Read about the dangers of arc and gas welding, including tips for welders on how to stay safe in the workplace.
Welding can generate metal particulates and noxious gases including ozone, nitrogen oxides and carbon monoxide. The most frequent acute respiratory complaint among welders is metal fume fever, a common self-limiting febrile illness of short duration that may be caused by exposure to welding fumes that contain zinc, copper, magnesium and cadmium. Persistent pulmonary bronchitis is the most frequent chronic problem. There are case reports of interstitial fibrosis in welders from exposure to excessive welding fume concentrations.
Examples of welding hazards
The dangers associated with welding include:
- The arc - the temperature can reach 6000 degrees celsius. The intense ultraviolet and infra-red rays can be harmful to both the welder and anyone else nearby. It is not unusual for welders who are not wearing overalls to suffer symptoms similar to extreme sunburn.
- The fumes - depending on the item being welded, in the open air, fumes may be adequately dissipated. However, in confined spaces fumes may be hazardous to health and precautions should be taken. Where it is not possible to ensure good ventilation, a suitable respirator should be worn.
- The volatile combination of heat and gas - fatalities have resulted where drums and other containers have exploded as a result of some welding or cutting work. The nature of the previous contents should be established to ensure that any heating does not liberate toxic fumes or cause an explosion.
- The electrical circuit - the electrical circuit is a hazard to the welder. The risk of electrical shock is high and welders should note the following points:
- Never attempt to connect or change welding cables before switching off the power at the mains first.
- Always install the welding machine as near as possible to the power point.
- Always keep the welding machine terminals and cable connections clean and tight - only use welding cables that are fully insulated throughout their entire length.
- Work on a well insulated floor wherever possible.
- Wear rubber insulated shoes.
- Always wear dry gloves when handling equipment that is live, e.g. when placing an electrode in a holder.
- Always get a qualified electrician to do any electrical repairs.
- Do not attempt to use gas pipes or water pipes as part of the welding circuit as explosions or shocks to other workmates may result.
- Fit hazard-reducing devices (such as a device that will reduce the voltage to a low level, or a switching device that automatically switches the no-load voltage to DC) to all manual metal-arc welding machines which are used in humid conditions and/or in category B and C environments. Category B and C are environments with increased hazard of electric shock such as:
- Category B: steel building structures, inside pressure vessels, storage tanks, conductive confined space and general fabrication activities.
- Category C: coffer dams, trenches, underground mines, in rain, in partially submerged areas, and splash zones. Refer to Australian Standards AS1674.2 and AS60974.1 for further details
- The finished work will be very hot.
You should notify WHSQ of an incident that occurs in relation to welding at your workplace.
When choosing appropriate protective clothing, you should take into account protection of body parts from electric shock and burns from radiation or hot metal parts and splashes. Welders should wear:
- a shield or helmet with a filtered lens
- fire resistant gauntlet leather gloves with internal seams to prevent stitches burning or trapping hot particles
- wool or fire-resistant canvas protective clothing that covers arms, legs and neck that also provide UV protection
- a leather apron
- leather steel-capped safety boots with leather spats
- a felt skull-cap or beret
Eye and face protection should:
- be non-flammable and have anti-glare sides
- ensure adequate visibility
- be equipped with a shade filter appropriate to the cutting and welding process.
Where possible, wear full helmet equipment to protect the head from falling objects, impact from protruding objects, hot or flying metal particles. Helmets should:
- allow adequate breathing and ventilation
- be light and durable
- be constructed from non-flammable and non-conducting materials
- have a non-reflective surface.
- Gas leakage is one of the greatest risks involved with gas welding. Leaking fuel gas is usually recognised by odour. Oxygen leaks are potentially more dangerous as they are usually not recognised easily.
- Leaking oxygen leads to an oxygen enriched atmosphere where normal events such as naked flames, cigarettes, sparks and electrical faults become more dangerous situations. Oils and greases may spontaneously ignite in the presence of pure oxygen.
- Under no circumstances should any fittings of oxy-acetylene equipment be allowed to be contaminated with grease or oil.
- Regulators can fail in two ways - by the controlled forward flow of gas which is known as regulator creep or by the reverse flow of another gas in the gas lines. Regular maintenance should avoid these situations.
- Either of these failures can be recognised by a higher than expected reading on the operational or low pressure gauge. The gauge needle creeps beyond the pressure set for actual welding or cutting.
- Excess pressure or the presence of a different gas in a regulator can cause fire and explosion in varying degrees of severity, resulting in damaged equipment and operator injury.
- Operators should never use equipment fitted with a regulator in which a creep condition is known to exist.
- Use the correct colour and type of hoses and fittings recommended by the manufacturers. Copper must never be used on acetylene lines as substances which may spontaneously detonate are formed.
- Flashback arresters should be fitted to all oxy-acetylene equipment to overcome the danger of flashback.
- Oxy-acetylene equipment should not be left near hot equipment or metals which could burn the leads. Gas leaks can be tested by using soap and water.
- Proper attention to maintenance of equipment is necessary to prevent accidents.
- Don't smoke when welding or near welding and don't keep your lighter in your pocket - it could explode. Simple prevention may save your life.