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Welding: Safety and SelectionPosted 12/13/2000
Welding Safety Makes SenseBy Mike Pankratz
Arc Rays and Eye Protection Arc rays produce intense visible and invisible (ultraviolet and infrared) rays that can burn eyes and skin. Any exposed skin can be burned quickly by these rays. Welding helmets should be fitted with a proper filter shade to protect the operator's face and eyes when welding or watching. Approved safety glasses with side shields should also be worn. Screens or barriers to protect others from flash and glare should be installed where appropriate, and maintained. Clothing Gloves and clothing should be flame-resistant. Clothing made from a dark-colored, tightly woven material is best suited for welding. Gauntlet type leather gloves should be worn to protect hands and wrists. Shirt collars and shirt cuffs should be buttoned, and open front pockets are not advisable as they may catch sparks. Also, operators should never store matches or lighters in their pockets. Pants cuffs are not recommended, as they will also catch sparks. Tennis shoes do not qualify as adequate foot protection. High-top leather shoes or boots are absolutely necessary. Environment The area surrounding the welder will be subjected to light, heat, smoke, sparks and fumes. Permanent booths or portable partitions can be used to contain light rays in one area. The heat and sparks given off are capable of setting flammable materials on fire. Therefore, welding should not be done in areas containing flammable gases, vapors, liquids or dust because explosions are a possibility. Metals with plating, coatings or paint that come near the region of the arc may give off smoke and fumes during welding. These fumes may pose a health hazard to the lungs, therefore an exhaust hood or booth should be used to remove fumes from the area. When welding in confined spaces, such as inside tanks or large containers, toxic fumes may gather. Also, in an enclosed room, breathable oxygen can be replaced by shielding gases used for welding or purging. Care must be taken to ensure enough clean air for breathing. In many companies, it is routine to provide welders with air masks or self-contained breathing equipment. The Power Source and Primary Power LineGrounding the Equipment Welders must always be concerned about the possibility of electrical shock. Wet working conditions must be avoided because water is an excellent conductor and electricity will always follow the path of least resistance. Even a person's perspiration can lower the body's resistance to electrical shock. Standing on a dry rubber mat or, when welding outdoors, standing on a dry board is always advisable. Poor connections and bare spots on cables further increase the possibility of electrical shock, so daily inspection of these items is recommended. Aside from these more obvious shock hazards, equipment operators should routinely inspect for effective ground connections. A proper ground connection is always necessary because it provides a safety connection from a welding machine frame to the earth. Connections typically used for grounding an engine-driven welding machine include a cable connected from a ground stud on the welding machine to a metal stake placed in the ground. The workpiece being welded and the frame or chassis of all electrically powered machines must be connected to a good electrical ground. This can be accomplished by connecting it to a properly grounded building frame or other appropriate ground. Chains, wire ropes, cranes hoists and elevators must never be used as grounding connectors. The work lead is not the grounding lead. The work lead connects the work terminal on the power source to the workpiece. A separate lead is required to ground the workpiece or power source. When arc welding equipment is properly grounded in accordance with the National Electrical Code and to ANSI Z49.1 “Safety in Welding and Cutting” standards, a voltage may safely exist between the electrode and any conducting object. Examples of conducting objects include buildings, power tools, work benches, welding power source cases and workpieces. Never touch the electrode and any metal object unless the welding power source is off. When installing a welding system, connect the frames of each unit such as welding power source, control, work table and water circulator to the building ground. Conductors must be adequate to carry ground currents safely. Equipment made electrically hot by stray current may deliver a powerful shock. Never ground to an electrical conduit or to a pipe carrying any gas or flammable liquid such as oil or fuel. For a three-phase connection, check phase requirements of equipment before installing. If only three-phase power is available, connect single-phase equipment to only two wires of the three-phase line. Do not connect the equipment ground lead to the third (live) wire, or the equipment will become electrically hot. Also, before welding, check the ground for continuity. Make sure conductors are touching bare metal of equipment frames at connections. If a line cord with a ground lead is provided with the equipment for connection to a switchbox, connect the ground lead to the grounded switchbox. If a three-prong plug is added for connection to a grounded mating receptacle, the ground lead must be connected to the ground prong only. If the line cord comes with a three-prong plug, connect to a grounded mating receptacle. Never remove the ground prong from a plug, or use a plug with a broken ground prong. Electrical "Hardware" Poor electrical connections can yield any number of problems, including excessive resistance in the weld circuit resulting in arc wanders, or an arc that won't start or is difficult to start. The following items require routine inspection:
The Gas Cylinder and Distribution System (Shielding Gas System)Cylinders Cylinders should be securely fastened at all times. Chains are usually used to secure a cylinder to a wall or cylinder cart. When moving or storing a cylinder, a threaded protector cap must be fastened to the top of the cylinder. This protects the valve system should it be bumped or dropped. Cylinders should not be stored or used in a horizontal position. This is because some cylinders contain a liquid that would leak out or be forced out if the cylinder were laid in a flat position. Also, welding guns and other cables should not be hung on or near cylinders. A gun could cause an arc against the cylinder wall or valve assembly, possibly resulting in a weakened cylinder or even a rupture. Regulators Remove a faulty regulator from service immediately for repair (but remember to first close the cylinder valve). The following symptoms indicate a faulty regulator:
Do not attempt to repair a faulty regulator. It should be sent to the manufacturer's designated repair center, where special techniques and tools are used by trained personnel. Hoses Use only ferrules or clamps designed for the hose, never ordinary wire or other substitutes, as a binding to connect hoses to fittings. Avoid long runs to prevent kinks and abuse. Suspend hose off ground to keep it from being run over, stepped on or otherwise damaged. Coil up excess hose to prevent kinks and tangles. Examine hose regularly for leaks, wear and loose connections. Immerse pressured hose in water to check for leaks (bubbles will indicate leaks). Repair a leaky or worn hose by cutting out damaged area and splicing. Do NOT use tape. By following proper safety measures, accidents can be avoided. Always refer to the equipment manufacturer's owner manual for a thorough explanation of safety issues. This article does not give complete coverage of all the safety issues that exist.
How to Select a Wire Feed WelderBy Jim Harris
Ask yourself: Which arc welding process best suits my needs? Beginners often turn to either a wire feed or stick welding process, but which is the best one for your particular application? For some users, wire feed welding (also referred to as wire welding) provides higher productivity efficiencies since the wire is fed in a continuous process and you don't have to change stick electrode rods as you are welding. Wire welding has a lower skill level requirement and may be picked up more readily. Stick welding may require more hand movement coordination to feed the electrode rod into the weld puddle. Although there may be some applications where stick might be a better selection, beginners who look toward wire welding when making their first welding machine purchase should also ask themselves the following questions: Which wire process is best for me? The next decision is to choose the type of wire welding you will perform the majority of the time. The category breaks down into two: Gas Metal Arc Welding (commonly called MIG) and flux-cored wire welding. MIG is the best choice when cosmetic appearance is an issue since it provides lower spatter levels. In addition, MIG can weld a wider range of materials, including thinner materials, and different material types such as stainless or aluminum. Since a bottle of shielding gas is necessary with the MIG process, it might not be the most attractive option if portability and convenience is a factor. On the other hand, flux-cored wire welding may be the optimal choice for outdoor procedures since an external shielding gas is not required with the flux built into the wire to shield the weld. This process is most suitable for thicker materials where weld appearance may not be as critical. One drawback is that flux-cored can only be used to weld mild steel, so if you are looking to weld more exotic metals, this process may be too limiting for you. Most industrial products sold through a welding distributor would be equipped to handle both processes. Some manufacturers sell ready-to-weld packages that include a gas regulator and hose kit. What is the thickness of material that will most frequently be welded? As a rule of thumb, it is recommended that you use a MIG process on materials that are 24 gauge to 12 gauge; while flux-cored is only recommended down to 20 gauge. The machine's output amperage will determine how thick you can weld. However, in general the flux-cored process will weld thicker than the MIG process with a single pass weld. The material thickness that you most often weld will not only determine the process that you choose, it will also determine the voltage of the unit you need. For instance, if you plan to weld over 1/8-inch-thick material the majority of the time using a MIG process, it is recommended that you invest in a 230v system. The higher amperage range of this machine can better handle your welding needs in a single pass and you won't have to waste time with second or third passes. Examples of heavy materials can be such things as frames to tool benches or maybe even a fence. If most of your welding will be performed on material less than 1/8-inch thick, a 115v MIG machine is probably your best bet for economic reasons. (Be sure to check specifications for flux-cored welding with a 115v machine.) Also look at the amperage ratings of the machine - you don't want to overburden a machine by continuously welding at an amperage higher than what is recommended. What input power is available? Another key question to ask yourself is what input power you have available. For instance, if you will be doing most of your welding in your home or garage, you may only have access to a 115v input power source - this will limit your selection to a 115v-wire welder. If you have access to 230v power in your home due to special wiring or are doing most of your welding in your shop, you may look to a machine that has higher voltage capabilities (230v is usually readily accessible in an industrial setting). What's your budget? There are a number of technology features that set one compact wire feed welder apart from another. For instance, with both a 115v and 230v machine, you can purchase either a tapped or continuous control model. Tapped control basically offers you four or five discrete voltage settings. With continuous control, you have a continuous range of settings that can provide for fine adjustments and heat control. The continuous control may be a nice feature when working with thin materials where a finer heat control helps to achieve an aesthetically pleasing weld - this fine control is typically more expensive than tapped control but will benefit those welding a lot of thinner sheet metal. What's included in the package? Not all compact wire feed welders offer the same accessories in their package. Pay careful attention to what is included. For instance, does it come with a regulator? A hose? Instructional videos? What is the quality of the machine and the manufacturer? It is always recommended to buy from a recognized name in the industry and to make sure that the machine carries a warranty. Also, check to see that the manufacturer offers technical support and whether that support is available online and/or over the phone. What are the safety features of the machine? Some machines have wire that will remain electronically cold until the trigger is pulled. What this means is that if you accidentally touch the torch to an object as you are setting up to weld, it will not cause sparks that could damage your eyes or the workpiece. Look also for units that offer thermostatic overload protection to prevent high current from damaging the machine - especially when you are trying to weld heavy gauge material. In addition, a machine that offers an input circuit breaker protects the wiring in your home or shop setting. Some machines feature drive motors that have circuit breaker protection so they automatically stop if something impedes wire feeding. And last but not least, a good fan will be sure to keep internal components cool and provide a longer lifespan for your machine. Additional Questions Some of the “finer points” to consider when purchasing include:
Armed with the answers to these questions, you should be a well-educated consumer in your quest for a compact wire feed welder!
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Copyright (c) 1996-2008. Automotive Service Association. All rights reserved.
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The process of arc welding poses several potential hazards that must be guarded against. Therefore, all information relating to the safe operation of welding equipment and welding processes must be fully understood before attempting to begin work. This article covers the most common safety issues, but does not cover all of them. Always read and follow the safety information in the operator's manual or contact the manufacturing company when in doubt.
With so many choices of welding machines on the market today, how does a novice welding operator choose what he or she needs? There are some key questions that can guide you through the process and make the choice a little easier.
