Welding Safety

Definitions

Weld A localized fusion of metals produced by heating to suitable temperatures. Pressure and/or filler metal may or may not be used. The filler material has a melting point approximately the same or below that of the base metals, but always above 800 °F.

Gas Metal-Arc (MIG) Welding (GMAW) Fusion is produced by heating with an electric arc between a consumable metal electrode and the work. Shielding from an inert gas such as helium or argon. Electrode fed continuously and deposited as weld material in the intense heat of the arc.

Gas Tungsten-Arc (TIG) Welding (GTAW) Fusion is produced by heating with an electric arc between a non-consumable tungsten electrode and the work. An inert gas forms around the weld area to prevent oxidation. A welding rod with no flux is used.

Shielded Metal Arc Welding (SMAW) Most widely used type of arc welding Also known as manual metal arc (MMA) welding or informally as stick welding. Uses a consumable electrode coated in flux to lay the weld.

Spot Welding Resistance welding process in which fusion is produced by converting electrical energy to heat energy and transferring it to the work pieces held together under pressure by electrodes. Size and shape of the individually formed welds are limited by the size and contour of the electrodes.

Stud Welding Arc welding process in which fusion is produced by heating with an electric arc drawn between a metal stud and the other work piece. They are brought together under pressure.

General Safety Rules Study the Owners Manual. Pay particular attention to safety information. Only qualified persons should install, operate, maintain, and repair welding units. MSDS – metals, consumables, coatings. Wear approved safety glasses with side shields under your welding helmet. Welding, chipping, wire brushing, and grinding cause sparks and flying metal. Turn off equipment when not in use.

Electrical Safety Wear dry, hole-free insulating gloves and body protection. Do not touch electrode with bare hand. Do not wear wet or damaged gloves. Do not touch live electrical parts.

Electrical Safety (Cont.) Protect yourself from electric shock by insulating yourself from work and ground. Use non-flammable, dry insulating material such as dry rubber mats, dry wood big enough to cover your full area of contact with the work or ground.

Electrical Safety (Cont.) Disconnect input plug or power before working on machine. Frequently inspect input power cord for damage or bare wiring – repair or replace cord immediately if damaged. Keep cords dry, free of oil and grease, and protected from hot metal and sparks. Properly install and ground all equipment.

Respiratory Safety Keep your head out of the fumes. Do not breathe the fumes. Refer to Material Safety Data Sheets (MSDSs) for metals, consumables, and coatings.

Respiratory Safety (Cont.) Use local exhaust at the arc to remove the fumes from your breathing area. Use a ventilating fan to remove fumes from the breathing zone and welding area. If adequacy of ventilation or exhaust is uncertain, have your exposure checked by an industrial hygienist.

Fire Safety Flying sparks, hot work piece, and hot equipment can cause fires and burns. Do not weld near flammable material or where the atmosphere may contain flammable dust, gas, or liquid vapors (such as gasoline). Watch for fire, and keep a fire extinguisher nearby.

Fire Safety (Cont.) A fire watch person shall be provided during and for 1-hour (UEI policy) past the completion of the welding project when (a) appreciable combustible materials are closer than 35 feet to the point of operation or (b) appreciable combustibles are more than 35 feet away but are easily ignited by sparks (OSHA rule.) At least one 10-lb. dry chemical fire extinguisher. Ensure area is free of sparks, glowing embers, and flames.

Fire Safety (Cont.) Be alert that welding sparks and hot materials from welding can easily go through small cracks and openings to adjacent areas. Be aware that welding on a ceiling, floor, bulkhead, or partition can cause fire on the hidden side.

Fire Safety (Cont.) Do not weld on drums, tanks, or any closed containers unless a qualified person has tested it and declared it or prepared it to be safe. Welding on closed containers, such as tanks, drums, or pipes, can cause them to blow up.

Fire Safety (Cont.) Connect work cable to the work as close to the welding area as practical to prevent welding current from traveling long paths and causing electric shock and fire hazards. Remove any combustibles, such as a butane lighter or matches, from your person before doing any welding. Remove stick electrode from holder or cut off welding wire at contact tip when not in use.

PPE Safety Wear complete body protection. Wear oil-free protective clothing such as leather gloves, heavy shirt, cuff-less pants, and high boots. Wear clothing made from durable, flame-resistant material (leather and wool) as a protection against sparks and hot metal. Shirt should have full sleeves, no pockets and should be worn outside the trousers with collar buttoned.

PPE Safety (Cont.) Arcs produce intense visible and invisible rays that can burn eyes and skin. Wear a welding helmet fitted with a proper shade of filter to protect your face and eyes when welding or watching. Should be an insulator for heat and electricity.

PPE Safety (Cont.)

PPE Safety (Cont.) Do not touch hot welded or cut parts with bare hand. If handling is needed, use proper tools and/or wear heavy, insulated welding gloves to prevent burns. Allow cooling period before handling parts or working on equipment.

PPE Safety (Cont.) Wear welders cap and safety glasses with side shields. Use protective screens or barriers to protect others from flash and glare; warn others not to watch the arc. Where the work permits, the welder should be enclosed in an individual booth.

Gas Cylinder Safety Shielding gas cylinders contain gas under high pressure. If damaged, a cylinder can explode. Since gas cylinders are normally part of the welding process, be sure to treat them carefully. What’s wrong with this picture?

Gas Cylinder Safety (Cont.) “A cylinder that leaks, is bulged, has defective valves or safety devices, bears evidence of physical abuse, fire or heat damage, or detrimental rusting or corrosion, must not be used unless it is properly repaired and requalified.”

Gas Cylinder Safety (Cont.) Protect compressed gas cylinders from excessive heat, mechanical shocks, slag, open flames, sparks, and arcs. Secure cylinders in an upright position. Keep cylinders away from any electrical circuits. Never drape a welding torch over a gas cylinder. Never allow a welding electrode to touch any cylinder. Never weld on a pressurized cylinder – explosion will result.

Gas Cylinder Safety (Cont.) Before attaching the regulator, remove the protective cap from the cylinder. Turn face away from valve outlet. “Crack” the valve slightly for an instant, and then close it, to clean the valve of dust and dirt that can damage the regulator and cause a fire or explosion. What’s wrong with this picture?

Gas Cylinder Safety (Cont.) Unless cylinders are secured on a special truck, remove regulators and install valve-protection caps before moving. Close the valve and release the gas from the regulator before removing it from the cylinder. Keep protective cap in place over valve except when cylinder is in use or connected for use. Do not use valve protection caps for lifting cylinders. Cylinders can be heavy — use lifting device and proper methods to injury to yourself or damage to the cylinder.

Gas Cylinder Safety (Cont.) Keep cylinders, valves, couplings, regulators, hose, and apparatus free from oily or greasy substances. Use only correct shielding gas cylinders, regulators, hoses, and fittings designed for the specific application; maintain them and associated parts in good condition.

Confined Space Safety Spaces that can be entered but not designed for continuous human occupancy and have restricted means of entry and exit such as tanks, pits, attics, and crawl spaces. All normal arc welding and cutting hazards are amplified in confined spaces.

Confined Space Safety (Cont.) Always open all covers, remove any hazardous or toxic materials and provide forced ventilation. Have constant communication with someone outside who can quickly turn off power and gas, is trained in rescue procedures, and is able to pull you out in case of emergency. Do not use AC weld output in confined spaces.

EMF Safety Welding current creates an EMF field around the welding circuit and welding equipment. EMF fields may interfere with some medical implants, e.g. pacemakers. Protective measures for persons wearing medical implants have to be taken. For example, access restrictions for passersby or individual risk assessment for welders.

EMF Safety (Cont.) Use the following procedures in order to minimize exposure to EMF fields from the welding circuit: Keep cables close together by twisting or taping them. Keep welding power source and cables as far away from operator as practical. Connect work clamp to work piece as close to the weld as possible

Summary Wear dry, insulated gloves and other protective clothing in good condition. Insulate yourself with rubber-soled shoes or stand on a dry, insulated mat. Use fully insulated electrode holders. Do not touch an energized electrode with bare hands.

Summary (Cont.) Inspect equipment and cables before each use and repair or replace damaged parts. Avoid breathing the welding fumes. Treat gas cylinders with respect. Beware of fire hazards. Turn off equipment when not in use.