The first consideration for safety in welding is the location and peculiarities of the space in which the welding operation is to be performed.
Weld or cut only in locations specifically designated for this purpose unless you have obtained approval of the job and have taken the necessary precautions to eliminate fire and explosion hazards.
Do not weld in any location outside the shop unless you take the necessary precautions and get authorization. Before you weld in any compartment, room, tank, or adjacent space which contains or which has contained flammable or explosive materials, liquids, or vapors, make sure they are:
These restrictions also apply to closed drums, tanks, and similar containers.
Allow welding or cutting only in areas that are or have been made “fire safe.”
Do not permit welding or cutting in the following situations:
Eliminate fire and explosion hazards by removing or reducing combustible or explosive materials or vapors by preventing them from accumulating. The methods for making a space safe for welding and the tests used to ensure a space is free of fire and explosion hazards should be the responsibility of a welding supervisor.
Combustible material: Wherever there are floor openings or cracks in the flooring that you cannot close, you should take precautions so no readily combustible materials on the floor below is exposed to sparks that might drop through the floor. Use the same precautions for cracks or holes in walls, open doorways and open or broken windows.
Combustible covers: Never weld on a metal partition, wall, ceiling or roof having a combustible covering nor on walls or partitions of combustible sandwich-type panel construction.
Relocation of combustibles: If possible, relocate all combustibles at least 35 feet (10.7 m) from the work site. When relocation is not possible:
Floors: Where combustible materials such as paper clippings, wood shavings, or textile fibers are on the floor, sweep the floor clean within a radius of 35 feet (10.7 m). In addition:
Ducts: Protect or shut down ducts and conveyor systems that might carry sparks to distant combustibles.
Combustible walls: Where cutting or welding is done near walls, partitions, ceiling or roof of combustible construction, provide fire-resistant shields or guards to prevent ignition.
Non-combustible walls: If you need to do welding on a metal wall, partition, ceiling or roof, prevent ignition of combustibles on the other side, preferably by relocating combustibles. Where you are not able to relocate the combustibles, be sure to provide a fire watch on the opposite side from the work.
Pipes: Do not cut or weld on pipes or other metal in contact with combustible walls, partitions, ceilings or roofs if the work is close enough to cause ignition by conduction.
Fire extinguishers: Position suitable fire extinguishing equipment and maintain it in a state of readiness for instant use. Depending on the nature and quantity of the combustible material, fire-extinguishing equipment may consist of:
Hot work is any work that involves burning, welding, using fire- or spark-producing tools or that produces a source of ignition. Follow these general best practices below for hot work.
Fire Watch: A worker designated as the "Fire Watch" is required whenever welding or cutting is performed in locations where other than a minor fire might develop, or any of the following conditions exist:
Fire Watch Duties: The duties of a qualified fire watch include:
Used containers: Do not weld, cut, or perform other hot work on used drums, barrels, tanks or other containers until you clean them.
Venting and purging: Vent all hollow spaces, cavities or containers to permit air or gases to escapte before preheating, cutting or welding. You should purge with inert gas.
Shielding gases are inert or semi-inert gases such as argon, helium, and carbon dioxide used in welding processes to protect the weld the molten metal from the contamination and oxidation. Damage to the weld can be caused by harmful gases such as nitrogen, oxygen and water vapor in the atmosphere. Air in the weld zone is displaced by a shielding gas in order to prevent contamination of the molten weld puddle.
The types of welding in which shielding gases are use include Metal Inert Gas (MIG) and Tungsten Inert Gas (TIG) welding. Improper choice of a welding gas can lead to a porous and weak weld, or to excessive spatter.
The hazards involved in using shielding gases involve primarily handling gas cylinders. For more information on compressed gas cylinder safety, see OSHA's Small Business Handbook.
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