Welding Cutting and Brazing by Progressive Business Publications
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Welding Cutting and Brazing
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Welding Cutting and Brazing by Progressive Business Publications
- 1. Copyright Progressive Business Welding, Cutting and Brazing
- 2. Copyright Progressive Business Safety Hazards of Welding Fire and explosions Compressed gases and cylinders Confined spaces Electrical hazards Dangerous machinery Trips and falls
- 3. Copyright Progressive Business Health Hazards of Welding Welding fumes and smoke Heat and sparks Visible light, ultraviolet and infrared radiation Musculoskeletal injuries Noise
- 4. Copyright Progressive Business Fire Prevention: Basic Precautions Asses the fire hazards If object to be welded or cut can’t be easily moved, remove all fire hazards in vicinity If object and fire hazards can’t be moved, use guards to confine heat, sparks and slag If these requirements can’t be met, then welding shouldn’t be done Have fire extinguishers ready for instant use
- 5. Copyright Progressive Business Special Precautions: Fire Watch Purpose: detect and extinguish smoldering fires Required for locations where more than a minor fire might develop or: – Appreciable combustible materials closer than 35 feet to operation OR more than 35 feet away, but easily ignitable by sparks – Wall of floor openings expose combustible materials within a 35-radius – Combustible materials on other side of walls/ceilings Maintained for at least 1/2 hour after completion
- 6. Copyright Progressive Business Fire Prevention: Welding is Prohibited in Certain Areas Areas not authorized by management Buildings with impaired sprinkler systems Areas with explosive atmospheres Areas where explosive atmospheres may develop
- 7. Copyright Progressive Business Fire Prevention: Used containers Make sure used drums barrels, tanks or other containers have been thoroughly cleaned Disconnect pipes or connections to the container
- 8. Copyright Progressive Business Personal Protection: Fall Protection When working at heights – Use railings, safety belts, lifelines or other safeguards – Protect workers below from falling sparks or slag Place welding cables and other equipment clear of passageways, ladders or stairways
- 9. Copyright Progressive Business Personal Protection: Eye Protection Use helmets, shields and goggles during arc welding or cutting Use goggles or other eye protection during gas welding or oxygen cutting operations Shield other from welding light with an individual booth or screen, if practical
- 10. Copyright Progressive Business Personal Protection: Eye Protection - Shading Requirments Shielded metal arc welding 10 Gas shielded arc welding (non-ferrous) 11 Gas-shielded arc welding (ferrous) 12 Torch Brazing 3 or 4 Heavy cutting (6 inches & over) 5 or 6
- 11. Copyright Progressive Business Personal Protection: Clothing Welding gloves, gauntlets and sleeves Flame resistant aprons High-cut safety boots and leggings Shirts: heavyweight, wool, sleeved, collars buttoned, no pockets Pants: no cuffs and long enough to extend over boots For overhead work: shoulder capes, skullcaps, ear protection
- 12. Copyright Progressive Business Personal Protection: Ventilation Ensure adequate ventilation prior to working Use local exhaust ventilation where needed Respirators worn: – When cancer-causing agents present – During certain confined space work Materials requiring extra precautions: fluorine compounds, zinc, lead, beryllium, cadmium, mercury, cleaning compounds, stainless steel
- 13. Copyright Progressive Business Before Entering Confined Spaces Acquire confined space permit Ensure adequate ventilation – Test before entering for flammable/toxic gases or oxygen deficiency – If flammable or toxic gases are present - ventilate – If ventilation is inadequate, use a respirator Disconnect pipes, ducts and power lines Leave gas cylinders and welding machines outside of the confined space
- 14. Copyright Progressive Business Confined Spaces Attendant must observe the welder and be ready to execute a pre-planned emergency rescue plan If arc welding is suspended for a period of time: – Remove electrodes from holders – Disconnect machines from power sources If gas welding is suspended for a period of time: – Close the torch valves – Shut off the gas supply to the torch – Remove the torch and hose, if practical
- 15. Copyright Progressive Business Cylinder Storage In a well-ventilated, dry, location >20 ft away from highly combustible materials such as oil Away from sources of heat and ignition Away from high traffic areas and exits Stored in compatible groups – Oxygen and Acetylene: separated by 20 feet or a 5-foot wall with 1/2-hour fire rating In upright position with valve protection caps on and secured with straps or chains
- 16. Copyright Progressive Business Cylinder Handling Never work with unidentified cylinders Refer to MSDS for specific hazards, special handling instructions, emergency response and first aid information Inspect cylinders for damage prior to work When transporting: – Secure to wheeled hand cart with the regulator removed – Never use valve caps to lift the unit – Don’t drop or bang
- 17. Copyright Progressive Business Cylinder Handling (cont’d) Valve protection caps must always be in place when not in use - empties included If cylinder must be left unattended, close cylinder valve and shut down system Keep cylinder in an upright position at all times Keep cylinders and valve caps free from oil or grease Mark work areas when finished work
- 18. Copyright Progressive Business Placement of Cylinders During Use Cylinders must be placed where sparks, hot slag or flames can’t reach them If that’s not possible, use fire-resistant shields Keep cylinders away from electrical circuits or objects used for grounding Cylinders must be placed outside any confined space
- 19. Copyright Progressive Business To Begin Work “Crack” the cylinder valve Ensure regulators are compatible, clean and in good condition before attaching them Make sure hoses and connections are secure When opening the cylinder valve, stand to the side and open s-l-o-w-l-y. Keep any vendor-supplied keys in place Keep the valve within easy reach
- 20. Copyright Progressive Business Purge Hoses Prior to Lighting First, acetylene –Open acetylene cylinder valve 3/4 turn –Open torch valve 1/4 turn –Adjust to working pressure with regulator screw –Close torch valve Then, oxygen – Open oxygen cylinder valve fully (slowly) – Open torch valve 1/4 turn – Adjust to working pressure with regulator screw – Close torch valve
- 21. Copyright Progressive Business Lighting and Shutting the Torch To light torch: – Reopen acetylene torch valve – Light with friction lighter: • Never matches • Never cigarettes – Open oxygen 1/4 turn and adjust flame To shut off torch: – Close torch valves: acetylene then oxygen – Close cylinder valves: acetylene then oxygen – Open both torch valves to release pressure – Shut off regulator adjusting handle – Close torch valves
- 22. Copyright Progressive Business For Safe Use of Acetylene Never used at pressure in excess of 30 psi absolute or 15 psi gage Never open acetylene valve more than 1 1/2 turns. Never use copper fittings or connections
- 23. Copyright Progressive Business Arc Welding and Cutting Ensure the work area is dry Double-check the grounding Check connections to the machine – Make sure work lead is firmly attached – Keep metal clamps free from debris Never use cables with splices within 10 feet of the holder Replace cables with damaged insulation or exposed bare connectors
- 24. Copyright Progressive Business Arc Welding and Cutting (cont’d) Spread out cables Never coil cables around your body Never strike an arc on a gas cylinder Never change polarity switch during operation If work must be stopped, disconnect power source and remove electrodes Store holders where they can’t make unwanted contact
- 25. Copyright Progressive Business Summary Safety and health hazards = special precautions Fire prevention Personal Protection – Fall safety – PPE – Confined spaces – Ventilation Use of compressed gas cylinders Safe welding procedures
Editor's Notes
- Today’s topic is Welding, Cutting and Brazing. This training is a part of OSHA’s Welding Cutting and Brazing Standard (29 CFR 1910.252). You have a dangerous job. Every day you face a unique combination of safety and health risks. These come from the heat and energy present during welding and cutting -- the types of materials you’re working with, and some of the environments in which you do your job. Even so-called “routine” jobs can be dangerous when someone takes a short-cut and doesn’t follow safe procedures. Today, we’re going to look at: Fire prevention precautions that must be taken before, during and after welding, cutting or brazing. Measures you must take for your own personal protection. These include how to: use personal protective equipment (PPE), work safely in confined spaces, ensure adequate ventilation and prevent trips and falls. Safe operating procedures for working with compressed gas cylinders and some of the unique safety requirements of other welding procedures.
- The greatest safety hazard you face is the risk of fire and explosions. The intense heat, flame and sparks from the welding process can easily cause a fire or explosion if you haven’t taken the proper precautions. Compressed gases used in many welding processes are stored under intense pressure, making their cylinders potential explosives or deadly rockets able to penetrate concrete walls, if accidentally ruptured. The gases themselves also present hazards. Some are highly flammable. Others, such as nitrogen are asphyxiates. Some will react with other materials and become dangerous. Others are toxic and can cause adverse health effects. Sometimes, you’ll be asked to work in a confined space where it’s easy to be overcome by fumes if you don’t have adequate ventilation. The confined space can also increases the risk of a build-up of explosive concentrations of flammable gas vapors. Although welding may use low voltages, you still run the risk of electrical shock. A small shock can cause falls and other accidents. Larger shocks can cause brain damage or death. Many times, you’ll work around electric-powered machinery that has moving parts. Although equipment needing repair may be locked out and tagged, accidents do happen. If you’re careless, you can trip or fall over the equipment, machines, cables, hoses, safety lines, and other objects used on the job. Working at elevated heights becomes even more dangerous when dealing with heat, sparks, and other hazards that could provoke an accident.
- When considering health hazards, welding fumes and smoke are the most important hazards to be aware of. Many substances in welding fumes and smoke, such as zinc, lead, cadmium, chromium and ozone can be extremely toxic. They can permanently damage your respiratory system and even kill you if the exposure is high enough. The intense heat of welding, electrodes, hot slag, and sparks can burn or damage your eyes, limbs, and torso if not properly protected. In addition, the tremendous amount of heat generated in the process puts you at greater risk for heat stroke and other heat-related illnesses. Eye injuries from arc light and radiation are constant risks. The intense light from arc welding can damage your retina. Continually working around UV radiation without proper protection can lead to permanent eye damage. Invisible ultraviolet light (UV) from the arc can lead to “arc eye” or “welders flash” even after a very brief exposure of less than one minute. Exposure to UV light can also cause skin burns similar to sunburn. Infrared radiation may damage your cornea. Welders also suffer a high degree of musculoskeletal injuries. These include back and shoulder pain, tendonitis, carpal tunnel syndrome and knee problems. Remaining in awkward working positions for long periods of time, welding overhead and lifting heavy objects all contribute to these disorders. Exposure to loud noise, particularly during grinding operations, can permanently damage your hearing if protection isn’t used.
- Safe welding starts with fire prevention. Ideally, you’d like to take any object to be welded or cut back to your shops or work areas. However, if you can’t do that, basic precautions to prevent fires and explosions are aimed at removing fire hazards from the work area. When you come upon a work area, start by assessing the fire hazards present. For example, are there any fuel sources or combustibles nearby, such as canisters of paint? Are there exposed pipes or openings in any walls that could lead to sources of combustibles? What’s on the other side of any walls? Are there materials such as paper on the floor? Once you’ve identified the fire hazards, you can then take the necessary precautions to deal with them. If the object that you’re about to weld or cut can’t be easily moved from its location and taken back to the shop, all moveable fire hazards in the vicinity must be removed and taken to a safe place. Check with the workers in the area and their supervisor to make sure items can be safely moved. If both the fire hazards and the object itself can’t be moved, then you must set up guards to confine the heat and protect the fire hazards from sparks and slag. If you can’t meet these two requirements, then welding should not be performed. Fire extinguishing equipment needs to be available and ready for instant use. Know where your nearest fire extinguisher is located and make sure it’s adequately charged. While working, make sure your work area remains free of substances that could ignite.
- The purpose of a fire watch is to watch for any fires that may develop in exposed areas and extinguish any possible smoldering fires. A fire watch is required whenever welding or cutting is performed in a location where more than a minor fire might develop, or where any of the following conditions exist: Appreciable combustible materials are closer than 35 feet to the point of operation. Appreciable combustible materials more than 35 feet away, but easily ignited by sparks. Wall or floor openings within a 35-foot radius that expose combustible material in adjacent areas or rooms. Combustible materials on the other side of walls or ceilings that can be ignited by conduction or radiation. If these conditions exist, you’re required to maintain a fire watch from the time welding begins to at least a half-hour after the completion of the welding or cutting operation. Fire watchers must have fire extinguishers readily available and be trained to use them. A fire watcher should only try to extinguish fires within the range of their equipment’s capacity and should be familiar with the alarm systems and prepared to use them in the event of a fire.
- Despite some of the precautions we just looked at, there are some areas where you simply can’t perform any welding operation. Welding shouldn’t be started in an area that hasn’t been approved by management. Welding operations require a hot work permit prior to the start of any job. Never simply pick up a job without first getting a hot work permit. Never weld in a building with a sprinkler system that’s not working. Check the sprinkler records for inspection dates. This is to prevent a disaster in a worst-case scenario. Never weld if the air in the work area contains explosive atmospheres. These may be mixtures of flammable gases, vapors, liquids or dusts. For example, inside unclean or improperly prepared tanks or equipment that previously contained flammable gases, vapors, liquids or dusts. And never weld where explosive atmospheres may develop. Rooms that have recently been painted are a good example.
- We just talked about explosive atmospheres. Large containers such as tanks are one place these types of conditions may develop. Additional safety precautions are required before work on used containers. Never start welding, cutting or doing other hot work on used drums, barrels, tanks or other containers until you make sure they’ve been thoroughly cleaned. By “thoroughly cleaned,” we mean cleaning that has removed all flammable materials or any substances such as greases, tars, or acids, which might produce flammable or toxic vapors when exposed to heat. In addition, if there are any pipes or connections to the container, these must be disconnected prior to beginning any hot work.
- There may be times when you’re required to work at an elevated height - for example, on a scaffold or platform. When working at heights, use railings, safety belts, lifelines or some other equally effective safeguard to prevent falling. You also should take steps to protect workers below your work area from any falling sparks or slag. Use a fire resistant blanket or tarp to catch falling materials and set up signs below. Less obvious are simple trips and falls. The last thing you want is a co-worker to get an ankle tangled in a cable, knocking over the gas cylinder you’re using. When welding, make sure you place your cable and other equipment clear of passageways, ladders and stairways.
- Now we’ll turn to PPE. It starts with eye protection. Welding, cutting and brazing without the proper eye protection can lead to serious eye injuries. Eye protection shields you from potential harm from ultraviolet (UV) light and infrared radiation and prevents you from getting sparks and pieces of hot metal in your eyes. Wear helmets, shields and goggles during all arc welding or arc cutting operations, excluding submerged arc welding. Protect your eyes by wearing a welder’s helmet fitted with a filter shade suitable to the type of welding you’re doing. Wear goggles or other suitable eye protection during all gas welding or oxygen cutting operations. Wear safety glasses with side shields or goggles when chipping or grinding a work piece if you’re not wearing a helmet. You’re not the only one at risk. Passers-by viewing a welding arc without eye protection can also damage their eyes. When possible, you should set up an individual booth or a non-combustible screen to shield passers-by from the welding arc.
- It’s not enough to simply wear a helmet or goggles. You need to make sure you’re using eye protection that has the proper filter installed. Without the appropriate grade filter, even though you may be wearing a helmet or goggles, you can still do serious damage to your eyesight. For shielded metal arc welding of 1/16, 3/32, 1/8, 5/32-inch electrodes, use a shade of at least 10. For gas-shielded non-ferrous arc welding of 1/16, 3/32, 1/8, 5/32-inch electrodes, use a shade of at least 11. For gas-shielded ferrous arc welding of 1/16, 3/32, 1/8, 5/32-inch electrodes, use a shade of at least 12. When soldering, use a shade of at least 2. When torch brazing use a shade of at least 3-4. For heavy cutting, 6 inches and over, use a shade of at least 5-6.
- Do a quick hazard assessment before every procedure to judge which type of PPE is needed. Burns are a primary hazard of welding. The goal is simple: selection of clothing material which will provide maximum protection from sparks and hot metal. A large percentage of injuries to welders are to the hands and limbs. Wear gauntlet-type leather gloves or leather gloves coupled with protective sleeves to protect wrists and forearms. To protect your chest and lap from sparks when standing or sitting, wear flame-resistant aprons made out of leather or other suitable materials. For maximum foot and leg protection, especially during heavy work, wear high top boots, fully laced. Use fire resistant boot protectors or spats strapped around the pant legs and boot tops to prevent sparks from bouncing in the tops of the boots. Shirts should be made from heavyweight, tightly woven, 100% wool or cotton to protect you from UV radiation, hot metal, sparks and open flames. They should have full sleeves, no pockets, and be worn outside the pants with the collar buttoned. If you have pockets, tape them shut. Pants should have no cuffs -- sparks can collect there -- and extend down below the top of your safety footwear. To protect your head from burns and UV radiation, wear a fire resistant skull cap or hood under your helmet. When welding overhead, use extra precautions. Wear shoulder capes, skull caps and ear plugs to prevent sparks or hot splatter from getting into your ears.
- Exposure to fumes from the metals and gases involved in welding are a constant hazard. Before starting any welding job, ensure that you have adequate ventilation. The ventilation system may consist of moveable exhaust hoods, flexible and stationary ducts, a powered fan, or a dust collector. The most effective control is local exhaust ventilation in which an exhaust hood is placed near the welding arc or flame and the contaminants are drawn away from your breathing zone. Respirators must be worn when any cancer-causing agent is present at any detectable concentration or when welding in confined spaces with insufficient oxygen levels or where mechanical ventilation cannot adequately remove hazardous fumes. Some materials require specific ventilation because they are so hazardous. Mechanical ventilation or other specific control measures are required when welding or cutting is done with any of the following materials: fluorine compounds, zinc, lead, beryllium, cadmium, mercury, cleaning compounds and stainless steel.
- Welding in a confined space is extremely dangerous and requires additional safety precautions. Never enter a confined space without first acquiring a confined space permit. Before entering, make sure the space is safe to enter and has been tested for toxic fumes, flammable or combustible gases or vapors, and oxygen levels. Never enter without a respirator if the percentage of oxygen is below 19.5%. In addition, continuous air monitoring may also be necessary during welding. During welding, the space must be adequately ventilated to prevent the accumulation of toxic materials or possible oxygen deficiencies. Sometimes, local exhaust ventilation will not be sufficient and you will be required to wear a respirator. If you’re not sure, ask your supervisor. All pipes, ducts, and power lines connected to the space, but not necessary to the operation, should be disconnected or shut off. All shutoff valves should be tagged and locked out so they cannot be accidentally restarted. When welding or cutting in a confined space, the gas cylinders and welding machines must be left outside. Chock the wheels of any heavy, portable equipment to prevent accidental movement.
- Any work in a confined space requires a trained attendant stationed outside the confined space to observe the welder at all times, and be able to put a pre-planned rescue operation into effect, if necessary. The attendant should be equipped with a fire extinguisher and appropriate PPE. The welder entering the confined space should wear a safety harness attached to a lifeline. Confined spaces also require unique precautions to remove fire hazards. If you are arc welding, and you need to stop for any substantial period of time -- for example, lunch or the end of shift -- make sure you remove the electrodes from their holders and place the holders where accidental contact can’t occur. Also disconnect the machine from its power source. The same thing applies to any type of gas welding or cutting. If you need to stop for a substantial period of time, make sure you close the torch valves and shut off the gas supply to the torch. This is done to eliminate the possibility that gas might escape through leaks or improperly closed valves. When it’s practical, the torch and hose should also be removed from the confined space.
- Now we’ll turn to working with compressed gas cylinders. Compressed gas cylinder safety starts with storage. When storing cylinders, follow the following rules: The cylinder storage area should be in a well-ventilated, dry location at least 20 feet away from combustible materials such as oil. Cylinders should be kept away from any sources of heat -- such as radiators -- and ignition -- such as oil, fuels, or any other combustible materials. They should also be stored away from electrical wiring or corrosive chemicals and fumes. Cylinders should also be kept away from high traffic areas and clear of doorways, aisles, elevators and stairs. You don’t want anyone knocking them over. Store cylinders in compatible groups. Flammables, corrosives and oxidizers must all be kept separate. If oxygen and fuel gases, such as acetylene, are stored in the same room, they must be kept 20 feet apart. If this isn’t possible, they should be separated by a 5-foot firewall rated for 1/2-hour of fire resistance. Empties should be separated from full or partially-full cylinders. Cylinders must be stored in an upright position with their valve protection caps on -- even on empties -- and secured with straps or chains.
- You need to know the dangers of the gases you work with. Never work with an unidentified cylinder or one with a label you can’t read. Refer to the MSDS for specific hazards, special handling instructions, emergency response and first aid information. Be familiar with the information contained on the MSDS in the event of an emergency. Before working with a cylinder, perform a visual inspection for damage. Look for dents, cracks, rust or any other damage that may compromise cylinder safety. When transporting cylinders, never lift them or move them using valve protection caps. Valve protection caps must be in place. Unless you’re using a special welding cart, regulators must be removed prior to moving. If you’re not using a designated welding cart, use a wheeled hand cart and secure the cylinder using strapsor chains. Never drop or bang cylinders.
- Valve protection caps -- if the cylinder is designed to use one -- should always be in place. This goes for transport, storage, and all other times you’re not directly using the cylinder. This goes for empties as well. Never leave a system setup with the cylinder valve open. If you’re going to be away for any amount of time, make sure the cylinder valve is closed. If it’s a substantial period of time, such as lunch or overnight, break down the system and replace the protective valve cap. Keep cylinders in an upright position at all times. Cylinders, valves, couplings, regulators, hoses and other equipment should be kept free from oily and greasy substances. Never handle oxygen cylinders or related equipment with greasy hands or gloves. Oxygen reacts with these types of materials and you may have an explosion on your hands. Whenever you’re finished your work, hot metals will still be present, and are a danger to unsuspecting co-workers. Always mark the area you’ve been working on to warn of hot metals.
- One of the most important precautions of using compressed gas cylinders is protecting them while you’re performing welding, cutting or brazing. You need to keep cylinders far enough away from the work you’re doing so that sparks, hot slag or flames can’t reach them. If this isn’t possible, place a fire-resistant shield around the cylinder. Taking this step will help prevent an explosion. Never place a cylinder where it may become part of an electrical circuit: They could explode. Check for wires, plugs and machinery in the area and be sure to keep cylinders away from any objects that may be used as grounding. As mentioned earlier, when welding in confined spaces, the cylinders should be located outside the confined space, not inside it. This protects you in the event of leaks.
- Before connecting a regulator to a cylinder, open the cylinder valve slightly for an instant and then close it. This “cracking” will clean out any dirt or dust that may have settled in the valve. Never use a cylinder without a regulator attached. The only exception is when you’re using a cylinder already attached to a manifold. Regulators are non-interchangeable. Use only the regulator that goes with the type of cylinder you’re using. If it doesn’t fit, that’s a strong clue you’re using the wrong one. The mixture of gases from incompatible regulators can form toxic or explosive combinations. Make sure the regulator is clean. If the regulator is broken or damaged and repairs are needed, don’t attempt to fix it yourself. Set it aside and tell your supervisor. Only trained personnel can fix these. Also, check your connections and hoses for any signs of wear or damage that may cause gas to leak. Hoses with holes, burns, wear and tear or other defects should be taken out of service. Once connected, double-check to make sure they are securely fastened. Once regulators and other apparatus have been attached and the lines have been secured, stand to the side of the valve and open slowly. Once the valve is open, keep any vendor-supplied keys or stems in place. You want to be able to quickly shut the valve in case of emergency, so make sure the valve is always within reach.
- Once your connections are made, purge the system prior to lighting the torch. To do this, start with your gas fuel cylinder - in this case we’re using acetylene. Open the acetylene valve 3/4 turn. Open your torch valve 1/4 turn. Now adjust to working pressure using the regulator screw. Once you’re at working pressure, close the torch valve. Perform the same steps for your oxygen supply. Open the oxygen valve slowly. Open the torch valve 1/4-turn, then adjust the regulator to your working pressure. Once you’ve got it, close the torch valve.
- To light the torch, re-open the gas fuel valve. Light the torch using a friction lighter. Never use matches or other sources of ignition, such as a cigarette. Once the torch is lit, slowly open the oxygen torch valve 1/4 turn and adjustthe flame. To shut off the torch, start by closing the torch valves. Always close the gas-fuel torch valve first followed by the oxygen torch valve. Next, close the cylinder valves. Again, the order is gas-fuel valve first and oxygen valve second. Open both torch valves to relieve any pressure left in the system. Shut off the regulator adjusting handle and bring the system down to zero. Close both torch valves.
- Just a few quick notes on some of the special precautions you need to know when working with acetylene, which is highly flammable and can be extremely unstable. When working with acetylene, never generate, pipe or use at a pressure in excess of 15 pounds per square inch gage or 30 pounds per square inch absolute. This is extremely hazardous. Acetylene is unstable at pressure above this level and could cause a violent explosion. When using a cylinder containing acetylene, never open the cylinder valve more than 1 1/2 turns. This is recommended so that in an emergency situation you can shut off the gas flow quicker. Also, make sure you never use fittings or any connections containing copper. Acetylene will react violently when exposed to copper.
- Most of the precautions and safe practices we’ve covered for oxygen-gas welding are also applicable to arc welding. However, arc welding requires some additional unique precautions. We’ll look at those now. Arc welding with wet equipment or on wet floors can be disastrous. Make sure everything is dry. If you have wet equipment, disconnect the power source, and dry the equipment off. Mop up any wet floors. If you’re AC welding under humid conditions and you’re perspiring a lot, make sure you have an automatic control to reduce the no-load voltage. Also, always be sure you know where the power disconnect switch is located in case you need to shut down the machine immediately in case of an emergency. Make sure the welding machine is properly grounded and double-check the grounding connections. Pipelines carrying gases of flammable liquids should never be used as grounds. Before starting, check all connections to the machine. Make sure the work lead is firmly attached to the work. Magnetic work clamps must be free of metal splatter and other debris. Never use cables with splices within 10 feet of the holder. If you do, you increase your chances of getting an electrical shock. Cables showing damaged insulation or exposed, bare connections must be replaced.
- Spread out coiled welding cables to avoid serious overheating or damage to the insulation. You should never coil or loop welding cable around you body. Never strike an arc on a gas cylinder and keep electrodes and their holders away from gas cylinders. Never change the polarity of the switch when the machine is under load. Arcing caused by high current can burn the switch contact surface and possibly you as well. Whenever you’re going to stop welding for a few minutes, disconnect the power source and remove the electrodes. When electrode holders aren’t in use, store them where they can’t make contact with co-workers, conductors, fuels or compressed gas tanks.
- Now we’ll review some of what we’ve seen today. You face both health and safety hazards during welding, cutting, and brazing operations. Foremost are the dangers of fires, fumes, burns, and eye injuries from arc light. Fire prevention - assess the fire hazards and remove them if possible. If you can’t move them, set up shields or guards in your area. Know where fire extinguishers are located. Keep a fire watch if required. Personal protection - take fall prevention measures when working at elevated heights and don’t be careless with equipment. Wear appropriate PPE and make sure your eye filters are suitable for the type of welding you’re doing. When working in confined spaces get a confined space permit, have an attendant present, ensure adequate ventilation and handle equipment in the manner we reviewed. Remember to handle compressed gas cylinders carefully. Always upright with caps on whenever not in use. Keep protected from heat and sparks in work area and store properly. Following the guidelines we’ve discussed will help to keep you and your co-workers safe.