Setting Up a Welding Shop by the Numbers
Chapter 7 of 10 · 10 min read
Fire, safety and the hot work area
Estimate how far welding and grinding sparks travel, keep a small shop's hot work from starting fires, plan first aid and emergencies, and set up the controls a two-person shop needs.
A welding shop makes heat, sparks and molten metal all day, in a building that also holds fuel gas, oxygen, paint, oil, cardboard, rags and timber. Most days nothing happens. The day something does, a fire can destroy the business, its equipment, its customers’ jobs and the neighbouring units, and an injury can change someone’s life. The early writers knew this: Dunham told garages to keep the welding away from any place where petrol vapour might be present, and Willis advised keeping a fire extinguisher close at hand because of the grease and oil near the flying sparks. Their advice is the start of a modern shop’s fire and safety plan, not the end of it.
This chapter estimates how far sparks travel, sets out the fire precautions for hot work in the shop and on site, and plans the first aid, emergency and safety arrangements a two-person shop needs from its first day. It names AS 1674.1, the Australian standard for fire precautions in welding and allied processes, by number and scope only, and Safe Work Australia’s model code of practice for welding processes, as adopted in each jurisdiction.
How far sparks go
Welding spatter, cutting slag and grinding sparks are small particles of hot or burning metal thrown from the work. How far they travel depends on how fast they leave and from what height. A simple calculation, ignoring air resistance and bouncing, gives a first idea.
- Speed leaving the work
- 10 m/s
- Height above the floor
- 1.5 m
- g
- 9.81 m/s²
- time to fall = √(2 × 1.5 ÷ 9.81) ≈ 0.55 s
- distance ≈ 10 × 0.55 ≈ 5.5 m before first landing
The numbers show why a clear zone of a few metres round hot work is not overcautious. A grinding disc can throw sparks faster than these examples, and a cut on a platform drops slag from height. The sparks that cause fires are usually the ones nobody watched: the ones that bounced under a bench, rolled into a gap in the floor or a wall, or lodged in a pile of rags, to smoulder for an hour.
Fire precautions in the shop
The precautions for hot work are set out in AS 1674.1, the code of practice and the insurer’s requirements, and the common ones for a shop are:
- remove combustibles from the hot work area, or protect what cannot be moved with fire-resistant blankets or screens;
- close gaps in floors and walls near hot work, or cover them, so that sparks cannot fall into hidden spaces;
- keep flammable liquids, paints, solvents and fuel in a proper store, away from the hot work area, and keep gas cylinders in their store (Chapter 4);
- keep fire extinguishers of suitable types at the hot work areas, with people trained to use them;
- keep the floor clean, free of oil, rags, cardboard and dust;
- check the area after hot work for smouldering material, for a period after work stops.
Mara’s layout (Chapter 2) put the cylinder store outside, the paint and solvent store in a separate steel cabinet away from the welding and grinding areas, and the grinding area facing a blank wall. Each hot work area has an extinguisher, and the shop closes each day with a walk-round to check for anything smouldering. Extinguishers are serviced at the intervals their maker and the regulations require.
Containers and tanks
The most dangerous job a small shop is offered is the repair of a tank, drum or container that has held something flammable: a fuel tank, an oil drum, a chemical container. Vapour in an apparently empty container can explode when heated, with fatal results. Industrial Gases by the Numbers describes the hazard in its chapter on hazards and the gas plan. Mara’s rule, from Chapter 1, is that the shop does not weld or cut any container that has held flammable material unless it has been cleaned and made safe by a recognised method and certified gas-free by a competent person, and in practice she refers most such work to specialists.
Hot work on site
Site work is riskier than shop work, because the shop’s controls are absent: combustibles are wherever the customer keeps them, and the welder may be at height, near fuel, in a shed full of hay, or beside a working machine. For site hot work, Mara uses a written check before starting, agreed with the customer: what is nearby, what must be moved or covered, where the extinguisher is, who will watch for fire during and after the work, and how to raise the alarm. Larger sites usually require their own hot work permit, which the shop follows. Construction sites may also require a safe work method statement for some work, as the regulations set out.
Electrical safety
Chapter 3 covered the supply, circuits and residual current protection, and Chapter 6 the testing of equipment. Day to day, electrical safety in a welding shop depends on habits: dry gloves and clothing, inspecting leads and guns before use, never welding while standing in water, isolating machines before changing parts, and keeping the work return on the work. Arc Welding by the Numbers sets out the electrical hazards of welding in its chapter on fume, radiation and electrical safety.
Light and the people nearby
Arc light reaches everyone who can see the arc. The welding bay screens (Chapter 2) protect people elsewhere in the shop, and customers and visitors are kept out of the welding and grinding areas, as Dunham advised. When Sam and Mara both weld in the trailer bay, each warns the other before striking an arc, and both wear eye protection under their helmets for grinding and chipping.
Working alone
A two-person shop has times when one person works alone: early mornings, late finishes, a site job where the other is in the shop. Working alone with heat, heavy steel and electricity raises the stakes of any injury, because nobody is there to help. Mara’s arrangements are a regular check-in by phone when either works alone, a rule that the riskiest tasks, such as lifting heavy chassis with the hoist, work in confined spaces or at height, and hot work on site, are not done alone, and a personal alarm device for site work in places with poor mobile coverage. The arrangements cost little and are written into the risk assessment.
Manual handling
Steel is heavy, and lifting it by hand is the most common cause of injury in many fabrication shops, through strains to backs and shoulders and crushed fingers. The lifting beam and hoist over the trailer bay (Chapter 2), the shared forklift, roller stands on the saw line, trestles at working height and clamps that hold work while it is tacked all reduce the lifting. Mara’s rule is that anything heavier than one person can lift comfortably is lifted with the hoist or forklift or by two people, and that steel is stored on the rack at heights that do not require lifting above the shoulder.
Noise
Grinding, cutting, chipping and hammering are loud, and long exposure damages hearing permanently. Hearing protection is worn for grinding and cutting, and the risk assessment considers whether noise levels in the shop need measuring. Choosing quieter tools where there is a choice, such as a cold saw rather than an abrasive cut-off saw, reduces noise at the source.
First aid
The most common injuries in a welding shop are burns, eye injuries from grinding particles and arc flash, cuts from sharp steel, and strains from lifting. A shop’s first aid arrangements must suit those hazards and the number of people. Mara’s shop has a first aid kit stocked for burns and eye injuries, an eyewash station near the grinding and welding areas, burn gel and cool running water close at hand, and both Mara and Sam hold current first aid training. The shop is two people, so if one is injured the other must be able to act; the site ute carries its own first aid kit and a means of calling for help where mobile coverage is poor.
Emergencies
An emergency plan for a small shop is short but must exist: how to raise the alarm, how to get out, where to meet, how to shut off the gas at the cylinder store and the power at the switchboard, what to tell the fire brigade about the cylinders and their location, and who to call. Mara posted it beside the door and the cylinder store, gave a copy to the neighbouring units, and walked through it with Sam on the first day. Because the shop stores oxygen and acetylene, the fire brigade needs to know where the cylinders are before they arrive, and the plan says so in its first lines.
Risk assessment
Underneath these arrangements is a risk assessment: a list of the hazards, who could be harmed, the controls, and what more is needed. For a small shop, it can be a few pages, reviewed when the work, equipment or people change and after any incident. Mara wrote hers before opening, using the code of practice as a guide, and reviewed it after the first month and after each near miss. Its main value was that it made her think through each hazard before the shop opened, rather than after something went wrong. It also gave Sam a written record of the controls and the reasons for them on his first day, and it is the first document an inspector or insurer asks to see.
Housekeeping
Housekeeping sounds trivial and is not. Steel offcuts on the floor cause trips and cuts; cardboard packaging from consumables is fuel; oily rags can heat and ignite; grinding dust coats everything and burns. Mara and Sam spend the last fifteen minutes of each day cleaning the floor, emptying the bins into a metal bin outside, and putting tools and leads away, which is also when the end-of-day fire check happens. The time is unbillable, and it is in the utilisation figure in Chapter 1. A clean floor at the end of the day is also the best defence against the fire that starts after everyone has gone home, which is the fire that does the most damage because nobody is there to put it out.
The cost of safety
This is an illustration. Mara’s safety set-up cost about A$3,300, excluding GST, for screens, extinguishers, fire blankets, first aid kits and eyewash, PPE for two people and signage, which is in the equipment list in Chapter 6, plus about A$400 a year for first aid training and about A$600 a year for extinguisher servicing, PPE replacement and consumables. Against the cost of a single fire, a serious burn or an eye injury, and the insurance excess and higher premiums that follow one, it is small.
A failure: the cardboard behind the bench
This is an illustration. In the second month, Sam was grinding a weld on a bracket at the bench when Mara smelled smoke. A carton of wire spools, delivered that morning and left on the floor behind the bench, had caught a stream of grinding sparks that bounced off the wall, and was smouldering at one corner. Mara put it out with the extinguisher beside the bench, and nothing else was damaged.
The carton should have been unpacked and taken outside on delivery. The fix was a rule: deliveries are unpacked straight away, packaging goes to the outside bin the same day, and nothing is stored behind or under the grinding bench. The bench also gained a sheet-steel splash panel behind it, so that sparks hitting the wall fall straight down onto the concrete.
Exercise: a cut on a platform
Sam has to cut a bracket off a steel platform 3 m above the floor of a customer’s shed, with slag leaving the cut at about 8 m/s. Using the formula in this chapter, estimate how far the slag could travel before first landing, and say what the hot work check should cover.
The fall time from 3 m is about √(2 × 3 ÷ 9.81) ≈ 0.78 s, so the slag could travel about 8 × 0.78 ≈ 6.3 m before first landing, and further by bouncing and rolling. The hot work check should clear or cover combustibles for at least that distance below and around the platform, including hay, fuel and timber, check for gaps in the floor below, place an extinguisher and a fire watch at floor level, and keep the watch for a period after the cut is finished, because smouldering material may not show flame for some time.
