What Is Oxyfuel Welding? 100
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Class Outline
Objectives
What Is Oxyfuel Welding?
Types of Metals
Oxyfuel Gases
Gas Cylinders
Oxyfuel Torches
Torch Types
Welding Torch Tips
Filler Metals
Types of Welds
Cutting with an Oxyfuel Torch
Brazing and Soldering
Advantages of Oxyfuel Welding
Summary
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Class Outline
Objectives
What Is Oxyfuel Welding?
Types of Metals
Oxyfuel Gases
Gas Cylinders
Oxyfuel Torches
Torch Types
Welding Torch Tips
Filler Metals
Types of Welds
Cutting with an Oxyfuel Torch
Brazing and Soldering
Advantages of Oxyfuel Welding
Summary
Lesson: 1/14
Objectives
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Define oxyfuel welding.
Describe the types of metals used for
welding.
Describe the gases used in oxyfuel
welding.
Describe oxyfuel gas cylinders.
Label the parts of an oxyfuel torch.
Distinguish between the types of oxyfuel
torches.
Describe welding torch tips.
Describe filler metals.
Identify the types of welds.
Describe cutting with an oxyfuel torch.
Describe other uses for a torch.
Describe the advantages of oxyfuel
welding.
Figure 1. Oxyfuel welding can be used on a variety of metals and can be supplemented with
a filler metal.
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Lesson: 1/14
Objectives
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Define oxyfuel welding.
Describe the types of metals used for
welding.
Describe the gases used in oxyfuel
welding.
Describe oxyfuel gas cylinders.
Label the parts of an oxyfuel torch.
Distinguish between the types of oxyfuel
torches.
Describe welding torch tips.
Describe filler metals.
Identify the types of welds.
Describe cutting with an oxyfuel torch.
Describe other uses for a torch.
Describe the advantages of oxyfuel
welding.
Figure 1. Oxyfuel welding can be used on a variety of metals and can be supplemented with
a filler metal.
Figure 2. The oxyfuel torch is a relatively simple component that can be used for a wide
variety of tasks.
Lesson: 2/14
What Is Oxyfuel Welding?
Welding
joining
process
permanently
joins two separate components with
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U, LLC.that
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Reserved.
heat and pressure to make one new part. Welding is often an art form that requires a
high level of skill. There are as many as 50 different types of welding that use different
sources of energy.
Lesson: 2/14
What Is Oxyfuel Welding?
Welding is a joining process that permanently joins two separate components with
heat and pressure to make one new part. Welding is often an art form that requires a
high level of skill. There are as many as 50 different types of welding that use different
sources of energy.
Oxyfuel welding is a type of welding that uses a mix of gases to fuel a torch to join
two metal parts. The "oxy" in the word "oxyfuel" refers to oxygen, which is always
one of the gases used in this type of welding. Oxygen is mixed with another gas to
intensify its flammability.
The most common gas to mix with oxygen is acetylene. Other gases, such as
propylene, propane, natural gas, MAPP gas, butane, gasoline, liquid petroleum gas,
and hydrogen, may be used for oxyfuel processes. However, acetylene is usually
preferred because it creates a hotter flame than any other mixture.
Figure 1. Oxyfuel welding involves these basic
components along with oxygen and acetylene gas.
Oxyfuel welding is the oldest welding process, having been developed in 1903. Though
arc welding has become more popular than oxyfuel welding, the wide variety of uses
of oxyfuel torches and their low cost have guaranteed the continued use of oxyfuel in
modern manufacturing. Oxyfuel is well suited for work on pipes and fittings, but can
meet other welding needs as well.
In this class you will learn the basic process of oxyfuel welding as it applies to metals.
You will also learn about the components used during oxyfuel welding and the
advantages of this unique process.
Figure 2. Oxygen and acetylene are the two most
commonly used oxyfuel gases.
Lesson: 3/14
Types of Metals
Almost all materials that are welded are metals. A metal is classified as a ferrous
metal or non-ferrous metal. Ferrous metals contain iron, while non-ferrous
metals do not. Often, for welding to be successful, the metals being joined must
be similar in composition. However, certain welding processes can be used to weld
dissimilar metals.
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Many types of metal form good welds. However, the most commonly welded metal
is low-carbon steel, or mild steel. This ferrous metal can be welded using almost
Lesson: 3/14
Types of Metals
Almost all materials that are welded are metals. A metal is classified as a ferrous
metal or non-ferrous metal. Ferrous metals contain iron, while non-ferrous
metals do not. Often, for welding to be successful, the metals being joined must
be similar in composition. However, certain welding processes can be used to weld
dissimilar metals.
Many types of metal form good welds. However, the most commonly welded metal
is low-carbon steel, or mild steel. This ferrous metal can be welded using almost
any method. Manufacturers use low-carbon steel to make a wide range of
products, including cars, buildings, and washing machines. Oxyfuel welding is used
primarily with mild steel.
Stainless steel is another ferrous metal that can be welded using various
methods. As the name implies, stainless steel does not tarnish easily, and it is
smooth and hard.
Welders also work with non-ferrous metals, including copper and aluminum,
shown in Figure 1. You can see the difference between low-carbon steel, stainless
steel, and aluminum in Figure 2. Welding ferrous and non-ferrous materials
together can be successful, but only with a limited number of welding methods.
Figure 1. Aluminum is one of the common welding
metals, though it is not usually used with oxyfuel
welding.
Figure 2. The differences between metals are usually
noticeable upon visual inspection.
Lesson: 4/14
Oxyfuel Gases
The most common form of oxyfuel welding uses oxygen mixed with acetylene to create a
flame with a temperature of 5,589 °F (3087°C). Both of these gases have special
properties and are stored in special cylinders, as shown in Figure 1. Oxygen is a very
common element. Air contains approximately 21% oxygen, and most of the oxygen used in
oxyfuel welding is obtained from air by a process called distillation. Oxygen will not burn on
its own, but must be combined with another gas, at which point it becomes extremely
flammable.
Acetylene is a compound made of carbon and hydrogen. Acetylene is very unstable. For
instance, when mixed with certain gases, acetylene can become dangerously explosive.
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LLC.pressure
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Reserved.
Additionally,
when
under
15 psi, acetylene can explode. Due to its
volatility, extra care must be taken when handling acetylene.
Lesson: 4/14
Oxyfuel Gases
The most common form of oxyfuel welding uses oxygen mixed with acetylene to create a
flame with a temperature of 5,589 °F (3087°C). Both of these gases have special
properties and are stored in special cylinders, as shown in Figure 1. Oxygen is a very
common element. Air contains approximately 21% oxygen, and most of the oxygen used in
oxyfuel welding is obtained from air by a process called distillation. Oxygen will not burn on
its own, but must be combined with another gas, at which point it becomes extremely
flammable.
Acetylene is a compound made of carbon and hydrogen. Acetylene is very unstable. For
instance, when mixed with certain gases, acetylene can become dangerously explosive.
Additionally, when under any pressure above 15 psi, acetylene can explode. Due to its
volatility, extra care must be taken when handling acetylene.
Other gases that can be used for oxyfuel welding include gasoline, propane, propylene,
MAPP gas, and many more. A MAPP cylinder is shown in Figure 2. Each of these gases has
its own properties. Therefore, you should familiarize yourself with the properties of different
gases when using them. However, acetylene is still the most widely used gas for oxyfuel
welding.
Figure 1. Oxyfuel gases must be properly
stored in cylinders like these.
Figure 2. MAPP gas can be used in some
oxyfuel welding instead of acetylene.
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Lesson: 5/14
Lesson: 5/14
Gas Cylinders
The gases used in oxyfuel welding are transported in specially built cylinders. Each
gas has a unique cylinder, specific to its use. Cylinders can come in a variety of sizes,
including smaller portable cylinders, as shown in Figure 1.
Oxygen is stored in seamless tanks that are shaped by a die. These cylinders
feature walls that are 1/4 in. (0.64 cm ) thick. Two hundred forty four cu. ft. (558
cu. m) of oxygen is normally stored at around 2,200 psi at 70 °F (21°C). A bronze
valve is fitted over the cylinder's only opening. This valve should be fully closed at all
times when the oxygen is not being used. When it is being used, the valve should
be fully open. If it is not fully open, oxygen can escape through the valve.
Acetylene cylinders are welded steel tubes. These tubes are filled with a porous
material that is saturated with liquid acetone. The acetone liquid absorbs the
acetylene gas for storage. Each cylinder can normally hold about 280 cu. ft. (641 cu.
m) of acetylene gas at between 200 and 300 psi. Low-temperature melting fuse
plugs at each end of the cylinder will melt if temperature gets above 212°F (100 °C),
to prevent the tanks from exploding. Though no explosion will occur, this escaping
gas is flammable.
Cylinders should be handled carefully. Cylinders should always be used and stored in
an upright position. Oxygen valves should be opened only by hand, never with a
wrench. Some acetylene valves can be opened by hand, but keyed acetylene valves
should only be opened using the key supplied with the tank.
Figure 1. Oxygen and acetylene cylinders appear quite
different from each other, even when sized smaller to
be more portable.
Lesson: 6/14
Oxyfuel Torches
A torch is the tool used to create the flame for welding and is shown in Figure 1. A
torch is made of the following parts:
A flashback arrestor (Figure 2) is installed between the hose and the hose
connector to prevent flashback. Flashback occurs when the welding flame moves
from the tip of a torch back into the torch itself, and eventually into the regulators
attached to the cylinders, or even to cylinders themselves. Flashback arrestors
reduce the chance of dangerous explosions.
l Hose connectors connect the flashback arrestor to the torch. Each gas has its
own hose connector.
l Valves are used to regulate the amount of gas flowing into the torch. Valves may
be located close to the hose connectors, or closer to the tip of the torch.
l The torch body, or handle, is held by the welder while using the torch. Inside the
torch body are hoses which keep the gases separated until they reach the mixing
chamber.
l The mixing chamber is connected to the welding tip and is where oxygen and
acetylene are combined.
l The welding tip is where the actual welding flame is ignited. Tips are made of
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U, LLC.
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solid© copper
and come
in All
different
sizes and types.
l
Each torch has all of these parts, although they may be located in different places in
Figure 1. An oxyfuel torch is made of a variety of
parts.
Lesson: 6/14
Oxyfuel Torches
A torch is the tool used to create the flame for welding and is shown in Figure 1. A
torch is made of the following parts:
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A flashback arrestor (Figure 2) is installed between the hose and the hose
connector to prevent flashback. Flashback occurs when the welding flame moves
from the tip of a torch back into the torch itself, and eventually into the regulators
attached to the cylinders, or even to cylinders themselves. Flashback arrestors
reduce the chance of dangerous explosions.
Hose connectors connect the flashback arrestor to the torch. Each gas has its
own hose connector.
Valves are used to regulate the amount of gas flowing into the torch. Valves may
be located close to the hose connectors, or closer to the tip of the torch.
The torch body, or handle, is held by the welder while using the torch. Inside the
torch body are hoses which keep the gases separated until they reach the mixing
chamber.
The mixing chamber is connected to the welding tip and is where oxygen and
acetylene are combined.
The welding tip is where the actual welding flame is ignited. Tips are made of
solid copper and come in different sizes and types.
Each torch has all of these parts, although they may be located in different places in
individual torches. Also, some torches use tips that have mixing chambers built in.
Figure 1. An oxyfuel torch is made of a variety of
parts.
Figure 2. A flashback arrestor connects the hoses
to the torch and prevents flashback.
Lesson: 7/14
Torch Types
Two types of torches are commonly used in oxyfuel welding: the positive pressure
torch and the injector torch. These torches have similar parts, but differ in how gases
are fed into the mixing chamber.
As shown in Figure 1, a positive pressure torch uses equal pressures of oxygen and
acetylene to fill the mixing chamber. For most torches of this type, medium pressure
(between 1 and 15 psi) is needed to ensure that the gases mix properly. Care must be
taken to keep pressures equal, or else proper mixing may not occur.
Though it generally looks like a positive pressure torch from the outside, an injector
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torch
features
one
different
internal
part,
the injector, as shown in in Figure 2. Oxygen
at high pressure is fed into the torch through the injector, which pulls low pressure
acetylene into the mixing chamber. Injector torches use unequal pressures of acetylene
Figure 1. Positive pressure torches use equal
Lesson: 7/14
Torch Types
Two types of torches are commonly used in oxyfuel welding: the positive pressure
torch and the injector torch. These torches have similar parts, but differ in how gases
are fed into the mixing chamber.
As shown in Figure 1, a positive pressure torch uses equal pressures of oxygen and
acetylene to fill the mixing chamber. For most torches of this type, medium pressure
(between 1 and 15 psi) is needed to ensure that the gases mix properly. Care must be
taken to keep pressures equal, or else proper mixing may not occur.
Though it generally looks like a positive pressure torch from the outside, an injector
torch features one different internal part, the injector, as shown in in Figure 2. Oxygen
at high pressure is fed into the torch through the injector, which pulls low pressure
acetylene into the mixing chamber. Injector torches use unequal pressures of acetylene
and oxygen to fuel the welding flame. The pressure of acetylene used by an injector
torch can be as low as 0.25 psi.
Figure 1. Positive pressure torches use equal
pressures of oxygen and acetylene.
The injector torch has a few advantages over the positive pressure torch. The low
acetylene pressure means that an acetylene generator can be used with an injection
torch. Also, injector torches are capable of drawing all of the gas out of a cylinder,
whereas some gas may be left behind when using a positive pressure torch.
Figure 2. The injector nozzle in an injector torch
feeds oxygen into the mixing chamber.
Lesson: 8/14
Welding Torch Tips
Welding torch tips come in a variety of sizes and shapes, as shown in Figure 1. Some
tips come with integrated mixing chambers. These are commonly referred to as in-tip
mixers. Aside from in-tip mixers, tips may come in a one-piece tube and tip
combination, or as a separate tube and tip.
Tip size is an important variable among tips. Tip size is measured by the diameter of
the orifice at the end of the tip, where the mixed gas leaves the tip and the flame
begins. A larger orifice means more gas escapes the torch, which means the torch’s
flame produces more heat because it is bigger. The temperature of the flame does not
change, but the larger flame means more heat is being released.
Most welding supply companies provide their customers with a tip size recommendation
chart. This chart should give you an idea of what size tip to use for different metals.
Though there is no standard size identification system for welding tips currently, you
can use a drill bit to figure out the orifice size. Be careful to not scratch or harm the tip
while figuring out the size. In most of the different numbering systems for welding
tips, the lower-numbered tips are smaller than the tips with higher numbers.
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Figure 1. Welding tips can be many different
shapes and sizes.
Lesson: 8/14
Welding Torch Tips
Welding torch tips come in a variety of sizes and shapes, as shown in Figure 1. Some
tips come with integrated mixing chambers. These are commonly referred to as in-tip
mixers. Aside from in-tip mixers, tips may come in a one-piece tube and tip
combination, or as a separate tube and tip.
Tip size is an important variable among tips. Tip size is measured by the diameter of
the orifice at the end of the tip, where the mixed gas leaves the tip and the flame
begins. A larger orifice means more gas escapes the torch, which means the torch’s
flame produces more heat because it is bigger. The temperature of the flame does not
change, but the larger flame means more heat is being released.
Most welding supply companies provide their customers with a tip size recommendation
chart. This chart should give you an idea of what size tip to use for different metals.
Though there is no standard size identification system for welding tips currently, you
can use a drill bit to figure out the orifice size. Be careful to not scratch or harm the tip
while figuring out the size. In most of the different numbering systems for welding
tips, the lower-numbered tips are smaller than the tips with higher numbers.
Figure 1. Welding tips can be many different
shapes and sizes.
Lesson: 9/14
Filler Metals
A filler metal is used during welding when additional metal is needed to complete a joint.
Figure 1 shows a welder using a filler metal. Filler metals are also called welding rods and can
be used in welding, brazing, and soldering. Oxyfuel welding can use both ferrous and nonferrous filler metals.
When selecting a filler metal, there are several factors to consider. The thickness of the metal
and the type of metal being welded are the biggest deciding factors. Metals should be welded
with welding rods with a diameter close to the thickness of the pieces.
The metal composing a filler rod should match the metal being welded, with a few exceptions.
High-strength steel rod can be used with not only high-carbon steel, but also to produce
stronger joints in low-carbon steel welds. Cast iron rods should be selected according to
manufacturer recommendations. There are several different types of cast iron filler metals,
some of which have added alloys. Brass welding rods are used for welding any copper alloys,
but can also be used with a flux to weld together many types of steel and cast iron.
A flux is a liquid, powder, or paste used to remove oxides and other impurities. When added
to a weld, fluxes cause the impurities in a joint to float out to the surface of the weld. There
are different fluxes made for use with each type of metal. Also, many welding rods come with
flux already coating the rod, so no additional flux is needed. When welding steel with a steel
welding rod, no flux is needed.
Figure 1. A welder adds filler metal to
strengthen a joint.
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Lesson: 9/14
Filler Metals
A filler metal is used during welding when additional metal is needed to complete a joint.
Figure 1 shows a welder using a filler metal. Filler metals are also called welding rods and can
be used in welding, brazing, and soldering. Oxyfuel welding can use both ferrous and nonferrous filler metals.
When selecting a filler metal, there are several factors to consider. The thickness of the metal
and the type of metal being welded are the biggest deciding factors. Metals should be welded
with welding rods with a diameter close to the thickness of the pieces.
The metal composing a filler rod should match the metal being welded, with a few exceptions.
High-strength steel rod can be used with not only high-carbon steel, but also to produce
stronger joints in low-carbon steel welds. Cast iron rods should be selected according to
manufacturer recommendations. There are several different types of cast iron filler metals,
some of which have added alloys. Brass welding rods are used for welding any copper alloys,
but can also be used with a flux to weld together many types of steel and cast iron.
A flux is a liquid, powder, or paste used to remove oxides and other impurities. When added
to a weld, fluxes cause the impurities in a joint to float out to the surface of the weld. There
are different fluxes made for use with each type of metal. Also, many welding rods come with
flux already coating the rod, so no additional flux is needed. When welding steel with a steel
welding rod, no flux is needed.
Figure 1. A welder adds filler metal to
strengthen a joint.
Lesson: 10/14
Types of Welds
Oxyfuel welding can be used for joining metals in a wide variety of ways. Some of
the different joints made with oxyfuel welding include the following:
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A lap joint (Figure 1) is a joint between two overlapping pieces of metal.
Lap joints can be challenging because the edge of one piece is being welded
to the surface of another, and the edge melts faster than the surface.
An outside corner joint (Figure 2) is formed by the edges of two metal
pieces being welded together at an angle of around 90°. There are four
different types of outside corner joints, depending on where the pieces are
welded together.
A T-joint (Figure 3) is a joint formed when the edge of one piece is welded
to the surface of another piece at a 90° angle. T-joint welds can have
problems similar to the lap joint due to the edge and surface melting at
different rates.
A butt joint (Figure 4) is used to join two pieces of metal edge to edge.
Butt joint welding is a very common use of oxyfuel welding.
An edge joint (Figure 5) joins the edges of two pieces of metal. Edge
joints have relatively few complications compared to other joints.
Figure 1. A lap joint is formed when two pieces of metal
overlap.
These joints are capable of being welded in a variety of positions, including
horizontal, vertical, flat, and overhead. Though oxyfuel welding can be used to
perform welds in these positions, additional training and experience are essential
before
a welder
them.
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© 2009 tries
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U, LLC. All Rights Reserved.
Figure 2. An outside corner joint is formed by welding
the ends of two pieces of metal to form a corner.
Lesson: 10/14
Types of Welds
Oxyfuel welding can be used for joining metals in a wide variety of ways. Some of
the different joints made with oxyfuel welding include the following:
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A lap joint (Figure 1) is a joint between two overlapping pieces of metal.
Lap joints can be challenging because the edge of one piece is being welded
to the surface of another, and the edge melts faster than the surface.
An outside corner joint (Figure 2) is formed by the edges of two metal
pieces being welded together at an angle of around 90°. There are four
different types of outside corner joints, depending on where the pieces are
welded together.
A T-joint (Figure 3) is a joint formed when the edge of one piece is welded
to the surface of another piece at a 90° angle. T-joint welds can have
problems similar to the lap joint due to the edge and surface melting at
different rates.
A butt joint (Figure 4) is used to join two pieces of metal edge to edge.
Butt joint welding is a very common use of oxyfuel welding.
An edge joint (Figure 5) joins the edges of two pieces of metal. Edge
joints have relatively few complications compared to other joints.
Figure 1. A lap joint is formed when two pieces of metal
overlap.
These joints are capable of being welded in a variety of positions, including
horizontal, vertical, flat, and overhead. Though oxyfuel welding can be used to
perform welds in these positions, additional training and experience are essential
before a welder tries them.
Figure 2. An outside corner joint is formed by welding
the ends of two pieces of metal to form a corner.
Figure 3. A T-joint is formed by welding the edge of one
piece to the surface of another.
Figure 4. A butt joint is formed by joining two pieces of
metal edge to edge.
Figure 5. An edge joint is formed by joining the edges of
two metal pieces together.
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two metal pieces together.
Lesson: 11/14
Cutting with an Oxyfuel Torch
Oxyfuel can be used for several other procedures. Cutting, brazing, and soldering
are all tasks that an oxyfuel welder can perform on a regular basis.
Cutting is an essential use of oxyfuel equipment for many manufacturers. Oxyfuel can
be used to cut steel and ferrous metals. The only differences between oxyfuel welding
equipment and cutting equipment are the torch itself and the amount of oxygen used.
As shown in Figure 1, the cutting torch is similar to the welding torch, with a few
additions. The cutting torch has a third tube in the handle, which provides the highpressure oxygen needed to cut. This additional oxygen is controlled by a lever on the
torch. Additionally, the torch features a different tip than a welding torch, as shown in
Figure 2.
Figure 1. Compared to a welding torch, the cutting
torch has a different handle and tip.
Cutting torches can be either completely separate torches or attachments added to a
welding torch. If a cutting attachment is being added to a welding torch, the tip of the
torch is removed and replaced with the cutting torch.
Cutting tips are made of copper, similar to welding tips. Externally, the cutting tip
appears larger. The orifice of a cutting tip is different as well. The hole in the center of
the tip is for the high-pressure oxygen that actually performs the cutting.
Figure 2. Cutting requires a different type of tip
with a different orifice.
Lesson: 12/14
Brazing and Soldering
In addition to cutting, oxyfuel can also be used for brazing. Brazing is a metal joining
technique similar to welding. The essential difference is that brazing uses filler metals that
melt at a temperature above 840 °F (449 °C), but below the melting point of the metals
being joined. A torch is used to heat the filler metal, which is drawn into the space between
the pieces by a process called capillary action. Brazing requires the use of a flux.
Similar to brazing, braze welding is another process that uses an oxyfuel torch to melt a
filler metal at a temperature low enough to not melt the pieces being joined. The difference
between brazing and braze welding is that the joint is filled by a braze pool, not by
capillary action.
Brazing and braze welding are used often in manufacturing for repairs and for welding
together different metals. For some metals, brazing means that they can be joined without
losing their unique qualities. For example, cast iron loses much of its ductility if it is welded.
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Soldering is similar to brazing, but uses filler metals that melt at below 840°F (449°C).
Soldering requires the use of a flux to clean joints. Because properly soldered joints are
airtight and watertight, they are often used in pipe repair. Unlike the soldering done on
Lesson: 11/14
Cutting with an Oxyfuel Torch
Oxyfuel can be used for several other procedures. Cutting, brazing, and soldering
are all tasks that an oxyfuel welder can perform on a regular basis.
Cutting is an essential use of oxyfuel equipment for many manufacturers. Oxyfuel can
be used to cut steel and ferrous metals. The only differences between oxyfuel welding
equipment and cutting equipment are the torch itself and the amount of oxygen used.
As shown in Figure 1, the cutting torch is similar to the welding torch, with a few
additions. The cutting torch has a third tube in the handle, which provides the highpressure oxygen needed to cut. This additional oxygen is controlled by a lever on the
torch. Additionally, the torch features a different tip than a welding torch, as shown in
Figure 2.
Figure 1. Compared to a welding torch, the cutting
torch has a different handle and tip.
Cutting torches can be either completely separate torches or attachments added to a
welding torch. If a cutting attachment is being added to a welding torch, the tip of the
torch is removed and replaced with the cutting torch.
Cutting tips are made of copper, similar to welding tips. Externally, the cutting tip
appears larger. The orifice of a cutting tip is different as well. The hole in the center of
the tip is for the high-pressure oxygen that actually performs the cutting.
Figure 2. Cutting requires a different type of tip
with a different orifice.
Lesson: 12/14
Brazing and Soldering
In addition to cutting, oxyfuel can also be used for brazing. Brazing is a metal joining
technique similar to welding. The essential difference is that brazing uses filler metals that
melt at a temperature above 840 °F (449 °C), but below the melting point of the metals
being joined. A torch is used to heat the filler metal, which is drawn into the space between
the pieces by a process called capillary action. Brazing requires the use of a flux.
Similar to brazing, braze welding is another process that uses an oxyfuel torch to melt a
filler metal at a temperature low enough to not melt the pieces being joined. The difference
between brazing and braze welding is that the joint is filled by a braze pool, not by
capillary action.
Brazing and braze welding are used often in manufacturing for repairs and for welding
together different metals. For some metals, brazing means that they can be joined without
losing their unique qualities. For example, cast iron loses much of its ductility if it is welded.
Soldering is similar to brazing, but uses filler metals that melt at below 840°F (449°C).
Soldering requires the use of a flux to clean joints. Because properly soldered joints are
airtight
watertight,
areRights
oftenReserved.
used in pipe repair. Unlike the soldering done on
Copyrightand
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Tooling U, they
LLC. All
electronics and circuit boards, soldering with oxyfuel is an inexact, large-scale method of
soldering.
Lesson: 12/14
Brazing and Soldering
In addition to cutting, oxyfuel can also be used for brazing. Brazing is a metal joining
technique similar to welding. The essential difference is that brazing uses filler metals that
melt at a temperature above 840 °F (449 °C), but below the melting point of the metals
being joined. A torch is used to heat the filler metal, which is drawn into the space between
the pieces by a process called capillary action. Brazing requires the use of a flux.
Similar to brazing, braze welding is another process that uses an oxyfuel torch to melt a
filler metal at a temperature low enough to not melt the pieces being joined. The difference
between brazing and braze welding is that the joint is filled by a braze pool, not by
capillary action.
Brazing and braze welding are used often in manufacturing for repairs and for welding
together different metals. For some metals, brazing means that they can be joined without
losing their unique qualities. For example, cast iron loses much of its ductility if it is welded.
Soldering is similar to brazing, but uses filler metals that melt at below 840°F (449°C).
Soldering requires the use of a flux to clean joints. Because properly soldered joints are
airtight and watertight, they are often used in pipe repair. Unlike the soldering done on
electronics and circuit boards, soldering with oxyfuel is an inexact, large-scale method of
soldering.
Figure 1. Brazing uses capillary action to fill a
gap between two pieces.
Lesson: 13/14
Advantages of Oxyfuel Welding
Oxyfuel welding offers many advantages that guarantee its continued use in welding. The
main advantage of oxyfuel is cost. For a welder working independently or for a small
company, oxyfuel is a cost-effective welding solution for mild steel applications, certain
aluminum applications, brazing, and soldering.
Also, oxyfuel is more mobile than many welding solutions. Arc welding equipment can only
be used to weld, and only if a power source is nearby. Oxyfuel does not require any
electrical power. Rather, it simply requires gas cylinders and some method to ignite the
flame. In addition, oxyfuel welding equipment can be used for cutting, brazing, and
soldering.
However, oxyfuel is not without disadvantages. Because the flame of an oxyfuel torch is
much larger than a welding arc, oxyfuel welding is not as clean or exact as arc welding.
Burning acetylene also releases high amounts of carbon, which can cause problems with
welds, as well as environmental issues.
Despite these disadvantages, the cost and flexibility of oxyfuel welding mean that many
welders still use the method on a daily basis.
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Lesson: 13/14
Advantages of Oxyfuel Welding
Oxyfuel welding offers many advantages that guarantee its continued use in welding. The
main advantage of oxyfuel is cost. For a welder working independently or for a small
company, oxyfuel is a cost-effective welding solution for mild steel applications, certain
aluminum applications, brazing, and soldering.
Also, oxyfuel is more mobile than many welding solutions. Arc welding equipment can only
be used to weld, and only if a power source is nearby. Oxyfuel does not require any
electrical power. Rather, it simply requires gas cylinders and some method to ignite the
flame. In addition, oxyfuel welding equipment can be used for cutting, brazing, and
soldering.
However, oxyfuel is not without disadvantages. Because the flame of an oxyfuel torch is
much larger than a welding arc, oxyfuel welding is not as clean or exact as arc welding.
Burning acetylene also releases high amounts of carbon, which can cause problems with
welds, as well as environmental issues.
Despite these disadvantages, the cost and flexibility of oxyfuel welding mean that many
welders still use the method on a daily basis.
Figure 1. The portability of oxyfuel is a major
advantage for many welders.
Lesson: 14/14
Summary
Oxyfuel welding is a type of welding that uses a mix of gases to fuel a torch to
join two metal parts. Oxygen is mixed with another gas to intensify the
flammability of the gas. Many different metals form good welds. However, the
most commonly welded metal is low-carbon steel, or mild steel.
The most common form of oxyfuel welding uses oxygen mixed with acetylene
to create a flame with a temperature of 5,589 ° F (3,087°C). The gases used in
oxyfuel welding are transported in specially built cylinders. An oxyfuel torch is
used to create the flame for welding by mixing the gases. Torches can be either
positive pressure torches or injector torches.
Welding torches have welding tips that come in a variety of shapes and sizes.
Though size numbering systems are not universal, drill bits can be used to
determine the size of a tip.
Oxyfuel torches can be used to perform many different welds, including lap
joints, outside corner joints, T-joints, butt joints, and edge joints. In addition,
oxyfuel torches can be used for cutting, brazing, braze welding, and soldering.
Oxyfuel welding offers advantages in terms of mobility and cost.
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Figure 1. Oxyfuel equipment can be used in a variety of
environments, and to cut as well as weld.
Lesson: 14/14
Summary
Oxyfuel welding is a type of welding that uses a mix of gases to fuel a torch to
join two metal parts. Oxygen is mixed with another gas to intensify the
flammability of the gas. Many different metals form good welds. However, the
most commonly welded metal is low-carbon steel, or mild steel.
The most common form of oxyfuel welding uses oxygen mixed with acetylene
to create a flame with a temperature of 5,589 ° F (3,087°C). The gases used in
oxyfuel welding are transported in specially built cylinders. An oxyfuel torch is
used to create the flame for welding by mixing the gases. Torches can be either
positive pressure torches or injector torches.
Welding torches have welding tips that come in a variety of shapes and sizes.
Though size numbering systems are not universal, drill bits can be used to
determine the size of a tip.
Oxyfuel torches can be used to perform many different welds, including lap
joints, outside corner joints, T-joints, butt joints, and edge joints. In addition,
oxyfuel torches can be used for cutting, brazing, braze welding, and soldering.
Oxyfuel welding offers advantages in terms of mobility and cost.
Figure 1. Oxyfuel equipment can be used in a variety of
environments, and to cut as well as weld.
Figure 2. Welding tips used in oxyfuel welding come in a
variety of sizes and shapes.
Class Vocabulary
Term
Definition
acetone A flammable liquid used in acetylene cylinders to dissolve and store acetylene.
acetylene A colorless, flammable gas that is used in oxyfuel welding. Acetylene is the most commonly used gas for mixing with oxygen
to fuel oxyfuel torches.
airtight Not allowing any gases or air to penetrate. An airtight joint will not leak any gas.
aluminum A silvery white metal that is soft, light, and has a high strength-to-weight ratio. Aluminum is one of the most difficult metals
to weld.
arc welding A joining process that uses electricity to generate the heat needed to melt the base metals.
braze pool The pool formed by the melted filler metal during braze welding. The temperature to melt the filler metal is low enough that
the pieces being joined do not melt.
braze welding A process in which a filler metal is melted at a temperature above 840° F (450° C), but below the melting point of the base
metals to fill in a gap between two base metals. Braze welding differs from brazing because the filler metal is used to fill a
gap.
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brazing A joining process that is used to combine dissimilar metals at temperatures lower than welding.
butt joint A joint formed by joining two pieces of metal edge to edge.
Class Vocabulary
Term
Definition
acetone A flammable liquid used in acetylene cylinders to dissolve and store acetylene.
acetylene A colorless, flammable gas that is used in oxyfuel welding. Acetylene is the most commonly used gas for mixing with oxygen
to fuel oxyfuel torches.
airtight Not allowing any gases or air to penetrate. An airtight joint will not leak any gas.
aluminum A silvery white metal that is soft, light, and has a high strength-to-weight ratio. Aluminum is one of the most difficult metals
to weld.
arc welding A joining process that uses electricity to generate the heat needed to melt the base metals.
braze pool The pool formed by the melted filler metal during braze welding. The temperature to melt the filler metal is low enough that
the pieces being joined do not melt.
braze welding A process in which a filler metal is melted at a temperature above 840° F (450° C), but below the melting point of the base
metals to fill in a gap between two base metals. Braze welding differs from brazing because the filler metal is used to fill a
gap.
brazing A joining process that is used to combine dissimilar metals at temperatures lower than welding.
butt joint A joint formed by joining two pieces of metal edge to edge.
capillary action The ability of a substance to draw a liquid upwards against the force of gravity. In brazing, capillary action causes a filler
metal to be drawn into the space between workpieces.
copper A reddish metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Copper can be welded using
limited methods.
cutting The use of an oxyfuel torch to separate metal from a workpiece. Oxyfuel cutting uses an additional high-pressure stream of
oxygen to cut metal.
cylinder A container for compressed gases. Each gas is stored in a unique type of cylinder.
die A reusable mold that holds heated liquid metal and imparts its shape as the metal cools. Oxygen cylinders are shaped in dies.
distillation The process by which oxygen is extracted from the air to be stored in a cylinder.
ductility The ability of a metal to be drawn, stretched, or formed without breaking.
edge joint A joint formed by joining the edges of two pieces of metal that are parallel to each other.
ferrous metal A metal that contains iron. Ferrous metals are the most common type of welded metal.
filler metal A type of metal sometimes added to the joint in fusion welding. Filler metal adds to the strength and mass of the welded
joint.
flashback A torch malfunction in which the flame briefly or continually moves up into the torch and hoses. If a flame reaches the hoses,
an explosion can occur.
flashback A part of an oxyfuel outfit that is installed between the hoses and the torch. A flashback arrestor reduces the chances of
arrestor flashback occurring while a torch is used.
flux A non-metallic material used to protect the weld puddle and solid metal from atmospheric contamination.
hose connector The part of an oxyfuel torch where the flashback arrestor is attached to the torch.
impurities Any elements contained in an oxyfuel weld that are not the metal being joined or the filler metal.
injector The part of an injector torch that pulls low-pressure acetylene into the torch and mixes it with oxygen.
injector torch A type of torch that uses lower-pressure acetylene and features an internal injector that pulls the acetylene into the torch.
in-tip mixer A welding tip that contains a mixing chamber as part of the tip.
joining Bringing two separate materials together through some type of forming. Joining is one of the main ways metals can be
formed.
lap joint A joint formed by two overlapping pieces of metal.
low-carbon Carbon steels that contain less than 0.3% carbon. Also referred to as mild steel, low-carbon steel is the most commonly
steel welded metal.
MAPP gas Also called methylacetylene-propadiene gas. A liquefied petroleum gas that can be used in oxyfuel processes. The main
disadvantage of MAPP gass is that it costs much more than acetylene.
metal A hard, crystalline solid that conducts electricity and heat. It is shiny when polished, and it can be hammered, bent, formed,
and machined.
mixing chamber A part of an oxyfuel outfit that is connected to the tip of the torch, or is part of the tip. The mixing chamber is where the
two gases are combined before being burned by the flame.
non-ferrous
A metal that does not contain iron. Nonferrous metals are more difficult to weld than ferrous metals.
metal
orifice The hole or holes at the end of a torch tip. The shape and number of holes determine the use of the tip.
outside corner A joint formed by the edges of two metal pieces being welded together at an angle of around 90 degrees. The weld is done
joint on the outside of the corner.
oxide A chemical compund containing oxygen and one other element. Oxides form during oxyfuel welding are harmful to the weld.
oxyfuel welding A joining process that uses a mix of gases to fuel a torch to join two metal parts.
oxygen A nonmetallic element that is colorless, odorless, and tasteless. Oxygen is one of the two gases used in oxyfuel welding.
porous Full of holes that allow the material to absorb liquids. The material inside an acetylene cylinder is porous, enabling it to hold
acetone.
positive
A torch that uses equal pressures of oxygen and acetylene and does not have an injector.
pressure torch
propylene Also known as propane. A flammable gas that can be used in oxyfuel welding instead of acetylene.
soldering A joining process in which a filler metal is melted at temperatures below 840° (450° C) to form a joint between two base
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U, LLC.
All Rights
Reserved.
metals.
Soldering
is often
used for delicate projects such as jewelry and electronics.
stainless steel A type of steel that contains more than 15% chromium and exhibits excellent corrosion resistance. Stainless steel can be
welded using many methods.
pressure torch
A torch that uses equal pressures of oxygen and acetylene and does not have an injector.
propylene Also known as propane. A flammable gas that can be used in oxyfuel welding instead of acetylene.
soldering A joining process in which a filler metal is melted at temperatures below 840° (450° C) to form a joint between two base
metals. Soldering is often used for delicate projects such as jewelry and electronics.
stainless steel A type of steel that contains more than 15% chromium and exhibits excellent corrosion resistance. Stainless steel can be
welded using many methods.
T-joint A joint formed when the edge of one piece is welded to the surface of another piece at a 90° angle.
torch A tool used to generate the flame for oxyfuel welding by mixing oxygen and a fuel gas, usually acetylene.
torch body Also called the handle. The part of the torch held by the welder. Inside the torch body are hoses which direct the flow of
gases to the mixing chamber.
unstable Highly reactive and dangerous, possibly explosive. Unstable chemicals require careful handling to ensure safety.
valve The part of the torch used to regulate the amount of oxygen and fuel gas flowing into the torch.
watertight Not allowing any liquids to penetrate. A watertight joint will not leak any liquids at all.
welding rod Also know as a filler metal. Filler metals come in rods that are used during the welding process.
welding tip The end of the torch where the flame is ignited. Tips are usually interchangable, and are made of solid copper.
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