Part 1. Preparation and safety
Objective
- Set up an oxyacetylene torch for heating.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Oxygen and acetylene cylinders must be securely stored in an upright position.
- An oxyacetylene torch can produce a large amount of heat. Be aware that any objects you direct the flame towards will become hot.
- Always have a suitable fire extinguisher near your work area.
- Do not use an oxyacetylene torch near any flammable materials.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- If a cylinder falls over and breaks the main valve off, the cylinder will become a missile and cause extreme damage.
- Wear a leather apron or similar protective clothing and welding gloves when using an oxyacetylene torch. T-shirts, nylon and polyester blend clothing will not provide enough protection. Ultraviolet light and sparks of hot metal will pass through them.
- Always use proper welding goggles. Do not use sunglasses because they do not filter the extreme ultraviolet light as effectively. The plastic used in sunglass lenses will not protect your eyes from sparks.
- Never point the lighted flame toward another person or any flammable material.
- Always light the oxyacetylene torch with the striker. A cigarette lighter or match would put your hand too close to the igniting tip.
- Wherever possible, use a heat shield behind the component you are heating. This will prevent nearby objects from becoming hot.
- After heating a piece of metal, label it as "HOT" with a piece of chalk so that others will not attempt to pick it up.
Component identification
- Some parts of this illustration are labeled. It is important to learn the names of these equipment components.
Part 2: Step-by-step instruction
- Check equipment
First, make sure that the gas flow from both the oxygen and the acetylene cylinders is turned off tightly. The two cylinders are secured in an upright position. This is usually on a wheeled trolley. Look at the hose pressure and cylinder pressure gauges on top of each cylinder. Both gauges on each cylinder should read zero. If both gauges do not read zero, turn the main cylinder valve on the top of the cylinder clockwise, to close it completely. Then you must purge the system of any gas.
- Purge the system
To purge the system, make sure the main cylinder valve is closed tightly. Pick up the torch handle and note that it has two hoses attached. One hose supplies acetylene, the other oxygen. Turn the oxygen regulator under the gauges clockwise, and open the oxygen valve on the handle. This will purge any gas that may still be in the system and the gauges should both drop back to zero. Repeat this procedure with the acetylene cylinder.
- Install the torch handle
The torch handle is the connection between the hoses and the working tips. It consists of a body and two taps. It’s used for both welding and heating. Different attachments are connected to the handle to enable welding, heating or cutting. Examine the connections. One connection is marked ”OX”, and is for the oxygen hose. The other is marked “AC”, and is for the acetylene hose.
- Connect the hoses
As a further safety precaution, you’ll find the oxygen connector is right hand thread and the acetylene connector is a left hand thread.
- Install the correct tip
Welding tips come in sizes that are stamped with a number. Number one is the smallest tip. The larger the number, the larger the tip and the greater the heat that it will provide. Select the tip size suitable for the heating task and screw it onto the end of the torch handle. Hold the torch handle in your hand, so that you can comfortably adjust the oxygen and acetylene taps. Position the tip so that it faces away from you. Gently tighten the tip-securing fitting.
- Adjust the pressure of the gas flow
You are now ready to adjust the gas pressure for heating. Look at the two valves on the torch handle. The valve next to the oxygen hose controls the flow of oxygen to the tip. Close it tightly clockwise. The valve next to the acetylene hose controls the flow of acetylene to the tip. Also, close it tightly clockwise.
- Turn on the gases
Now that you’re ready to use the torch, turn the main valve on the top of each cylinder counter-clockwise half a turn to open the valve. The needle on the cylinder pressure gauge will rise to show you the pressure in the cylinder. Turn the oxygen regulator handle clockwise until the needle in the gauge registers 10 PSI. Turn the acetylene regulator handle clockwise until the needle in the gauge registers 5 PSI. This is your working pressure for heating.
- Check the area
Before you light the torch, check the area you’re working in to make sure there are no flammable materials or fluids nearby. Workmates should also be clear of the area. The welding flame is not only extremely hot; it also produces dangerous ultra violet rays, which will damage your eyes. It is absolutely vital that you are wearing the right safety gear: gloves and tinted goggles or face mask. So put them on and adjust them comfortably.
- Ignite the torch
Now you are ready to ignite the torch with the striker. The tip of the torch must be pointing downwards away from your body and away from the gas cylinders. Turn the acetylene valve on the torch handle slightly towards the ‘ON’ position. You should hear the gas hissing. Hold the striker against the tip of the torch with the lighter cup between the torch and you. Flick the striker to create the spark that will ignite the gas at the tip of the torch. Open the acetylene valve slowly until the sooty smoke produced by the torch disappears. Then slowly open the oxygen valve on the torch handle.
- Adjust the flame
As you open the oxygen valve, you will see the color of the flame change. The pure acetylene flame is yellow, and it will change to blue as you add the oxygen. Continue to open the oxygen valve until you can observe a small, sharp blue cone in the center of the torch flame. This is the “neutral” flame you need for general heating.
