• SkillCat Team

How to Operate a Gas Torch

Updated: Jun 23

Brazing and Soldering: Chapter 3


Torches


In this module, we will discuss what is a torch and its components. We will review its types and how to use it safely. Skip to quiz!


Torches


Welding, brazing, and soldering techniques use a tool called torch to melt the metals by

heating. A torch produces a very hot flame from its tip. Think about a lighter. It produces a flame from its tip when we click a button.


Like a lighter, torches are used to heat a small area very quickly. But, the flame of a torch is very hot. It is hot enough to melt metals!


Torch Gases


As seen in the video, lighter uses butane gas to produce flame. Similarly, different gases are used for producing a flame in torches.


Recall that presence of oxygen is essential for combustion to take place. In case of lighter, oxygen present in the air helps the gas to burn.


To produce very hot flame in a torch for melting metal, oxygen present in the atmosphere is

not sufficient. Every fuel gas used in a torch is added with compressed oxygen. This produces hot flame required for metal-joining process.


There are three basic gases used in torches:

  • Acetylene,

  • MAPP (methylacetylene-propadiene), and

  • Propane

These are classified based on the temperatures at which they burn and their application.


Acetylene has unstable nature. It can suddenly explode unless it is kept at the proper pressure between 15 psi and 29.4 psi. It is a colorless gas with a strong garlic odor.


Acetylene produces an extremely hot flame, up to temperatures of 10,832 °F. Due to its high heat, acetylene is often used to cut and weld hard metals such as cast iron and steel.


MAPP gas is part of the acetylene family. This gas can burn up to 5,300 °F and is used for heating and cutting metals.


MAPP gas is not prone to explosion if the cylinder is hit or bumped. It also can withstand higher pressures. It's good for underwater work, like repairing ships.


Propane is the same gas we commonly use in household grills. Propane is sold in a liquid state in tanks that range from 20 to 100 lbs. Propane burns at about 5,200 °F and is used for heating and cutting metals, and even cooking!


The torch gases are supplied to the torches through various components. Let us now look at each of them.


A torch consists of the following main components:

  • Cylinder,

  • Regulator,

  • Hose, and

  • Torch Tip


The cylinder is a storage device that holds the fuel for the torch. Typically, oxygen and the gas fuel are kept in different tanks and will only mix when they enter the torch tip.


The torch regulator is a knob that adjusts the pressure of the gas fuel. This is just like the knob we use to adjust a gas stove. The more we turn the knob to the right, the bigger the flame gets.


The hose connects the fuel cylinder to the torch. The fuel from the cylinder travels through the hose to the torch tip. Again, this is very similar to the pipe that connects the gas to the stove.


The torch tip is the end of the torch that produces the flame. Fuel exits the tip through several holes and mixes with oxygen to produce a flame. The number of holes in the tip of the torch depends on the type of fuel being used.


There are two types of torch tips:

  • One-Piece Torch Tip and

  • Two Piece Torch Tip

These tips are classified by the number of holes in the tip and the types of fuel they use.


A one piece torch tip usually has 4 to 6 holes in the tip. It is made from a copper alloy so that it can withstand the high heat from the cutting process. These tips are usually used with the acetylene fuel.


A two piece torch tip consists of an outer shell and a splined insert. The splined insert consists of grooves cut into the metal tip while the outer shell goes over top of the splined insert. This forms the complete two piece torch tip.


The splined insert eliminates the need to drill the numerous holes as needed in a one piece torch tip. These tips are used when the burning action needs to be slow and calm. They typically are used with MAPP gas.


Torch Types


Torches are classified based on the type of fuel they use. They are:

  • MAPP Gas Torch,

  • Oxy-Acetylene Torch, and

  • Propane Torch


MAPP torches use methylacetylene-propadiene gas. These torches can reach temperatures

up to 5,300 °F. When used in combination with oxygen they can be used for soldering, brazing and even welding.


The oxy-acetylene torch uses an oxygen-acetylene gas mixture. This allows the gas to burn up to temperatures of 10,832 °F. It is preferred for brazing, cutting, and welding of cast iron and steel.

Propane torch is commonly used for soldering and brazing. The flame temperature of propane torch is 5,200 °F. This is very similar to the propane torch lighter used to light a cooking grill.


Torches are used in welding, soldering, and brazing. They produce a very hot flame using several different types of gases as fuel. These gases include:

  • MAPP Gas,

  • Oxy-Acetylene, and

  • Propane


How to Operate a Gas Torch


In this module we will summarize how to safely operate a gas torch. Skip to quiz!


Torch Safety


There are many dangers involved when using a torch. We should always wear proper protective equipment when operating a torch. This equipment includes gloves, an apron, and safety goggles.


Recall that regulators are knobs that control the pressure of the fuel in the cylinder to the torch tip. The pressure should never be over 15 psi for acetylene. Always review the torch manual for proper pressure settings.


Cylinders are used to store fuel gasses such as oxygen and acetylene. Oxygen can catch fire


when exposed to flames, grease, and oil. It is important to keep hands and clothes clear of grease and oil when handling these cylinders.


Acetylene, unlike oxygen, is rather unstable. This means it can catch fire quickly. You should never open cylinder valves more than 1.5 turns. This allows you to quickly close the valve in the event of an emergency.


Check valves are placed between the gas hose and the torch. They prevent the backflow of the gas. This means they stop gas from traveling backward in the hose. However, check valves do NOT prevent flashback.


Flashback arrestors prevent flashback. Flashback is when flames flow backward into the cylinders and react with the fuel. This can cause an explosion!


Flashback arrestors contain shutoff valves. They have low melting points. When flames enter the arrestor, they melt the valve, and it shuts off.


Recall that we use different gases in a torch. A proper procedure should be followed while using these gases.



How to Operate a Torch


As seen in the video, for operating gas torch, we start by inserting pressurised gas into the torch handle. We then need to adjust the amount of oxygen to produce a neutral flame. We make use of knobs present on torch handle to a adjust oxygen.


As we have seen operating a torch can be very dangerous. Always follow the proper safety procedures when operating your torch. This will ensure you keep yourself and others out of harm's way.




Question #1: Why do we need to add compressed oxygen with fuel gas?

  1. To utilize oxygen when fuel gas is not available

  2. To produce hot flame required for melting metal

  3. To increase cost

  4. To make weak joint

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Answer: To produce hot flame required for melting metal

Recall that every fuel gas used in a torch is added with compressed oxygen. This produces hot flame required for metal-joining process.


Question #2: Acetylene is a colorless gas with a strong _____ odor?

  1. Metallic

  2. Sulphur

  3. Garlic

  4. Sweet

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Answer: Garlic

Recall that acetylene is a colorless gas with a strong garlic odor.


Question #3: Which amongst the following gas has highest burning temperature?

  1. Acetylene

  2. MAPP (methylacetylene-propadiene), and

  3. Propane

  4. Oxygen

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Answer: Acetylene

Recall that acetylene produces an extremely hot flame, up to temperatures of 10,832 °F.


Question #4: What does a regulator knob of a torch control?

  1. Pressure of the gas

  2. Volume of the gas

  3. Area of the gas

  4. Type of gasScroll down for the answer...
















Answer: Pressure of the gas

Recall that the torch regulator is a knob that adjusts the amount of pressure of the gas.


Question #5: A one piece torch tip normally has how many holes?

  1. 1 to 3 holes

  2. 7 to 8 holes

  3. 3 to 5 holes

  4. 4 to 6 holes

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Answer: 4 to 6 holes

Recall that the one piece torch tip normally usually have 4 or 6 preheated holes.


Question #6:Which of the following gases are used in one piece torch tip? (select all that apply)

  1. Oxygen

  2. MAPP (methylacetylene-propadiene)

  3. Propane

  4. Acetylene

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Answer: Acetylene

Recall that A one piece torch tip usually has 4 to 6 holes in the tip.These tips are usually used with the acetylene fuel.


Question #7: Which of the following gases are used in two piece torch tip? (select all that apply)

  1. Oxygen

  2. MAPP (methylacetylene-propadiene)

  3. Propane

  4. Acetylene

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Answer: MAPP (methylacetylene-propadiene)

Recall that A two piece torch tip is used with MAPP gas.


Question #8: What protective equipment we should always wear when operating a torch.

  1. Respirator with HEPA filter

  2. Goggles and cap

  3. Gloves, an apron, and safety goggles.

  4. Tight clothing

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Answer: Gloves, an apron, and safety goggles.

Recall that we should always wear proper protective equipment when operating a torch. This equipment includes gloves, an apron, and safety goggles.


Question #9: The pressure setting for gas is not required since torch can be used for any pressure.

  1. True

  2. False

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Answer: False

Recall that we should always always review the torch manual for proper pressure settings.


Question #10: Cylinder valves should never be opened more than _____ turns?

  1. 3 turns

  2. 1.5 turns

  3. 1 turn

  4. 2 turns

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Answer: 1.5 turns

Recall that cylinder valves should never be opened more than 1.5 turns so they can be quickly closed in the event of an emergency.


Question #11: Check valves prevent both backflow and flashback of gas.

  1. True

  2. False

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Answer: False

Recall that They prevent the backflow of the gas. However, check valves do NOT prevent flashback.


Question #12: Check valves prevent gas from flowing backward but they do NOT prevent __________.

  1. Burns

  2. Pressure increase

  3. Flashback

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Answer: Flashback

Recall that although check valves prevent gas from flowing backward, they do not prevent Flashback. Flashback Arrestors are needed instead.


Question #13: How do you pressurise the system?

  1. By turning regulator knob counter clockwise

  2. By turning regulator knob clockwise

  3. By closing torch tip

  4. By rotating pressure gauge

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Answer: By turning regulator knob clockwise

Recall that to pressurise the system we need to open the main valve on the cylinder. This will allow gas in the cylinder to enter the system. Then we need to pressurise the gas by turning regulator knob clockwise.


Question #14: The main valve on each cylinder should be opened only after the torch is ready to use.

  1. True

  2. False

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Answer: True

Recall that after attaching torch tip to torch handle we start inserting gas to the torch. This is done using opening main valve on each cylinder.


Question #12: Adjusting amount of oxygen helps to produce neutral flame.

  1. True

  2. False

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Answer: True

Recall that adjusting oxygen knob affects the type of flame you get.


Question #13: Why there are two knobs present on the torch handle?

  1. One knob for fine adjustment and other for large pressure change.

  2. One knob for oxygen and other for fuel gas.

  3. One knob for temperature change and other for pressure.

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Answer: One knob for oxygen and other for fuel gas.

Recall that there are two knobs on torch handle to adjust each gas.

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