regulator you use is specified for the type of fuel gas you are using, do not use a propane regulator for acetylene or vice versa.

Oxygen regulator: A regulator designed to precisely control the pressure of the O2 coming from the tanks to the torch. UNDER NO CIRCUMSTANCES DO YOU EVER OIL THIS OR GET ANY GREASE ON IT! DOING SO CAN RESULT IN AN EXPLOSION.

pair of hoses: Two hoses, one red (Fuel) one green (O2) it's important to remember that the green hose has left handed connections and the red hose has right handed connections.


torch body: the "handle" of the torch, There are two basic types of torch bodies, Positive or equal pressure and low pressure or injector type. Equal pressure torches utilize similar levels of pressure from both O2 and the fuel source. Injector type torches use a low pressure inlet for fuel (below 2psi) and and a high pressure flow of O2. Most torches are equal pressure type, however if you raid a factory or plant, you may come across injector type torches hooked up to a gas manifold.

welding tip: Basically a nozzle made from a non-ferrous alloy with a hole in the tip, the bigger the hole, the more gas you suck, the bigger the flame, achieving higher heat output (I said heat, not Temperature pay attention to that). Tips are generally measured in gauge size ie, smaller gauge= bigger hole.

heating head: A nozzle with a long neck made from non ferrous alloys with multiple holes in the tip, designed specifically for maximum output.


Cutting Torch: An entire torch body designed for cutting operations. The primary difference between it and a welding tip is that there is an additional channel for O2 to run through the body so when the handle is squeezed, a pure stream of O2 is emitted from the tip of the torch. Tips are removable and come in multiple sizes and fuel types, propane nozzles and acetylene nozzles are not interchangeable. Acetylene nozzles are always one piece and have circular, well defined jets around a central hole, Fuel gas nozzles can be one or two pieces, and have multiple slotted holes around a central hole.

Acetylene Nozzle Fuel Gas nozzle


Fuel Gases: This is an area that even some engineers have difficulty with. Basically it comes down to understanding the difference between heat and temperature. I'm going to avoid complex definitions and try to show this graphically.




For these reasons, Propane, Propylene, and MAPP gas are all much more effective at cutting than Acetylene, however Acetylene is much more suited to welding than the other three gases, so if you need to tank only one, tank the Acetylene tank.

There are considerations to keep in mind with Acetylene. First, Acetylene is very volatile at pressures above 15 psi, as a precaution, most acetylene regulators will not go above 15 psi, and for that reason, do not use anything but a acetylene regulator on an acetylene tank. Additionally the rate of consumption cannot exceed 1/7th of the tanks contents per hour, doing so causes the tank to draw acetone from the bottom of the tank, causing a purple flame as well as melting your gas lines.

Regulators:

Compressed Gas tanks have pressures ranging from a few hundred to thousands of pounds of pressure. In order to control this immense pressure you need a piece of equipment called a regulator.

Simply put, a regulator is a piece of equipment that takes the high pressure gas, and converts it to a steady, stable stream that we can utilize.

Regulators have two gauges above, the gauge on the left is the outlet pressure, the gauge on the right is the inlet pressure. The Key controls the outlet pressure.

Important! regulators vary for the types of gas they are effective for, the key thing to remember these basic rules

#1. Only use Acetylene regulators for acetylene.
#2. Only use Fuel gas regulators for fuel gases.
#3 Only use 02 regulators with 02.


Safety Concerns:

Basically the worst case scenario with this equipment is an explosion. I'll go over specific safety concerns under each area as they come up, Pay attention and read anything bolded in red. This **** can kill you or worse, maim you. Respect it.

Welding:

OxyFuel welding involves using the flame to melt the base metal and form a puddle, after establishing the puddle you can either perform the weld autogenously (without filler metal) or you can dip filler rod into the molten puddle to add material.


Cutting:

An oxyfuel torch can be used to cut most mild and low alloy steels, stainless steel and aluminum can be cut using specialized gases, but you are better off leaving those to a plasma torch or mechanical method.

Oxyfuel cutting works by taking advantage of the following chemical reaction between Iron and the chemically pure oxygen: 4Fe 3O2 --> 2Fe2O3. A by-product of this reaction is a large amount of heat, so assuming you keep a steady stream of oxygen flowing then the reaction will produce enough heat to sustain itself.

The major variables to cutting steel with a oxyfuel torch are as follows

Oxygen Pressure: This is determined by the size of the cutting tip, if the pressure is too low or too high, you won't have a clean cut.

Fuel Pressure: This is also determined by the size of the cutting tip, too low of a pressure means you'll spend too much time preheating, too high of a pressure ruins your cut.

Travel speed. You need to move slowly enough to maintain the reaction, but quickly enough to not melt excess material, travel speed is determined by the material thickness.

To give you a rough idea of the above settings here is a chart:


Torch tip to work Distance: This also effects cut quality: Keep the tips of the inner blue flame about 3/16" above the base metal.

To see a cut in action, here's a quick video: I know the guy sorta sounds like an idiot, just pay attention to the technique.



Brazing and Soldering: