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1 AUSTRALIA CANADA USA UNITED KINGDOM SINGAPORE MALAYSIA Safetycare Australia Pty. Ltd. Telephone (03) Safetycare Inc. Telephone (905) Safetycare Inc. Telephone (800) Safetycare (UK) Limited. Telephone (0208) SafetyMax Corp Pte. Ltd. Telephone (65) SafetyMax Sdn Bhd Telephone (603) The information contained in this Facilitator s guide is distributed and sold as a guide and for informational purposes only. Safetycare makes no representation or warranty as to the compliance of this program with any and all applicable laws of the purchaser's jurisdiction. 2. Safetycare's liability for any damages to the purchaser or to any other party shall not exceed the amount paid by the purchaser for the guide. In no event shall Safetycare be responsible for any indirect or consequential damages or loss of profits, even if Safetycare has been advised of the possibility of such damage. Some provinces/states do not allow the limitations or exclusion of liability for incidental or consequential damages, so the above limitations or exclusions may not apply to the purchaser. 3. This Facilitator s Guide is supplied as part of a subscription service. This guide is only to be used during a valid subscription period. Where a subscription is not valid, this guide may not be used. Facilitator s Guide OXY-ACETYLENE CUTTING AND SAFETY Copyright - All Rights Reserved

2 Oxy-Acetylene Cutting and Safety CONTENTS Introduction to the Facilitator s Guide 3 Introduction to the Video Program; Oxy-Acetylene Cutting and Safety 4 Transcript of Video Program 5 Part 1 - Workshop and Personal Safety 10 Part 2 - The Cutting Attachment 12 Part 3 - Back Fire and Flashback 13 Part 4 - Oxy-Acetylene Cutting 15 Part 5 - Closing Down 17 Assessment 18 Answers 20 2

3 INTRODUCTION TO THE FACILITATOR S GUIDE Oxy-Acetylene Cutting and Safety The aim of this Facilitator s Guide, when used in conjunction with the Video program, is to provide the facilitator with discussion points important to the overall development of the program and to allow participants the opportunity of discussing the impact the program may have on current work practices and whether in fact changes may be required. The time allocated to the program will be determined by which areas are seen as important to each Organisation, the time taken to develop the points made in the program and whether other data specific to your own environment is included in addition to, or instead of, the program examples. EACH FACILITATOR SHOULD CAREFULLY READ THE GUIDE DISCUSSION NOTES SUGGESTED AND PREPARE THEIR OWN INPUT ACCORDINGLY. The program transcript is included to allow your Organisation to fully research the program content and develop specific examples critical to the performance of your own workforce. Where the Video program is made available to small or remote sections of your Organisation, some other examples or discussion points may be preferred to suit the needs of these people and if so, should be developed prior to distribution of the program. Maximum benefit will then be obtained by your people. All information included in the Facilitator s Guide may be copied and distributed with the exception of the transcript of the Video program. Any information which is copied or distributed must only be used internally by the Organisation that purchased the guide. SCREEN SHOT FROM THE VIDEO PROGRAM 3

4 INTRODUCTION TO THE VIDEO PROGRAM Duration: 15 minutes Oxy-Acetylene Welding is one of the most common forms of welding in use throughout industry. With the addition of a Cutting Torch the Oxy-acetylene Welding Unit becomes an efficient tool for the cutting of metals. This program shows the correct and safe use of Oxy-acetylene Cutting Equipment, and includes: Equipment and Workshop Safety Gas and Gas Cylinders, their types and flow rates The Cutting Torch and the types and applications of the Tips Equipment knowledge and maintenance Techniques for setting-up and the cutting of metals Closing down, safely and correctly The objective of this program is to highlight the importance of operating Oxy- Acetylene equipment safely as well as to demonstrate the correct and safe way to perform some of the most common cuts. 4

5 TRANSCRIPT OF THE VIDEO PROGRAM Oxy-Acetylene Cutting and Safety Copyright Safetycare. All rights reserved Oxy acetylene equipment can be used for a variety of purposes, heating to normalize or forge metal, to weld one metal to another and by attaching a cutting torch it converts to an efficient high speed tool for cutting carbon steel. The cutting action is in fact a chemical reaction. When steel is heated until it is red hot and then exposed to pure oxygen, a chemical reaction takes place between the heated metal and the oxygen. This is called oxidation. A jet of oxygen is used to remove the oxidized steel. Oxy-Acetylene Safety Because you re dealing with extremely high temperatures you must make sure that you are wearing the correct protective clothing. You should wear a protective shield visor or goggles, gloves, overalls that will button to the neck and at the cuffs, industrial safety boots and a protective apron. A commitment to workshop safety also means that you should ensure that the area you are working in is clean and tidy, well ventilated and clear of all fire hazards. So before you commence work ensure your work area is tidy and free of all rubbish and flammable materials. Sparks created by the oxy cutting process are a very real fire hazard. These sparks have caused numerous fires and they can cause injury to you and others in the workshop. Make sure that you protect others by using a welding screen. In addition you should make sure that there is a clear space under the intended cut and make sure that all flammable materials have been removed. And you should know the location of firefighting equipment and other emergency equipment The equipment The equipment used for oxy cutting is basically the same as used for oxy acetylene welding except for the addition of a cutting attachment to the torch. The oxy acetylene plant consists of the cylinders, the regulators, the hose and a trolley or truck that makes for safe manual handling and movement from one work area to another. There is also a safety chain fitted to the trolley which prevents the cylinders from moving away. 5

6 Throughout the plant there are built in safety features to ensure that you never confuse one gas with another. The oxygen cylinder is painted black and is fitted with right hand threaded connections as opposed to the maroon colored acetylene cylinder that is fitted with left hand threaded connections. The regulators are fitted with pressure gauges to indicate not only the pressure within the cylinders but also the working pressure. The cylinder pressure will decrease as your work proceeds and to maintain an even working pressure during the welding or cutting operation you simply use the adjusting screw or knob to set the desired pressure prior to starting. So, once you ve set the working pressure it will remain at that level until the cylinder is almost empty. Knowing how and where to turn the gases on and off is extremely important and you should familiarize yourself with the cylinder valve for each gas and the cylinder key, which should always be connected to the acetylene cylinder. Acetylene is the flammable gas and should be turned off if a leak or other emergency arises. The Cutting Attachment The Cutting Attachment is designed in such a way as to provide a mix of oxygen and acetylene, as well as having an ability to allow pure oxygen to reach the tip. The torch has separate fittings for the oxygen hose, and for the acetylene hose, and is fitted with valves to control the flow of the gases. In addition, there is an oxygen pre heat valve and an oxygen cutting lever. You will also note that the cutting nozzles, or tips, are designed with several holes. The outer holes are for pre heating the metal until it glows red, whereas the central and often larger hole is the cutting oxygen hole through which the pure oxygen will flow. The holes are arranged in this circular manner to give an equal distribution of heat around the nozzle, which adds to the versatility of the Cutting Attachment, enabling you to work the cut effectively in any direction. These holes in the nozzle can often block when they come into contact with molten metal. You should close down the plant temporarily to clean the tip by using the tip cleaners that have been specifically designed for the job. Cutting nozzles also vary in size and larger tips should be fitted when attempting to cut thicker metal. The accuracy of a cut can be aided by the use of a mechanical or roller guide that maintains nozzle height above the plate. Equipment safety The condition of your equipment will directly determine your safe welding operation and its essential therefore that your oxy acetylene equipment is kept in good repair. There are basic maintenance safety checks that you should carry out before you commence welding. 6

7 Make sure that the cylinders are always stored and used in the upright position and connections are free of gas leaks. To do this you should use a specially designed solution on the hose, regulator, torch, and cylinder connections. If bubbles appear then there is a gas leak. Oil or other materials should never be used as lubricants to fit regulators, hoses or the torch. If fittings don t join together smoothly they should be replaced. Prior to fitting the regulators, momentarily open the main cylinder valve and allow gas to blow away any particles of grit and dust. This can be referred to as cracking the cylinder. Always use the correct procedure for turning the cylinders on and off. Use the specially designed tip cleaners for cleaning the torch tip, make sure that you open valves slowly, use a flint to light the torch, always make sure you use a face respirator when you re welding metals that give off toxic fumes. Backfire and flashback Backfire and flashback are potentially dangerous and require prompt action when they occur during the operation of oxy acetylene equipment. Backfire can occur as the result of: Insufficient acetylene gas pressure, The tip being placed too close to the cutting surface, Overheated or dirty tips, The tip not being securely attached, Or the tip size selected is too large for the job being cut. If backfire occurs, the torch should be turned off. Check the settings and connections to make sure they are secure and only then can the torch be relit. It may be necessary to clean the tip before relighting. Flashback is usually caused by badly fitted connections and is potentially far more dangerous than backfire. With flashback: The flame actually burns back inside the torch and hoses, and Immediate action is required to prevent the flame burning back along the hoses to the gas cylinders. If flashback occurs, turn off the acetylene valve at the cylinder. This will extinguish the flame, as combustion cannot be supported without fuel. Then turn off both gas valves on the cutting torch, check the settings and connections to make sure that they are secure and let it cool down before you relight the torch. If the flame has reached the regulators causing the safety valves to blow out you must replace the hose before attempting to use the equipment again. 7

8 Oxy acetylene cutting Preparation is important. You need to plan the cut and prepare the surface of the metal you are going to cut. Use a cutting chart to establish the correct nozzle size and oxygen pressure for the material thickness to be cut. You should place the metal on fire bricks or another non flammable stable bench that allows sufficient space under the metal to be cut. This will allow sparks and molten metal to travel through away from the cuts. As for the metal itself you should remove dirt and scale from the surface by using a wire brush. Cutting a straight line free hand is a highly skilled action and it is better to use a guide or a roller guide. It is now possible to set a neutral flame. This type of flame has equal quantities of oxygen and acetylene, open the valve on the torch then set the working pressure of the acetylene at 100 kpa or 15PSI. When the pressure is set, turn it off at the torch. Then set the oxygen to 200 kpa or 30 PSI. Now you can ignite the torch using a flint lighter. Once ignited you can press the oxygen cutting lever and readjust the valves to reset the neutral flame, then release the oxygen lever. You can now preheat the metal until it glows red indicating that it is ready for the cut. To start the cutting process you then need to press the oxygen lever slowly. As the chemical reaction cuts through the metal and sparks appear from the bottom of the metal plate, you can then completely depress the oxygen lever. Once the cut has been started like this, then you can move the torch at a steady pace. It s the travel speed of the torch that determines the quality of the cut. You should move the torch at a speed that allows the metal to be cut all the way through without creating excessive melting of the metal. It s through experience that you ll discover the correct speed to cut at, relative to the thickness of metal you re cutting. A fast cut or a poorly adjusted torch will lead to an inferior and very rough result. Often slag will form underneath the cut this can be removed easily by tapping it with a hammer. A good cut on the other hand will leave you with a smooth surface line and even vertical lines along the cut of the metal. Closing down You may wish to stop using the equipment for a short period perhaps to check the progress of your cut. Whatever the reason there are close down procedures you should follow. 8

9 Turn off the torch acetylene valve, turn off the torch oxygen valve and place the torch in a safe place preferably on a torch stand or in a position where it can t fall and be damaged. When it s necessary to close down for long periods such as for lunch breaks or overnight the oxy plant must be completely closed down. You must follow the correct procedure. Turn off the torch acetylene valve. Turn off the torch oxygen valve. Close the oxygen cylinder valve. Open the torch oxygen valve to release all pressure from the hose and the regulator. Turn out the pressure adjusting screw of the oxygen regulator. Close the torch oxygen valve. Close the acetylene cylinder valve. Open the torch acetylene valve to release all pressure from the hose and regulator. Turn out the pressure adjusting screw of the acetylene regulator. Close the torch acetylene valve and wind the hoses neatly around the plant and make sure the torch is safely tucked into the hose or hung from the plant so it cannot fall and be damaged when the plant is moved. With this basic understanding of oxy acetylene cutting, familiarity with the equipment and a conscious commitment to safe workshop practices you ll be able to increase your knowledge and skills in oxy cutting. If you encounter difficulty or you re not exactly sure of what you re about to do with oxy acetylene equipment don t hesitate to speak with your supervisor, and remember safety comes first. 9

10 PART ONE WORKSHOP AND PERSONAL SAFETY Oxy-Acetylene safety A commitment to safety at work means you should ensure you are dressed appropriately for the job and the area you are working in is clean and tidy, well ventilated and clear of all fire hazards. So before you commence work ensure that your work area is tidy and free of all rubbish and flammable materials. Oxy-acetylene welding requires protective clothing such as shield visor or goggles, gloves, long sleeve overalls, safety boots and a protective apron. Sparks from oxy-acetylene are extremely hot pieces of metal that can burn through normal clothing and can also cause fires. It is also a good idea to work well away from the oxy-acetylene cylinders. You should know the location of firefighting equipment and other emergency equipment. Equipment safety The condition of your equipment will directly determine your safe welding operation. There are basic maintenance safety checks that you should carry out before you commence welding. Make sure that the cylinders are always stored and used in the upright position and connections are free of gas leaks. To do this you should use a specially designed leak detecting solution. Apply to the hose, regulator, torch and cylinder connections, if bubbles appear then there s a gas leak. Oil or other materials should never be used as lubricants to fit regulators, hoses or the torch. If fittings don t join together smoothly, they should be replaced. Prior to fitting the regulators, momentarily open the main cylinder valve and allow gas to blow away any particles of grit and dust. This can be referred to as cracking the cylinder. Always use the correct procedures for turning the cylinders on and off. Use the specially designed tip cleaners for cleaning the torch tip. Make sure that you open valves slowly. Use a flint to light the torch. 10

11 Always make sure you use a face respirator when you re welding metals that give off toxic fumes. DISCUSSION Discuss the following question with participants. 1. What is the purpose of cracking the cylinder? 2. What PPE should be worn when welding in your workplace? 11

12 PART TWO THE CUTTING ATTACHMENT The Cutting Attachment is designed in such a way as to provide a mix of oxygen and acetylene, as well as having an ability to allow pure oxygen to reach the tip. The torch has separate fittings for the oxygen hose, and for the acetylene hose, and is fitted with valves to control the flow of the gases. In addition, there is an oxygen pre heat valve and an oxygen cutting lever. You will also note that the cutting nozzles, or tips, are designed with several holes. The outer holes are for pre heating the metal until it glows red, whereas the central and often larger hole is the cutting oxygen hole through which the pure oxygen will flow. The holes are arranged in this circular manner to give an equal distribution of heat around the nozzle which adds to the versatility of the Cutting Attachment enabling you to work the cut effectively in any direction. These holes in the nozzle can often block when they come into contact with molten metal. You should close down the plant temporarily to clean the tip by using the tip cleaners that have been specifically designed for the job. Cutting nozzles also vary in size and larger tips should be fitted when attempting to cut thicker metal. The accuracy of a cut can be aided by the use of a mechanical or roller guide that maintains nozzle height above the plate. DISCUSSION Discuss the following questions with participants. 1. In your workplace, what are the most common cutting tip sizes used? 12

13 PART THREE BACK FIRE AND FLASHBACK Backfire and flash back are potentially dangerous and require prompt action when they occur during the operation of oxy-acetylene equipment. Backfire can occur as the result of: insufficient acetylene gas pressure, the tip being placed too close to the weld area, overheated or dirty tips, the tip not being securely attached, Or the tip size selected is too large for the job being welded. If backfire occurs the torch should be turned off, check the settings and connections to make sure they are secure, and only then can the torch be relit. It may be necessary to clean the tip before relighting. Flashback is usually caused by badly fitted connections and is potentially far more dangerous than backfire. With flashback: the flame actually burns back inside the torch and hoses, and Immediate action is required to prevent the flame burning back along the hoses to the gas cylinders. If flashback occurs turn off the acetylene valve at the cylinder, this will extinguish the flame as combustion cannot be supported without fuel. Then turn off both gas valves on the welding torch. Check the settings and connections to make sure that they are secure and let it cool down before you re-light the torch. If the flame has reached the regulators causing the safety valves to blow out you must replace the hose before attempting to use the equipment again. 13

14 DISCUSSION Discuss the following question with participants. 1. What measures are in place in your workplace to prevent back fire and flashback? 14

15 PART FOUR OXY-ACETYLENE CUTTING Preparation is important. You need to plan the cut and prepare the surface of the metal you are going to cut. Use a cutting chart to establish the correct nozzle size and oxygen pressure for the material thickness to be cut. You should place the metal on fire bricks or another non flammable stable bench that allows sufficient space under the metal to be cut. This will allow sparks and molten metal to travel through away from the cuts. As for the metal itself you should remove dirt and scale from the surface by using a wire brush. Cutting a straight line free hand is a highly skilled action and it is better to use a guide or a roller guide. It is now possible to set a neutral flame. This type of flame has equal quantities of oxygen and acetylene, open the valve on the torch then set the working pressure of the acetylene at 100 kpa or 15PSI. When the pressure is set turn it off at the torch. Then set the oxygen to 200 kpa or 30 PSI. Now you can ignite the torch using a flint lighter. Once ignited you can press the oxygen cutting lever and readjust the valves to reset the neutral flame then release the oxygen lever. You can now preheat the metal until it glows red indicating that it is ready for the cut. To start the cutting process you then need to press the oxygen lever slowly. As the chemical reaction cuts through the metal and sparks appear from the bottom of the metal plate, you can then completely depress the oxygen lever. Once the cut has been started like this then you can move the torch at a steady pace. It s the travel speed of the torch that determines the quality of the cut. You should move the torch at a speed that allows the metal to be cut all the way through without creating excessive melting of the metal. It s through experience that you ll discover the correct speed to cut at, relative to the thickness of metal you re cutting. A fast cut or a poorly adjusted torch will lead to a inferior and very rough result. Often slag will form underneath the cut this can be removed easily by tapping it with a hammer. A good cut on the other hand will leave you with a smooth surface line and even vertical lines along the cut of the metal. 15

16 DISCUSSION Discuss the following with participants. 1. What thicknesses are the metals commonly cut in your workplace? 16

17 PART FIVE CLOSING DOWN You may wish to stop using the equipment for a short period perhaps to check the progress of your cut. Whatever the reason there are close down procedures you should follow. Turn off the torch acetylene valve, turn off the torch oxygen valve and place the torch in a safe place preferably on a torch stand or in a position where it can t fall and be damaged. When it s necessary to close down for long periods such as for lunch breaks or overnight the oxy plant must be completely closed down. You must follow the correct procedure. Turn off the torch acetylene valve. Turn off the torch oxygen valve. Close the oxygen cylinder valve. Open the torch oxygen valve to release all pressure from the hose and the regulator. Turn out the pressure adjusting screw of the oxygen regulator. Close the torch oxygen valve. Close the acetylene cylinder valve. Open the torch acetylene valve to release all pressure from the hose and regulator. Turn out the pressure adjusting screw of the acetylene regulator. Close the torch acetylene valve and wind the hoses neatly around the plant and make sure the torch is safely tucked into the hose or hung from the plant so it cannot fall and be damaged when the plant is moved. With this basic understanding of oxy acetylene cutting familiarity with the equipment and a conscious commitment to safe workshop practices you ll be able to increase your knowledge and skills in oxy cutting. DISCUSSION Discuss the following with participants. 1. What is the closing down procedure in your workplace? 17

18 ASSESSMENT OXY-ACTELYNE CUTTING AND SAFETY Name: Date:. I.D. (if applicable): Score 1. Accuracy in Oxy-Acetylene cutting can be aided by use of a? a) Roller guide b) Spare hand c) Piece of magnesium d) Piece of paper 2. Which of these is an important piece of oxy acetylene cutting personal protective equipment? a) Face shield b) Leather gloves c) Apron d) All of the above 3. Which of these is an acceptable way of lighting an Oxy-Acetylene torch? a) Using matches b) Using an Oxy-Acetylene flint lighter c) Using a cigarette lighter d) Lighting the torch off a workmates lit Oxy-Acetylene torch 4. Cutting in excessively hot environments can lead to fainting, exhaustion and heat a) Waves b) Stress c) Reduction d) None of the above 18

19 5. What colour is an oxygen cylinder? a) Black b) Brown c) Any colour d) Blue 6. What colour is an acetylene cylinder? a) Black b) Maroon c) Bright red d) White 7. Which of these gases is used in oxy-acetylene cutting? a) Helium b) Argon c) Oxygen d) Nitrogen. 8. If you suspect an oxygen or acetylene cylinder has a leak, what should you do? a) Finish your job then move the cylinder outside b) It depends on the gas c) Tag the cylinder d) Immediately move the cylinders outside and notify your supervisor 9. Which of these is not one of the 3 types of flames used in Oxy-Acetylene Cutting? a) Fluctuating b) Neutral c) Carburising d) Oxidising 10. What should you use if you re welding in an environment that is not wellventilated? a) Water b) A different welding type c) A short welding schedule d) A fume extractor and/or a respirator 19

20 ANSWERS TO ASSESSMENT 1. A) Roller guide 2. D) All of the above 3. B) Using an Oxy-Acetylene flint lighter 4. B) Stress 5. A) Black 6. B) Maroon 7. C) Oxygen 8. D) Immediately move the cylinders outside and notify your supervisor 9. A) Fluctuating 10. D) A fume extractor and/or a respirator 20