4.3 Welding and Cutting in Construction

Compressed gas cylinders

• Valve protection caps must be in place and secure.
• Do not hoist or transport cylinders with magnets or choker slings.
• Hoist cylinders only on a cradle, slingboard or pallet.
• Do not drop cylinders or let them be struck violently.
• Move a single cylinder by tilting it and rolling it along its bottom edge.

Fuel gas

• Crack the valve before connecting: open it slightly and close it at once, to clear dust and dirt. Stand to one side, and make sure the gas does not reach sparks, flames or other ignition sources.
• Open cylinder valves slowly to avoid damaging the regulator, and no more than one and a half turns, so that they can be closed fast. If a special wrench is needed to close the valve, leave it on the valve stem.
• Leave nothing on top of a fuel gas cylinder that could damage the safety device or interfere with closing the valve quickly.

Arc welding and cutting

• A manual electrode holder must be able to carry the maximum rated current, and only electrodes made for arc welding and cutting may be used. Current carrying parts that touch the holder must be fully insulated for the highest voltage.
• Welding must not be done where flammable paints or compounds could cause a hazard.

Ventilation

Mechanical ventilation may be general or local exhaust. General ventilation must give enough air changes to keep fumes and smoke within safe limits. Local ventilation uses freely moving hoods that the welder can place as close as practical to the work, to remove smoke and fumes at the source and keep the breathing zone safe. Contaminated air must be discharged to an open area and away from the intake, and replacement air must be clean and breathable.

Toxic metals and coatings need special care. Beryllium, cadmium, chromium, lead, zinc, mercury and fluorine compounds, and preservative coatings, can give off dangerous fumes when heated, and ultraviolet rays from the arc harm the eyes and skin.

Fire prevention

• Whenever possible, move the object to be welded or cut to a safe place. If it cannot be moved, move or shield all fire hazards nearby.
• Equip the work area with suitable fire extinguishing equipment that is maintained and ready to use at once.
• If these measures are not enough, assign additional people to watch for fire.

A study aid, not published or endorsed by IOSH or OSHA. Laws and limits differ between countries.