To achieve safe working conditions in the metal fabrication and welding industry, all personnel should be able to recognise the hazards which apply to their particular occupation. Welding operators must also know the correct operating procedures for the equipment.
An operator can be subjected to many safety hazards associated with the industry. As with any other industrial worker, they may be injured through incorrect lifting practices, falling or tripping, or incorrect use of hand tools and machines. The operator will also encounter particular hazards associated with welding.
A clean, tidy workplace, free from combustible materials, is an essential requirement for the safety of welding personnel.
Additionally, others working in the vicinity of welding operations are at risk from hazards such as electrocution, fumes, radiation, burns or flying slag and noise. They too must be protected if their health and safety is not to be put at risk.
Types of hazards
- electric shock
- fire and explosion
Electrical principles and requirements for arc welding machines is necessary to clarify some basic electrical terms. Term Definition voltage (V) the force which makes current flow voltage is essentially electrical pressure current (A) the flow of electrons and is measured in amperes open circuit voltage (OCV)
Electric shock may only cause a minor tingling sensation or it may cause muscle spasms, or paralysis and this may cause an operator to grip onto the source of electricity. In the worst case scenario this may contribute to the welding operator’s death. In arc welding processes a number of potential electrocution sources can be identified. The primary input lead is either 415 V or 240 V and should never be tampered with, altered, or repaired except by a licensed electrician. The output circuit of an arc welder is controlled at a ‘safe voltage’ but this safe voltage can also kill if given ideal conditions.
The ancillary circuits of most welders are also at a safe voltage of either 32 V or 24 V, although some machine manufacturers also use 110 V on older control circuits.
Fumes are produced in all welding and cutting operations. They are a mixture of: atmospheric gases arc shielding gases vaporised elements from the parent metal, metal coatings, or flux coated welding consumables airborne particles small enough to be inhaled. Welding fumes are normally at levels low enough to pose no great health risk. However, when fume concentration is excessive the operator will be deprived of the oxygen needed to maintain good health. Fumes of highly toxic metals, even in low concentrations, may also cause health problems with respect to the upper respiratory tract, lungs, blood, liver, kidneys and central nervous system. Certain substances found in welding fumes are recognised as being particularly dangerous, even in very low concentrations. Welding operators should be aware of the dangers associated with metals such as beryllium, cadmium, zinc and lead
To ensure that the concentration of fumes and exposure to fumes is within safe limits, various controls can be applied. Substitution Where practicable, a less dangerous material, consumable, process or procedure can be substituted. Limiting the period of exposure Limiting the time any one operator is exposed to excessive fume concentration is not the most desirable method, but in some cases may be the only practical solution. Work methods Good housekeeping and work practices can avoid the unnecessary generation and exposure to fumes. For example, removing surface contaminants from parent material prior to welding or cutting. It should be noted that certain degreasing agents decompose under heat and ultraviolet radiation to give off toxic fumes. Ventilation is the most common method of control and can be achieved by various means.
Protection from radiation
Personal protection Protection is needed for both the eyes and skin. For arc welding, a suitable welding helmet or face shield, fitted with the recommended filter for the job in hand, is necessary
For gas welding and cutting, the use of protective goggles fitted with the recommended shade 5 filter, is essential. Clear safety spectacles give only limited protection from stray radiation, however spectacles fitted with lenses not less than 2 mm thick incorporating a shade filter of up to 2.5 are highly desirable to give protection from stray arc welding flashes. In order to protect the skin from radiation it is essential that suitable clothing is worn to cover all areas which could be exposed. Woollen materials have much greater resistance to ultraviolet radiation than synthetic and plain cotton materials which can rapidly deteriorate or rot when exposed to strong ultraviolet radiation. Leather aprons, sleeves, jackets and gloves are usually required in welding processes where strong radiation is emitted. Where reflection is likely, for example in welding on highly reflective metals such as aluminium or stainless steel, protection for the eyes and skin against indirect radiation is required
Prevention of fire and explosion
Maintain clean and tidy work areas, free from accumulations of combustible materials. Check that work introduced for cutting or welding does not constitute a fire or explosion hazard. Ensure that screens, aids, and building fittings are not constructed from flammable materials. Ensure that personal clothing is sound and made from suitable materials. Store flammable substances and gases in a safe area or separate building. Be aware of fire extinguisher locations and how to operate each type. Avoid oxygen enrichment of clothing or work space, which may be caused by leaking oxygen valves
Protection from burns
Use tongs to handle hot metal. Make provision for disposal of hot metal and electrode stubs. Wear all the necessary protective clothing. Protective clothing must be non-flammable, and free from oil, grease, tears, and fraying.