PRESENTATION ON ARC WELDING SAFETY

Before starting actual arc welding the operator should be fully aware of the dangers involved. The high temperature arc and hot metal can cause severe burns. In addition the electric arc itself provides an additional safety hazard.

The electric arc emits large amounts of ultra violet and infra-red rays. Both types of rays are invisible to the naked eye just as the same type of rays emitted by the sun are invisible. However they both have the identical properties of causing sunburn on the human skin, except that the arc burns much more rapidly and deeply. Since these rays are produced very close to the operator they can cause very severe burns to the eyes in a short exposure time.

When welding with the electric arc, there is added danger that the small globules or droplets of molten metal may leave the arc and fly in all directions. These so called sparks range in temperature from 2000 ° to 3000° Fahrenheit and in size from very small to as large as ¼ inch. They present a personal burn hazard plus a fire hazard if they fall in inflammable material.

The welding operator needs to protect himself, by means of a helmet and other protective devices from the harmful rays of the arc and flying sparks. The filter plates in the welding helmet will remove 99% of the harmful rays if the proper shade lens is used.

Other dangers associated with electric arc welding are: a. Electric shock-which may be caused by standing in damp areas, welding without gloves, bare cables, uninsulated holder, etc. b. Harmful fumes given off in welding process especially when welding on galvanized or other coated materials.

The operator should be familiar with all safety precautions and take care to adequately protect himself at all times against any hazards associated with arc welding by wearing protective clothing and equipment, working in dry conditions, providing adequate ventilation and in general using good common sense.

Following is a list of safety precautions that should be observed in the use of the arc welding equipment.

1.Make sure machine is properly grounded. 2.Never permit “live” parts of the electric welder to touch bare skin or wet clothing. 3.Do not cool electrode holders by emersion in water. 4.Turn off power supply when welder is not in use. 5.Do not stand on wet areas while welding. 6.Wear leather gloves. 7.Make sure cable are covered and in good condition. 8.Make certain that electrode holders are properly insulated.

1.Protect eyes and face from flying particles of slag by use of safety glasses or face shield. 2.Wear adequate protective clothing. 3.Always wear leather gloves. 4.Wear high top shoes. 5.Keep collar, shirt pockets, etc buttoned. 6.Do not touch the electrode or metal where welding has taken place. 7.Handle hot metal with pliers or tongs. 8.Keep electrode stubs properly disposed of.

1.Use a welding helmet with the correct shade lens in good condition. 2.Wear suitable clothing—do not leave bare skin exposed to the rays of the arc. 3.Do not strike the arc without covering the face and eyes. Give warning to others before striking the arc. 4.Avoid looking directly at the arc where others are welding without proper eye protection.

FILTER RECOMMENDATIONS (adapted from ANSI Safety Standard Z49.1) Application Lens Shade No.* Mig 160 to 250 amps Tig (Gas Tungsten Arc) up to 50 amps 10 Plasma Arc Welding up to 100 amps 10 Stick (Shielded Metal Arc) 10 * As a rule of thumb, start with a shade that is too dark to see the arc zone. Then go to a lighter shade which gives sufficient view of the arc zone without exerting a strain on your eyes.

1.Work only in well-ventilated areas. 2.Use great care when working on metals covered with lead or zinc. 3.If working in a confined area use respirator or other approved breathing devices.

Examples of Confined Spaces Small rooms Unventilated Degreasers Process vessels corners of a Boilers Pits room Compartments of Tunnels Furnaces ships Vats Storage tanks Ventilation and Reactor vessels Pipelines exhaust ducts Underground utili- Sewers ty vaults Silos

Reasons For Deaths and Serious Injuries From Welding In Confined Spaces Fire Exposure to hazardous Explosion Electric shock air contaminants Asphyxiation

Actions Required Before Approving Start of Work In A Confined Space Open all covers and secure them from closing. Test confined space atmosphere for suitable oxygen content, no combustibles or reactives, no toxics.

Isolate lines by capping or double valving and venting, if feasible-keep vents open and valves leak-free. Lock out all systems not required during welding, cutting, or heating. Provide means for readily turning off power, gas, and other supplies from outside the confined space. Protect or remove any hazardous materials or materials which may become a physical or health risk when heated or exposed to an arc.

1.Keep shop clean in areas where welding is to be done. 2.Do not weld near combustible materials of any kind. 3.Never weld on covered containers which may have held combustible materials without first taking adequate safety precautions. For example, fill them with water, steam clean or fill with an inert gas.

1.Be familiar with location and types of fire extinguishers. 2.Report any unsafe conditions that might start a fire. 3.Do not weld near inflammable materials. 4.Do not weld on containers that have held inflammable materials. 5.Do not weld near electrical fittings or lines.

REFERENCE “Safety & Health in Arc Welding and Gas Welding & Cutting”, NIOSH Publication No , (1978) U.S. Department of Health, Education and Welfare, Public Health Service, Center for Disease Control, Superintendent of Documents, U.S. Government Printing Office, Washington, D.C ( aspx Use Product Code: PB )

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