Welding Health and Safety by the Numbers
Chapter 9 of 10 · 10 min read
Noise, heat and ergonomics
Compare the noise of welding and its allied work, add decibels from several sources, manage heat stress under leathers in summer, and cut the strains of awkward postures, heavy torches and lifting.
The hazards in this chapter are the ones welders often accept as part of the job: the noise of grinding and gouging, the heat of a summer afternoon under leathers and a helmet, the ache of welding overhead or kneeling on a steel floor. None of them is dramatic, and their harm builds slowly, which is exactly why they are neglected. Noise-induced hearing loss is permanent; heat stress can kill; back, neck, shoulder and knee injuries end careers. Each can be measured or estimated, and each can be reduced.
This chapter compares the noise of welding and the work around it, shows how sound levels from several sources add, sets out how heat stress is recognised and managed, and covers the ergonomics of welding: postures, tools and manual handling.
Noise in the welding shop
The welding arc itself is often less noisy than the work around it. Gas tungsten arc welding is quiet; gas metal arc and flux-cored welding, especially in spray transfer, can be loud; air carbon arc gouging is among the loudest operations in metalworking. Grinding, chipping, hammering, needle scaling and plasma cutting add their own noise, and in a busy shop the noise from every station reaches every worker.
The work health and safety regulations set an exposure standard for noise of an eight-hour average of 85 dB(A), with a peak limit, and above it every 3 dB halves the time that makes up a full day’s dose. Forge Welding by the Numbers and Cutting and Gouging by the Numbers work through daily doses. In a welding shop, grinding and gouging usually set the dose; welders who do much of their own grinding often exceed the standard even if their welding alone would not.
Adding sound levels
Decibels do not add like ordinary numbers, because they are a logarithmic scale. Two sources each producing 95 dB(A) at a point do not give 190 dB(A), but about 98 dB(A): doubling the sound energy adds 3 dB. A loud source dominates a quieter one; a 100 dB(A) grinder beside a 90 dB(A) welder gives only about 100.4 dB(A).
- Own welding
- 95 dB(A)
- Neighbour's welding
- 92 dB(A)
- Grinding nearby
- 100 dB(A)
- sum of 10^(level ÷ 10) ≈ 10^9.5 + 10^9.2 + 10^10.0 ≈ 3.16 × 10⁹ + 1.58 × 10⁹ + 10.0 × 10⁹ ≈ 14.7 × 10⁹
- total ≈ 10 × log₁₀(14.7 × 10⁹) ≈ 101.7 dB(A)
- the grinding dominates; quietening the welder's own process would barely change the total
The arithmetic points to the controls that matter: deal first with the loudest source. Moving grinding to a screened, sound-absorbing area, choosing quieter grinding discs and tools, replacing arc-air gouging with plasma gouging or grinding where it will do, and lining the shop’s walls and roof with absorptive materials reduce the noise everyone hears. Hearing protection, chosen for the levels and worn whenever the noise is present, protects what remains. Earmuffs and plugs must be compatible with welding helmets and respirators; some powered welding helmets integrate hearing protection.
Hearing loss
Noise-induced hearing loss develops over years, painlessly, starting at the high frequencies that make speech clear, so that the affected person first notices difficulty following conversation in noise. It is permanent, and it is often accompanied by tinnitus, a ringing or hissing in the ears. Regular hearing tests, described in Chapter 10, find it early, while there is still time to protect what hearing remains.
Heat stress
Welding is hot work in every sense. The welder is close to the arc and the hot work, wears heavy, enclosing clothing, a helmet and often a respirator, and may be working in a hot shop, in the sun on site, or inside a vessel. The body cools itself mainly by sweating, and when the heat it gains from work, surroundings and its own effort exceeds what sweating can remove, its temperature rises. Heat stress ranges from discomfort and loss of concentration, which increase the risk of mistakes and injuries, through heat exhaustion, with heavy sweating, weakness, headache and nausea, to heat stroke, a medical emergency in which the body’s cooling fails and the person may become confused, collapse and die.
A welder working hard in heat can sweat a litre or more an hour, and without enough fluid replacement becomes dehydrated, which makes heat illness much more likely. Thirst is a poor guide to how much a working welder needs to drink; by the time a person feels thirsty they are already losing fluid faster than they are replacing it.
Managing heat
The controls follow the hierarchy. Reduce the heat at its source: shade outdoor work, ventilate and cool the shop, insulate hot surfaces, and schedule heavy and hot work for the cooler parts of the day. Reduce the heat on the person: lighter welding clothing where the process allows, powered respirators that blow cooling air, cooling vests for very hot work. Organise the work: rest breaks in cool areas, job rotation, and acclimatisation for new workers and those returning after time away, who are most at risk. Make cool drinking water easily available and encourage frequent drinking, small amounts often. And train everyone to recognise the signs of heat illness in themselves and others, and to stop work and seek help at once if they appear. Safe Work Australia publishes guidance on managing the risks of working in heat.
Postures
Welders work in positions dictated by the work: bent over a low bench, reaching overhead, kneeling or lying on the floor, twisting into a corner, holding a torch and helmet steady for long periods. Sustained awkward postures load the neck, shoulders, back and knees, and welders have high rates of shoulder and neck disorders. The controls that matter most bring the work to the welder: positioners and turntables that turn the work so that welds are made flat and at a comfortable height, height-adjustable benches and stands, and fixtures that hold the work where the welder can reach it. Welding Automation by the Numbers showed that positioners also make welding faster and better.
- Avoid: Work heightbenches and stands adjustable; work brought to about elbow height for most welding
- Avoid: Positionersheavy and large work turned so welds are flat or horizontal
- Avoid: Reach and accessthe welder can reach the joint without twisting or overreaching
- Avoid: Torch and cablelightweight torches; cables supported on booms so their weight is not on the wrist
- Avoid: Helmetauto-darkening, lightweight, well balanced; no constant nodding to drop it
- Avoid: Kneeling and floor workknee pads, mats, low stools; floor work minimised
- Do: ? Rotation and breaksvaried tasks; micro-breaks during long runs
Eyesight and comfort
Welders who strain to see the work lean closer to it, which puts their faces deeper in the fume and their necks in worse postures. Good lighting at the station, a helmet whose filter gives a clear view, a magnifying cheater lens for welders who need one, and prescription safety glasses where needed all reduce the strain and improve the welds.
Tools and equipment
The weight and balance of torches, helmets and grinders, carried for hours, add up. A gas metal arc torch with its cable and on-torch extraction can be heavy; a cable hanging from the torch pulls on the wrist with every movement. Cable booms or balancers that carry the weight overhead, lighter torches, and auto-darkening helmets that end the repeated neck jerk of flipping a helmet down all reduce the strain. Grinders’ vibration, over years, damages the hands and arms; low-vibration tools, well-maintained discs and limits on daily use reduce it.
Manual handling
Fabrication involves lifting, carrying, pushing and positioning heavy steel, and strains from manual handling are a large share of injuries in most fabrication shops, as they were in the running case’s record. The controls are mechanical aids, cranes, hoists, lifting magnets, trolleys and roller conveyors, used for anything heavy or awkward; layouts that keep material moving at working height rather than being lifted from the floor; team lifts for awkward loads; and training in safe handling. Safe Work Australia’s model code on hazardous manual tasks sets out how to assess and control these risks.
Hearing protection that works
Hearing protection, like a respirator, protects only while it is worn and only if it fits. A protector that would reduce the level at the ear by a large margin when worn all the time gives far less if it is removed for even a few minutes in each hour of loud work, because the dose from the unprotected minutes dominates. Earplugs that are not inserted properly, earmuffs pushed up by a welding helmet’s headband, and protectors chosen for comfort rather than the levels all fall short. The coordinator chose protectors with the welders, compatible with their helmets, had a hearing conservation provider fit-check earplugs for each welder, and made hearing protection compulsory in marked zones around grinding and gouging, where the levels were highest.
Noise at the source
The cheapest decibels are those never made. Air carbon arc gouging, the loudest job in the shop, was replaced by plasma gouging wherever the groove allowed, and the remaining arc-air gouging moved to a lined booth. Grinding was reduced by better cutting and fitting, so that less weld preparation and dressing was needed, and by smoother welds from positioners. Pneumatic tools were fitted with silencers, compressed air blow-off guns with quieter nozzles, and the compressor was moved outside. Each change reduced the noise everyone in the shop heard, not just the person doing the job.
Fatigue and long shifts
Long shifts, overtime and night work increase fatigue, which slows reactions, impairs judgement and makes every other hazard in this book more dangerous. Fatigued welders take shortcuts, skip extraction, leave helmets up and lift heavy work without help. Exposure standards for noise and airborne contaminants also assume an eight-hour day; longer shifts mean more exposure and less recovery time, and need adjusted limits. The shop limited regular overtime, planned rest breaks into long jobs, and avoided scheduling confined space and hot site work at the end of long shifts.
Cold and wet
Site welding in winter brings the opposite problems: cold hands lose dexterity and sensation, wet clothing and gloves raise the electrical risk of Chapter 7, and slippery surfaces raise the risk of falls. Windbreaks, shelters, warm and dry spare gloves and clothing, heated rest areas and planning work around the weather all help. Cold stiffens muscles, too, which makes strains in manual handling more likely.
Reporting early
Most musculoskeletal injuries give warnings before they become serious: aches, stiffness, tingling or weakness that persist after work. Encouraging people to report them early, and acting on the reports by looking at the task, lets the cause be fixed before the injury becomes a lost-time claim. The shop’s committee added a simple discomfort report to its monthly walk, and several of its ergonomic changes came from welders describing which jobs hurt.
The running case: the heat and strain programme
This is an illustration. In the shop’s first summer under the coordinator, the shop installed roof ventilators and evaporative coolers in the welding bays, provided chilled water stations, moved the heaviest site work to early mornings, and trained supervisors to recognise heat illness. It bought two positioners for the implement frames, cable booms for the chassis bay, and adjustable stands for the fitting area, and introduced job rotation between welding, fitting and grinding. Strain injuries fell from about three a year to one in the following year, and the welders reported that the positioners had made the worst jobs bearable.
A failure: the hot afternoon
This is an illustration. At a site elsewhere, a welder working on a steel structure in full sun on a very hot afternoon, in leathers and a helmet, kept going to finish a job before a crane booking. A workmate noticed the welder had become confused and unsteady and had stopped sweating. The welder collapsed shortly after and was taken to hospital with heat stroke.
The welder recovered. The investigation found no plan for heat, no shade, no water at the work position, and pressure to finish. The site now has a heat plan that stops or reschedules heavy work in extreme heat, provides shade and water at every work position, and makes it clear that no job is worth finishing at that cost.
Exercise: which source to quieten?
At a welder’s position, their own gas metal arc welding produces about 90 dB(A), a neighbour’s flux-cored welding about 93 dB(A), and grinding at the next bench about 99 dB(A). What is the combined level? If the grinding were moved to a screened booth and its level at this position fell to about 85 dB(A), what would the combined level be?
The combined level is 10 × log₁₀(10^9.0 + 10^9.3 + 10^9.9) ≈ 10 × log₁₀(1.0 + 2.0 + 7.9) × 10⁹ ≈ 10 × log₁₀(10.9 × 10⁹) ≈ 100.4 dB(A).
With the grinding at 85 dB(A), it is 10 × log₁₀((1.0 + 2.0 + 0.32) × 10⁹) ≈ 10 × log₁₀(3.32 × 10⁹) ≈ 95.2 dB(A), a reduction of about 5 dB, which roughly cuts the sound energy to a third. Quietening the welder’s own process would have made almost no difference while the grinding dominated.
